- Inherits from:
- NSResponder : NSObject
- Conforms to:
- NSCoding
- (NSResponder)
- NSObject (NSObject)
Declared in:
- AppKit/NSView.h
NSView is an abstract class that defines the basic drawing, event-handling, and printing architecture of an application. You typically don't interact with NSView API directly; rather, your custom view classes inherit from NSView and override many of its methods, which are invoked automatically by the Application Kit. If you're not creating a custom view class, there are few methods you need to use.
- frame | Returns the NSView's location and size. |
- bounds | Returns the NSView's internal origin and size. |
- setNeedsDisplay: | Marks the NSView as needing to be redrawn. |
- window | Returns the NSWindow that contains the NSView. |
- drawRect: | Draws the NSView. (All subclasses must implement this method, but it's rarely invoked explicitly.) |
NSView is an abstract class that provides concrete subclasses with a structure for drawing, printing, and handling events. NSViews are arranged within an NSWindow, in a nested hierarchy of subviews. A view object claims a rectangular region of its enclosing superview, is responsible for all drawing within that region, and is eligible to receive mouse events occurring in it as well. In addition to these major responsibilities, NSView handles dragging of icons and works with the NSScrollView class to support efficient scrolling. The following sections explore these areas and more.
Most of the functionality of NSView is either automatically invoked by the Application Kit, or is available in Interface Builder. Unless you're implementing a concrete subclass of NSView or working intimately with the content of the view hierarchy at run time, you don't need to know much about this class's interface. See "Commonly Used Methods" above for methods you might use regardless.
To be displayed, an NSView must be placed in an NSWindow. All view objects within an NSWindow are arranged in a hierarchy that begins at the NSWindow's content view, with each NSView having a single superview and zero or more subviews (see the NSWindow class specification for more on the content view). An NSView's superview and all the NSViews above the superview are sometimes referred to as the NSView's ancestors. An NSView's subviews and all of their subviews on down are known as the NSView's descendants. Each NSView in the view hierarchy has its own area to draw in and its own coordinate system, expressed as a transformation of its superview's coordinate system. An NSView can scale, translate, or rotate its coordinates dynamically, and a subclass can declare its y axis flipped to allow drawing from top to bottom-useful for drawing text, for example.
Graphically, an NSView can be regarded as a framed canvas. The frame locates the NSView in its superview, defines its size, and clips drawing to its edges, while the canvas defines the NSView's own internal coordinate system and hosts the actual drawing. The frame can be moved around, resized, and rotated in the superview, so that the NSView's image moves with it. Similarly, the canvas can be shifted, stretched, and rotated, so that the drawn image moves within the frame. The frame maps onto a region of the canvas that defines the bounds of what can possibly be seen. An NSView therefore keeps track of its space using two rectangles, one for each perspective: The frame rectangle gives the exterior perspective and the bounds rectangle give the interior. The frame and bounds methods, respectively, return these rectangles. This figure shows the relation between the frame rectangle, on the left, and the bounds rectangle over the canvas, on the right:
Although the bounds rectangle indicates the portion of the NSView that is potentially visible through the frame, if the frame runs outside of the superview the image will be clipped even within the bounds rectangle. An NSView's visible rectangle reflects the portion of an NSView that actually displays, in terms of its own coordinate system (the darker gray rectangle in the figure below). It isn't often important to know what the visible rectangle is, since the display mechanism automatically limits drawing to visible portions of a view. If a subclass must perform expensive precalculation to build its image, though, it can use the visibleRect method to limit its work to what's actually needed.
The initWithFrame: method establishes an NSView's frame rectangle, but doesn't insert it into an NSWindow's view hierarchy. This is the job of the addSubview: method, which you send to the NSView that you want to contain the newly initialized one. The frame rectangle is then interpreted in terms of the superview, properly locating the new NSView both by its place in the view hierarchy and its location in the superview's NSWindow.
After initialization, you can move an NSView programmatically using any of the frame-setting methods: setFrame:, setFrameOrigin:, setFrameSize:, and setFrameRotation:. When you move an NSView all of its subviews move along with it. When you change the frame rectangle's size, the bounds rectangle is automatically resized to match (see figure below), and the subviews are automatically resized as described in "Moving and Resizing NSViews" below. setFrameRotation: rotates the NSView around the origin of the frame rectangle (which is typically the lower left corner).
A number of methods access the view hierarchy itself. superview returns the receiver's containing NSView, while subviews returns an NSArray containing its immediate descendant NSViews. The window method returns the NSWindow whose view hierarchy the receiver belongs to. You can add NSViews to and remove them from the view hierarchy using the methods addSubview:, removeFromSuperview, and replaceSubview:with:. An additional method, addSubview:positioned:relativeTo:, allows you to specify the ordering of NSViews that may overlap (though laying out NSViews so that they overlap isn't recommended).
When you add a subview with addSubview:, the receiver retains the view. When you remove a subview from a view hierarchy with removeFromSuperview, or replace it with replaceSubview:with:, the view is released. If you want to keep using a view after removing it from a view hierarchy (if, for example, you are swapping through a number of views), you must retain it before removing or replacing it.
When an NSView is added as a subview of another view, it automatically invokes the viewWillMoveToSuperview: and viewWillMoveToWindow: methods. Concrete subclasses can override these methods, allowing an instance to query its new superview or NSWindow about relevant state and update itself accordingly. A few other methods allow you to inspect relationships among NSViews: isDescendantOf: confirms the containment of the receiver, ancestorSharedWithView: finds the common container of two NSViews, and opaqueAncestor returns the closest containing NSView that's guaranteed to draw every pixel in the receiver's frame (possible the receiver itself).
At various times, particularly when handling events, you need to convert a rectangle or point from the coordinate system of one NSView to another (typically a superview or subview). NSView defines six methods that convert rectangles, points, and sizes in either direction:
- convertPoint:fromView: | - convertPoint:toView: |
- convertSize:fromView: | - convertSize:toView: |
- convertRect:fromView: | - convertRect:toView: |
These methods convert geometric structures between the receiver's coordinate system and another NSView's within the same NSWindow, returning an alternate expression for the same on-screen location or area. Note that the structure in question needn't actually be located within the NSView's bounds rectangle; it's merely assumed to be expressed in that NSView's coordinate system. If the second argument to a conversion method is nil, the conversion is made between the receiver's coordinate system and the base coordinate system of its NSWindow.
For converting to and from the screen coordinate system, NSWindow defines the convertBaseToScreen: and convertScreenToBase: methods. Using the NSView conversion methods along with these allows you to convert a geometric structure between an NSView's coordinate system and the screen's with only two messages.
Conversion is straightforward when neither NSView is rotated, or when dealing only with points. When converting rectangles or sizes between NSViews with different rotations, the geometric structure must be altered in a reasonable way. In converting a rectangle NSView makes the assumption that you want to guarantee coverage of the original screen area. To this end, the converted rectangle is enlarged so that when located in the appropriate NSView it completely covers the original rectangle (the left side of the figure below, with 15 degrees of rotation). In converting a size NSView simply treats it as a vector from (0.0, 0.0) and maps it onto the destination coordinate system. Though the length remains the same, the balance along the two axes shifts according to the rotation (the right side of the figure below, rotated 45 degrees).
Drawing in an NSView is as simple as implementing the drawRect: method to generate the appropriate code for the image you want displayed-the display mechanism handles the rest of the work. On the other hand, it can be as complex as dealing with the graphics generation language itself, the coordinate transformations from superview to subview, and the operation of the display mechanism. This section and "The Display Mechanism" progress from the basic to the esoteric, keeping the picture correct, if incomplete, at each stage.
In order for a concrete subclass of NSView to display any kind of image, it must implement the drawRect: method. This method is invoked during the display process to generate code that's rendered by the Window Server into a raster image. drawRect: takes a single argument, an NSRect describing the area that needs to be drawn in the receiver's own coordinate system.
Except for the background, this implementation of drawRect: ignores the rectangle provided, drawing everything each time it's invoked. This isn't a problem for a simple image, but for complex drawing it can be an extremely inefficient practice. Sending drawing instructions and data to the Window Server has a cost, and it's best to minimize that cost where possible. You can do this by testing whether a particular graphic shape intersects the rectangle being drawn, using NSIntersectsRect() and similar functions.
As indicated in the example above, drawing can be performed by invoking client library functions (also known as single-operator functions), which map directly to rendering operators. The Application Kit provides a few higher-level mechanisms for handing instructions to the Window Server. Wrapping complex drawing procedures minimizes the overhead of communication with the Window Server by passing a group of instructions in one interprocess message, as opposed to a number of such messages for repeated single-operator calls.
The second higher-level mechanism is provided by Application Kit classes that perform drawing within an NSView, such as NSImage and the various NSCell subclasses. These classes send instructions to the Window Server but don't have the overhead of maintaining a drawing context that NSView has. Objects that draw themselves are useful for encapsulating graphic elements that need to be drawn over and over, at different locations, or in slightly different ways. See the appropriate class specifications for more information on drawing with them.
Another way of drawing within an NSView is to add subviews that each do their own drawing. This is somewhat more heavyweight than using NSCells or NSImages, but the elements of such a constructed group have the full power of the NSView machinery at their disposal, including the autosizing of components and event handling, features described later in this class description.
Most of an NSView's displayed image is a stable representation of its state. View objects also interact dynamically with the user, however, and this interaction often involves drawing that isn't integral to the image itself-selections and other highlighting, for example. Such drawing should be performed only to the computer screen, and never to a printer or fax device, or to the pasteboard (as when drawing an EPS image).
