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javax.swing
Class JViewport
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JComponent
javax.swing.JViewport
-
All Implemented Interfaces:
-
Accessible
,
ImageObserver
,
MenuContainer
,
Serializable
-
public class
JViewport
-
extends
JComponent
-
implements
Accessible
The "viewport" or "porthole" through which you see the underlying information. When you scroll, what moves is the viewport. It is like peering through a camera's viewfinder. Moving the viewfinder upwards brings new things into view at the top of the picture and loses things that were at the bottom.
By default, JViewport is opaque. To change this, use the setOpaque method.
NOTE:
We have implemented a faster scrolling algorithm that does not require a buffer to draw in. The algorithm works as follows:
-
The view and parent view and checked to see if they are JComponents, if they aren't, stop and repaint the whole viewport.
-
If the viewport is obscured by an ancestor, stop and repaint the whole viewport.
-
Compute the region that will become visible, if it is as big as the viewport, stop and repaint the whole view region.
-
Obtain the ancestor Window's graphics and do a copyArea on the scrolled region.
-
Message the view to repaint the newly visible region.
-
The next time paint is invoked on the viewport, if the clip region is smaller than the viewport size a timer is kicked off to repaint the whole region.
In general this approach is much faster. Compared to the backing store approach this avoids the overhead of maintaining an offscreen buffer and having to do two copyAreas. Compared to the non backing store case this approach will greatly reduce the painted region.
This approach can cause slower times than the backing store approach when the viewport is obscured by another window, or partially offscreen. When another window obscures the viewport the copyArea will copy garbage and a paint event will be generated by the system to inform us we need to paint the newly exposed region. The only way to handle this is to repaint the whole viewport, which can cause slower performance than the backing store case. In most applications very rarely will the user be scrolling while the viewport is obscured by another window or offscreen, so this optimization is usually worth the performance hit when obscured.
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 applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans
TM
has been added to the java.beans package. Please see
XMLEncoder
.
-
See Also:
-
JScrollPane
Nested Class Summary
|
protected class |
JViewport.AccessibleJViewport
This class implements accessibility support for the JViewport class. |
protected class |
JViewport.ViewListener
A listener for the view. |
Nested classes inherited from class java.awt.
Component
|
Component.AccessibleAWTComponent
,
Component.BltBufferStrategy
,
Component.FlipBufferStrategy
|
Field Summary
|
protected boolean |
backingStore
Deprecated.
As of Java 2 platform v1.3
|
static int |
BACKINGSTORE_SCROLL_MODE
Draws viewport contents into an offscreen image. |
protected
Image
|
backingStoreImage
The view image used for a backing store. |
static int |
BLIT_SCROLL_MODE
Use graphics.copyArea to implement scrolling. |
protected boolean |
isViewSizeSet
True when the viewport dimensions have been determined. |
protected
Point
|
lastPaintPosition
The last viewPosition that we've painted, so we know how much of the backing store image is valid. |
protected boolean |
scrollUnderway
The scrollUnderway flag is used for components like JList. |
static int |
SIMPLE_SCROLL_MODE
This mode uses the very simple method of redrawing the entire contents of the scrollpane each time it is scrolled. |
Fields inherited from interface java.awt.image.
