Class BasicLabelUI

java.lang.Object

javax.swing.plaf.ComponentUI

javax.swing.plaf.LabelUI

javax.swing.plaf.basic.BasicLabelUI

All Implemented Interfaces:

PropertyChangeListener, EventListener

Direct Known Subclasses:

MetalLabelUI, SynthLabelUI

public class BasicLabelUI
extends LabelUI
implements PropertyChangeListener

A Windows L&F implementation of LabelUI. This implementation is completely static, i.e. there's only one UIView implementation that's shared by all JLabel objects.

Field Summary

Fields

Modifier and Type	Field	Description
protected static BasicLabelUI	labelUI	The default BasicLabelUI instance.

Constructor Summary

Constructors

Constructor	Description
BasicLabelUI()	Constructs a BasicLabelUI.

Method Summary

Modifier and Type	Method	Description
static ComponentUI	createUI(JComponent c)	Returns an instance of BasicLabelUI.
int	getBaseline(JComponent c, int width, int height)	Returns the baseline.
Component.BaselineResizeBehavior	getBaselineResizeBehavior(JComponent c)	Returns an enum indicating how the baseline of the component changes as the size changes.
Dimension	getMaximumSize(JComponent c)	Returns the specified component's maximum size appropriate for the look and feel.
Dimension	getMinimumSize(JComponent c)	Returns the specified component's minimum size appropriate for the look and feel.
Dimension	getPreferredSize(JComponent c)	Returns the specified component's preferred size appropriate for the look and feel.
protected void	installComponents(JLabel c)	Registers components.
protected void	installDefaults(JLabel c)	Installs default properties.
protected void	installKeyboardActions(JLabel l)	Registers keyboard actions.
protected void	installListeners(JLabel c)	Registers listeners.
void	installUI(JComponent c)	Configures the specified component appropriately for the look and feel.
protected String	layoutCL(JLabel label, FontMetrics fontMetrics, String text, Icon icon, Rectangle viewR, Rectangle iconR, Rectangle textR)	Forwards the call to SwingUtilities.layoutCompoundLabel().
void	paint(Graphics g, JComponent c)	Paints the label text with the foreground color, if the label is opaque then paints the entire background with the background color.
protected void	paintDisabledText(JLabel l, Graphics g, String s, int textX, int textY)	Paint clippedText at textX, textY with background.lighter() and then shifted down and to the right by one pixel with background.darker().
protected void	paintEnabledText(JLabel l, Graphics g, String s, int textX, int textY)	Paint clippedText at textX, textY with the labels foreground color.
void	propertyChange(PropertyChangeEvent e)	This method gets called when a bound property is changed.
protected void	uninstallComponents(JLabel c)	Unregisters components.
protected void	uninstallDefaults(JLabel c)	Uninstalls default properties.
protected void	uninstallKeyboardActions(JLabel c)	Unregisters keyboard actions.
protected void	uninstallListeners(JLabel c)	Unregisters listeners.
void	uninstallUI(JComponent c)	Reverses configuration which was done on the specified component during installUI.

Methods inherited from class ComponentUI

contains, getAccessibleChild, getAccessibleChildrenCount, update

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

labelUI

protected static BasicLabelUI labelUI

The default BasicLabelUI instance. This field might not be used. To change the default instance use a subclass which overrides the createUI method, and place that class name in defaults table under the key "LabelUI".

Constructor Details

BasicLabelUI

public BasicLabelUI()

Constructs a BasicLabelUI.

Method Details

layoutCL

protected String layoutCL(JLabel label,
 FontMetrics fontMetrics,
 String text,
 Icon icon,
 Rectangle viewR,
 Rectangle iconR,
 Rectangle textR)

Forwards the call to SwingUtilities.layoutCompoundLabel(). This method is here so that a subclass could do Label specific layout and to shorten the method name a little.

Parameters:

label - an instance of JLabel

fontMetrics - a font metrics

text - a text

icon - an icon

viewR - a bounding rectangle to lay out label

iconR - a bounding rectangle to lay out icon

textR - a bounding rectangle to lay out text

Returns:

a possibly clipped version of the compound labels string

See Also:

• SwingUtilities.layoutCompoundLabel(JComponent, FontMetrics, String, Icon, int, int, int, int, Rectangle, Rectangle, Rectangle, int)

paintEnabledText

protected void paintEnabledText(JLabel l,
 Graphics g,
 String s,
 int textX,
 int textY)

Paint clippedText at textX, textY with the labels foreground color.

