- java.lang.Object
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- javax.swing.plaf.ComponentUI
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- Direct Known Subclasses:
ButtonUI,ColorChooserUI,ComboBoxUI,DesktopIconUI,DesktopPaneUI,FileChooserUI,InternalFrameUI,LabelUI,LayerUI,ListUI,MenuBarUI,OptionPaneUI,PanelUI,PopupMenuUI,ProgressBarUI,RootPaneUI,ScrollBarUI,ScrollPaneUI,SeparatorUI,SliderUI,SpinnerUI,SplitPaneUI,TabbedPaneUI,TableHeaderUI,TableUI,TextUI,ToolBarUI,ToolTipUI,TreeUI,ViewportUI
public abstract class ComponentUI extends Object
The base class for all UI delegate objects in the Swing pluggable look and feel architecture. The UI delegate object for a Swing component is responsible for implementing the aspects of the component that depend on the look and feel. TheJComponentclass invokes methods from this class in order to delegate operations (painting, layout calculations, etc.) that may vary depending on the look and feel installed. Client programs should not invoke methods on this class directly.- See Also:
JComponent,UIManager
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Constructor Summary
Constructors Constructor Description ComponentUI()Sole constructor.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description booleancontains(JComponent c, int x, int y)Returnstrueif the specified x,y location is contained within the look and feel's defined shape of the specified component.static ComponentUIcreateUI(JComponent c)Returns an instance of the UI delegate for the specified component.AccessiblegetAccessibleChild(JComponent c, int i)Returns theithAccessiblechild of the object.intgetAccessibleChildrenCount(JComponent c)Returns the number of accessible children in the object.intgetBaseline(JComponent c, int width, int height)Returns the baseline.Component.BaselineResizeBehaviorgetBaselineResizeBehavior(JComponent c)Returns an enum indicating how the baseline of the component changes as the size changes.DimensiongetMaximumSize(JComponent c)Returns the specified component's maximum size appropriate for the look and feel.DimensiongetMinimumSize(JComponent c)Returns the specified component's minimum size appropriate for the look and feel.DimensiongetPreferredSize(JComponent c)Returns the specified component's preferred size appropriate for the look and feel.voidinstallUI(JComponent c)Configures the specified component appropriately for the look and feel.voidpaint(Graphics g, JComponent c)Paints the specified component appropriately for the look and feel.voiduninstallUI(JComponent c)Reverses configuration which was done on the specified component duringinstallUI.voidupdate(Graphics g, JComponent c)Notifies this UI delegate that it is time to paint the specified component.
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Method Detail
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installUI
public void installUI(JComponent c)
Configures the specified component appropriately for the look and feel. This method is invoked when theComponentUIinstance is being installed as the UI delegate on the specified component. This method should completely configure the component for the look and feel, including the following:- Install default property values for color, fonts, borders, icons, opacity, etc. on the component. Whenever possible, property values initialized by the client program should not be overridden.
- Install a
LayoutManageron the component if necessary. - Create/add any required sub-components to the component.
- Create/install event listeners on the component.
- Create/install a
PropertyChangeListeneron the component in order to detect and respond to component property changes appropriately. - Install keyboard UI (mnemonics, traversal, etc.) on the component.
- Initialize any appropriate instance data.
- Parameters:
c- the component where this UI delegate is being installed- See Also:
uninstallUI(javax.swing.JComponent),JComponent.setUI(javax.swing.plaf.ComponentUI),JComponent.updateUI()
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uninstallUI
public void uninstallUI(JComponent c)
Reverses configuration which was done on the specified component duringinstallUI. This method is invoked when thisUIComponentinstance is being removed as the UI delegate for the specified component. This method should undo the configuration performed ininstallUI, being careful to leave theJComponentinstance in a clean state (no extraneous listeners, look-and-feel-specific property objects, etc.). This should include the following:- Remove any UI-set borders from the component.
- Remove any UI-set layout managers on the component.
- Remove any UI-added sub-components from the component.
- Remove any UI-added event/property listeners from the component.
- Remove any UI-installed keyboard UI from the component.
- Nullify any allocated instance data objects to allow for GC.