ImageObserver
|
ABORT
,
ALLBITS
,
ERROR
,
FRAMEBITS
,
HEIGHT
,
PROPERTIES
,
SOMEBITS
,
WIDTH
|
Constructor Summary
|
JViewport
()
Creates a JViewport. |
Method Summary
|
void |
addChangeListener
(
ChangeListener
l)
Adds a ChangeListener to the list that is notified each time the view's size, position, or the viewport's extent size has changed. |
protected void |
addImpl
(
Component
child,
Object
constraints, int index)
Sets the JViewport's one lightweight child, which can be null. |
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. |
protected
LayoutManager
|
createLayoutManager
()
Subclassers can override this to install a different layout manager (or null) in the constructor. |
protected
JViewport.ViewListener
|
createViewListener
()
Creates a listener for the view. |
protected void |
firePropertyChange
(
String
propertyName,
Object
oldValue,
Object
newValue)
Notifies listeners of a property change. |
protected void |
fireStateChanged
()
Notifies all ChangeListeners when the views size, position, or the viewports extent size has changed. |
AccessibleContext
|
getAccessibleContext
()
Gets the AccessibleContext associated with this JViewport. |
ChangeListener
[] |
getChangeListeners
()
Returns an array of all the ChangeListeners added to this JViewport with addChangeListener(). |
Dimension
|
getExtentSize
()
Returns the size of the visible part of the view in view coordinates. |
Insets
|
getInsets
()
Returns the insets (border) dimensions as (0,0,0,0), since borders are not supported on a JViewport. |
Insets
|
getInsets
(
Insets
insets)
Returns an Insets object containing this JViewports inset values. |
int |
getScrollMode
()
Returns the current scrolling mode. |
ViewportUI
|
getUI
()
Returns the L&F object that renders this component. |
String
|
getUIClassID
()
Returns a string that specifies the name of the L&F class that renders this component. |
Component
|
getView
()
Returns the JViewport's one child or null. |
Point
|
getViewPosition
()
Returns the view coordinates that appear in the upper left hand corner of the viewport, or 0,0 if there's no view. |
Rectangle
|
getViewRect
()
Returns a rectangle whose origin is getViewPosition and size is getExtentSize. |
Dimension
|
getViewSize
()
If the view's size hasn't been explicitly set, return the preferred size, otherwise return the view's current size. |
boolean |
isBackingStoreEnabled
()
Deprecated.
As of Java 2 platform v1.3, replaced by getScrollMode().
|
boolean |
isOptimizedDrawingEnabled
()
The JViewport overrides the default implementation of this method (in JComponent) to return false. |
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. |
protected
String
|
paramString
()
Returns a string representation of this JViewport. |
void |
remove
(
Component
child)
Removes the Viewports one lightweight child. |
void |
removeChangeListener
(
ChangeListener
l)
Removes a ChangeListener from the list that's notified each time the views size, position, or the viewports extent size has changed. |
void |
repaint
(long tm, int x, int y, int w, int h)
Always repaint in the parents coordinate system to make sure only one paint is performed by the RepaintManager. |
void |
reshape
(int x, int y, int w, int h)
Sets the bounds of this viewport. |
void |
scrollRectToVisible
(
Rectangle
contentRect)
Scrolls the view so that Rectangle within the view becomes visible. |
void |
setBackingStoreEnabled
(boolean enabled)
Deprecated.
As of Java 2 platform v1.3, replaced by setScrollMode().
|
void |
setBorder
(
Border
border)
The viewport "scrolls" its child (called the "view") by the normal parent/child clipping (typically the view is moved in the opposite direction of the scroll). |
void |
setExtentSize
(
Dimension
newExtent)
Sets the size of the visible part of the view using view coordinates. |
void |
setScrollMode
(int mode)
Used to control the method of scrolling the viewport contents. |
void |
setUI
(
ViewportUI
ui)
Sets the L&F object that renders this component. |
void |
setView
(
Component
view)
Sets the JViewport's one lightweight child (view), which can be null. |
void |
setViewPosition
(
Point
p)
Sets the view coordinates that appear in the upper left hand corner of the viewport, does nothing if there's no view. |
void |
setViewSize
(
Dimension
newSize)
Sets the size of the view. |
Dimension
|
toViewCoordinates
(
Dimension
size)
Converts a size in pixel coordinates to view coordinates. |
Point
|
toViewCoordinates
(
Point
p)
Converts a point in pixel coordinates to view coordinates. |
void |
updateUI
()
Resets the UI property to a value from the current look and feel. |
Methods inherited from class javax.swing.