By default, an NSView's coordinate system is based at (0.0, 0.0) in the lower-left corner of its bounds rectangle, its units are the same size as those of its superview, and its axes are parallel to those of its frame rectangle. To change this coordinate system you can alter the NSView's bounds rectangle, thereby placing the canvas inside the frame rectangle, or transform it directly using operators in the drawRect: method. Changing the bounds rectangle sets up the basic coordinate system, with which all drawing performed by the NSView begins; concrete subclasses of NSView typically alter the bounds rectangle immediately as needed in their initWithFrame: methods (or other designated initializers). Direct transformations are useful for temporary effects, such as scaling one axis to draw an oval instead of a circle, then scaling it back before stroking the path to preserve line widths; rotating the axes to draw text at an angle; or repeatedly translating the origin to draw the same figure in several locations.
The basic method for changing the bounds rectangle is setBounds:, which both positions and stretches the canvas. The origin of the rectangle provided to setBounds: becomes the lower-left corner of the bounds rectangle, and the size of the rectangle is made to fit in the frame rectangle, effectively scaling the NSView's drawn image. In the figure below, the bounds rectangle from the previous example is moved and doubled in size; the result appears on the right:
You can also set the parts of the bounds rectangle independently, using setBoundsOrigin: and setBoundsSize:. An additional method, setBoundsRotation:, rotates the coordinate system around its origin within the bounds rectangle (not the origin of the bounds rectangle itself). It also enlarges the visible rectangle to account for the rotation, so that it's expressed in the rotated coordinates yet completely covers the visible portion of the frame rectangle. This adds regions that must be drawn, yet will never be displayed (the triangular areas in the figure below). For this reason, rotating the bounds rectangle is strongly discouraged. It's better to rotate the coordinate system by using operators in the drawRect: method rather than by rotating the bounds rectangle.
setBoundsOrigin:, setBoundsSize:, and setBoundsRotation: all express their transformations in absolute terms. Another set of methods transform the coordinate system in relative terms; if you invoke them repeatedly, their effects accumulate. These methods are translateOriginToPoint:, scaleUnitSquareToSize:, and rotateByAngle:. See the individual method descriptions for more information.
One final type of coordinate transformation is statically established by overriding the
isFlipped
method. NSView's implementation returns
NO
, which means that the origin of the coordinate system lies at the lower-left corner of the default bounds rectangle and the y axis runs from bottom to top. When a subclass overrides this method to return
YES
, the NSView machinery automatically adjusts itself to assume that the upper-left corner of the NSView holds the origin. In other words, when
isFlipped
returns
YES
the y axis runs from top to bottom. A flipped coordinate system affects all drawing in the NSView itself and reckons the frame rectangles of all immediate subviews from their upper-left corners, but it doesn't affect the coordinate systems of those subviews or the drawing performed by them.
A flipped coordinate system doesn't affect an NSView's subviews, but the other coordinate transformations do. Translation of the bounds rectangle from the coordinate system origin shifts all subviews along with the rest of the NSView's image. Scaling and rotation actually affect the drawing of the subviews, as their coordinate systems inherit and build on these alterations. You can determine whether an NSView's coordinate system is (or was ever) altered from the base coordinate system of its window using two methods.
isRotatedFromBase
returns
YES
if the receiver or any of its ancestors in the view hierarchy has ever been rotated, whether of the frame or of the bounds rectangle.
isRotatedOrScaledFromBase
similarly returns
YES
if the receiver or any of its ancestors has ever been rotated or been scaled from the base coordinate system's unit size. You can determine whether the NSView has never been rotated by checking that
isRotatedOrScaledFromBase
returns
YES
while
isRotatedFromBase
returns
NO
. Note that these methods only offer hints about the coordinate system. Their purpose is to help optimize certain operations, not to reflect the present state: Once an NSView is marked as having been rotated or scaled, it remains so marked for its lifetime.
To get the actual amount of rotation, use the frameRotation and boundsRotation methods. These return the rotation relative to the superview only, not to the base coordinate system, so if you want the latter amount you have to progress up through each superview to the NSWindow's content view, accumulating the rotation as you go. To get the scaling relative to the superview you can use convertSize:toView: and examine the ratio of the original size to that of the superview. To get the scaling relative to the base coordinate system, use nil as the second argument. This causes convertSize:toView: to convert to the NSWindow's base coordinate system.
Displaying an NSView centers around the drawRect: method, which transmits drawing instructions to the Window Server. Before this can happen, however, a number of other things must be established. First, of course, is the rectangle in the view that needs to be drawn. Once this is known, the view must be checked for opacity; if the view is partially transparent, its nearest opaque ancestor must be found and drawing must commence from there. Once all of this is determined and a particular view is to be drawn, the Window Server must know which window device the view is in, how to clip drawing to the appropriate region, and what coordinate system to use. This is all handled outside drawRect:, by NSView's various display methods. The following sections examine each of these points in turn.
The most common way of causing an NSView to redisplay is to tell it that its image is invalid. On each pass through the event loop, all views that need to redisplay do so. NSView defines two methods for marking a view's image as invalid; setNeedsDisplay:, which invalidates the view's entire bounds rectangle, and setNeedsDisplayInRect:, which invalidates a portion of the view. The automatic display of views is controlled by their window; you can turn this behavior off using NSWindow's setAutodisplay: method. You should rarely need to do this however; the autodisplay mechanism is well-suited to most kinds of update and redisplay.
The autodisplay mechanism invokes various methods that actually do the work of displaying. You can also use these methods to force a view to redisplay itself immediately when necessary. display and displayRect: are the counterparts to the methods mentioned above; both cause the receiver to redisplay itself regardless of whether it needs to or not. Two additional methods, displayIfNeeded and displayIfNeededInRect:, redisplay invalidated rectangles in the receiver if it's been marked invalid with the methods above. The rectangles that actually get drawn are guaranteed to be at least those marked as invalid, but the view may coalesce them into larger rectangles to save multiple invocations of drawRect:.
NSViews don't necessarily cover every bit of their frames with drawing. Because of this, the display methods must be sure to find an opaque background behind the view that's ostensibly being drawn, and begin displaying from there forward. The display methods above all pull back up the view hierarchy to the first view that responds
YES
to an
isOpaque
message, bringing the invalidated rectangles along. NSView by default responds
NO
to
isOpaque, so it's important to remember to override this method to return
YES
if appropriate when defining a subclass. Most Application Kit subclasses of NSView actually do this.
If you want to exclude background views from drawing when forcing display to occur unconditionally, you can use NSView methods that explicitly omit backing up to an opaque ancestor. These methods, parallel to those mentioned above, are displayRectIgnoringOpacity:, displayIfNeededIgnoringOpacity, and displayIfNeededInRectIgnoringOpacity:.
Before a display... method invokes drawRect:, it sets the Window Server up with information about the view, including the window device it draws in, the coordinate system and clipping path it uses, and other graphics state information. The method used to do this is lockFocus, and it has a companion method that undoes its effects, called unlockFocus.
All drawing code invoked by an NSView must be bracketed by invocations of these methods to produce proper results. If you define some methods that need to draw in a view without going through the display methods above, for example, you must send lockFocus to the view that you're drawing in before sending commands to the Window Server, and unlockFocus as soon as you are done.
It's perfectly reasonable to lock the focus on one view when another already has it. In fact, this is exactly what happens when subviews are drawn in their superview. The focusing machinery keeps a stack of which views have been focused, so that when one view is sent an unlockFocus message, the focus is restored to the view that was focused immediately before.
Repositioning an NSView is a potentially complex operation. Moving or resizing can expose portions of the NSView's superview that weren't previously visible, requiring the superview to redisplay. Resizing can also affect the layout of an NSView's subviews. Changes to an NSView's layout in any case may be of interest to other objects, which might need to be notified of the change. The following sections explore each of these areas.
None of the methods that alter an NSView's frame rectangle redisplays the NSView or marks it as needing display. When using the
setFrame...
methods, then, you must mark both the view being repositioned and its superview as needing display. This can be as simple as marking the superview in its entirety as needing display, or better, marking the superview in the old frame of the repositioned view and the view itself in its entirety. This code fragment sets
theView
's frame rectangle, and updates its superview appropriately:
NSView *theView; /* Assume this exists. */ NSRect newFrame; /* Assume this exists. */ [[theView superview] setNeedsDisplayInRect:[theView frame]]; [theView setFrame:newFrame]; [theView setNeedsDisplay:YES];
This sample marks the superview as needing display in the frame of the view about to be moved. Then, after
theView
is repositioned, it's marked as needing display in its entirety, which will nearly always be the case. The
setBounds...
methods also don't redisplay the NSView, but because their changes don't affect superviews you can simply mark the repositioned NSView as needing display.
The NSView class provides a mechanism to notify interested objects when a view object's frame rectangle is changed or its bounds rectangle is changed. The setFrame... methods post an NSViewFrameDidChangeNotification to the default notification center, unless the setPostsFrameChangedNotifications: method has been used to turn notification off. The setBounds... methods post an NSViewBoundsDidChangeNotification to the default notification center, unless the setPostsBoundsChangedNotifications: method has been used to turn notification off. Your application can use these notifications to perform special handling when a view object is moved or resized.
