Class JLayer<V extends Component>
- Type Parameters:
V- the type ofJLayer's view component
- All Implemented Interfaces:
ImageObserver,MenuContainer,PropertyChangeListener,Serializable,EventListener,Accessible,Scrollable
JLayer is a universal decorator for Swing components
which enables you to implement various advanced painting effects as well as
receive notifications of all AWTEvents 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).- Since:
- 1.7
- See Also:
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Nested Class Summary
Nested classes/interfaces declared in class javax.swing.JComponent
JComponent.AccessibleJComponentNested classes/interfaces declared in class java.awt.Container
Container.AccessibleAWTContainerNested classes/interfaces declared in class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy -
Field Summary
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_WINDOWFields declared in class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENTFields declared in interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected voidThis method is not supported byJLayerand always throwsUnsupportedOperationExceptionCalled by the constructor methods to create a defaultglassPane.voiddoLayout()Delegates its functionality to theLayerUI.doLayout(JLayer)method, ifLayerUIis set.Gets the AccessibleContext associated with thisJLayer.Delegates its functionality to thegetView().getBorder()method, if the view component is an instance ofjavax.swing.JComponent, otherwise returnsnull.Returns theJLayer's glassPane component ornull.longReturns the bitmap of event mask to receive by thisJLayerand itsLayerUI.Returns the preferred size of the viewport for a view component.intgetScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) 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.booleanReturnsfalseto 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.booleanReturnsfalseto 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.intgetScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) 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.getUI()Returns theLayerUIfor thisJLayer.getView()Returns theJLayer's view component ornull.booleanimageUpdate(Image img, int infoflags, int x, int y, int w, int h) Delegates its functionality to theLayerUI.imageUpdate(java.awt.Image, int, int, int, int, int, JLayer)method, if theLayerUIis set.booleanTheJLayeroverrides the default implementation of this method (inJComponent) to returnfalse.protected booleanAlways returnstrueto cause painting to originate fromJLayer, or one of its ancestors.voidDelegates all painting to theLayerUIobject.protected voidThis method is empty, because all painting is done bypaint(Graphics)andComponentUI.update(Graphics, JComponent)methodsvoidpaintImmediately(int x, int y, int w, int h) Delegates its functionality to theLayerUI.paintImmediately(int, int, int, int, JLayer)method, ifLayerUIis set.voidThis method gets called when a bound property is changed.voidDelegates its functionality to thegetView().setBorder(Border)method, if the view component is an instance ofjavax.swing.JComponent, otherwise this method is a no-op.voidsetGlassPane(JPanel glassPane) Sets theJLayer's glassPane component, which can benull.voidsetLayerEventMask(long layerEventMask) Enables the events from JLayer and all its descendants defined by the specified event mask parameter to be delivered to theLayerUI.eventDispatched(AWTEvent, JLayer)method.voidsetLayout(LayoutManager mgr) Sets the layout manager for this container.voidSets theLayerUIwhich will perform painting and receive input events for thisJLayer.voidSets theJLayer's view component, which can benull.voidupdateUI()Delegates its functionality to theLayerUI.updateUI(JLayer)method, ifLayerUIis set.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, 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, updateMethods declared in class java.awt.Container
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, validateTreeMethods 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, 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
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Constructor Details
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JLayer
public JLayer()- See Also:
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JLayer
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JLayer
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Method Details
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getView
Returns theJLayer's view component ornull.
This is a bound property.- Returns:
- the
JLayer's view component ornullif none exists - See Also:
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setView
Sets theJLayer's view component, which can benull.
This is a bound property.- Parameters:
view- the view component for thisJLayer- See Also:
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setUI
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getUI
Returns theLayerUIfor thisJLayer.- Overrides:
getUIin classJComponent- Returns:
- the
LayerUIfor thisJLayer
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getGlassPane
Returns theJLayer's glassPane component ornull.
This is a bound property.- Returns:
- the
JLayer's glassPane component ornullif none exists - See Also:
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setGlassPane
Sets theJLayer's glassPane component, which can benull.