JComponent
|
addAncestorListener
,
addNotify
,
addPropertyChangeListener
,
addPropertyChangeListener
,
addVetoableChangeListener
,
computeVisibleRect
,
contains
,
createToolTip
,
disable
,
enable
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
fireVetoableChange
,
getActionForKeyStroke
,
getActionMap
,
getAlignmentX
,
getAlignmentY
,
getAncestorListeners
,
getAutoscrolls
,
getBorder
,
getBounds
,
getClientProperty
,
getComponentGraphics
,
getComponentPopupMenu
,
getConditionForKeyStroke
,
getDebugGraphicsOptions
,
getDefaultLocale
,
getFontMetrics
,
getGraphics
,
getHeight
,
getInheritsPopupMenu
,
getInputMap
,
getInputMap
,
getInputVerifier
,
getListeners
,
getLocation
,
getMaximumSize
,
getMinimumSize
,
getNextFocusableComponent
,
getPopupLocation
getPreferredSize
,
getPreferredSize
getPropertyChangeListeners
,
getPropertyChangeListeners
,
getRegisteredKeyStrokes
,
getRootPane
,
getSize
,
getToolTipLocation
,
getToolTipText
,
getToolTipText
,
getTopLevelAncestor
,
getTransferHandler
,
getVerifyInputWhenFocusTarget
,
getVetoableChangeListeners
,
getVisibleRect
,
getWidth
,
getX
,
getY
,
grabFocus
,
isDoubleBuffered
,
isLightweightComponent
,
isManagingFocus
,
isMaximumSizeSet
,
isMinimumSizeSet
,
isOpaque
,
isPaintingTile
,
isPreferredSizeSet
,
isRequestFocusEnabled
,
isValidateRoot
,
paintBorder
,
paintChildren
,
paintComponent
,
paintImmediately
,
paintImmediately
,
print
,
printAll
,
printBorder
,
printChildren
,
printComponent
,
processComponentKeyEvent
,
processKeyBinding
,
processKeyEvent
,
processMouseEvent
,
processMouseMotionEvent
,
putClientProperty
,
registerKeyboardAction
,
registerKeyboardAction
,
removeAncestorListener
,
removeNotify
,
removePropertyChangeListener
,
removePropertyChangeListener
,
removeVetoableChangeListener
,
repaint
,
requestDefaultFocus
,
requestFocus
,
requestFocus
,
requestFocusInWindow
,
requestFocusInWindow
,
resetKeyboardActions
,
revalidate
,
setActionMap
,
setAlignmentX
,
setAlignmentY
,
setAutoscrolls
,
setBackground
,
setComponentPopupMenu
,
setDebugGraphicsOptions
,
setDefaultLocale
,
setDoubleBuffered
,
setEnabled
,
setFocusTraversalKeys
,
setFont
,
setForeground
,
setInheritsPopupMenu
,
setInputMap
,
setInputVerifier
,
setMaximumSize
,
setMinimumSize
,
setNextFocusableComponent
,
setOpaque
,
setPreferredSize
,
setRequestFocusEnabled
,
setToolTipText
,
setTransferHandler
,
setUI
,
setVerifyInputWhenFocusTarget
,
setVisible
,
unregisterKeyboardAction
,
update
|
Methods inherited from class java.awt.
Container
|
add
,
add
,
add
,
add
,
add
,
addContainerListener
,
addPropertyChangeListener
,
addPropertyChangeListener
,
applyComponentOrientation
,
areFocusTraversalKeysSet
,
countComponents
,
deliverEvent
,
doLayout
,
findComponentAt
,
findComponentAt
,
getComponent
,
getComponentAt
,
getComponentAt
,
getComponentCount
,
getComponents
,
getComponentZOrder
,
getContainerListeners
,
getFocusTraversalKeys
,
getFocusTraversalPolicy
,
getLayout
,
getMousePosition
,
insets
,
invalidate
,
isAncestorOf
,
isFocusCycleRoot
,
isFocusCycleRoot
,
isFocusTraversalPolicyProvider
,
isFocusTraversalPolicySet
,
layout
,
list
,
list
,
locate
,
minimumSize
,
paintComponents
,
preferredSize
,
printComponents
,
processContainerEvent
,
processEvent
,
remove
,
removeAll
,
removeContainerListener
,
setComponentZOrder
setFocusCycleRoot
,
setFocusCycleRoot
setFocusTraversalKeys
,
setFocusTraversalPolicy
,
setFocusTraversalPolicyProvider
,
setLayout
,
transferFocusBackward
,
transferFocusDownCycle
,
validate
,
validateTree
|
Methods inherited from class java.awt.