When an NSView's frame size changes, the layout of its subviews must often be adjusted to fit in the new size. NSView defines a mechanism that automates this process, allowing you to specify how any NSView should reposition itself when its superview is resized. Interface Builder allows you to set these attributes graphically with its Size Inspector, and in test mode you can examine the effects of autoresizing. You can also set autoresizing attributes programmatically using setAutoresizingMask: with a mask containing any of the constants illustrated below, combined using the bitwise OR operator:
When one of these mask flags is omitted, the NSView's layout is fixed in that aspect; when it's included the NSView's layout is flexible in that aspect. For example, to keep an NSView in the lower left corner of its superview, you specify
NSViewMaxXMargin
|
NSViewMaxYMargin
. When more than one aspect along an axis is made flexible, the resize amount is distributed evenly among them.
Autoresizing is on by default, but you can turn it off using the setAutoresizesSubviews: method. Note that when you turn off an NSView's autoresizing, all of its descendants are likewise shielded from changes in the superview. Changes to subviews, however, can still percolate downward. Similarly, if a subview has no autoresize mask, it won't change in size, and therefore none of its subview will autoresize.
Autoresizing is accomplished using two methods. resizeSubviewsWithOldSize: is invoked automatically by an NSView whenever its frame size changes. This method then simply sends a resizeWithOldSuperviewSize: message to each subview. Each subview compares the old frame size to the new size and adjusts its position and size according to its autoresize mask. Subclasses of NSView can override either method to alter their autoresizing behavior.
Two cautions apply to autoresizing. First, it doesn't work at all in NSViews that have been rotated. Subviews that have been rotated can autoresize within a nonaltered superview, but then their descendants aren't autoresized. Also, for autoresizing to work correctly, the subview being autoresized must lie completely within its superview's frame. Apart from these limitations, autoresizing covers most layout changes quite well.
Beyond resizing its subviews, an NSView broadcasts notifications to interested observers any time its bounds and frame rectangles change. The notification names are NSViewFrameDidChangeNotification and NSBoundsDidChangeNotification, respectively. An NSView that bases its own display on the layout of its subviews, for example, can register itself as an observer for those subviews and update itself any time they're moved or resized. NSScrollView and NSClipView cooperate in this manner to adjust the NSScrollView's NSScrollers. You can turn notifications on and off using setPostsFrameChangedNotifications: and setPostsBoundsChangedNotifications:.
NSViews are the most typical receivers of event and action messages, as described in the NSResponder and NSEvent class specifications. An NSView subclass can handle any event or action message simply by implementing it (being sure to invoke
super
's implementation as needed). Then, if an instance of that class is the first in the responder chain to respond to that message, it receives such messages as they're generated.
Except for an NSWindow's content view, an NSView's next responder is always its superview-most of the responder chain, in fact, comprises the NSViews from an NSWindow's first responder up to its content view. NSView addSubview: method automatically sets the receiver as the new subview's superview; you should never send setNextResponder: to an NSView object. You can safely add responders to the top end of an NSWindow's responder chain-the NSWindow itself if it has no delegate, or the delegate if it does.
As the class that handles display, NSView is the typical recipient of mouse and keyboard events. Mouse clicks, drags, and movements usually occur in some NSView or other, and most keystrokes represent text to be added for display at some point in a window. A mouse event starts at the lowest NSView containing it in the view hierarchy (or, the topmost NSView displayed under the cursor), and proceeds up the responder chain through superviews until some object handles it. "Mouse Events" below covers the details of handling mouse events. Most keyboard events start at the first responder, whatever it might be, and are similarly offered up the responder chain. Some actually change the first responder, thus allowing the user to perform many actions without using the mouse. See the NSResponder class specification for information on keyboard events. Tracking-rectangle events are monitored by the NSWindow and dispatched directly to the object that owns the tracking rectangle. "Tracking Rectangles and Cursor Rectangles" describes how to set up and handle these. An additional section covers the use of context-sensitive pop-up menus by your views.
An NSView can receive mouse events of three general types: clicks, drags, and movements. A custom subclass of NSView can interpret a mouse event as a cue to perform a certain action, such as sending a target-action message, selecting a graphic element, and so on. NSViews automatically receive mouse-clicked and mouse-dragged events, but because mouse-moved events occur so often and can bog down the event queue, an NSView must explicitly request its NSWindow to watch for them using NSWindow's setAcceptsMouseMovedEvents: method. Tracking rectangles, described below, are a less expensive way of following the mouse's location.
The NSView selected to receive a mouse event is determined by the NSWindow using NSView's hitTest: method, which returns the lowest descendant that contains the cursor location of the event (this is also the topmost NSView displayed). Once the recipient is determined, the NSWindow sends it a mouseDown: message, which includes an NSEvent object containing information about the click. NSEvent's locationInWindow locates the cursor's hot spot in the coordinate system of the receiver's NSWindow. To convert it to the NSView's coordinate system, use convertPoint:fromView: with a nil NSView argument. From here, you can use mouse:inRect: to determine whether the click occurred in an interesting area.
One of the earliest things to consider in handling mouse-down events is whether the receiving NSView should become the first responder, which means that it will be the first candidate for subsequent key events and action messages. NSViews that handle graphic elements that the user can select-drawing shapes or text, for example-should typically accept first responder status on a mouse-down event, by overriding the
acceptsFirstResponder
method to return
YES
. This results in the window making the receiving NSView first responder with NSWindow's
makeFirstResponder:
method. Some NSViews, however, may not wish to change the selection upon the first mouse click in a non-key window, which should normally only order the window to the front. NSView's
acceptsFirstMouse:
method controls whether an initial mouse click is sent to the NSView or not. By default it returns
NO
, which in most cases is appropriate behavior. Certain subclasses, such as controls that don't affect the selection, override this method to return
YES
.
Once an NSView has accepted a mouse event and determined its location, it can also check which mouse button was clicked and how many times. NSEvent's type method distinguishes between left and right mouse events, and the NSView can base its behavior on this information. Right mouse events are defined by the Application Kit to open pop-up menus, but you can override this behavior if necessary. NSEvent's clickCount method returns a number identifying the mouse event as a single-, double-, or triple-click (and so on).
NSViews that handle mouse clicks as a single event, from mouse down, through dragging, to mouse up, must usually short-circuit the application's normal event loop, entering a modal event loop to catch and process only events of interest. For example, an NSButton highlights upon a mouse-down event, then follows the mouse location during dragging, highlighting when the mouse is inside and unhighlighting when the mouse is outside. If the mouse is inside on the mouse-up event, the NSButton sends its action message. This method template shows one possible kind of modal event loop:
- (void)mouseDown:(NSEvent *)theEvent { BOOL keepOn = YES; BOOL isInside = YES; NSPoint mouseLoc; do { mouseLoc = [self convertPoint:[theEvent mouseLocationInWindow] fromView:nil]; isInside = [self mouse:mouseLoc inRect:[self bounds]]; switch ([theEvent type]) { case NSLeftMouseDragged: [self highlight:isInside]; break; case NSLeftMouseUp: if (isInside) [self doSomethingSignificant]; [self highlight:NO]; keepOn = NO; break; default: /* Ignore any other kind of event. */ break; } theEvent = [[self window] nextEventMatchingMask: NSLeftMouseUpMask | NSLeftMouseDraggedMask]; }while (keepOn); return; }
This loop converts the mouse location and checks whether it's inside the receiver. It highlights itself using the fictional highlight: method according to this, and on a mouse up inside, invokes doSomethingSignificant to perform an important action. Instead of merely highlighting, a custom NSView might move a selected object, draw a graphic image according to the mouse's location, and so on.
This kind of modal event loop is driven only as long as the user actually moves the mouse. It won't work, for example, to cause continual scrolling if the user presses the mouse button but never moves the mouse itself. For this, your modal loop should start a periodic event stream using NSEvent's class method
startPeriodicEventsAfterDelay:withPeriod:, and add
NSPeriodicMask
to the mask passed to
nextEventMatchingMask:. In the
switch()
statement the NSView can then check for a case of NSPeriodic and take whatever action it needs to; scrolling a document view or moving a step in an animation, for example. If you need to check the mouse location during a periodic event, you can use NSWindow's
mouseLocationOutsideOfEventStream
method.
One special type of event is that for tracking mouse movement into and out of a region in the NSView. Such a region is known as a tracking rectangle; it triggers mouse-entered events when the cursor enters it and mouse-exited events when the cursor leaves it. This can be useful for displaying context-sensitive messages or highlighting graphic elements under the cursor, for example. An NSView can have any number of tracking rectangles, which can overlap or be nested one within the other; the NSEvent objects generated for tracking events include a tag that identifies the rectangle that triggered the event.
To create a tracking rectangle, use the addTrackingRect:owner:userData:assumeInside: method. This method registers an owner for the tracking rectangle provided, so that the owner receives the event messages. This is typically the NSView itself, but need not be. The method returns the tracking rectangle's tag so that you can store it for later reference in the event handling methods, mouseEntered: and mouseExited:. To remove a tracking rectangle, use the removeTrackingRect: method, which takes as an argument the tag of the tracking rectangle to remove.
Tracking rectangles, though created and used by NSViews, are actually maintained by NSWindows. Because of this, a tracking rectangle is a static entity; it doesn't move or change its size when the NSView does. If you use tracking rectangles, you should be sure to remove and reestablish them any time you change the frame rectangle of the NSView that contains them. If you're using a custom subclass of NSView, you can override the frame- and bounds-setting methods to do this. You can also register an observer for the NSViewFrameDidChangeNotification (described below), and have it reestablish the tracking rectangles on receiving the notification.
