- 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 thesetOpaque
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 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 JavaBeansTM has been added to the
java.beans
package. Please seeXMLEncoder
.- See Also:
JScrollPane
-
-
Nested Class Summary
Nested Classes Modifier and Type Class and Description protected class
JViewport.AccessibleJViewport
This class implements accessibility support for theJViewport
class.protected class
JViewport.ViewListener
A listener for the view.-
Nested classes/interfaces inherited from class javax.swing.JComponent
JComponent.AccessibleJComponent
-
Nested classes/interfaces inherited from class java.awt.Container
Container.AccessibleAWTContainer
-
Nested classes/interfaces inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
-
-
Field Summary
Fields Modifier and Type Field and Description protected boolean
backingStore
Deprecated.As of Java 2 platform v1.3static 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
Usegraphics.copyArea
to implement scrolling.protected boolean
isViewSizeSet
True when the viewport dimensions have been determined.protected Point
lastPaintPosition
The lastviewPosition
that we've painted, so we know how much of the backing store image is valid.protected boolean
scrollUnderway
ThescrollUnderway
flag is used for components likeJList
.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 class javax.swing.JComponent
accessibleContext, listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW
-
Fields inherited from class java.awt.Component
BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
-
-
Constructor Summary
Constructors Constructor and Description JViewport()
Creates aJViewport
.
-
Method Summary
Methods Modifier and Type Method and Description void
addChangeListener(ChangeListener l)
Adds aChangeListener
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 theJViewport
's one lightweight child, which can benull
.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 containsoldLoc
in the upper left hand corner and we're scrolling tonewLoc
.protected LayoutManager
createLayoutManager()
Subclassers can override this to install a different layout manager (ornull
) 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 allChangeListeners
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 theChangeListener
s 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 aJViewport
.Insets
getInsets(Insets insets)
Returns anInsets
object containing thisJViewport
s 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 theJViewport
's one child ornull
.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 isgetViewPosition
and size isgetExtentSize
.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 bygetScrollMode()
.boolean
isOptimizedDrawingEnabled()
TheJViewport
overrides the default implementation of this method (inJComponent
) to return false.protected boolean
isPaintingOrigin()
Returns true if scroll mode is aBACKINGSTORE_SCROLL_MODE
to cause painting to originate fromJViewport
, or one of its ancestors.void
paint(Graphics g)
Depending on whether thebackingStore
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 thisJViewport
.void
remove(Component child)
Removes theViewport
s one lightweight child.void
removeChangeListener(ChangeListener l)
Removes aChangeListener
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 theRepaintManager
.void
reshape(int x, int y, int w, int h)
Sets the bounds of this viewport.void
scrollRectToVisible(Rectangle contentRect)
Scrolls the view so thatRectangle
within the view becomes visible.void
setBackingStoreEnabled(boolean enabled)
Deprecated.As of Java 2 platform v1.3, replaced bysetScrollMode()
.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 theJViewport
's one lightweight child (view
), which can benull
.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, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, 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, hide, 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 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, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, 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, 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, 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, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle
-
-
-
-
Field Detail
-
isViewSizeSet
protected boolean isViewSizeSet
True when the viewport dimensions have been determined. The default is false.
-
lastPaintPosition
protected Point lastPaintPosition
The lastviewPosition
that we've painted, so we know how much of the backing store image is valid.
-
backingStore
@Deprecated protected boolean backingStore
Deprecated. As of Java 2 platform v1.3True 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 isfalse
.- See Also:
setScrollMode(int)
-
backingStoreImage
protected transient Image backingStoreImage
The view image used for a backing store.
-
scrollUnderway
protected boolean scrollUnderway
ThescrollUnderway
flag is used for components likeJList
. When the downarrow key is pressed on aJList
and the selected cell is the last in the list, thescrollpane
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 tosetViewPosition(Point)
. WhensetBounds
is called through other routes, the flag is off and the view repaints normally. Another approach would be to remove this from theJViewport
class and have theJList
manage this case by usingsetBackingStoreEnabled
. The default isfalse
.
