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Application Kit Reference: Objective-C
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Inherits
from: NSObject
Conforms to: NSCoding
NSCopying
NSObject (NSObject)
Declared in: AppKit/NSImageRep.h
Class Description
NSImageRep is a semi-abstract superclass ("semi," because
it has some instance variables and implementation of its own); each
of its subclasses knows how to draw an image from a particular kind
of source data. While an NSImageRep subclass can be used directly,
it's typically used through an NSImage object. An NSImage manages
a group of representations, choosing the best one for the current
output device.
There are four subclasses defined in the Application Kit:
Subclass |
Source Data |
NSBitmapImageRep |
Tag Image File Format (TIFF), Windows bitmap (BMP) and
other bitmap data |
NSCachedImageRep |
A rendered image, usually in an off-screen window |
NSCustomImageRep |
A delegated method that can draw the image |
NSEPSImageRep |
Encapsulated PostScript code (EPS) |
You can define other NSImageRep subclasses for objects that
render images from other types of source information. New subclasses
must be added to the NSImageRep class registry by invoking the registerImageRepClass: class method.
The NSImageRep subclass informs the registry of the data types it
can support through its imageUnfilteredFileTypes, imageUnfilteredPasteboardTypes, and canInitWithData: class
methods. Once an NSImageRep subclass is registered, an instance
of that subclass is created any time NSImage encounters the type
of data handled by that subclass.
Subclasses which deal with file and pasteboard types should
implement imageUnfilteredFileTypes, imageUnfilteredPasteboardTypes, initWithData:, canInitWithData:,
and, if they have the ability to read multiple images from a file, imageRepsWithData:.
These last three should not do any filtering; all filtering is automatic.
Adopted
Protocols
- NSCoding
- - encodeWithCoder:
- - initWithCoder:
- NSCopying
- - copyWithZone:
Method Types
- Creating an NSImageRep
- + imageRepsWithContentsOfFile:
- + imageRepsWithPasteboard:
- + imageRepWithContentsOfFile:
- + imageRepWithPasteboard:
- Checking data types
- + canInitWithData:
- + canInitWithPasteboard:
- + imageFileTypes
- + imagePasteboardTypes
- + imageUnfilteredFileTypes
- + imageUnfilteredPasteboardTypes
- Setting the size of the
image
- - setSize:
- - size
- Specifying information
about the representation
- - bitsPerSample
- - colorSpaceName
- - hasAlpha
- - isOpaque
- - pixelsHigh
- - pixelsWide
- - setAlpha:
- - setBitsPerSample:
- - setColorSpaceName:
- - setOpaque:
- - setPixelsHigh:
- - setPixelsWide:
- Drawing the image
- - draw
- - drawAtPoint:
- - drawInRect:
- Managing NSImageRep subclasses
- + imageRepClassForData:
- + imageRepClassForFileType:
- + imageRepClassForPasteboardType:
- + registeredImageRepClasses
- + registerImageRepClass:
- + unregisterImageRepClass:
Constructors
Class
Methods
+ (BOOL)canInitWithData:(NSData *)data
Overridden in subclasses to
return trueYES if the receiver can initialize itself from data,
and NO if it cannot. Note that this method doesn't
need to do a comprehensive check; it should return NO only if it
knows the receiver can't initialize itself from data.
+ (BOOL)canInitWithPasteboard:(NSPasteboard *)pasteboard
Returns YES if the NSImageRep
can handle the data represented by pasteboard, otherwise returns NO.This
method invokes the imageUnfilteredPasteboardTypes class
method and checks the list of types returned by that method against
the data types in pasteboard. If it finds a match, it returns YES.
When creating a subclass of NSImageRep that accepts image data from
a non-default pasteboard type, override the imageUnfilteredPasteboardTypes method
to assure this method returns the correct response.