- Parameters:
c- the component from which this UI delegate is being removed; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- See Also:
installUI(javax.swing.JComponent),JComponent.updateUI()
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paint
public void paint(Graphics g, JComponent c)
Paints the specified component appropriately for the look and feel. This method is invoked from theComponentUI.updatemethod when the specified component is being painted. Subclasses should override this method and use the specifiedGraphicsobject to render the content of the component.- Parameters:
g- theGraphicscontext in which to paintc- the component being painted; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- See Also:
update(java.awt.Graphics, javax.swing.JComponent)
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update
public void update(Graphics g, JComponent c)
Notifies this UI delegate that it is time to paint the specified component. This method is invoked byJComponentwhen the specified component is being painted.By default this method fills the specified component with its background color if its
opaqueproperty istrue, and then immediately callspaint. In general this method need not be overridden by subclasses; all look-and-feel rendering code should reside in thepaintmethod.- Parameters:
g- theGraphicscontext in which to paintc- the component being painted; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- See Also:
paint(java.awt.Graphics, javax.swing.JComponent),JComponent.paintComponent(java.awt.Graphics)
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getPreferredSize
public Dimension getPreferredSize(JComponent c)
Returns the specified component's preferred size appropriate for the look and feel. Ifnullis returned, the preferred size will be calculated by the component's layout manager instead (this is the preferred approach for any component with a specific layout manager installed). The default implementation of this method returnsnull.- Parameters:
c- the component whose preferred size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- Returns:
- a
Dimensionobject containing given component's preferred size appropriate for the look and feel - See Also:
JComponent.getPreferredSize(),LayoutManager.preferredLayoutSize(java.awt.Container)
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getMinimumSize
public Dimension getMinimumSize(JComponent c)
Returns the specified component's minimum size appropriate for the look and feel. Ifnullis returned, the minimum size will be calculated by the component's layout manager instead (this is the preferred approach for any component with a specific layout manager installed). The default implementation of this method invokesgetPreferredSizeand returns that value.- Parameters:
c- the component whose minimum size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- Returns:
- a
Dimensionobject ornull - See Also:
JComponent.getMinimumSize(),LayoutManager.minimumLayoutSize(java.awt.Container),getPreferredSize(javax.swing.JComponent)
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getMaximumSize
public Dimension getMaximumSize(JComponent c)
Returns the specified component's maximum size appropriate for the look and feel. Ifnullis returned, the maximum size will be calculated by the component's layout manager instead (this is the preferred approach for any component with a specific layout manager installed). The default implementation of this method invokesgetPreferredSizeand returns that value.- Parameters:
c- the component whose maximum size is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components- Returns:
- a
Dimensionobject ornull - See Also:
JComponent.getMaximumSize(),LayoutManager2.maximumLayoutSize(java.awt.Container)
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contains
public boolean contains(JComponent c, int x, int y)
Returnstrueif the specified x,y location is contained within the look and feel's defined shape of the specified component.xandyare defined to be relative to the coordinate system of the specified component. Although a component'sboundsis constrained to a rectangle, this method provides the means for defining a non-rectangular shape within those bounds for the purpose of hit detection.- Parameters:
c- the component where the x,y location is being queried; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple componentsx- the x coordinate of the pointy- the y coordinate of the point- Returns:
trueif the specifiedx,ylocation is contained within the look and feel's defined shape for the given component- See Also:
JComponent.contains(int, int),Component.contains(int, int)
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createUI
public static ComponentUI createUI(JComponent c)
Returns an instance of the UI delegate for the specified component. Each subclass must provide its own staticcreateUImethod that returns an instance of that UI delegate subclass. If the UI delegate subclass is stateless, it may return an instance that is shared by multiple components. If the UI delegate is stateful, then it should return a new instance per component. The default implementation of this method throws an error, as it should never be invoked.- Parameters:
c- aJComponentfor which to create a UI delegate- Returns:
- a
ComponentUIobject forc
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getBaseline
public int getBaseline(JComponent c, int width, int height)
Returns the baseline. The baseline is measured from the top of the component. This method is primarily meant forLayoutManagers to align components along their baseline. A return value less than 0 indicates this component does not have a reasonable baseline and thatLayoutManagers should not align this component on its baseline.This method returns -1. Subclasses that have a meaningful baseline should override appropriately.
- Parameters:
c-JComponentbaseline is being requested forwidth- the width to get the baseline forheight- the height to get the baseline for- Returns:
- baseline or a value < 0 indicating there is no reasonable baseline
- Throws:
NullPointerException- ifcisnullIllegalArgumentException- if width or height is < 0- Since:
- 1.6
- See Also:
JComponent.getBaseline(int,int)
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getBaselineResizeBehavior
public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)
Returns an enum indicating how the baseline of the component changes as the size changes. This method is primarily meant for layout managers and GUI builders.This method returns
BaselineResizeBehavior.OTHER. Subclasses that support a baseline should override appropriately.- Parameters:
c-JComponentto return baseline resize behavior for- Returns:
- an enum indicating how the baseline changes as the component size changes
- Throws:
NullPointerException- ifcisnull- Since:
- 1.6
- See Also:
JComponent.getBaseline(int, int)
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getAccessibleChildrenCount
public int getAccessibleChildrenCount(JComponent c)
Returns the number of accessible children in the object. If all of the children of this object implementAccessible, this method should return the number of children of this object. UIs might wish to override this if they present areas on the screen that can be viewed as components, but actual components are not used for presenting those areas. Note: As of v1.3, it is recommended that developers callComponent.AccessibleAWTComponent.getAccessibleChildrenCount()instead of this method.- Parameters:
c-JComponentfor which to get count of accessible children- Returns:
- the number of accessible children in the object
- See Also:
getAccessibleChild(javax.swing.JComponent, int)
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getAccessibleChild
public Accessible getAccessibleChild(JComponent c, int i)
Returns theithAccessiblechild of the object. UIs might need to override this if they present areas on the screen that can be viewed as components, but actual components are not used for presenting those areas.Note: As of v1.3, it is recommended that developers call
Component.AccessibleAWTComponent.getAccessibleChild()instead of this method.- Parameters:
c- aJComponentfor which to get a child objecti- zero-based index of child- Returns:
- the
ithAccessiblechild of the object - See Also:
getAccessibleChildrenCount(javax.swing.JComponent)
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