-
BLIT_SCROLL_MODE
public static final int BLIT_SCROLL_MODE
Usegraphics.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 forJTable
. 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
-
-
Method Detail
-
getUI
public ViewportUI getUI()
Returns the L&F object that renders this component.- Returns:
- a
ViewportUI
object - Since:
- 1.3
-
setUI
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 theJViewport
's one lightweight child, which can benull
. (Since there is only one child which occupies the entire viewport, theconstraints
andindex
arguments are ignored.)- Overrides:
addImpl
in classContainer
- Parameters:
child
- the lightweightchild
of the viewportconstraints
- theconstraints
to be respectedindex
- the index- See Also:
setView(java.awt.Component)
-
remove
public void remove(Component child)
Removes theViewport
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 thatRectangle
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 aWindow
orApplet
.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()
,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 aJViewport
with a border, add it to aJPanel
that has a border.Note: If
border
is non-null
, this method will throw an exception as borders are not supported on aJViewPort
.- 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 aJViewport
.- Overrides:
getInsets
in classJComponent
- Returns:
- a
Rectange
of zero dimension and zero origin - See Also:
setBorder(javax.swing.border.Border)
-
getInsets
public final Insets getInsets(Insets insets)
Returns anInsets
object containing thisJViewport
s inset values. The passed-inInsets
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()
TheJViewport
overrides the default implementation of this method (inJComponent
) to return false. This ensures that the drawing machinery will call theViewport
'spaint
implementation rather than messaging theJViewport
's children directly.- Overrides:
isOptimizedDrawingEnabled
in classJComponent
- Returns:
- false
-
isPaintingOrigin
protected boolean isPaintingOrigin()
Returns true if scroll mode is aBACKINGSTORE_SCROLL_MODE
to cause painting to originate fromJViewport
, or one of its ancestors. Otherwise returnsfalse
.- Overrides:
isPaintingOrigin
in classJComponent
- Returns:
- true if if scroll mode is a
BACKINGSTORE_SCROLL_MODE
. - See Also:
JComponent.isPaintingOrigin()
-
paint
public void paint(Graphics g)
Depending on whether thebackingStore
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 aStateChanged
event.- Overrides:
reshape
in classJComponent
- Parameters:
x
- left edge of the originy
- top edge of the originw
- width in pixelsh
- 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
@Deprecated public boolean isBackingStoreEnabled()
Deprecated. As of Java 2 platform v1.3, replaced bygetScrollMode()
.Returnstrue
if this viewport is maintaining an offscreen image of its contents.- Returns:
true
ifscrollMode
isBACKINGSTORE_SCROLL_MODE
-
setBackingStoreEnabled
@Deprecated public void setBackingStoreEnabled(boolean enabled)
Deprecated. As of Java 2 platform v1.3, replaced bysetScrollMode()
.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 theviewPosition
. Rather than repainting the entire viewport we useGraphics.copyArea
to effect some of the scroll.- Parameters:
enabled
- if true, maintain an offscreen backing store
-
getView
public Component getView()
Returns theJViewport
's one child ornull
.- Returns:
- the viewports child, or
null
if none exists - See Also:
setView(java.awt.Component)
-
setView
public void setView(Component view)
Sets theJViewport
's one lightweight child (view
), which can benull
.- 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 isgetViewPosition
and size isgetExtentSize
. 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 containsoldLoc
in the upper left hand corner and we're scrolling tonewLoc
. The parameters are modified to return the values required for the blit.- Parameters:
dx
- the horizontal deltady
- the vertical deltablitFrom
- thePoint
we're blitting fromblitTo
- thePoint
we're blitting toblitSize
- theDimension
of the area to blitblitPaint
- 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 (ornull
) in the constructor. Returns theLayoutManager
to install on theJViewport
.- Returns:
- a
LayoutManager
-
addChangeListener
public void addChangeListener(ChangeListener l)
Adds aChangeListener
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 aChangeListener
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 theChangeListener
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 allChangeListeners
when the views size, position, or the viewports extent size has changed.
-
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 theRepaintManager
.- Overrides:
repaint
in classJComponent
- Parameters:
tm
- maximum time in milliseconds before updatex
- thex
coordinate (pixels over from left)y
- they
coordinate (pixels down from top)w
- the widthh
- the height- See Also:
Component.update(java.awt.Graphics)
-
paramString
protected String paramString()
Returns a string representation of thisJViewport
. 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 benull
.- 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 thewindowBlit
property. (TheputClientProperty
property is final).- Overrides:
firePropertyChange
in classComponent
- Parameters:
propertyName
- a string containing the property nameoldValue
- the old value of the propertynewValue
- 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 classJComponent
- Returns:
- an AccessibleJViewport that serves as the AccessibleContext of this JViewport
-
-
Document created the 11/06/2005, last modified the 04/03/2020
Source of the printed document:https://www.gaudry.be/en/java-api-rf-javax/swing/JViewport.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.