One common use of tracking rectangles is to change the cursor image over different types of graphic elements. Text, for example, typically requires an I-beam cursor. Changing the cursor is such a common operation that NSView defines several convenience methods to ease the process. A tracking rectangle generated by these methods is called a cursor rectangle. The Application Kit itself assumes ownership of cursor rectangles, so that when the user moves the mouse over the rectangle the cursor automatically changes to the appropriate image. Unlike general tracking rectangles, cursor rectangles may not partially overlap. They may, however, be completely nested, one within the other.
Because cursor rectangles need to be reset often as the NSView's size and graphic elements change, NSView defines a single method, resetCursorRects, that's invoked any time its cursor rectangles need to be reestablished. A concrete subclass overrides this method, invoking addCursorRect:cursor: for each cursor rectangle it wishes to set. Thereafter, the NSView's cursor rectangles can be rebuilt by invoking NSWindow's invalidateCursorRectsForView: method. If you find you need to temporarily remove a single cursor rectangle, you can do this with removeCursorRect:cursor:. Be aware that resetCursorRects will reestablish that rectangle, unless you implement it to do otherwise.
An NSView's cursor rectangles are automatically reset whenever:
You can temporarily disable all the cursor rectangles in a window using NSWindow's discardCursorRects method or enable them with the enableCursorRects method. NSWindow's areCursorRectsEnabled method tells you whether they're currently enabled.
setMenu: assigns an NSMenu to a view, and menu returns it. Your subclass can define a menu that's used for all instances by implementing the defaultMenu class method. It can also change the menu displayed based on the mouse event by overriding the menuForEvent: instance method. This allows the view clicked to display different menus based on the location of the mouse and of the view's state, or to change or enable individual menu items based on the commands available for the view or for that region of the view. See the NSMenu and NSMenuItem class and protocol specifications for more information on using menus.
A tooltip is a bit of text that provides information about a view. If the user holds the cursor over the view for more than the default delay, the tooltip text is displayed in a small framed rectangle next to the cursor. By default, a view does not display a tooltip. To turn on tooltip display for a view, you invoke the setToolTip: method to install tooltip text for the view. To turn display off, you invoke setToolTip: with an empty string.
Printing an NSView uses the same description as for displaying on the screen, by simply changing the device. An NSView can check whether it's drawing to the screen in order to conditionally include or omit elements such as highlighting, but normally doesn't need to be involved with the generation process in a special way for printing. It may, however, need to take part in peripheral issues, including how it's divided into pages and placed on them, and generation of document structuring comments used by some document programs. The sections below cover these areas.
To print an NSView, send it a print: message. You can also generate an EPS representation using either dataWithEPSInsideRect: or writeEPSInsideRect:toPasteboard:. For any of these jobs, the NSView creates an NSPrintOperation object that manages the process of generating proper code for a printer device. NSPageLayout, NSPrintInfo, and NSPrintPanel objects are also involved in the process. See those classes' specifications for more information on the printing process itself.
When an NSView is printed onto pages smaller than itself, it tiles itself out onto separate logical pages so that its entire visible region is printed. A subclass of NSView can alter the way pagination is performed by overriding two small sets of methods. The first set affects automatic pagination; the second replaces automatic pagination completely. One extra method allows the NSView to adjust the location of the printed image on the page. Finally, after pagination has actually been performed, the NSView is given the chance to draw additional marks on the page.
NSView's automatic pagination tries to fit as much of the view being printed onto a logical page, slicing the view into the largest possible chunks. This is sufficient for many views, but if a view's image must be divided only at certain places-between lines of text or cells in a table, for example, the view can adjust the automatic mechanism to accommodate this by reducing the height or width of each page. It does so by overriding up to four methods. adjustPageHeightNew:top:bottom:limit: provides an out parameter for the new bottom coordinate of the page, followed by the proposed top and bottom. An additional parameter limits the height of the page; the bottom can't be moved above it. adjustPageWidthNew:left:right:limit: works in the same way to allow the view to adjust the width of a page. The limits are calculated as a percentage of the proposed page's height or width. Your view subclass can also customize this percentage by overriding the methods heightAdjustLimit and widthAdjustLimit to return the reducible fraction of the page.
More complex views, such as those that display separate pages over a background, need to direct their own pagination. An NSView subclass that needs to do so overrides the
knowsPageRange:
method to return
YES
, which signals that it will be calculating each page's dimensions, and returns by reference its first and last page numbers. The pagination machinery then uses these numbers, sending
rectForPage:
to the NSView, which uses the page number and the current printing information to calculate an appropriate rectangle in its coordinate system. The
adjustPage...
methods aren't used in this case.
The last stage of pagination involves placing the image to be printed on the logical page. NSView's
locationOfPrintRect:
places it according to the NSPrintInfo's status. By default it places the image in the upper left corner of the page, but if NSPrintInfo's
isHorizontallyCentered
or
isVerticallyCentered
methods return
YES
, it centers a single-page image along the appropriate axis. A multiple-page document, however, is always placed so that the divided pieces can be assembled at their edges.
After the NSView has sliced out a rectangle and positioned it on a page, it's given two chances to add extra marks to the page, such as crop marks or fold lines. drawPageBorderWithSize: is used for logical pages, and is invoked for each paginated portion of the view. drawSheetBorderWithSize: is used for actual physical pages, or sheets, on which one or more logical pages may be laid out. In a 2-up printing, for example, the former method is invoked twice for each sheet, while the latter is invoked once for each sheet.
While an NSView is printing, its connection to the Window Server is replaced by a connection to the print job output. Sometimes the NSView needs to communicate briefly with the Window Server while printing; for example, it may need to read some data stored only on the Window Server, or open an attention panel to alert the user of a problem. In these cases, it can temporarily swap in the NSApplication object's display context to restore access to the application's Window Server state and to the screen. When finished, the view object restores the print operation's context to continue generating its image.
Besides the fundamentals of drawing and event handling, NSView includes several auxiliary features. These are tagging NSViews for quick location, support for dragging of images and file icons, and cooperation with the scrolling machinery to facilitate viewing larger NSViews through smaller ones. The following sections introduce each of these features and name the methods and cooperating classes or protocols involved in each.
NSView defines methods that allow you to tag individual view objects with integer tags and to search the view hierarchy based on those tags. NSView's tag method always returns -1. You can override this in subclasses to return a special value, or even add a setTag: method to allow the tag to be changed at run time (several Application Kit classes, especially NSControl and NSCell, do just this). The viewWithTag: method proceeds through all of the receiver's descendants (including itself), searching for a subview with the given tag and returning it if it's found.
A view object can act as either the source or destination for dragged images and file icons. The basic dragging methods, dragImage:at:offset:event:pasteboard:source:slideBack: and dragFile:fromRect:slideBack:event: methods, handle the mechanics of moving the image on the screen and notifying the destination of the dragging operations. To act as a source for dragging operations, a concrete subclass of NSView can adopt the NSDraggingSource protocol, by which the source indicates what kinds of dragging operations are allowed and is notified of dragging operations as they begin. Both NSView and NSWindow subclasses can act as destinations for dragging operations, by adopting the NSDraggingDestination protocol and making use of the NSDraggingInfo protocol. For more information see the dragging protocol specifications and the descriptions of dragImage:at:offset:event:pasteboard:source:slideBack: and dragFile:fromRect:slideBack:event: in this specification.
NSView defines a number of methods to support scrolling, whereby the NSView being scrolled-the document view-is displayed partially through another-the content or clip view (not to be confused with a window's content view). Scrolling is effected by moving the clip view's bounds rectangle, which reveals the different regions of the document view. Most of the scrolling methods assume that the NSView is enclosed within an NSClipView and an NSScrollView, which handle the mechanics of scrolling for you. You can, however, reproduce the effects of scrolling yourself if you wish. See the NSScrollView, NSClipView, and NSScroller class specifications for information on how scrolling is implemented by the Application Kit.
NSView's most direct scrolling methods are scrollPoint: and scrollRectToVisible:, both of which assume that the receiver is embedded in an NSClipView. These methods move the clip view so that the requested point or rectangle in the receiver become visible. Another method, autoscroll:, automatically scrolls the receiver in an NSClipView based on the location of the mouse. It's useful for moving the document view when the user drags an icon outside of the visible area. The enclosingScrollView method returns the NSScrollView that contains the NSView, allowing you to tune the way scrolling occurs.
Two other methods aid in scrolling. A subclass of NSView can override adjustScroll: to change the way automatic (user-driven) scrolling occurs. It can quantize scrolling into regular units, to the edges of a spreadsheet's cells, for example, or simply limit scrolling to a specific region of the NSView. The last scrolling method, scrollRect:by:, copies an already-drawn portion of the NSView to a new location. It's useful for producing temporary effects, but note that any subsequent drawing will obliterate the copied portion.
