Class JViewport
- java.lang.Object
-
- java.awt.Component
-
- java.awt.Container
-
- javax.swing.JComponent
-
- javax.swing.JViewport
- All Implemented Interfaces:
-
ImageObserver
,MenuContainer
,Serializable
,Accessible
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 are 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 acopyArea
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.
copyArea
s. 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: Swing is not thread safe. For more information see Swing's Threading Policy.
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™ has been added to the java.beans
package. Please see XMLEncoder
.
- Since:
- 1.2
- See Also:
-
JScrollPane
, Serialized Form
Nested Class Summary
Modifier and Type | Class | Description |
---|---|---|
protected class | JViewport.AccessibleJViewport | This class implements accessibility support for the |
protected class | JViewport.ViewListener | A listener for the view. |
Nested classes/interfaces declared in class javax.swing.JComponent
JComponent.AccessibleJComponent
Nested classes/interfaces declared in class java.awt.Container
Container.AccessibleAWTContainer
Nested classes/interfaces declared in class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
Field Summary
Modifier and Type | Field | Description |
---|---|---|
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 |
protected boolean | isViewSizeSet | True when the viewport dimensions have been determined. |
protected Point | lastPaintPosition | The last |
protected boolean | scrollUnderway | The |
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 declared in class javax.swing.JComponent
listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW
Fields declared in class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
Fields declared in interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
Constructor Summary
Constructor | Description |
---|---|
JViewport() | Creates a |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | addChangeListener(ChangeListener l) | Adds a |
protected void | addImpl(Component child,
Object constraints,
int index) | Sets the |
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 |
protected LayoutManager | createLayoutManager() | Subclassers can override this to install a different layout manager (or |
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 |
AccessibleContext | getAccessibleContext() | Gets the AccessibleContext associated with this JViewport. |
ChangeListener[] | getChangeListeners() | Returns an array of all the |
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 |
Insets | getInsets(Insets insets) | Returns an |
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 |
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 |
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 |
protected boolean | isPaintingOrigin() | Returns true if scroll mode is a |
void | paint(Graphics g) | Depending on whether the |
protected String | paramString() | Returns a string representation of this |
void | remove(Component child) | Removes the |
void | removeChangeListener(ChangeListener l) | Removes a |
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 |
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 |
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 |
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 declared in class javax.swing.JComponent
addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBorder, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isPaintingForPrint, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paintBorder, paintChildren, paintComponent, paintImmediately, paintImmediately, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, 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 declared in 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, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, transferFocusDownCycle, validate, validateTree
Methods declared in 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, firePropertyChange, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, 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, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setMixingCutoutShape, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Field Detail
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
@Deprecated protected boolean backingStore
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
Constructor Detail
JViewport
public JViewport()
Creates a JViewport
.
Method Detail
getUI
public ViewportUI getUI()
Returns the L&F object that renders this component.
- Overrides:
-
getUI
in classJComponent
- Returns:
- a
ViewportUI
object - Since:
- 1.3
setUI
@BeanProperty(hidden=true, visualUpdate=true, description="The UI object that implements the Component\'s LookAndFeel.") public void setUI(ViewportUI ui)
Sets the L&F object that renders this component.
- Parameters:
-
ui
- theViewportUI
L&F object - Since:
- 1.3
- 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 classJComponent
- 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 classJComponent
- 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 classContainer
- Parameters:
-
child
- the lightweightchild
of the viewport -
constraints
- theconstraints
to be respected -
index
- the index - See Also:
setView(java.awt.Component)
remove
public void remove(Component child)
Removes the Viewport
s one lightweight child.
- Overrides:
-
remove
in classContainer
- 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 classJComponent
- Parameters:
-
contentRect
- theRectangle
to display - See Also:
-
JComponent.isValidateRoot()
,Component.isValid()
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 classJComponent
- Parameters:
-
border
- theBorder
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 classJComponent
- Returns:
- a
Rectangle
of zero dimension and zero origin - See Also:
setBorder(javax.swing.border.Border)
getInsets
@BeanProperty(expert=true) public final Insets getInsets(Insets insets)
Returns an Insets
object containing this JViewport
s inset values. The passed-in Insets
object will be reinitialized, and all existing values within this object are overwritten.
- Overrides:
-
getInsets
in classJComponent
- Parameters:
-
insets
- theInsets
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 classJComponent
- Returns:
- false
isPaintingOrigin
protected boolean isPaintingOrigin()
Returns true if scroll mode is a BACKINGSTORE_SCROLL_MODE
to cause painting to originate from JViewport
, or one of its ancestors. Otherwise returns false
.
- Overrides:
-
isPaintingOrigin
in classJComponent
- Returns:
- true if scroll mode is a
BACKINGSTORE_SCROLL_MODE
. - See Also:
JComponent.isPaintingOrigin()
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 classJComponent
- Parameters:
-
g
- theGraphics
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 classJComponent
- 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
@BeanProperty(bound=false, enumerationValues={"JViewport.BLIT_SCROLL_MODE","JViewport.BACKINGSTORE_SCROLL_MODE","JViewport.SIMPLE_SCROLL_MODE"}, description="Method of moving contents for incremental scrolls.") 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
@Deprecated public boolean isBackingStoreEnabled()
getScrollMode()
.Returns true
if this viewport is maintaining an offscreen image of its contents.
- Returns:
-
true
ifscrollMode
isBACKINGSTORE_SCROLL_MODE
setBackingStoreEnabled
@Deprecated public void setBackingStoreEnabled(boolean enabled)
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
- aDimension
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
- aPoint
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
- thePoint
we're blitting from -
blitTo
- thePoint
we're blitting to -
blitSize
- theDimension
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
- aDimension
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
- aPoint
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
- aDimension
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
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
- theChangeListener
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
- theChangeListener
to remove - See Also:
addChangeListener(javax.swing.event.ChangeListener)
getChangeListeners
public ChangeListener[] getChangeListeners()
Returns an array of all the ChangeListener
s added to this JViewport with addChangeListener().
- Returns:
- all of the
ChangeListener
s 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 classJComponent
- Parameters:
-
tm
- maximum time in milliseconds before update -
x
- thex
coordinate (pixels over from left) -
y
- they
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 classJComponent
- 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
in classComponent
- Parameters:
-
propertyName
- a string containing the property name -
oldValue
- the old value of the property -
newValue
- the new value of the property
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 interfaceAccessible
- Overrides:
-
getAccessibleContext
in classComponent
- Returns:
- an AccessibleJViewport that serves as the AccessibleContext of this JViewport