Component
|
action
,
add
,
addComponentListener
,
addFocusListener
,
addHierarchyBoundsListener
,
addHierarchyListener
,
addInputMethodListener
,
addKeyListener
,
addMouseListener
,
addMouseMotionListener
,
addMouseWheelListener
,
bounds
,
checkImage
,
checkImage
,
coalesceEvents
,
contains
,
createImage
,
createImage
,
createVolatileImage
,
createVolatileImage
,
disableEvents
,
dispatchEvent
,
enable
,
enableEvents
,
enableInputMethods
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
firePropertyChange
,
getBackground
,
getBounds
,
getColorModel
,
getComponentListeners
,
getComponentOrientation
,
getCursor
,
getDropTarget
,
getFocusCycleRootAncestor
,
getFocusListeners
,
getFocusTraversalKeysEnabled
,
getFont
,
getFontMetrics
,
getForeground
,
getGraphicsConfiguration
,
getHierarchyBoundsListeners
,
getHierarchyListeners
,
getIgnoreRepaint
,
getInputContext
,
getInputMethodListeners
,
getInputMethodRequests
,
getKeyListeners
,
getLocale
,
getLocation
,
getLocationOnScreen
,
getMouseListeners
,
getMouseMotionListeners
,
getMousePosition
,
getMouseWheelListeners
,
getName
,
getParent
,
getPeer
,
getPropertyChangeListeners
,
getPropertyChangeListeners
,
getSize
,
getToolkit
,
getTreeLock
,
gotFocus
,
handleEvent
,
hasFocus
,
hide
,
imageUpdate
,
inside
,
isBackgroundSet
,
isCursorSet
,
isDisplayable
,
isEnabled
,
isFocusable
,
isFocusOwner
,
isFocusTraversable
,
isFontSet
,
isForegroundSet
,
isLightweight
,
isMaximumSizeSet
,
isMinimumSizeSet
,
isPreferredSizeSet
,
isShowing
,
isValid
,
isVisible
,
keyDown
,
keyUp
,
list
,
list
,
list
,
location
,
lostFocus
,
mouseDown
,
mouseDrag
,
mouseEnter
,
mouseExit
,
mouseMove
,
mouseUp
,
move
,
nextFocus
,
paintAll
,
postEvent
,
prepareImage
,
prepareImage
,
processComponentEvent
,
processFocusEvent
,
processHierarchyBoundsEvent
,
processHierarchyEvent
,
processInputMethodEvent
,
processMouseEvent
,
processMouseWheelEvent
,
remove
,
removeComponentListener
,
removeFocusListener
,
removeHierarchyBoundsListener
,
removeHierarchyListener
,
removeInputMethodListener
,
removeKeyListener
,
removeMouseListener
,
removeMouseMotionListener
,
removeMouseWheelListener
,
removePropertyChangeListener
,
removePropertyChangeListener
,
repaint
,
repaint
,
repaint
,
resize
,
resize
,
setBounds
,
setBounds
,
setComponentOrientation
,
setCursor
,
setDropTarget
,
setFocusable
,
setFocusTraversalKeysEnabled
,
setIgnoreRepaint
,
setLocale
,
setLocation
,
setLocation
,
setName
,
setSize
,
setSize
,
show
,
show
,
size
,
toString
,
transferFocus
,
transferFocusUpCycle
|
isViewSizeSet
protected boolean isViewSizeSet
-
True when the viewport dimensions have been determined. The default is false.
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
-
Deprecated.
As of Java 2 platform v1.3
-
True when this viewport is maintaining an offscreen image of its contents, so that some scrolling can take place using fast "bit-blit" operations instead of by accessing the view object to construct the display. The default is false.
-
See Also:
-
setScrollMode(int)
backingStoreImage
protected transient Image backingStoreImage
-
The view image used for a backing store.
scrollUnderway
protected boolean scrollUnderway
-
The scrollUnderway flag is used for components like JList. When the downarrow key is pressed on a JList and the selected cell is the last in the list, the scrollpane autoscrolls. Here, the old selected cell needs repainting and so we need a flag to make the viewport do the optimized painting only when there is an explicit call to setViewPosition(Point). When setBounds is called through other routes, the flag is off and the view repaints normally. Another approach would be to remove this from the JViewport class and have the JList manage this case by using setBackingStoreEnabled. The default is false.
BLIT_SCROLL_MODE
public static final int BLIT_SCROLL_MODE
-
Use graphics.copyArea to implement scrolling. This is the fastest for most applications.
-
Since:
-
1.3
-
See Also:
-
setScrollMode(int)
,
Constant Field Values
BACKINGSTORE_SCROLL_MODE
public static final int BACKINGSTORE_SCROLL_MODE
-
Draws viewport contents into an offscreen image. This was previously the default mode for JTable. This mode may offer advantages over "blit mode" in some cases, but it requires a large chunk of extra RAM.
-
Since:
-
1.3
-
See Also:
-
setScrollMode(int)
,
Constant Field Values
SIMPLE_SCROLL_MODE
public static final int SIMPLE_SCROLL_MODE
-
This mode uses the very simple method of redrawing the entire contents of the scrollpane each time it is scrolled. This was the default behavior in Swing 1.0 and Swing 1.1. Either of the other two options will provide better performance in most cases.
