OpenJDK 27 · javax.swing.JViewport · APIdia, the JavaDoc alternative

Modifier and Type	Class and Description
protected class	JViewport.AccessibleJViewport This class implements accessibility support for the `JViewport` class.
pack-priv static class	JViewport.BackingStoreMultiResolutionImage
protected class	JViewport.ViewListener A listener for the view.

Modifier and Type	Field and Description
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.
public static final int	BACKINGSTORE_SCROLL_MODE Draws viewport contents into an offscreen image.
protected transient Image	backingStoreImage The view image used for a backing store.
public static final int	BLIT_SCROLL_MODE Use `graphics.copyArea` to implement scrolling.
private transient ChangeEvent	changeEvent
pack-priv static final Object	EnableWindowBlit Property used to indicate window blitting should not be done.
private boolean	hasHadValidView Whether or not a valid view has been installed.
private transient boolean	inBlitPaint Set to true in paintView when paint is invoked.
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.
private transient boolean	repaintAll This is set to true in `setViewPosition` if doing a window blit and the viewport is obscured.
private transient Timer	repaintTimer Instead of directly invoking repaint, a `Timer` is started and when it fires, repaint is invoked.
private int	scrollMode
protected boolean	scrollUnderway The `scrollUnderway` flag is used for components like `JList`.
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.
private static final String	uiClassID Hides javax.swing.JComponent.uiClassID.
private boolean	viewChanged When view is changed we have to synchronize scrollbar values with viewport (see the BasicScrollPaneUI#syncScrollPaneWithViewport method).
private ComponentListener	viewListener
private transient boolean	waitingForRepaint This is set to true in paint, if `repaintAll` is true and the clip rectangle does not match the bounds.

Access	Constructor and Description
public	JViewport() Creates a `JViewport`.