- Creating instances
- - initWithFrame:
- Managing the view hierarchy
- - superview
- - subviews
- - window
- - addSubview:
- - addSubview:positioned:relativeTo:
- - didAddSubview:
- - removeFromSuperview
- - removeFromSuperviewWithoutNeedingDisplay
- - replaceSubview:with:
- - isDescendantOf:
- - opaqueAncestor
- - ancestorSharedWithView:
- - sortSubviewsUsingFunction:context:
- - viewWillMoveToSuperview:
- - viewWillMoveToWindow:
- - willRemoveSubview:
- Searching by tag
- - viewWithTag:
- - tag
- Modifying the frame rectangle
- - setFrame:
- - frame
- - setFrameOrigin:
- - setFrameSize:
- - setFrameRotation:
- - frameRotation
- Modifying the bounds rectangle
- - setBounds:
- - bounds
- - setBoundsOrigin:
- - setBoundsSize:
- - setBoundsRotation:
- - boundsRotation
- Modifying the coordinate system
- - translateOriginToPoint:
- - scaleUnitSquareToSize:
- - rotateByAngle:
- Examining coordinate system modifications
- - isFlipped
- - isRotatedFromBase
- - isRotatedOrScaledFromBase
- Converting coordinates
- - convertPoint:fromView:
- - convertPoint:toView:
- - convertSize:fromView:
- - convertSize:toView:
- - convertRect:fromView:
- - convertRect:toView:
- - centerScanRect:
- Controlling notifications
- - setPostsFrameChangedNotifications:
- - postsFrameChangedNotifications
- - setPostsBoundsChangedNotifications:
- - postsBoundsChangedNotifications
- Resizing subviews
- - resizeSubviewsWithOldSize:
- - resizeWithOldSuperviewSize:
- - setAutoresizesSubviews:
- - autoresizesSubviews
- - setAutoresizingMask:
- - autoresizingMask
- Focusing
- - lockFocus
- - lockFocusIfCanDraw
- - unlockFocus
- + focusView
- Displaying
- - setNeedsDisplay:
- - setNeedsDisplayInRect:
- - needsDisplay
- - display
- - displayRect:
- - displayRectIgnoringOpacity:
- - displayIfNeeded
- - displayIfNeededInRect:
- - displayIfNeededIgnoringOpacity
- - displayIfNeededInRectIgnoringOpacity:
- - isOpaque
- Drawing
- - drawRect:
- - visibleRect
- - canDraw
- - shouldDrawColor
- Managing a graphics state
- - allocateGState
- - gState
- - setUpGState
- - renewGState
- - releaseGState
- Event handling
- - acceptsFirstMouse:
- - hitTest:
- - mouse:inRect:
- - performKeyEquivalent:
- - performMnemonic:
- Dragging operations
- - dragImage:at:offset:event:pasteboard:source:slideBack:
- - dragFile:fromRect:slideBack:event:
- - registerForDraggedTypes:
- - unregisterDraggedTypes
- - shouldDelayWindowOrderingForEvent:
- Managing cursor rectangles
- - addCursorRect:cursor:
- - removeCursorRect:cursor:
- - discardCursorRects
- - resetCursorRects
- Managing tool tips
- - addToolTipRect:owner:userData:
- - removeAllToolTips
- - removeToolTip:
- - setToolTip:
- - toolTip
- Managing tracking rectangles
- - addTrackingRect:owner:userData:assumeInside:
- - removeTrackingRect:
- Scrolling
- - scrollPoint:
- - scrollRectToVisible:
- - autoscroll:
- - adjustScroll:
- - scrollRect:by:
- - enclosingScrollView
- - scrollClipView:toPoint:
- - reflectScrolledClipView:
- Context-sensitive menus
- - menuForEvent:
- + defaultMenu
- Managing the key view loop
- - setNextKeyView:
- - nextKeyView
- - nextValidKeyView
- - previousKeyView
- - previousValidKeyView
- Printing
- - print:
- - dataWithEPSInsideRect:
- - dataWithPDFInsideRect:
- - printJobTitle
- - writeEPSInsideRect:toPasteboard:
- - writePDFInsideRect:toPasteboard:
- Pagination
- - heightAdjustLimit
- - widthAdjustLimit
- - adjustPageWidthNew:left:right:limit:
- - adjustPageHeightNew:top:bottom:limit:
- - rectForPage:
- - locationOfPrintRect:
- Adorning pages in printout
- - drawPageBorderWithSize:
- - drawSheetBorderWithSize:
- Writing conforming rendering instructions
- - beginDocument
- - endDocument
- - endPage
+ (NSMenu *)defaultMenu
nil
.
See Also: - menuForEvent:, - menu (NSResponder)
+ (NSView *)focusView
nil
if there is none.
See Also: - lockFocus, - unlockFocus
- (BOOL)acceptsFirstMouse:(NSEvent *)theEvent
YES
if the receiver should be sent a
mouseDown:
message for
theEvent, an initial mouse-down event over the receiver in its window,
NO
if not. The receiver can either return a value unconditionally, or use
theEvent's location to determine whether or not it wants the event. NSView's implementation ignores
theEvent
and returns
NO
.
Override this method in a subclass to allow instances to respond to initial mouse-down events. For example, most view objects refuse an initial mouse-down event, so the event simply activates the window. Many control objects, however, such as NSButton and NSSlider, do accept them, so the user can immediately manipulate the control without having to release the mouse button.
See Also: - hitTest:
- (void)addCursorRect:(NSRect)aRect
cursor:(NSCursor *)aCursor
This method is intended to be invoked only by the resetCursorRects method. If invoked in any other way, the resulting cursor rectangle will be discarded the next time the NSView's cursor rectangles are rebuilt.
See Also: - removeCursorRect:cursor:, - discardCursorRects, - resetCursorRects, - visibleRect
- (void)addSubview:(NSView *)aView
The receiver retains aView. If you use removeFromSuperview to remove aView from the view hierarchy, aView is released. If you want to keep using aView after removing it from the view hierarchy (if, for example, you are swapping through a number of views), you must retain it before invoking removeFromSuperview.
See Also: - addSubview:positioned:relativeTo:, - subviews, - removeFromSuperview, - setNextResponder: (NSResponder), - viewWillMoveToSuperview:, - viewWillMoveToWindow:
- (void)addSubview:(NSView *)aView
positioned:(NSWindowOrderingMode)place
relativeTo:(NSView *)otherView
NSWindowAbove
or
NSWindowBelow
. If
otherView
is
nil
(or isn't a subview of the receiver),
aView
is added above or below all of its new siblings. Also sets the receiver as
aView's next responder.
The receiver retains aView. If you use removeFromSuperview to remove aView from the view hierarchy, aView is released. If you want to keep using aView after removing it from the view hierarchy (if, for example, you are swapping through a number of views), you must retain it before invoking removeFromSuperview.
See Also: - addSubview:, - subviews, - removeFromSuperview, - setNextResponder: (NSResponder)
- (NSToolTipTag)addToolTipRect:(NSRect)aRect
owner:(id)anObject
userData:(void *)data
- (NSTrackingRectTag)addTrackingRect:(NSRect)aRect
owner:(id)anObject
userData:(void *)userData
assumeInside:(BOOL)flag
YES
, the first event will be generated when the mouse leaves
aRect; if
flag
is
NO
the first event will be generated when the mouse enters it.
Tracking rectangles provide a general mechanism that can be used to trigger actions based on the mouse location (for example, a status bar or hint field that provides information on the item the cursor lies over). To simply change the cursor over a particular area, use addCursorRect:cursor:. If you must use tracking rectangles to change the cursor, the NSCursor class specification describes the additional methods that must be invoked to change cursors by using tracking rectangles.
See Also: - removeTrackingRect:, - userData (NSEvent)
- (void)adjustPageHeightNew:(float *)newBottom
top:(float)top
bottom:(float)proposedBottom
limit:(float)bottomLimit
NSView's implementation of this method propagates the message to its subviews, allowing nested views to adjust page height for their drawing as well. An NSButton or other small view, for example, will nudge the bottom edge up if necessary to prevent itself from being cut in two (thereby pushing it onto an adjacent page). Subclasses should invoke
super
's implementation, if desired, after first making their own adjustments.
See Also: - adjustPageWidthNew:left:right:limit:
- (void)adjustPageWidthNew:(float *)newRight
left:(float)left
right:(float)proposedRight
limit:(float)rightLimit
NSView's implementation of this method propagates the message to its subviews, allowing nested views to adjust page width for their drawing as well. An NSButton or other small view, for example, will nudge the bottom edge up if necessary to prevent itself from being cut in two (thereby pushing it onto an adjacent page). Subclasses should invoke
super
's implementation, if desired, after first making their own adjustments.
See Also: - adjustPageHeightNew:top:bottom:limit:
- (NSRect)adjustScroll:(NSRect)proposedVisibleRect
NSClipView only invokes this method during automatic or user-controlled scrolling. Its scrollToPoint: method doesn't invoke this method, so you can still force a scroll to an arbitrary point.
- (void)allocateGState
The receiver builds the graphics state parameters using setUpGState, then automatically establishes this graphics state each time the focus is locked on it. A graphics state may improve performance for view objects that are focused often and need to set many parameters, but use of standard rendering operators is normally efficient enough.
Because graphics states occupy a fair amount of memory, they can actually degrade performance. Be sure to test application performance with and without the private graphics state before committing to its use.
See Also: - setUpGState, - gState, - renewGState, - releaseGState, - lockFocus
- (NSView *)ancestorSharedWithView:(NSView *)aView
nil
if there's no such object. Returns
self
if
aView
is identical to the receiver.
See Also: - isDescendantOf:
- (BOOL)autoresizesSubviews
YES
if the receiver automatically resizes its subviews using
resizeSubviewsWithOldSize:
whenever its frame size changes,
NO
otherwise.
See Also: - setAutoresizesSubviews:
- (unsigned int)autoresizingMask
NSViewNotSizable
(that is, if none of the options are set), then the receiver doesn't resize at all in
resizeWithOldSuperviewSize:.
- (BOOL)autoscroll:(NSEvent *)theEvent
YES
if any scrolling is performed; otherwise returns
NO
.