-
Since:
-
1.3
-
See Also:
-
setScrollMode(int)
,
Constant Field Values
JViewport
public JViewport()
-
Creates a JViewport.
getUI
public ViewportUI getUI()
-
Returns the L&F object that renders this component.
-
-
-
Returns:
-
a ViewportUI object
setUI
public void setUI(ViewportUI ui)
-
Sets the L&F object that renders this component.
-
-
-
Parameters:
-
ui - the ViewportUI L&F object
-
See Also:
-
UIDefaults.getUI(javax.swing.JComponent)
updateUI
public void updateUI()
-
Resets the UI property to a value from the current look and feel.
-
-
Overrides:
-
updateUI
in class
JComponent
-
-
See Also:
-
JComponent.updateUI()
getUIClassID
public String getUIClassID()
-
Returns a string that specifies the name of the L&F class that renders this component.
-
-
Overrides:
-
getUIClassID
in class
JComponent
-
-
Returns:
-
the string "ViewportUI"
-
See Also:
-
JComponent.getUIClassID()
,
UIDefaults.getUI(javax.swing.JComponent)
addImpl
protected void addImpl(Component child,
Object constraints,
int index)
-
Sets the JViewport's one lightweight child, which can be null. (Since there is only one child which occupies the entire viewport, the constraints and index arguments are ignored.)
-
-
Overrides:
-
addImpl
in class
Container
-
-
Parameters:
-
child - the lightweight child of the viewport
-
constraints - the constraints to be respected
-
index - the index
-
See Also:
-
setView(java.awt.Component)
remove
public void remove(Component child)
-
Removes the Viewports one lightweight child.
-
-
Overrides:
-
remove
in class
Container
-
-
Parameters:
-
child - the component to be removed
-
See Also:
-
setView(java.awt.Component)
scrollRectToVisible
public void scrollRectToVisible(Rectangle contentRect)
-
Scrolls the view so that Rectangle within the view becomes visible.
This attempts to validate the view before scrolling if the view is currently not valid - isValid returns false. To avoid excessive validation when the containment hierarchy is being created this will not validate if one of the ancestors does not have a peer, or there is no validate root ancestor, or one of the ancestors is not a Window or Applet.
Note that this method will not scroll outside of the valid viewport; for example, if contentRect is larger than the viewport, scrolling will be confined to the viewport's bounds.
-
-
Overrides:
-
scrollRectToVisible
in class
JComponent
-
-
Parameters:
-
contentRect - the Rectangle to display
-
See Also:
-
JComponent.isValidateRoot()
,
Component.isValid()
,
Component.getPeer()
setBorder
public final void setBorder(Border border)
-
The viewport "scrolls" its 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 create a JViewport with a border, add it to a JPanel that has a border.
Note: If border is non-null, this method will throw an exception as borders are not supported on a JViewPort.
-
-
Overrides:
-
setBorder
in class
JComponent
-
-
Parameters:
-
border - the Border to set
-
Throws:
-
IllegalArgumentException
- this method is not implemented
-
See Also:
-
Border
,
CompoundBorder
getInsets
public final Insets getInsets()
-
Returns the insets (border) dimensions as (0,0,0,0), since borders are not supported on a JViewport.
-
-
Overrides:
-
getInsets
in class
JComponent
-
-
Returns:
-
a Rectange of zero dimension and zero origin
-
See Also:
-
setBorder(javax.swing.border.Border)
getInsets
public final Insets getInsets(Insets insets)
-
Returns an Insets object containing this JViewports inset values. The passed-in Insets object will be reinitialized, and all existing values within this object are overwritten.
-
-
Overrides:
-
getInsets
in class
JComponent
-
-
Parameters:
-
insets - the Insets object which can be reused
-
Returns:
-
this viewports inset values
-
See Also:
-
getInsets()
isOptimizedDrawingEnabled
public boolean isOptimizedDrawingEnabled()
-
The JViewport overrides the default implementation of this method (in JComponent) to return false. This ensures that the drawing machinery will call the Viewport's paint implementation rather than messaging the JViewport's children directly.
-
-
Overrides:
-
isOptimizedDrawingEnabled
in class
JComponent
-
-
Returns:
-
false
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.