Method Summary

Modifier and Type	Method and Description
public void	addChangeListener(ChangeListener the `ChangeListener` to add 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 the lightweight `child` of the viewport child, Object the `constraints` to be respected constraints, int the index index) Overrides java.awt.Container.addImpl. Sets the `JViewport`'s one lightweight child, which can be `null`.
private void	blitDoubleBuffered(JComponent view, Graphics g, int clipX, int clipY, int clipW, int clipH, int blitFromX, int blitFromY, int blitToX, int blitToY, int blitW, int blitH)
private boolean	canUseWindowBlitter() Returns true if the viewport is not obscured by one of its ancestors, or its ancestors children and if the viewport is showing.
protected boolean	Returns: true if the parameters are modified and we're ready to blit; false otherwise computeBlit(int the horizontal delta dx, int the vertical delta dy, Point the `Point` we're blitting from blitFrom, Point the `Point` we're blitting to blitTo, Dimension the `Dimension` of the area to blit blitSize, Rectangle the area to blit 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	Returns: a `LayoutManager` createLayoutManager() Subclassers can override this to install a different layout manager (or `null`) in the constructor.
private Timer	createRepaintTimer()
private Image	createScaledImage(final int width, final int height, int scaledWidth, int scaledHeight)
protected JViewport.ViewListener	Returns: a `ViewListener` createViewListener() Creates a listener for the view.
protected void	firePropertyChange(String a string containing the property name propertyName, Object the old value of the property oldValue, Object the new value of the property newValue) Overrides java.awt.Component.firePropertyChange. Notifies listeners of a property change.
protected void	fireStateChanged() Notifies all `ChangeListeners` when the views size, position, or the viewports extent size has changed.
private void	flushViewDirtyRegion(Graphics the `Graphics` context within which to paint g, Rectangle dirty) If the repaint manager has a dirty region for the view, the view is asked to paint.
public AccessibleContext	Returns: an AccessibleJViewport that serves as the AccessibleContext of this JViewport getAccessibleContext() Overrides java.awt.Component.getAccessibleContext. Implements javax.accessibility.Accessible.getAccessibleContext. Gets the AccessibleContext associated with this JViewport.
private Graphics	getBackingStoreGraphics(Graphics g)
public ChangeListener[]	Returns: all of the `ChangeListener`s added or an empty array if no listeners have been added getChangeListeners() Returns an array of all the `ChangeListener`s added to this JViewport with addChangeListener().
public Dimension	Returns: a `Dimension` object giving the size of the view getExtentSize() Returns the size of the visible part of the view in view coordinates.
public final Insets	Returns: a `Rectangle` of zero dimension and zero origin getInsets() Overrides javax.swing.JComponent.getInsets. Returns the insets (border) dimensions as (0,0,0,0), since borders are not supported on a `JViewport`.
public final Insets	Returns: this viewports inset values getInsets(Insets the `Insets` object which can be reused insets) Overrides javax.swing.JComponent.getInsets. Returns an `Insets` object containing this `JViewport`s inset values.
public int	Returns: the `scrollMode` property getScrollMode() Returns the current scrolling mode.
public ViewportUI	Returns: a `ViewportUI` object getUI() Overrides javax.swing.JComponent.getUI. Returns the L&F object that renders this component.
public String	Returns: the string "ViewportUI" getUIClassID() Overrides javax.swing.JComponent.getUIClassID. Returns a string that specifies the name of the L&F class that renders this component.
public Component	Returns: the viewports child, or `null` if none exists getView() Returns the `JViewport`'s one child or `null`.
private Point	getViewLocation() Only used by the paint method below.
public Point	Returns: a `Point` object giving the upper left coordinates getViewPosition() Returns the view coordinates that appear in the upper left hand corner of the viewport, or 0,0 if there's no view.
public Rectangle	Returns: a `Rectangle` giving the visible part of the view using view coordinates. getViewRect() Returns a rectangle whose origin is `getViewPosition` and size is `getExtentSize`.
public Dimension	Returns: a `Dimension` object specifying the size of the view getViewSize() If the view's size hasn't been explicitly set, return the preferred size, otherwise return the view's current size.
public boolean	Returns: `true` if `scrollMode` is `BACKINGSTORE_SCROLL_MODE` 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.
private boolean	isBlitting()
private boolean	isFPScale()
public boolean	Returns: false isOptimizedDrawingEnabled() Overrides javax.swing.JComponent.isOptimizedDrawingEnabled. The `JViewport` overrides the default implementation of this method (in `JComponent`) to return false.
protected boolean	Returns: true if scroll mode is a `BACKINGSTORE_SCROLL_MODE`. isPaintingOrigin() Overrides javax.swing.JComponent.isPaintingOrigin. Returns true if scroll mode is a `BACKINGSTORE_SCROLL_MODE` to cause painting to originate from `JViewport`, or one of its ancestors.
private boolean	needsRepaintAfterBlit() Returns true if the component needs to be completely repainted after a blit and a paint is received.
public void	paint(Graphics the `Graphics` context within which to paint g) Overrides javax.swing.JComponent.paint. 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.
private void	paintViaBackingStore(Graphics g)
private void	paintViaBackingStore(Graphics g, Rectangle oClip)
private void	paintView(Graphics the `Graphics` context within which to paint g) Called to paint the view, usually when `blitPaint` can not blit.
protected String	Returns: a string representation of this `JViewport` paramString() Overrides javax.swing.JComponent.paramString. Returns a string representation of this `JViewport`.
private int	positionAdjustment(int parentWidth, int childWidth, int childAt)
public void	remove(Component child) Overrides java.awt.Container.remove. Removes the `Viewport`s one lightweight child.
public void	removeChangeListener(ChangeListener the `ChangeListener` to remove l) Removes a `ChangeListener` from the list that's notified each time the views size, position, or the viewports extent size has changed.
public void	repaint(long maximum time in milliseconds before update tm, int the `x` coordinate (pixels over from left) x, int the `y` coordinate (pixels down from top) y, int the width w, int the height h) Overrides javax.swing.JComponent.repaint. Always repaint in the parents coordinate system to make sure only one paint is performed by the `RepaintManager`.
public void	reshape(int left edge of the origin x, int top edge of the origin y, int width in pixels w, int height in pixels h) Overrides javax.swing.JComponent.reshape. Sets the bounds of this viewport.
public void	scrollRectToVisible(Rectangle the `Rectangle` to display contentRect) Overrides javax.swing.JComponent.scrollRectToVisible. Scrolls the view so that `Rectangle` within the view becomes visible.
public void	setBackingStoreEnabled(boolean if true, maintain an offscreen backing store 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.
public final void	setBorder(Border the `Border` to set border) Overrides javax.swing.JComponent.setBorder. 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).
public void	setExtentSize(Dimension a `Dimension` object specifying the size of the view newExtent) Sets the size of the visible part of the view using view coordinates.
public void	setScrollMode(int one of the following values: JViewport.BLIT_SCROLL_MODE JViewport.BACKINGSTORE_SCROLL_MODE JViewport.SIMPLE_SCROLL_MODE mode) Used to control the method of scrolling the viewport contents.
public void	setUI(ViewportUI the `ViewportUI` L&F object ui) Sets the L&F object that renders this component.
public void	setView(Component the viewport's new lightweight child view) Sets the `JViewport`'s one lightweight child (`view`), which can be `null`.
public void	setViewPosition(Point a `Point` object giving the upper left coordinates p) Sets the view coordinates that appear in the upper left hand corner of the viewport, does nothing if there's no view.
public void	setViewSize(Dimension a `Dimension` object specifying the new size of the view newSize) Sets the size of the view.
public Dimension	Returns: a `Dimension` object converted to view coordinates toViewCoordinates(Dimension a `Dimension` object using pixel coordinates size) Converts a size in pixel coordinates to view coordinates.
public Point	Returns: a `Point` object converted to view coordinates toViewCoordinates(Point a `Point` object using pixel coordinates p) Converts a point in pixel coordinates to view coordinates.
public void	updateUI() Overrides javax.swing.JComponent.updateUI. Resets the UI property to a value from the current look and feel.
private void	validateView() Ascends the `Viewport`'s parents stopping when a component is found that returns `true` to `isValidateRoot`.
private boolean	Returns: true if blitting succeeded; otherwise false windowBlitPaint(Graphics the `Graphics` context within which to paint g) Used when blitting.