View objects that track mouse-dragged events can use this method to scroll automatically when the mouse is dragged outside of the NSClipView. Repeated invocations of this method (with an appropriate delay) result in continual scrolling, even when the mouse doesn't move.
See Also: - autoscroll: (NSClipView), - scrollPoint:, - isDescendantOf:
- (void)beginDocument
- (NSRect)bounds
See Also: - frame, - setBounds:
- (float)boundsRotation
See Also: - rotateByAngle:, - setBoundsRotation:
- (BOOL)canDraw
YES
if drawing commands will produce any result,
NO
otherwise. Use this method when invoking a draw method directly along with
lockFocus
and
unlockFocus, bypassing the
display...
methods (which test drawing ability and perform locking for you). If this method returns
NO
, you shouldn't invoke
lockFocus
or perform any drawing.
An NSView can draw if it's attached to a view hierarchy in an NSWindow and the NSWindow has a corresponding window device, or during printing if the NSView is a descendant of the view being printed.
- (NSRect)centerScanRect:(NSRect)aRect
See Also: - isRotatedOrScaledFromBase
- (NSPoint)convertPoint:(NSPoint)aPoint
fromView:(NSView *)aView
nil
, this method instead converts from window base coordinates. Both
aView
and the receiver must belong to the same NSWindow. Returns the converted point.
See Also: - convertRect:fromView:, - convertSize:fromView:, - ancestorSharedWithView:, - contentView (NSWindow)
- (NSPoint)convertPoint:(NSPoint)aPoint
toView:(NSView *)aView
nil
, this method instead converts to window base coordinates. Both
aView
and the receiver must belong to the same NSWindow. Returns the converted point.
See Also: - convertRect:toView:, - convertSize:toView:, - ancestorSharedWithView:, - contentView (NSWindow)
- (NSRect)convertRect:(NSRect)aRect
fromView:(NSView *)aView
nil
, this method instead converts from window base coordinates. Both
aView
and the receiver must belong to the same NSWindow. Returns the converted rectangle.
See Also: - convertPoint:fromView:, - convertSize:fromView:, - ancestorSharedWithView:, - contentView (NSWindow)
- (NSRect)convertRect:(NSRect)aRect
toView:(NSView *)aView
nil
, this method instead converts to window base coordinates. Both
aView
and the receiver must belong to the same NSWindow. Returns the converted rectangle.
See Also: - convertPoint:toView:, - convertSize:toView:, - ancestorSharedWithView:, - contentView (NSWindow)
- (NSSize)convertSize:(NSSize)aSize
fromView:(NSView *)aView
nil
, this method instead converts from window base coordinates. Both
aView
and the receiver must belong to the same NSWindow. Returns the converted size.
See Also: - convertPoint:fromView:, - convertRect:fromView:, - ancestorSharedWithView:, - contentView (NSWindow)
- (NSSize)convertSize:(NSSize)aSize
toView:(NSView *)aView
nil
, this method instead converts to window base coordinates. Both
aView
and the receiver must belong to the same NSWindow. Returns the converted size.
See Also: - convertPoint:toView:, - convertRect:toView:, - ancestorSharedWithView:, - contentView (NSWindow)
- (NSData *)dataWithEPSInsideRect:(NSRect)aRect
See Also: - writeEPSInsideRect:toPasteboard:
- (NSData *)dataWithPDFInsideRect:(NSRect)aRect
See Also: - writePDFInsideRect:toPasteboard:
- (void)didAddSubview:(NSView *)subview
- (void)discardCursorRects
See Also: - discardCursorRects (NSWindow)
- (void)display
See Also: - canDraw, - opaqueAncestor, - visibleRect, - displayIfNeededIgnoringOpacity
- (void)displayIfNeeded
See Also: - display, - needsDisplay, - displayIfNeededIgnoringOpacity
- (void)displayIfNeededIgnoringOpacity
- (void)displayIfNeededInRect:(NSRect)aRect
- (void)displayIfNeededInRectIgnoringOpacity:(NSRect)aRect
- (void)displayRect:(NSRect)aRect
- (void)displayRectIgnoringOpacity:(NSRect)aRect
- (BOOL)dragFile:(NSString *)fullPath
fromRect:(NSRect)aRect
slideBack:(BOOL)slideBack
event:(NSEvent *)theEvent
YES
if the receiver successfully initiates the dragging operation (which doesn't necessarily mean the dragging operation concluded successfully). Otherwise returns
NO
.
The dragging operation uses these arguments:
YES
, the file is not accepted by the dragging destination, and the user has not disabled icon animation; otherwise it simply disappears.
See the NSDraggingSource, NSDraggingInfo, and NSDraggingDestination protocol specifications for more information on dragging operations.
See Also: - dragImage:at:offset:event:pasteboard:source:slideBack:, - shouldDelayWindowOrderingForEvent:
- (void)dragImage:(NSImage *)anImage
at:(NSPoint)imageLoc
offset:(NSSize)mouseOffset
event:(NSEvent *)theEvent
pasteboard:(NSPasteboard *)pboard
source:(id)sourceObject
slideBack:(BOOL)slideBack
YES
, the image isn't accepted by the dragging destination, and the user hasn't disabled icon animation; otherwise it simply disappears.
Before invoking this method, you must place the data to be transferred on
pboard. To do this, get the drag pasteboard object (NSDragPboard
), declare the types of the data, and then put the data on the pasteboard. This code fragment initiates a dragging operation on an image itself (that is, the image is the data to be transferred):
- (void)mouseDown:(NSEvent *)theEvent { NSSize dragOffset = NSMakeSize(0.0, 0.0); NSPasteboard *pboard; pboard = [NSPasteboard pasteboardWithName:NSDragPboard]; [pboard declareTypes:[NSArray arrayWithObject:NSTIFFPboardType] owner:self]; [pboard setData:[[self image] TIFFRepresentation] forType:NSTIFFPboardType]; [self dragImage:[self image] at:[self imageLocation] offset:dragOffsetevent:theEvent pasteboard:pboard source:self slideBack:YES]; return; }
See the NSDraggingSource, NSDraggingInfo, and NSDraggingDestination protocol specifications for more information on dragging operations.
See Also: - dragFile:fromRect:slideBack:event:, - shouldDelayWindowOrderingForEvent:
- (void)drawPageBorderWithSize:(NSSize)borderSize
See Also: - drawSheetBorderWithSize:
- (void)drawRect:(NSRect)aRect
This method is intended to be completely overridden by each subclass that performs drawing. Don't invoke
super
's implementation in your subclass.
See Also: - display, - shouldDrawColor, - isFlipped
- (void)drawSheetBorderWithSize:(NSSize)borderSize
See Also: - drawPageBorderWithSize:
- (NSScrollView *)enclosingScrollView
nil
.
- (void)endDocument
- (void)endPage
- (NSRect)frame
See Also: - bounds, - setFrame:
- (float)frameRotation
See Also: - setFrameRotation:, - boundsRotation
- (int)gState
Although applications rarely need to use the value returned by gState , it can be passed to the few methods that take an object identifier as a parameter.
See Also: - allocateGState, - setUpGState, - renewGState, - releaseGState, - lockFocus
- (float)heightAdjustLimit
See Also: - widthAdjustLimit
- (NSView *)hitTest:(NSPoint)aPoint
nil
if
aPoint
lies completely outside the receiver.
aPoint
is in the coordinate system of the receiver's superview, not of the receiver itself.
This method is used primarily by an NSWindow to determine which NSView should receive a mouse-down event. You'd rarely need invoke this method, but you might want to override it to have a view object hide mouse-down events from its subviews.
See Also: - mouse:inRect:, - convertPoint:toView:
- (id)initWithFrame:(NSRect)frameRect
See Also: - addSubview:, - addSubview:positioned:relativeTo:, - setFrame:
- (BOOL)isDescendantOf:(NSView *)aView
See Also: - superview, - subviews, - ancestorSharedWithView:
- (BOOL)isFlipped
YES
if the receiver uses flipped drawing coordinates or
NO
if it uses native coordinates. NSView's implementation returns
NO
; subclasses that use flipped coordinates should override this method to return
YES
.
- (BOOL)isOpaque
YES
if the receiver is opaque,
NO
otherwise. A view object is opaque if it completely covers its frame rectangle when drawing itself. NSView, being an abstract class, performs no drawing at all and so returns
NO
.
See Also: - opaqueAncestor, - displayRectIgnoringOpacity:, - displayIfNeededIgnoringOpacity, - displayIfNeededInRectIgnoringOpacity:
- (BOOL)isRotatedFromBase
YES
if the receiver or any of its ancestors has ever received a
setFrameRotation:
or
setBoundsRotation:
message; otherwise returns
NO
. This intent of this information is to optimize drawing and coordinate calculation, not necessarily to reflect the exact state of the receiver's coordinate system, so it may not reflect the actual rotation. For example, if an NSView is rotated to 45 degrees and later back to zero, this method still returns
YES
.
See Also: - frameRotation, - boundsRotation
- (BOOL)isRotatedOrScaledFromBase
YES
if the receiver or any of its ancestors have ever had a nonzero frame or bounds rotation, or has been scaled from the window's base coordinate system; otherwise returns
NO
. This intent of this information is to optimize drawing and coordinate calculation, not necessarily to reflect the exact state of the receiver's coordinate system, so it may not reflect the actual rotation or scaling. For example, if an NSView is rotated to 45 degrees and later back to zero, this method still returns
YES
.