The term "blit" is the pronounced version of the PDP-10 BLT (BLock Transfer) instruction, which copied a block of bits. (In case you were curious.)
-
-
Overrides:
-
paint
in class
JComponent
-
-
Parameters:
-
g - the Graphics context within which to paint
-
See Also:
-
JComponent.paintComponent(java.awt.Graphics)
,
JComponent.paintBorder(java.awt.Graphics)
,
JComponent.paintChildren(java.awt.Graphics)
,
JComponent.getComponentGraphics(java.awt.Graphics)
,
JComponent.repaint(long, int, int, int, int)
reshape
public void reshape(int x,
int y,
int w,
int h)
-
Sets the bounds of this viewport. If the viewport's width or height has changed, fire a StateChanged event.
-
-
Overrides:
-
reshape
in class
JComponent
-
-
Parameters:
-
x - left edge of the origin
-
y - top edge of the origin
-
w - width in pixels
-
h - height in pixels
-
See Also:
-
JComponent.reshape(int, int, int, int)
setScrollMode
public void setScrollMode(int mode)
-
Used to control the method of scrolling the viewport contents. You may want to change this mode to get maximum performance for your use case.
-
-
-
Parameters:
-
mode - one of the following values:
-
JViewport.BLIT_SCROLL_MODE
-
JViewport.BACKINGSTORE_SCROLL_MODE
-
JViewport.SIMPLE_SCROLL_MODE
-
Since:
-
1.3
-
See Also:
-
BLIT_SCROLL_MODE
,
BACKINGSTORE_SCROLL_MODE
,
SIMPLE_SCROLL_MODE
getScrollMode
public int getScrollMode()
-
Returns the current scrolling mode.
-
-
-
Returns:
-
the scrollMode property
-
Since:
-
1.3
-
See Also:
-
setScrollMode(int)
isBackingStoreEnabled
public boolean isBackingStoreEnabled()
-
Deprecated.
As of Java 2 platform v1.3, replaced by getScrollMode().
-
Returns true if this viewport is maintaining an offscreen image of its contents.
-
-
-
Returns:
-
true if scrollMode is BACKINGSTORE_SCROLL_MODE
setBackingStoreEnabled
public void setBackingStoreEnabled(boolean enabled)
-
Deprecated.
As of Java 2 platform v1.3, replaced by setScrollMode().
-
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.
-
-
-
Parameters:
-
enabled - if true, maintain an offscreen backing store
getView
public Component getView()
-
Returns the JViewport's one child or null.
-
-
-
Returns:
-
the viewports child, or null if none exists
-
See Also:
-
setView(java.awt.Component)
setView
public void setView(Component view)
-
Sets the JViewport's one lightweight child (view), which can be null.
-
-
-
Parameters:
-
view - the viewport's new lightweight child
-
See Also:
-
getView()
getViewSize
public Dimension getViewSize()
-
If the view's size hasn't been explicitly set, return the preferred size, otherwise return the view's current size. If there is no view, return 0,0.
-
-
-
Returns:
-
a Dimension object specifying the size of the view
setViewSize
public void setViewSize(Dimension newSize)
-
Sets the size of the view. A state changed event will be fired.
-
-
-
Parameters:
-
newSize - a Dimension object specifying the new size of the view
getViewPosition
public Point getViewPosition()
-
Returns the view coordinates that appear in the upper left hand corner of the viewport, or 0,0 if there's no view.
-
-
-
Returns:
-
a Point object giving the upper left coordinates
setViewPosition
public void setViewPosition(Point p)
-
Sets the view coordinates that appear in the upper left hand corner of the viewport, does nothing if there's no view.
-
-
-
Parameters:
-
p - a Point object giving the upper left coordinates
getViewRect
public Rectangle getViewRect()
-
Returns a rectangle whose origin is getViewPosition and size is getExtentSize. This is the visible part of the view, in view coordinates.
-
-
-
Returns:
-
a Rectangle giving the visible part of the view using 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 parameters are modified to return the values required for the blit.
-
-
-
Parameters:
-
dx - the horizontal delta
-
dy - the vertical delta
-
blitFrom - the Point we're blitting from
-
blitTo - the Point we're blitting to
-
blitSize - the Dimension of the area to blit
-
blitPaint - the area to blit
-
Returns:
-
true if the parameters are modified and we're ready to blit; false otherwise
getExtentSize
public Dimension getExtentSize()
-
Returns the size of the visible part of the view in view coordinates.