Inherited from javax.swing.JComponent:: _paintImmediately addAncestorListener addNotify addVetoableChangeListener alwaysOnTop checkIfChildObscuredBySibling clientPropertyChanged componentInputMapChanged computeVisibleRect computeVisibleRect compWriteObjectNotify contains createToolTip disable dndDone dropLocationForPoint enable firePropertyChange firePropertyChange firePropertyChange fireVetoableChange getActionForKeyStroke getActionMap getActionMap getAlignmentX getAlignmentY getAncestorListeners getAutoscrolls getBaseline getBaselineResizeBehavior getBorder getBounds getClientProperty getComponentGraphics getComponentPopupMenu getConditionForKeyStroke getCreatedDoubleBuffer getDebugGraphicsOptions getDefaultLocale getFontMetrics getGraphics getGraphicsInvoked getHeight getInheritsPopupMenu getInputMap getInputMap getInputMap getInputVerifier getListeners getLocation getManagingFocusBackwardTraversalKeys getManagingFocusForwardTraversalKeys getMaximumSize getMinimumSize getNextFocusableComponent getPopupLocation getPreferredSize getRegisteredKeyStrokes getRootPane getSize getToolTipLocation getToolTipText getToolTipText getTopLevelAncestor getTransferHandler getVerifyInputWhenFocusTarget getVetoableChangeListeners getVisibleRect getWidth getWriteObjCounter getX getY grabFocus hide isDoubleBuffered isLightweightComponent isManagingFocus isOpaque isPainting isPaintingForPrint isPaintingTile isRequestFocusEnabled isValidateRoot paintBorder paintChildren paintComponent paintForceDoubleBuffered paintImmediately paintImmediately paintToOffscreen print printAll printBorder printChildren printComponent processComponentKeyEvent processKeyBinding processKeyBindings processKeyBindingsForAllComponents processKeyEvent processMouseEvent processMouseMotionEvent putClientProperty rectangleIsObscured registerKeyboardAction registerKeyboardAction removeAncestorListener removeNotify removeVetoableChangeListener repaint requestDefaultFocus requestFocus requestFocus requestFocusInWindow requestFocusInWindow resetKeyboardActions revalidate safelyGetGraphics safelyGetGraphics setActionMap setAlignmentX setAlignmentY setAutoscrolls setBackground setComponentPopupMenu setCreatedDoubleBuffer setDebugGraphicsOptions setDefaultLocale setDoubleBuffered setDropLocation setEnabled setFocusTraversalKeys setFont setForeground setInheritsPopupMenu setInputMap setInputVerifier setMaximumSize setMinimumSize setNextFocusableComponent setOpaque setPaintingChild setPreferredSize setRequestFocusEnabled setToolTipText setTransferHandler setUI setUIProperty setVerifyInputWhenFocusTarget setVisible setWriteObjCounter shouldDebugGraphics superProcessMouseMotionEvent unregisterKeyboardAction update

public Class JViewport

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