+ (NSArray *)imageFileTypes
Returns an array of NSStrings
representing all file types supported by NSImageRep or one of its
subclasses. The list includes both those types
returned by the imageUnfilteredFileTypes class
method and those that can be converted to a supported type by a
user-installed filter service. Don't override this method when
subclassing NSImageRep-it always returns a valid list for any
subclass of NSImageRep that correctly overrides the imageUnfilteredFileTypes method.
+ (NSArray *)imagePasteboardTypes
Returns an array of NSStrings
representing all pasteboard types supported by NSImageRep or one
of its subclasses. The list includes both those
types returned by the imageUnfilteredPasteboardTypes class
method and those that can be converted by a user-installed filter
service to a supported type. Don't override this method when subclassing
NSImageRep-it always returns a valid list for any subclass of
NSImageRep that correctly overrides the imageUnfilteredPasteboardTypes method.
+ (Class)imageRepClassForData:(NSData *)data
Returns the NSImageRep subclass
that handles data of type data, or nil
if
the NSImage class registry contains no subclasses that handle data
of the specified type.
+ (Class)imageRepClassForFileType:(NSString *)type
Returns the NSImageRep subclass
that handles files of type type,
or nil
if the NSImage
class registry contains no subclasses that handle files of the specified type.
+ (Class)imageRepClassForPasteboardType:(NSString
*)type
Returns the NSImageRep subclass
that handles pasteboard data of type type, or nil
if
the NSImage class registry contains no subclasses that handle pasteboard
data of the specified type.
+ (id)imageRepWithContentsOfFile:(NSString *)filename
If sent to the NSImageRep class object, this
method returns a newly-allocated instance of a subclass of NSImageRep
(chosen through the use of imageRepClassForFileType:)
initialized with the contents of the file filename.
If sent to a subclass of NSImageRep that recognizes the type of
file specified by filename, it returns
an instance of that subclass initialized with the contents of the
file filename. imageRepWithContentsOfFile: returns nil
in
any of the following cases:
- The message
is sent to the NSImageRep class object, and there are no subclasses
in the NSImageRep class registry that handle data of the type indicated
by filename.
- The message is sent to a subclass of NSImageRep, and that
subclass doesn't handle data of the type indicated by filename.
- The NSImageRep subclass is unable to initialize itself with
the contents of filename.
filename may
be a full or relative pathname, and should include an extension that
identifies the data type in the file. By default, the files handled
are those with the extensions "tiff", "tif", "bmp",
and "eps".
The NSImageRep subclass is initialized
by creating an NSData object based on the contents of the file,
then passing it to imageRepWithData:.
See
Also: + imageFileTypes
+ (id)imageRepWithPasteboard:(NSPasteboard *)pasteboard
If sent to the NSImageRep class object, this
method returns a newly-allocated instance of a subclass of NSImageRep
initialized with the data in pasteboard.
If sent to a subclass of NSImageRep that recognizes the type of
data contained in pasteboard, it
returns an instance of that subclass initialized with the data in pasteboard. imageRepWithPasteboard: returns nil
in
any of the following cases:
- The message
is sent to the NSImageRep class object, and there are no subclasses
in the NSImageRep class registry that handle data of the type contained
in pasteboard.
- The message is sent to a subclass of NSImageRep, and that
subclass doesn't handle data of the type contained in pasteboard.
- The NSImageRep subclass is unable to initialize itself with
the contents of pasteboard.
The
NSImageRep subclass is initialized by creating an NSData object
based on the data in pasteboard,
then passing it to imageRepWithData:.
See
Also: + imagePasteboardTypes
+ (NSArray *)imageRepsWithContentsOfFile:(NSString
*)filename
If sent to the NSImageRep class object, this
method returns an array of objects (all newly-allocated instances
of a subclass of NSImageRep, chosen through the use of imageRepClassForFileType:)
that have been initialized with the contents of the file filename.
If sent to a subclass of NSImageRep that recognizes the type of
file specified by filename, it returns
an array of objects (all instances of that subclass) that have been
initialized with the contents of the file filename. imageRepsWithContentsOfFile: returns nil
in
any of the following cases:
- The message
is sent to the NSImageRep class object, and there are no subclasses
in the NSImageRep class registry that handle data of the type indicated
by filename.
