Class JViewport

public static final int BACKINGSTORE_SCROLL_MODE

Field Value:

2

public static final int BLIT_SCROLL_MODE

Field Value:

1

public static final int SIMPLE_SCROLL_MODE

Field Value:

0

protected boolean backingStore

Deprecated. since JDK 1.3

This flag indicates whether we use a backing store for drawing.

protected Image backingStoreImage

The backingstore image used for the backingstore and blit scroll methods.

protected boolean isViewSizeSet

protected Point lastPaintPosition

The position at which the view has been drawn the last time. This is used to determine the bittable area.

protected boolean scrollUnderway

public JViewport()

Creates a new JComponent instance.

public void addChangeListener(ChangeListener listener)

protected void addImpl(Component comp,
                       Object constraints,
                       int index)

This method is called by all the add() methods to perform the actual adding of the component. Subclasses who wish to perform their own processing when a component is added should override this method. Any subclass doing this must call the superclass version of this method in order to ensure proper functioning of the container.

Overrides:

addImpl in interface Container

Parameters:

comp - The component to be added.

constraints - The layout constraints for this component, or null if there are no constraints.

index - The index in the component list to insert this child at, or -1 to add at the end of the list.

Throws:

ArrayIndexOutOfBoundsException - If the specified index is invalid.

protected boolean computeBlit(int dx,
                              int dy,
                              Point blitFrom,
                              Point blitTo,
                              Dimension blitSize,
                              Rectangle blitPaint)

Computes the parameters for the blitting scroll method. dx and dy specifiy the X and Y offset by which the viewport is scrolled. All other arguments are output parameters and are filled by this method. blitFrom holds the position of the blit rectangle in the viewport rectangle before scrolling, blitTo where the blitArea is copied to. blitSize holds the size of the blit area and blitPaint is the area of the view that needs to be painted. This method returns true if blitting is possible and false if the viewport has to be repainted completetly without blitting.

Parameters:

dx - the horizontal delta

dy - the vertical delta

blitFrom - the position from where to blit; set by this method

blitTo - the position where to blit area is copied to; set by this method

blitSize - the size of the blitted area; set by this method

blitPaint - the area that needs repainting; set by this method

Returns:

true if blitting is possible, false otherwise

protected LayoutManager createLayoutManager()

Creates the LayoutManager that is used for this viewport. Override this method if you want to use a custom LayoutManager.

Returns:

a LayoutManager to use for this viewport

protected JViewport.ViewListener createViewListener()

Creates a JViewport.ViewListener that is supposed to listen for size changes on the view component.

Returns:

a ViewListener instance

protected void fireStateChanged()

public AccessibleContext getAccessibleContext()

Returns the accessible context for this JViewport. This will be an instance of JViewport.AccessibleJViewport.

Specified by:

getAccessibleContext in interface Accessible

Overrides:

getAccessibleContext in interface JComponent

Returns:

the accessible context for this JViewport

public ChangeListener[] getChangeListeners()

public Dimension getExtentSize()

public final Insets getInsets()

Get the component's insets, which are calculated from the JComponent.border property. If the border is null, calls Container.getInsets().

Overrides:

getInsets in interface JComponent

Returns:

The component's current insets

public final Insets getInsets(Insets insets)

Get the component's insets, which are calculated from the JComponent.border property. If the border is null, calls Container.getInsets(). The passed-in Insets value will be used as the return value, if possible.

Overrides:

getInsets in interface JComponent

Parameters:

insets - Return value object to reuse, if possible

Returns:

The component's current insets

public int getScrollMode()

public ViewportUI getUI()

This method returns the viewport's UI delegate.

Returns:

The viewport's UI delegate.

public String getUIClassID()

This method returns the String ID of the UI class of Separator.

Overrides:

getUIClassID in interface JComponent

Returns:

The UI class' String ID.

public Component getView()

public Point getViewPosition()

Get the viewport's position in view space. Despite confusing name, this really does return the viewport's (0,0) position in view space, not the view's position.

public Rectangle getViewRect()

public Dimension getViewSize()

Returns the viewSize when set, or the preferred size of the set Component view. If no viewSize and no Component view is set an empty Dimension is returned.

public boolean isBackingStoreEnabled()

Deprecated. 1.4

public boolean isOptimizedDrawingEnabled()

Overridden to return false, so the JViewport's paint method gets called instead of directly calling the children. This is necessary in order to get a useful clipping and translation on the children.

Overrides:

isOptimizedDrawingEnabled in interface JComponent

Returns:

false

public void paint(Graphics g)

Paint the component. This is a delicate process, and should only be called from the repaint thread, under control of the RepaintManager. Client code should usually call JComponent.repaint() to trigger painting.

The body of the paint call involves calling JComponent.paintComponent(Graphics), JComponent.paintBorder(Graphics), and JComponent.paintChildren(Graphics) in order. If you want to customize painting behavior, you should override one of these methods rather than paint.

For more details on the painting sequence, see this article.

Overrides:

paint in interface JComponent

Parameters:

g - The graphics context to paint with

See Also:

JComponent.paintImmediately(Rectangle)

public void removeChangeListener(ChangeListener listener)

public void repaint(long tm,
                    int x,
                    int y,
                    int w,
                    int h)

Forward repaint to parent to make sure only one paint is performed by the RepaintManager.

Overrides:

repaint in interface JComponent

Parameters:

tm - number of milliseconds to defer the repaint request

x - the X coordinate of the upper left corner of the dirty area

y - the Y coordinate of the upper left corner of the dirty area

w - the width of the dirty area

h - the height of the dirty area

public void reshape(int x,
                    int y,
                    int w,
                    int h)

Moves and resizes the component.

Overrides:

reshape in interface JComponent

Parameters:

x - the new horizontal location

y - the new vertial location

w - the new width

h - the new height

public void scrollRectToVisible(Rectangle contentRect)

Scrolls the view so that contentRect becomes visible.

Overrides:

scrollRectToVisible in interface JComponent

Parameters:

contentRect - the rectangle to make visible within the view

public void setBackingStoreEnabled(boolean b)

Deprecated. 1.4

public final void setBorder(Border border)

Set the value of the JComponent.border property.

Overrides:

setBorder in interface JComponent

Parameters:

See Also:

JComponent.getBorder()