This is a bound property.- Parameters:
glassPane- the glassPane component of thisJLayer- See Also:
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createGlassPane
Called by the constructor methods to create a defaultglassPane. By default this method creates a new JPanel with visibility set to true and opacity set to false.- Returns:
- the default
glassPane
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setLayout
Sets the layout manager for this container. This method is overridden to prevent the layout manager from being set.Note: If
mgris non-null, this method will throw an exception as layout managers are not supported on aJLayer.- Overrides:
setLayoutin classContainer- Parameters:
mgr- the specified layout manager- Throws:
IllegalArgumentException- this method is not supported- See Also:
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setBorder
Delegates its functionality to thegetView().setBorder(Border)method, if the view component is an instance ofjavax.swing.JComponent, otherwise this method is a no-op.- Overrides:
setBorderin classJComponent- Parameters:
border- the border to be rendered for theviewcomponent- See Also:
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getBorder
Delegates its functionality to thegetView().getBorder()method, if the view component is an instance ofjavax.swing.JComponent, otherwise returnsnull.- Overrides:
getBorderin classJComponent- Returns:
- the border object for the
viewcomponent - See Also:
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addImpl
This method is not supported byJLayerand always throwsUnsupportedOperationException- Overrides:
addImplin classContainer- Parameters:
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-1means append to the end- Throws:
UnsupportedOperationException- this method is not supported- See Also:
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isPaintingOrigin
protected boolean isPaintingOrigin()Always returnstrueto cause painting to originate fromJLayer, or one of its ancestors.- Overrides:
isPaintingOriginin classJComponent- Returns:
- true
- See Also:
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paintImmediately
public void paintImmediately(int x, int y, int w, int h) Delegates its functionality to theLayerUI.paintImmediately(int, int, int, int, JLayer)method, ifLayerUIis set.- Overrides:
paintImmediatelyin classJComponent- Parameters:
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 painted- See Also:
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imageUpdate
Delegates its functionality to theLayerUI.imageUpdate(java.awt.Image, int, int, int, int, int, JLayer)method, if theLayerUIis set.- Specified by:
imageUpdatein interfaceImageObserver- Overrides:
imageUpdatein classComponent- Parameters:
img- the image being observedinfoflags- seeimageUpdatefor more informationx- the x coordinatey- the y coordinatew- the widthh- the height- Returns:
falseif the infoflags indicate that the image is completely loaded;trueotherwise.- See Also:
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paint
Delegates all painting to theLayerUIobject.- Overrides:
paintin classJComponent- Parameters:
g- theGraphicsto render to- See Also:
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paintComponent
This method is empty, because all painting is done bypaint(Graphics)andComponentUI.update(Graphics, JComponent)methods- Overrides:
paintComponentin classJComponent- Parameters:
g- theGraphicsobject to protect- See Also:
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isOptimizedDrawingEnabled
public boolean isOptimizedDrawingEnabled()TheJLayeroverrides the default implementation of this method (inJComponent) to returnfalse. This ensures that the drawing machinery will call theJLayer'spaintimplementation rather than messaging theJLayer's children directly.- Overrides:
isOptimizedDrawingEnabledin classJComponent- Returns:
- false
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propertyChange
This method gets called when a bound property is changed.- Specified by:
propertyChangein interfacePropertyChangeListener- Parameters:
evt- A PropertyChangeEvent object describing the event source and the property that has changed.
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setLayerEventMask
public void setLayerEventMask(long layerEventMask) Enables the events from JLayer and all its descendants defined by the specified event mask parameter to be delivered to theLayerUI.eventDispatched(AWTEvent, JLayer)method.Events are delivered provided that
LayerUIis set for thisJLayerand theJLayeris displayable.The following example shows how to correctly use this method in the
LayerUIimplementations: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 defaultJLayerreceives no events and its event mask is0.- Parameters:
layerEventMask- the bitmask of event types to receive- See Also:
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getLayerEventMask
public long getLayerEventMask()Returns the bitmap of event mask to receive by thisJLayerand itsLayerUI.It means that
LayerUI.eventDispatched(AWTEvent, JLayer)method will only receive events that match the event mask.By default
JLayerreceives no events.- Returns:
- the bitmask of event types to receive for this
JLayer
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updateUI
public void updateUI()Delegates its functionality to theLayerUI.updateUI(JLayer)method, ifLayerUIis set.- Overrides:
updateUIin classJComponent- See Also:
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getPreferredScrollableViewportSize
Returns the preferred size of the viewport for a view component.If the view component of this layer implements
Scrollable, this method delegates its implementation to the view component.- Specified by:
getPreferredScrollableViewportSizein interfaceScrollable- Returns:
- the preferred size of the viewport for a view component
- See Also:
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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.If the view component of this layer implements
Scrollable, this method delegates its implementation to the view component.- Specified by:
getScrollableBlockIncrementin interfaceScrollable- Parameters:
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.- Returns:
- the "block" increment for scrolling in the specified direction
- See Also:
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getScrollableTracksViewportHeight
public boolean getScrollableTracksViewportHeight()Returnsfalseto 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.- Specified by:
getScrollableTracksViewportHeightin interfaceScrollable- Returns:
- whether the layer should track the height of the viewport
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getScrollableTracksViewportWidth
public boolean getScrollableTracksViewportWidth()Returnsfalseto 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.- Specified by:
getScrollableTracksViewportWidthin interfaceScrollable- Returns:
- whether the layer should track the width of the viewport
- See Also:
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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. Ideally, components should handle a partially exposed row or column by returning the distance required to completely expose the item.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.- Specified by:
getScrollableUnitIncrementin interfaceScrollable- Parameters:
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.- Returns:
- The "unit" increment for scrolling in the specified direction. This value should always be positive.
- See Also:
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doLayout
public void doLayout()Delegates its functionality to theLayerUI.doLayout(JLayer)method, ifLayerUIis set. -
getAccessibleContext
Gets the AccessibleContext associated with thisJLayer.- Specified by:
getAccessibleContextin interfaceAccessible- Overrides:
getAccessibleContextin classComponent- Returns:
- the AccessibleContext associated with this
JLayer.
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