- The message is sent to a subclass of NSImageRep, and that
subclass doesn't handle data of the type indicated by filename.
- The NSImageRep subclass is unable to initialize itself with
the contents of filename.
filename may
be a full or relative pathname, and should include an extension that
identifies the data type in the file. By default, the files handled
are those with the extensions "tiff", "tif", "bmp",
and "eps".
The NSImageRep subclass is initialized
by creating an NSData object based on the contents of the file,
then passing it to imageRepsWithData:.
See
Also: + imageFileTypes
+ (NSArray *)imageRepsWithPasteboard:(NSPasteboard
*)pasteboard
If sent to the NSImageRep class object, this
method returns an array of objects (all newly-allocated instances
of a subclass of NSImageRep) that have been initialized with the
data in pasteboard. If sent to a
subclass of NSImageRep that recognizes the type of data contained
in pasteboard, it returns an array
of objects (all instances of that subclass) initialized with the
data in pasteboard. imageRepsWithPasteboard: returns nil
in
any of the following cases:
- The message
is sent to the NSImageRep class object, and there are no subclasses
in the NSImageRep class registry that handle data of the type contained
in pasteboard.
- The message is sent to a subclass of NSImageRep, and that
subclass doesn't handle data of the type contained in pasteboard.
- The NSImageRep subclass is unable to initialize itself with
the contents of pasteboard.
The
NSImageRep subclass is initialized by creating an NSData object
based on the data in pasteboard,
then passing it to imageRepsWithData:.
See
Also: + imagePasteboardTypes
+ (NSArray *)imageUnfilteredFileTypes
Returns an array of NSStrings
representing all file types (extensions) supported by the NSImageRep. By
default, the returned array is empty.When creating a subclass
of NSImageRep, override this method to return a list of strings
representing the supported file types. For example, NSBitmapImageRep implements
the following code for this method:
+ (NSArray *)imageUnfilteredFileTypes {
static NSArray *types = nil;
if (!types) types = [[NSArray alloc]
initWithObjects:@"tiff", @"tif",
@"bmp", nil];
return types;
}
If your subclass
supports the types supported by its superclass, you must explicitly
get the array of types from the superclass and put them in the array returned
by this method.
See Also: + imageFileTypes, + imageUnfilteredFileTypes (NSImage)
+ (NSArray *)imageUnfilteredPasteboardTypes
Returns an array representing
all pasteboard types supported by the NSImageRep. By
default, the returned array is empty. When creating a subclass
of NSImageRep, override this method to return a list representing
the supported pasteboard types. For example, NSBitmapImageRep implements
the following code for this method:
+ (NSArray *)imageUnfilteredPasteboardTypes {
static NSArray *types = nil;
if (!types) types = [[NSArray alloc] initWithObjects:NSTIFFPboardType,
nil];
return types;
}
If your subclass
supports the types supported by its superclass, you must explicitly
get the list of types from the superclass and add them to the array returned
by this method.
See Also: + imagePasteboardTypes, + imageUnfilteredPasteboardTypes (NSImage)
+ (void)registerImageRepClass:(Class)imageRepClass
Adds imageRepClass to
the registry of available NSImageRep classes. This method
posts the NSImageRepRegistryChangedNotification notification, along with
the receiving object, to the default notification center.A
good place to add image representation classes to the registry is
in the load class method.
See
Also: + load (NSObject)
+ (NSArray *)registeredImageRepClasses
Returns an array containing
the registered NSImageRep classes.
+ (void)unregisterImageRepClass:(Class)imageRepClass
Removes imageRepClass from
the registry of available NSImageRep classes. This
method posts the NSImageRepRegistryChangedNotification notification, along
with the receiving object, to the default notification center.
Instance Methods
- (int)bitsPerSample
Returns the number of bits
used to specify a single pixel in each component of the data.
- (NSString *)colorSpaceName
Returns the name if the image's
color space, or NSCalibratedRGBColorSpace if no name has been assigned.
