V
- the type of JLayer
's view componentImageObserver
, MenuContainer
, PropertyChangeListener
, Serializable
, EventListener
, Accessible
, Scrollable
public final class JLayer<V extends Component> extends JComponent implements Scrollable, PropertyChangeListener, Accessible
JLayer
is a universal decorator for Swing components which enables you to implement various advanced painting effects as well as receive notifications of all AWTEvent
s generated within its borders. JLayer
delegates the handling of painting and input events to a LayerUI
object, which performs the actual decoration.
The custom painting implemented in the LayerUI
and events notification work for the JLayer itself and all its subcomponents. This combination enables you to enrich existing components by adding new advanced functionality such as temporary locking of a hierarchy, data tips for compound components, enhanced mouse scrolling etc and so on.
JLayer
is a good solution if you only need to do custom painting over compound component or catch input events from its subcomponents.
import javax.swing.*; import javax.swing.plaf.LayerUI; import java.awt.*; public class JLayerSample { private static JLayer<JComponent> createLayer() { // This custom layerUI will fill the layer with translucent green // and print out all mouseMotion events generated within its borders LayerUI<JComponent> layerUI = new LayerUI<JComponent>() { public void paint(Graphics g, JComponent c) { // paint the layer as is super.paint(g, c); // fill it with the translucent green g.setColor(new Color(0, 128, 0, 128)); g.fillRect(0, 0, c.getWidth(), c.getHeight()); } public void installUI(JComponent c) { super.installUI(c); // enable mouse motion events for the layer's subcomponents ((JLayer) c).setLayerEventMask(AWTEvent.MOUSE_MOTION_EVENT_MASK); } public void uninstallUI(JComponent c) { super.uninstallUI(c); // reset the layer event mask ((JLayer) c).setLayerEventMask(0); } // overridden method which catches MouseMotion events public void eventDispatched(AWTEvent e, JLayer<? extends JComponent> l) { System.out.println("AWTEvent detected: " + e); } }; // create a component to be decorated with the layer JPanel panel = new JPanel(); panel.add(new JButton("JButton")); // create the layer for the panel using our custom layerUI return new JLayer<JComponent>(panel, layerUI); } private static void createAndShowGUI() { final JFrame frame = new JFrame(); frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); // work with the layer as with any other Swing component frame.add(createLayer()); frame.setSize(200, 200); frame.setLocationRelativeTo(null); frame.setVisible(true); } public static void main(String[] args) throws Exception { SwingUtilities.invokeAndWait(new Runnable() { public void run() { createAndShowGUI(); } }); } }Note:
JLayer
doesn't support the following methods: Container.add(java.awt.Component)
Container.add(String, java.awt.Component)
Container.add(java.awt.Component, int)
Container.add(java.awt.Component, Object)
Container.add(java.awt.Component, Object, int)
UnsupportedOperationException
to be thrown, to add a component to JLayer
use setView(Component)
or setGlassPane(JPanel)
.JComponent.AccessibleJComponent
Container.AccessibleAWTContainer
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
Constructor | Description |
---|---|
JLayer() |
|
JLayer |
Creates a new JLayer object with default LayerUI . |
JLayer |
Creates a new JLayer object with the specified view component and LayerUI object. |
Modifier and Type | Method | Description |
---|---|---|
protected void |
addImpl |
This method is not supported by JLayer and always throws UnsupportedOperationException
|
JPanel |
createGlassPane() |
Called by the constructor methods to create a default glassPane . |
void |
doLayout() |
Delegates its functionality to the LayerUI.doLayout(JLayer) method, if LayerUI is set. |
AccessibleContext |
getAccessibleContext() |
Gets the AccessibleContext associated with this JLayer . |
Border |
getBorder() |
Delegates its functionality to the getView().getBorder() method, if the view component is an instance of javax.swing.JComponent , otherwise returns null . |
JPanel |
getGlassPane() |
Returns the JLayer 's glassPane component or null . |
long |
getLayerEventMask() |
Returns the bitmap of event mask to receive by this JLayer and its LayerUI . |
Dimension |
getPreferredScrollableViewportSize() |
Returns the preferred size of the viewport for a view component. |
int |
getScrollableBlockIncrement |
Returns a scroll increment, which is required for components that display logical rows or columns in order to completely expose one block of rows or columns, depending on the value of orientation. |