See Also: - frameRotation, - boundsRotation, - centerScanRect:, - setBounds:, - setBoundsSize:, - scaleUnitSquareToSize:
- (BOOL)knowsPageRange:(NSRangePointer)range
- (NSPoint)locationOfPrintRect:(NSRect)aRect
NSView's implementation places
aRect
according to the status of the NSPrintInfo object for the print job. By default it places the image in the upper left corner of the page, but if NSPrintInfo's
isHorizontallyCentered
or
isVerticallyCentered
method returns
YES
, it centers a single-page image along the appropriate axis. A multiple-page document, however, is always placed so the divided pieces can be assembled at their edges.
- (void)lockFocus
See Also: + focusView, - display, - drawRect:
- (BOOL)lockFocusIfCanDraw
- (NSMenu *)menuForEvent:(NSEvent *)theEvent
NSView's implementation returns the receiver's normal menu.
See Also: + defaultMenu, - menu (NSResponder)
- (BOOL)mouse:(NSPoint)aPoint
inRect:(NSRect)aRect
YES
if
aRect
contains
aPoint
(which represents the hot spot of the mouse cursor), accounting for whether the receiver is flipped or not.
aPoint
and
aRect
must be expressed in the receiver's coordinate system.
Never use the Foundation Kit's
NSPointInRect()
function as a substitute for this method. It doesn't account for flipped coordinate systems.
See Also: - hitTest:, - isFlipped, NSMouseInRect() (Foundation Kit), - convertPoint:fromView:
- (BOOL)needsDisplay
YES
if the receiver needs to be displayed, as indicated using the
setNeedsDisplay:
and
setNeedsDisplayInRect:
methods; returns
NO
otherwise. The
displayIfNeeded...
methods check this status to avoid unnecessary drawing, and all display methods clear this status to indicate that the view object is up to date.
- (BOOL)needsPanelToBecomeKey
YES
if the receiver requires its panel, which might otherwise avoid becoming key, to become the key window so that it can handle keyboard input. Such a subclass should also override
acceptsFirstResponder
to return
YES
. NSView's implementation returns
NO
.
See Also: - becomesKeyOnlyIfNeeded (NSPanel)
- (NSView *)nextKeyView
nil
if there is none. This view should, if possible, be made first responder when the user navigates forward from the receiver using keyboard interface control.
See Also: - nextValidKeyView, - setNextKeyView:, - previousKeyView, - previousValidKeyView
- (NSView *)nextValidKeyView
nil
if there is none.
See Also: - nextKeyView, - setNextKeyView:, - previousKeyView, - previousValidKeyView
- (NSView *)opaqueAncestor
See Also: - isOpaque, - displayRectIgnoringOpacity:, - displayIfNeededIgnoringOpacity, - displayIfNeededInRectIgnoringOpacity:
- (BOOL)performKeyEquivalent:(NSEvent *)theEvent
YES
. Otherwise, it should return the result of invoking
super
's implementation. NSView's implementation of this method simply passes the message down the view hierarchy (from superviews to subviews) and returns
NO
if none of the receiver's subviews responds
YES
.
See Also: - performMnemonic:, - keyDown: (NSWindow)
- (BOOL)performMnemonic:(NSString *)aString
YES
. Otherwise, it should return the result of invoking
super
's implementation. NSView's implementation of this method simply passes the message down the view hierarchy (from superviews to subviews) and returns
NO
if none of the receiver's subviews responds
YES
.
See Also: - performKeyEquivalent:, - keyDown: (NSWindow)
- (BOOL)postsBoundsChangedNotifications
YES
if the receiver posts notifications to the default notification center whenever its bounds rectangle changes; returns
NO
otherwise. See
setPostsBoundsChangedNotifications:
for a list of methods that result in notifications.
- (BOOL)postsFrameChangedNotifications
YES
if the receiver posts notifications to the default notification center whenever its frame rectangle changes; returns
NO
otherwise. See
setFrameRotation:
for a list of methods that result in notifications.
- (NSView *)previousKeyView
nil
if there is none. This view should, if possible, be made first responder when the user navigates backward from the receiver using keyboard interface control.
See Also: - previousValidKeyView, - nextKeyView, - nextValidKeyView, - setNextKeyView:
- (NSView *)previousValidKeyView
nil
if there is none.
See Also: - previousKeyView, - nextValidKeyView, - nextKeyView, - setNextKeyView:
- (void)print:(id)sender
See Also: - dataWithEPSInsideRect:, - writeEPSInsideRect:toPasteboard:
- (NSString *)printJobTitle
- (NSRect)rectForPage:(int)pageNumber
YES
to an earlier
knowsPageRange:
message, this method is invoked for each page it specified in the out parameters of that message. The receiver is later made to display this rectangle in order to generate the image for this page. This method should return
NSZeroRect
if
pageNumber
is outside the receiver's bounds.
If an NSView responds NO to knowsPageRange:, this method isn't invoked by the printing mechanism.
See Also: - adjustPageHeightNew:top:bottom:limit:, - adjustPageWidthNew:left:right:limit:
- (void)reflectScrolledClipView:(NSClipView *)aClipView
- (void)registerForDraggedTypes:(NSArray *)pboardTypes
Registering an NSView for dragged types automatically makes it a candidate destination object for a dragging session. As such, it must properly implement some or all of the NSDraggingDestination protocol methods. As a convenience, NSView provides default implementations of these methods. See the NSDraggingDestination protocol specification for details.
See Also: - unregisterDraggedTypes
- (void)releaseGState
See Also: - allocateGState
- (void)removeAllToolTips
- (void)removeCursorRect:(NSRect)aRect
cursor:(NSCursor *)aCursor
You should rarely need to use this method. resetCursorRects, which is invoked any time cursor rectangles need to be rebuilt, should establish only the cursor rectangles needed. If you implement resetCursorRects in this way, you can then simply modify the state that resetCursorRects uses to build its cursor rectangles and then invoke NSWindow's invalidateCursorRectsForView:.
See Also: - discardCursorRects
- (void)removeFromSuperview
Never invoke this method during display.
See Also: - addSubview:, - addSubview:positioned:relativeTo:, - removeFromSuperviewWithoutNeedingDisplay
- (void)removeFromSuperviewWithoutNeedingDisplay
Unlike its counterpart, removeFromSuperview, this method can be safely invoked during display.
See Also: - addSubview:, - addSubview:positioned:relativeTo:
- (void)removeToolTip:(NSToolTipTag)tag
- (void)removeTrackingRect:(NSTrackingRectTag)aTag
- (void)renewGState
See Also: - lockFocus
- (void)replaceSubview:(NSView *)oldView
with:(NSView *)newView
nil
if
oldView
is not a subview of the receiver.
This method causes oldView to be released; if you plan to reuse it, be sure to retain it before sending this message and to release it as appropriate when adding it as a subview of another NSView.
See Also: - addSubview:, - addSubview:positioned:relativeTo:
- (void)resetCursorRects
Application code should never invoke this method directly; it's invoked automatically as described in the "Tracking Rectangles and Cursor Rectangles" section. Use the invalidateCursorRectsForView: method instead to explicitly rebuild cursor rectangles.
See Also: - visibleRect
- (void)resizeSubviewsWithOldSize:(NSSize)oldFrameSize
NSView's implementation sends resizeWithOldSuperviewSize: to the receiver's subviews with oldFrameSize as the argument. You shouldn't invoke this method directly, but you can override it to define a specific retiling behavior.
See Also: - setAutoresizesSubviews:
- (void)resizeWithOldSuperviewSize:(NSSize)oldFrameSize
NSView's implementation resizes the receiver according to the autoresizing options listed under the setAutoresizingMask: method description. You shouldn't invoke this method directly, but you can override it to define a specific resizing behavior.
- (void)rotateByAngle:(float)angle
This method posts an NSViewBoundsDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - setFrameRotation:, - setPostsBoundsChangedNotifications:
- (void)scaleUnitSquareToSize:(NSSize)newUnitSize
This method neither redisplays the receiver nor marks it as needing display. You must do this yourself with display or setNeedsDisplay:.
This method posts an NSViewBoundsDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - setBoundsSize:, - setPostsBoundsChangedNotifications:
- (void)scrollClipView:(NSClipView *)aClipView
toPoint:(NSPoint)newOrigin
See Also: scrollToPoint: (NSClipView)
- (void)scrollPoint:(NSPoint)aPoint
See Also: - autoscroll:, scrollToPoint: (NSClipView), - isDescendantOf:
- (void)scrollRect:(NSRect)aRect
by:(NSSize)offset
You should rarely need to use this method, however. The scrollPoint:, scrollRectToVisible:, and autoscroll: methods automatically perform optimized scrolling.
See Also: - setBoundsOrigin:, - translateOriginToPoint:
- (BOOL)scrollRectToVisible:(NSRect)aRect
YES
if any scrolling is performed; otherwise returns
NO
.
See Also: - autoscroll:, scrollToPoint: (NSClipView), - isDescendantOf:
- (void)setAutoresizesSubviews:(BOOL)flag
YES
, the receiver invokes
resizeSubviewsWithOldSize:
whenever its frame size changes; if
flag
is
NO
, it doesn't. View objects do autoresize their subviews by default.