- (BOOL)draw
Implemented by subclasses to
draw the image at location (0.0, 0.0) in the current coordinate
system. Subclass methods return YES if the image
is successfully drawn, and NO if it isn't. This version of the
method simply returns YES.
- (BOOL)drawAtPoint:(NSPoint)aPoint
Sets the current coordinates
to aPoint, invokes the receiver's draw method
to draw the image at that point, then restores the current coordinates
to their original setting. If aPoint is
(0.0, 0.0), drawAtPoint: simply invokes draw.This
method returns NO without translating, scaling, or drawing if the
size of the image has not been set. Otherwise it returns the value
returned by the draw method, which indicates
whether the image is successfully drawn.
See
Also: - setSize:
- (BOOL)drawInRect:(NSRect)rect
Draws the image so it fits
inside rect. The
current coordinates are set to the point specified in the rectangle
and are scaled so the image will fit within the rectangle. The receiver's draw method
is then invoked to draw the image. After draw has been invoked,
the current coordinates and scale factors are restored to their
original settings.This method returns NO without translating,
scaling, or drawing if the size of the image has not been set. Otherwise
it returns the value returned by the draw method,
which indicates whether the image is successfully drawn.
See
Also: - setSize:
- (BOOL)hasAlpha
Returns YES if the receiver
has been informed that the image has a coverage component (alpha),
and NO if not.
- (BOOL)isOpaque
Returns YES if the receiver
is opaque; NO otherwise. Use this method to test whether
an NSImageRep completely covers the area within the rectangle returned by size. Use the method setOpaque: to set
the value returned by this method.
- (int)pixelsHigh
Returns the height of the image
in pixels, as specified in the image data.See
Also: - size
- (int)pixelsWide
Returns the width of the image
in pixels, as specified in the image data.See
Also: - size
- (void)setAlpha:(BOOL)flag
Informs the NSImageRep whether
the image has an alpha component. flag should
be YES if it does, and NO if it doesn't.
- (void)setBitsPerSample:(int)anInt
Informs the NSImageRep that
the image has anInt bits of data
for each pixel in each component.
- (void)setColorSpaceName:(NSString *)string
Informs the receiver of the
image's color space. By default, an NSImageRep's color
space name is NSCalibratedRGBColorSpace. Color space names are defined as
part of the NSColor class, in NSGraphics.h
.
The following are valid color space names:- NSCalibratedWhiteColorSpace
- NSCalibratedBlackColorSpace
- NSCalibratedRGBColorSpace
- NSDeviceWhiteColorSpace
- NSDeviceBlackColorSpace
- NSDeviceRGBColorSpace
- NSDeviceCMYKColorSpace
- NSNamedColorSpace
- NSCustomColorSpace
- (void)setOpaque:(BOOL)flag
Sets opacity of the NSImageRep's
image. If flag is YES,
the image is opaque.
- (void)setPixelsHigh:(int)anInt
Informs the NSImageRep that
the data specifies an image anInt pixels
high.See Also: - setSize:
- (void)setPixelsWide:(int)anInt
Informs the NSImageRep that
the data specifies an image anInt pixels
wide.See Also: - setSize:
- (void)setSize:(NSSize)aSize
Sets the size of the image
in units of the base coordinate system. This determines the
size of the image when it's rendered; it's not necessarily the
same as the width and height of the image in pixels as specified
in the image data. You must set the image size before you can render
it.See Also: - draw, - setPixelsHigh:, - setPixelsWide:
- (NSSize)size
Returns the size of the image
in units of the base coordinate system. This is
the size of the image when it's rendered; it's not necessarily
the same as the width and height of the image in pixels as specified
in the image data.See Also: - pixelsHigh, - pixelsWide
Notifications
NSImageRepRegistryDidChangeNotification
Posted whenever the NSImageRep class registry changes.
This notification contains a notification object but no userInfo dictionary.
The notification object is the image class that is registered or
unregistered.
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