boolean |
getScrollableTracksViewportHeight() |
Returns false to indicate that the height of the viewport does not determine the height of the layer, unless the preferred height of the layer is smaller than the height of the viewport. |
boolean |
getScrollableTracksViewportWidth() |
Returns false to indicate that the width of the viewport does not determine the width of the layer, unless the preferred width of the layer is smaller than the width of the viewport. |
int |
getScrollableUnitIncrement |
Returns a scroll increment, which is required for components that display logical rows or columns in order to completely expose one new row or column, depending on the value of orientation. |
LayerUI |
getUI() |
Returns the LayerUI for this JLayer . |
V |
getView() |
Returns the JLayer 's view component or null . |
boolean |
imageUpdate |
Delegates its functionality to the LayerUI.imageUpdate(java.awt.Image, int, int, int, int, int, JLayer) method, if the LayerUI is set. |
boolean |
isOptimizedDrawingEnabled() |
The JLayer overrides the default implementation of this method (in JComponent ) to return false . |
protected boolean |
isPaintingOrigin() |
Always returns true to cause painting to originate from JLayer , or one of its ancestors. |
void |
paint |
Delegates all painting to the LayerUI object. |
protected void |
paintComponent |
This method is empty, because all painting is done by paint(Graphics) and ComponentUI.update(Graphics, JComponent) methods |
void |
paintImmediately |
Delegates its functionality to the LayerUI.paintImmediately(int, int, int, int, JLayer) method, if LayerUI is set. |
void |
propertyChange |
This method gets called when a bound property is changed. |
void |
setBorder |
Delegates its functionality to the getView().setBorder(Border) method, if the view component is an instance of javax.swing.JComponent , otherwise this method is a no-op. |
void |
setGlassPane |
Sets the JLayer 's glassPane component, which can be null . |
void |
setLayerEventMask |
Enables the events from JLayer and all its descendants defined by the specified event mask parameter to be delivered to the LayerUI.eventDispatched(AWTEvent, JLayer) method. |
void |
setLayout |
Sets the layout manager for this container. |
void |
setUI |
Sets the LayerUI which will perform painting and receive input events for this JLayer . |
void |
setView |
Sets the JLayer 's view component, which can be null . |
void |
updateUI() |
Delegates its functionality to the LayerUI.updateUI(JLayer) method, if LayerUI is set. |
addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getUIClassID, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isPaintingForPrint, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paintBorder, paintChildren, paintImmediately, paramString, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, 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
add, add, add, add, add, addContainerListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, 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, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, transferFocusDownCycle, validate, validateTree
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, 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, 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
public JLayer()
public JLayer(V view)
JLayer
object with default LayerUI
.view
- the component to be decorated by this JLayer
public JLayer(V view, LayerUI<V> ui)
JLayer
object with the specified view component and LayerUI
object.view
- the component to be decoratedui
- the LayerUI
delegate to be used by this JLayer
public V getView()
JLayer
's view component or null
. JLayer
's view component or null
if none existspublic void setView(V view)
JLayer
's view component, which can be null
. view
- the view component for this JLayer
public void setUI(LayerUI<? super V> ui)
LayerUI
which will perform painting and receive input events for this JLayer
.ui
- the LayerUI
for this JLayer
public LayerUI<? super V> getUI()
LayerUI
for this JLayer
.getUI
in class JComponent
LayerUI
for this JLayer
public JPanel getGlassPane()
JLayer
's glassPane component or null
. JLayer
's glassPane component or null
if none existspublic void setGlassPane(JPanel glassPane)
JLayer
's glassPane component, which can be null
. glassPane
- the glassPane component of this JLayer
public JPanel createGlassPane()
glassPane
. By default this method creates a new JPanel with visibility set to true and opacity set to false.glassPane
public void setLayout(LayoutManager mgr)
Note: If mgr
is non-null
, this method will throw an exception as layout managers are not supported on a JLayer
.
setLayout
in class Container
mgr
- the specified layout managerIllegalArgumentException
- this method is not supportedpublic void setBorder(Border border)
getView().setBorder(Border)
method, if the view component is an instance of javax.swing.JComponent
, otherwise this method is a no-op.setBorder
in class JComponent
border
- the border to be rendered for the view
componentpublic Border getBorder()
getView().getBorder()
method, if the view component is an instance of javax.swing.JComponent
, otherwise returns null
.getBorder
in class JComponent
view
componentprotected void addImpl(Component comp, Object constraints, int index)
JLayer
and always throws UnsupportedOperationException
addImpl
in class Container
comp
- the component to be addedconstraints
- an object expressing layout constraints for this componentindex
- the position in the container's list at which to insert the component, where -1
means append to the endUnsupportedOperationException
- this method is not supportedprotected boolean isPaintingOrigin()
true
to cause painting to originate from JLayer
, or one of its ancestors.isPaintingOrigin
in class JComponent
public void paintImmediately(int x, int y, int w, int h)
LayerUI.paintImmediately(int, int, int, int, JLayer)
method, if LayerUI
is set.paintImmediately
in class JComponent
x
- the x value of the region to be paintedy
- the y value of the region to be paintedw
- the width of the region to be paintedh
- the height of the region to be paintedpublic boolean imageUpdate(Image img, int infoflags, int x, int y, int w, int h)
LayerUI.imageUpdate(java.awt.Image, int, int, int, int, int, JLayer)
method, if the LayerUI
is set.imageUpdate
in interface ImageObserver
imageUpdate
in class Component
img
- the image being observedinfoflags
- see imageUpdate
for more informationx
- the x coordinatey
- the y coordinatew
- the widthh
- the heightfalse
if the infoflags indicate that the image is completely loaded; true
otherwise.public void paint(Graphics g)
LayerUI
object.paint
in class JComponent
g
- the Graphics
to render toprotected void paintComponent(Graphics g)
paint(Graphics)
and ComponentUI.update(Graphics, JComponent)
methodspaintComponent
in class JComponent
g
- the Graphics
object to protectpublic boolean isOptimizedDrawingEnabled()
JLayer
overrides the default implementation of this method (in JComponent
) to return false
. This ensures that the drawing machinery will call the JLayer
's paint
implementation rather than messaging the JLayer
's children directly.isOptimizedDrawingEnabled
in class JComponent
public void propertyChange(PropertyChangeEvent evt)
propertyChange
in interface PropertyChangeListener
evt
- A PropertyChangeEvent object describing the event source and the property that has changed.public void setLayerEventMask(long layerEventMask)
LayerUI.eventDispatched(AWTEvent, JLayer)
method. Events are delivered provided that LayerUI
is set for this JLayer
and the JLayer
is displayable.
The following example shows how to correctly use this method in the LayerUI
implementations:
public void installUI(JComponent c) { super.installUI(c); JLayer l = (JLayer) c; // this LayerUI will receive only key and focus events l.setLayerEventMask(AWTEvent.KEY_EVENT_MASK | AWTEvent.FOCUS_EVENT_MASK); } public void uninstallUI(JComponent c) { super.uninstallUI(c); JLayer l = (JLayer) c; // JLayer must be returned to its initial state l.setLayerEventMask(0); }By default
JLayer
receives no events and its event mask is 0
.layerEventMask
- the bitmask of event types to receivepublic long getLayerEventMask()
JLayer
and its LayerUI
. It means that LayerUI.eventDispatched(AWTEvent, JLayer)
method will only receive events that match the event mask.
By default JLayer
receives no events.
JLayer
public void updateUI()
LayerUI.updateUI(JLayer)
method, if LayerUI
is set.updateUI
in class JComponent
public Dimension getPreferredScrollableViewportSize()
If the view component of this layer implements Scrollable
, this method delegates its implementation to the view component.
getPreferredScrollableViewportSize
in interface Scrollable
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction)
If the view component of this layer implements Scrollable
, this method delegates its implementation to the view component.
getScrollableBlockIncrement
in interface Scrollable
visibleRect
- The view area visible within the viewportorientation
- Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.direction
- Less than zero to scroll up/left, greater than zero for down/right.public boolean getScrollableTracksViewportHeight()
false
to indicate that the height of the viewport does not determine the height of the layer, unless the preferred height of the layer is smaller than the height of the viewport. If the view component of this layer implements Scrollable
, this method delegates its implementation to the view component.
getScrollableTracksViewportHeight
in interface Scrollable
public boolean getScrollableTracksViewportWidth()
false
to indicate that the width of the viewport does not determine the width of the layer, unless the preferred width of the layer is smaller than the width of the viewport. If the view component of this layer implements Scrollable
, this method delegates its implementation to the view component.
getScrollableTracksViewportWidth
in interface Scrollable
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction)
Scrolling containers, like JScrollPane
, will use this method each time the user requests a unit scroll.
If the view component of this layer implements Scrollable
, this method delegates its implementation to the view component.
getScrollableUnitIncrement
in interface Scrollable
visibleRect
- The view area visible within the viewportorientation
- Either SwingConstants.VERTICAL or SwingConstants.HORIZONTAL.direction
- Less than zero to scroll up/left, greater than zero for down/right.public void doLayout()
LayerUI.doLayout(JLayer)
method, if LayerUI
is set.public AccessibleContext getAccessibleContext()
JLayer
.getAccessibleContext
in interface Accessible
getAccessibleContext
in class Component
JLayer
.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/swing/JLayer.html