See Also: - autoresizesSubviews
- (void)setAutoresizingMask:(unsigned int)mask
Option | Meaning |
NSViewMinXMargin
|
The left margin between the receiver and its superview is flexible. |
NSViewWidthSizable
|
The receiver's width is flexible. |
NSViewMaxXMargin
|
The right margin between the receiver and its superview is flexible. |
NSViewMinYMargin
|
The bottom margin between the receiver and its superview is flexible. |
NSViewHeightSizable
|
The receiver's height is flexible. |
NSViewMaxYMargin
|
The top margin between the receiver and its superview is flexible. |
Where more than one option along an axis is set,
resizeWithOldSuperviewSize:
by default distributes the size difference as evenly as possible among the flexible portions. For example, if
NSViewWidthSizable
and
NSViewMaxXMargin
are set and the
superview's width has increased by 10.0 units, the receiver's frame and right margin are each widened by 5.0 units.
See Also: - autoresizingMask, - resizeSubviewsWithOldSize:, - setAutoresizesSubviews:
- (void)setBounds:(NSRect)boundsRect
This method posts an NSViewBoundsDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - bounds, - setBoundsRotation:, - setBoundsOrigin:, - setBoundsSize:, - setFrame:, - setPostsBoundsChangedNotifications:
- (void)setBoundsOrigin:(NSPoint)newOrigin
This method posts an NSViewBoundsDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - translateOriginToPoint:, - bounds, - setBoundsRotation:, - setBounds:, - setBoundsSize:, - setPostsBoundsChangedNotifications:
- (void)setBoundsRotation:(float)angle
This method posts an NSViewBoundsDidChangeNotification to the default notification center if the receiver is configured to do so.
Bounds rotation affects the orientation of the drawing within the view object's frame rectangle, but not the orientation of the frame rectangle itself. Also, for a rotated bounds rectangle to enclose all the visible areas of its view object-that is, to guarantee coverage over the frame rectangle-it must also contain some areas that aren't visible. This can cause unnecessary drawing to be requested, which may affect performance. It may be better in many cases to rotate the coordinate system in the drawRect: method rather than use this method.
See Also: - rotateByAngle:, - boundsRotation, - setFrameRotation:, - setPostsBoundsChangedNotifications:
- (void)setBoundsSize:(NSSize)newSize
This method posts an NSViewFrameDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - bounds, - setBoundsRotation:, - setBounds:, - setBoundsOrigin:, - setPostsBoundsChangedNotifications:
- (void)setFrame:(NSRect)frameRect
This method posts an NSViewFrameDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - frame, - setFrameRotation:, - setFrameOrigin:, - setFrameSize:, - setBounds:, - setPostsFrameChangedNotifications:
- (void)setFrameOrigin:(NSPoint)newOrigin
This method posts an NSViewFrameDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - frame, - setFrameSize:, - setFrame:, - setFrameRotation:, - setPostsFrameChangedNotifications:
- (void)setFrameRotation:(float)angle
This method neither redisplays the receiver nor marks it as needing display. You must do this yourself with display or setNeedsDisplay:.
This method posts an NSViewFrameDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - frameRotation, - setBoundsRotation:
- (void)setFrameSize:(NSSize)newSize
This method posts an NSViewFrameDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - frame, - setFrameOrigin:, - setFrame:, - setFrameRotation:, - setPostsFrameChangedNotifications:
- (void)setNeedsDisplay:(BOOL)flag
YES
, marks the receiver's entire bounds as needing display; if
flag
is
NO
, marks it as not needing display. Whenever the data or state used for drawing a view object changes, the view should be sent a
setNeedsDisplay:
message. NSViews marked as needing display are automatically redisplayed on each pass through the application's event loop. (View objects that need to redisplay before the event loop comes around can of course immediately be sent the appropriate
display...
method.)
See Also: - setNeedsDisplayInRect:, - needsDisplay
- (void)setNeedsDisplayInRect:(NSRect)invalidRect
See Also: - setNeedsDisplay:, - needsDisplay
- (void)setNextKeyView:(NSView *)aView
See Also: - nextKeyView, - nextValidKeyView, - previousKeyView, - previousValidKeyView
- (void)setPostsBoundsChangedNotifications:(BOOL)flag
YES
, the receiver will post notifications to the default notification center whenever its bounds rectangle changes; if
flag
is
NO
it won't. The following methods can result in notification posting:
See Also: - postsBoundsChangedNotifications
- (void)setPostsFrameChangedNotifications:(BOOL)flag
YES
, the receiver will post notifications to the default notification center whenever its frame rectangle changes; if
flag
is
NO
it won't. The following methods can result in notification posting:
See Also: - postsFrameChangedNotifications
- (void)setToolTip:(NSString *)string
nil
, cancels tooltip display for the view.
See Also: - toolTip
- (void)setUpGState
See Also: - allocateGState, - renewGState
- (BOOL)shouldDelayWindowOrderingForEvent:(NSEvent *)theEvent
YES
, the normal window ordering and activation mechanism is delayed (not necessarily prevented) until the next mouse-up event. If it returns
NO
then normal ordering and activation occurs. Never invoke this method directly; it's invoked automatically for each mouse-down event directed at the NSView.
An NSView subclass that allows dragging should implement this method to return
YES
if
theEvent, an initial mouse-down event, is potentially the beginning of a dragging session or of some other context where window ordering isn't appropriate. This method is invoked before a
mouseDown:
message for
theEvent
is sent. NSView's implementation returns
NO
.
If, after delaying window ordering, the receiver actually initiates a dragging session or similar operation, it should also send a
preventWindowOrdering
message to
NSApp
, which completely prevents the window from ordering forward and the activation from becoming active.
preventWindowOrdering
is sent automatically by NSView's
dragImage:...
and
dragFile:...
methods.
- (BOOL)shouldDrawColor
NO
if the receiver is being drawn in an NSWindow (as opposed, for example, to being printed) and the NSWindow can't store color; otherwise returns
YES
. An NSView can base its drawing behavior on the return value of this method to improve its appearance in grayscale windows.
See Also: - drawRect:, - canStoreColor (NSWindow)
- (void)sortSubviewsUsingFunction:(int (*)(id, id, void *))compare
context:(void *)context
NSOrderedAscending
if the first subview should be ordered lower,
NSOrderedDescending
if the second subview should be ordered lower, and
NSOrderedSame
if their ordering isn't important.
See Also: - sortedArrayUsingFunction:context: (NSArray class cluster of the Foundation Kit)
- (NSArray *)subviews
See Also: - superview, - addSubview:, - addSubview:positioned:relativeTo:, - removeFromSuperview
- (NSView *)superview
nil
if it has none. When applying this method iteratively or recursively, be sure to compare the returned NSView to the content view of the NSWindow to avoid proceeding out of the view hierarchy.
See Also: - window, - subviews, - removeFromSuperview
- (int)tag
See Also: - viewWithTag:
- (NSString *)toolTip
nil
if the view doesn't currently display tooltip text.
See Also: - setToolTip:
- (void)translateOriginToPoint:(NSPoint)newOrigin
-
newOrigin.x
,
-
newOrigin.y
). This method neither redisplays the receiver nor marks it as needing display. You must do this yourself with
display
or
setNeedsDisplay:.
Note the difference between this method and setting the bounds origin. Translation effectively moves the image inside the bounds rectangle, while setting the bounds origin effectively moves the rectangle over the image. The two are in a sense inverse, although translation is cumulative and setting the bounds origin is absolute.
This method posts an NSViewBoundsDidChangeNotification to the default notification center if the receiver is configured to do so.
See Also: - setBoundsOrigin:, - setBounds:, - setPostsBoundsChangedNotifications:
- (void)unlockFocus
See Also: - allocateGState
- (void)unregisterDraggedTypes
See Also: - registerForDraggedTypes:
- (void)viewWillMoveToSuperview:(NSView *)newSuperview
See Also: - viewWillMoveToWindow:
- (void)viewWillMoveToWindow:(NSWindow *)newWindow
See Also: - viewWillMoveToSuperview:
- (id)viewWithTag:(int)aTag
nil
if no subview has that tag.
See Also: - tag
- (NSRect)visibleRect
During a printing operation the visible rectangle is further clipped to the page being imaged.
See Also: - isVisible (NSWindow), - documentVisibleRect (NSScrollView), - documentVisibleRect (NSClipView)
- (float)widthAdjustLimit
See Also: - heightAdjustLimit
- (void)willRemoveSubview:(NSView *)subview
- (NSWindow *)window
nil
if it has none.
See Also: - superview
- (void)writeEPSInsideRect:(NSRect)aRect
toPasteboard:(NSPasteboard *)pboard
See Also: - dataWithEPSInsideRect:
- (void)writePDFInsideRect:(NSRect)aRect
toPasteboard:(NSPasteboard *)pboard
See Also: - dataWithPDFInsideRect:
- (NSString *)view:(NSView *)view
stringForToolTip:(NSToolTipTag)tag
point:(NSPoint)point
userData:(void *)data
@end
This notification contains a notification object but no userInfo dictionary. The notification object is the NSView whose bounds rectangle has changed.
The following methods can result in notification posting:
Note that the bounds rectangle resizes automatically to track the frame rectangle. Because the primary change is that of the frame rectangle, however, setFrame: and setFrameSize: don't result in a bounds-changed notification.
Posted whenever the NSView loses the focus other than by an unlockFocus message (for example, when its frame or bounds rectangle is changed).
This notification contains a notification object but no userInfo dictionary. The notification object is the NSView that has lost focus.
See Also: + focusView
This notification contains a notification object but no userInfo dictionary. The notification object is the NSView whose frame rectangle has changed.
The following methods can result in notification posting: