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Class com.sun.java.swing.JViewport

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Container
                   |
                   +----com.sun.java.swing.JComponent
                           |
                           +----com.sun.java.swing.JViewport

public class JViewport
extends JComponent
implements Accessible

The "view port" through which you see information as it scrolls by underneath the "port hole". Kind of like moving a square magnifying glass up and down a page. Moving the magnifying glass up brings the contents above into view.

Warning: serialized objects of this class will not be compatible with future swing releases. The current serialization support is appropriate for short term storage or RMI between Swing1.0 applications. It will not be possible to load serialized Swing1.0 objects with future releases of Swing. The JDK1.2 release of Swing will be the compatibility baseline for the serialized form of Swing objects.


Variable Index

backingStore
backingStoreImage
isViewSizeSet
lastPaintPosition
The last viewPosition that we've painted, so we know how much of the backing store image is valid.
scrollUnderway

Constructor Index

JViewport()

Method Index

addChangeListener(ChangeListener)
Add a ChangeListener to the list that's notified each time the views size, position, or the viewports extent size has changed.
addImpl(Component, Object, int)
Sets the Viewports one lightweight child, child can be null.
computeBlit(int, int, Point, Point, Dimension, Rectangle)
Computes the parameters for a blit where the backing store image currently contains oldLoc in the upper left hand corner and we're scrolling to newLoc.
createLayoutManager()
Subclassers can override this to install a different layout manager (or null) in the constructor.
createViewListener()
fireStateChanged()
getAccessibleContext()
Get the AccessibleContext associated with this JComponent
getExtentSize()
Returns the size of the visible part of the view in view coordinates.
getInsets()
getView()
Returns the Viewports one child or null.
getViewPosition()
Returns the view coordinates that appear in the upper left hand corner of the viewport, 0,0 if there's no view.
getViewRect()
Return a rectangle whose origin is getViewPosition and size is getExtentSize().
getViewSize()
If the views size hasn't been explicitly set return the preferred size, otherwise return the views current size.
isBackingStoreEnabled()
Returns true if this viewport is maintaining an offscreen image of its contents.
isOptimizedDrawingEnabled()
Returns true if this component tiles its children, i.e.
paint(Graphics)
Depending on whether the backingStore is enabled, either paint the image through the backing store or paint just the recently exposed part, using the backing store to "blit" the remainder.
remove(Component)
removeChangeListener(ChangeListener)
Remove a ChangeListener from the list that's notified each time the views size, position, or the viewports extent size has changed.
repaint(long, int, int, int, int)
We always repaint in our parent coordinate system to make sure only one paint is performed by the RepaintManager
scrollRectToVisible(Rectangle)
Overridden to scroll the View such that aRect within the View becomes visible.
setBackingStoreEnabled(boolean)
If true if this viewport will maintain an offscreen image of its contents.
setBorder(Border)
The viewport "scrolls" it's child (called the "view") by the normal parent/child clipping (typically the view is moved in the opposite direction of the scroll).
setBounds(int, int, int, int)
setExtentSize(Dimension)
Set the size of the visible part of the view, newExtent is in view coordinates.
setView(Component)
Sets the Viewports one lightweight child, view can be null.
setViewPosition(Point)
Sets the view coordinates that appear in the upper left hand corner of the viewport, null if there's no view.
setViewSize(Dimension)
Sets the view coordinates that appear in the upper left hand corner of the viewport, null if there's no view.
toViewCoordinates(Dimension)
Convert a size in pixel coordinates to view coordinates.
toViewCoordinates(Point)
Convert a point in pixel coordinates to view coordinates.

Variables

isViewSizeSet
 protected boolean isViewSizeSet
lastPaintPosition
 protected Point lastPaintPosition
The last viewPosition that we've painted, so we know how much of the backing store image is valid.

backingStore
 protected boolean backingStore
backingStoreImage
 protected transient Image backingStoreImage
scrollUnderway
 protected boolean scrollUnderway

Constructors

JViewport
 public JViewport()

Methods

addImpl
 protected void addImpl(Component child,
                        Object constraints,
                        int index)
Sets the Viewports one lightweight child, child can be null.

Overrides:
addImpl in class Container
See Also:
setView
remove
 public void remove(Component child)
Overrides:
remove in class Container
scrollRectToVisible
 public void scrollRectToVisible(Rectangle contentRect)
Overridden to scroll the View such that aRect within the View becomes visible.

Overrides:
scrollRectToVisible in class JComponent
setBorder
 public final void setBorder(Border border)
The viewport "scrolls" it's child (called the "view") by the normal parent/child clipping (typically the view is moved in the opposite direction of the scroll). A non-null border, or non-zero insets, isn't supported, to prevent the geometry of this component from becoming complex enough to inhibit subclassing. To createa JViewport with a border, add it to a JPanel that has a border.

Overrides:
setBorder in class JComponent
getInsets
 public final Insets getInsets()
Returns:
new Insets(0, 0, 0, 0)
Overrides:
getInsets in class JComponent
See Also:
setBorder
isOptimizedDrawingEnabled
 public boolean isOptimizedDrawingEnabled()
Returns true if this component tiles its children, i.e.

Overrides:
isOptimizedDrawingEnabled in class JComponent
paint
 public void paint(Graphics g)
Depending on whether the backingStore is enabled, either paint the image through the backing store or paint just the recently exposed part, using the backing store to "blit" the remainder.

Overrides:
paint in class JComponent
setBounds
 public void setBounds(int x,
                       int y,
                       int w,
                       int h)
Overrides:
setBounds in class Component
isBackingStoreEnabled
 public boolean isBackingStoreEnabled()
Returns true if this viewport is maintaining an offscreen image of its contents.

setBackingStoreEnabled
 public void setBackingStoreEnabled(boolean x)
If true if this viewport will maintain an offscreen image of its contents. The image is used to reduce the cost of small one dimensional changes to the viewPosition. Rather than repainting the entire viewport we use Graphics.copyArea() to effect some of the scroll.

getView
 public Component getView()
Returns the Viewports one child or null.

See Also:
setView
setView
 public void setView(Component view)
Sets the Viewports one lightweight child, view can be null.

See Also:
getView
getViewSize
 public Dimension getViewSize()
If the views size hasn't been explicitly set return the preferred size, otherwise return the views current size. If there's no view return 0,0.

setViewSize
 public void setViewSize(Dimension newSize)
Sets the view coordinates that appear in the upper left hand corner of the viewport, null if there's no view.

getViewPosition
 public Point getViewPosition()
Returns the view coordinates that appear in the upper left hand corner of the viewport, 0,0 if there's no view.

setViewPosition
 public void setViewPosition(Point p)
Sets the view coordinates that appear in the upper left hand corner of the viewport, null if there's no view.

getViewRect
 public Rectangle getViewRect()
Return a rectangle whose origin is getViewPosition and size is getExtentSize(). This is the visible part of the view, in view coordinates.

Returns:
The visible part of the view, in view coordinates.
computeBlit
 protected boolean computeBlit(int dx,
                               int dy,
                               Point blitFrom,
                               Point blitTo,
                               Dimension blitSize,
                               Rectangle blitPaint)
Computes the parameters for a blit where the backing store image currently contains oldLoc in the upper left hand corner and we're scrolling to newLoc. The blit* parameters are returned.

getExtentSize
 public Dimension getExtentSize()
Returns the size of the visible part of the view in view coordinates.

toViewCoordinates
 public Dimension toViewCoordinates(Dimension size)
Convert a size in pixel coordinates to view coordinates. Subclasses of viewport that support "logical coordinates" will override this method.

toViewCoordinates
 public Point toViewCoordinates(Point p)
Convert a point in pixel coordinates to view coordinates. Subclasses of viewport that support "logical coordinates" will override this method.

setExtentSize
 public void setExtentSize(Dimension newExtent)
Set the size of the visible part of the view, newExtent is in view coordinates.

createViewListener
 protected JViewport. ViewListener createViewListener()
createLayoutManager
 protected LayoutManager createLayoutManager()
Subclassers can override this to install a different layout manager (or null) in the constructor. Returns a new JViewportLayout object.

addChangeListener
 public void addChangeListener(ChangeListener l)
Add a ChangeListener to the list that's notified each time the views size, position, or the viewports extent size has changed.

See Also:
removeChangeListener, setViewPosition, setViewSize, setExtentSize
removeChangeListener
 public void removeChangeListener(ChangeListener l)
Remove a ChangeListener from the list that's notified each time the views size, position, or the viewports extent size has changed.

See Also:
addChangeListener
fireStateChanged
 protected void fireStateChanged()
repaint
 public void repaint(long tm,
                     int x,
                     int y,
                     int w,
                     int h)
We always repaint in our parent coordinate system to make sure only one paint is performed by the RepaintManager

Overrides:
repaint in class JComponent
getAccessibleContext
 public AccessibleContext getAccessibleContext()
Get the AccessibleContext associated with this JComponent

Returns:
the AccessibleContext of this JComponent
Overrides:
getAccessibleContext in class JComponent

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