-
-
-
Returns:
-
a Dimension object giving the size of the view
toViewCoordinates
public Dimension toViewCoordinates(Dimension size)
-
Converts a size in pixel coordinates to view coordinates. Subclasses of viewport that support "logical coordinates" will override this method.
-
-
-
Parameters:
-
size - a Dimension object using pixel coordinates
-
Returns:
-
a Dimension object converted to view coordinates
toViewCoordinates
public Point toViewCoordinates(Point p)
-
Converts a point in pixel coordinates to view coordinates. Subclasses of viewport that support "logical coordinates" will override this method.
-
-
-
Parameters:
-
p - a Point object using pixel coordinates
-
Returns:
-
a Point object converted to view coordinates
setExtentSize
public void setExtentSize(Dimension newExtent)
-
Sets the size of the visible part of the view using view coordinates.
-
-
-
Parameters:
-
newExtent - a Dimension object specifying the size of the view
createViewListener
protected JViewport.ViewListener createViewListener()
-
Creates a listener for the view.
-
-
-
Returns:
-
a ViewListener
createLayoutManager
protected LayoutManager createLayoutManager()
-
Subclassers can override this to install a different layout manager (or null) in the constructor.
Returns the LayoutManager to install on the JViewport.
Returns a new ViewportLayout object.
-
-
-
Returns:
-
a LayoutManager
addChangeListener
public void addChangeListener(ChangeListener l)
-
Adds a ChangeListener to the list that is notified each time the view's size, position, or the viewport's extent size has changed.
-
-
-
Parameters:
-
l - the ChangeListener to add
-
See Also:
-
removeChangeListener(javax.swing.event.ChangeListener)
,
setViewPosition(java.awt.Point)
,
setViewSize(java.awt.Dimension)
,
setExtentSize(java.awt.Dimension)
removeChangeListener
public void removeChangeListener(ChangeListener l)
-
Removes a ChangeListener from the list that's notified each time the views size, position, or the viewports extent size has changed.
-
-
-
Parameters:
-
l - the ChangeListener to remove
-
See Also:
-
addChangeListener(javax.swing.event.ChangeListener)
getChangeListeners
public ChangeListener[] getChangeListeners()
-
Returns an array of all the ChangeListeners added to this JViewport with addChangeListener().
-
-
-
Returns:
-
all of the ChangeListeners added or an empty array if no listeners have been added
-
Since:
-
1.4
fireStateChanged
protected void fireStateChanged()
-
Notifies all ChangeListeners when the views size, position, or the viewports extent size has changed.
-
-
-
See Also:
-
addChangeListener(javax.swing.event.ChangeListener)
,
removeChangeListener(javax.swing.event.ChangeListener)
,
EventListenerList
repaint
public void repaint(long tm,
int x,
int y,
int w,
int h)
-
Always repaint in the parents coordinate system to make sure only one paint is performed by the RepaintManager.
-
-
Overrides:
-
repaint
in class
JComponent
-
-
Parameters:
-
tm - maximum time in milliseconds before update
-
x - the x coordinate (pixels over from left)
-
y - the y coordinate (pixels down from top)
-
w - the width
-
h - the height
-
See Also:
-
Component.update(java.awt.Graphics)
paramString
protected String paramString()
-
Returns a string representation of this JViewport. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null.
-
-
Overrides:
-
paramString
in class
JComponent
-
-
Returns:
-
a string representation of this JViewport
firePropertyChange
protected void firePropertyChange(String propertyName,
Object oldValue,
Object newValue)
-
Notifies listeners of a property change. This is subclassed to update the windowBlit property. (The putClientProperty property is final).
-
-
Overrides:
-
firePropertyChange
firePropertyChange
in class
Component
JComponent
-
-
Parameters:
-
propertyName - a string containing the property name
-
oldValue - the old value of the property
-
newValue - the new value of the property
-
See Also:
-
PropertyChangeSupport
getAccessibleContext
public AccessibleContext getAccessibleContext()
-
Gets the AccessibleContext associated with this JViewport. For viewports, the AccessibleContext takes the form of an AccessibleJViewport. A new AccessibleJViewport instance is created if necessary.
-
-
Specified by:
-
getAccessibleContext
in interface
Accessible
-
Overrides:
-
getAccessibleContext
in class
JComponent
-
-
Returns:
-
an AccessibleJViewport that serves as the AccessibleContext of this JViewport