Parameters:

l - an instance of JLabel

g - an instance of Graphics

s - a text

textX - an X coordinate

textY - an Y coordinate

See Also:

• paint(Graphics, JComponent)
• paintDisabledText(JLabel, Graphics, String, int, int)

paintDisabledText

protected void paintDisabledText(JLabel l,
 Graphics g,
 String s,
 int textX,
 int textY)

Paint clippedText at textX, textY with background.lighter() and then shifted down and to the right by one pixel with background.darker().

Parameters:

l - an instance of JLabel

g - an instance of Graphics

s - a text

textX - an X coordinate

textY - an Y coordinate

See Also:

• paint(Graphics, JComponent)
• paintEnabledText(JLabel, Graphics, String, int, int)

paint

public void paint(Graphics g,
 JComponent c)

Paints the label text with the foreground color, if the label is opaque then paints the entire background with the background color. The Label text is drawn by paintEnabledText(JLabel, Graphics, String, int, int) or paintDisabledText(JLabel, Graphics, String, int, int). The locations of the label parts are computed by layoutCL(JLabel, FontMetrics, String, Icon, Rectangle, Rectangle, Rectangle).

Overrides:

paint in class ComponentUI

Parameters:

g - the Graphics context in which to paint

c - 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:

• paintEnabledText(JLabel, Graphics, String, int, int)
• paintDisabledText(JLabel, Graphics, String, int, int)
• layoutCL(JLabel, FontMetrics, String, Icon, Rectangle, Rectangle, Rectangle)

getPreferredSize

public Dimension getPreferredSize(JComponent c)

Description copied from class: ComponentUI

Returns the specified component's preferred size appropriate for the look and feel. If null is 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 returns null.

Overrides:

getPreferredSize in class ComponentUI

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 Dimension object containing given component's preferred size appropriate for the look and feel

See Also:

• JComponent.getPreferredSize()
• LayoutManager.preferredLayoutSize(Container)

getMinimumSize

public Dimension getMinimumSize(JComponent c)

Description copied from class: ComponentUI

Returns the specified component's minimum size appropriate for the look and feel. If null is 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 invokes getPreferredSize and returns that value.

Overrides:

getMinimumSize in class ComponentUI

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:

getPreferredSize(c)

See Also:

• JComponent.getMinimumSize()
• LayoutManager.minimumLayoutSize(Container)
• ComponentUI.getPreferredSize(JComponent)

getMaximumSize

public Dimension getMaximumSize(JComponent c)

Description copied from class: ComponentUI

Returns the specified component's maximum size appropriate for the look and feel. If null is 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 invokes getPreferredSize and returns that value.

Overrides:

getMaximumSize in class ComponentUI

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:

getPreferredSize(c)

See Also:

• JComponent.getMaximumSize()
• LayoutManager2.maximumLayoutSize(Container)

getBaseline

public int getBaseline(JComponent c,
 int width,
 int height)

Returns the baseline.

Overrides:

getBaseline in class ComponentUI

Parameters:

c - JComponent baseline is being requested for

width - the width to get the baseline for

height - the height to get the baseline for

Returns:

baseline or a value < 0 indicating there is no reasonable baseline

Throws:

NullPointerException - if c is null

IllegalArgumentException - if width or height is < 0

Since:

1.6

See Also:

• JComponent.getBaseline(int, int)

getBaselineResizeBehavior

public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)

Returns an enum indicating how the baseline of the component changes as the size changes.

Overrides:

getBaselineResizeBehavior in class ComponentUI

Parameters:

c - JComponent to return baseline resize behavior for

Returns:

an enum indicating how the baseline changes as the component size changes

Throws:

NullPointerException - if c is null

Since:

1.6

See Also:

• JComponent.getBaseline(int, int)

installUI

public void installUI(JComponent c)

Description copied from class: ComponentUI

Configures the specified component appropriately for the look and feel. This method is invoked when the ComponentUI instance 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:

1. 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.
2. Install a LayoutManager on the component if necessary.
3. Create/add any required sub-components to the component.
4. Create/install event listeners on the component.
5. Create/install a PropertyChangeListener on the component in order to detect and respond to component property changes appropriately.
6. Install keyboard UI (mnemonics, traversal, etc.) on the component.
7. Initialize any appropriate instance data.

Overrides:

installUI in class ComponentUI

Parameters:

c - the component where this UI delegate is being installed

See Also:

• ComponentUI.uninstallUI(JComponent)
• JComponent.setUI(ComponentUI)
• JComponent.updateUI()

uninstallUI

public void uninstallUI(JComponent c)

Description copied from class: ComponentUI

Reverses configuration which was done on the specified component during installUI. This method is invoked when this UIComponent instance is being removed as the UI delegate for the specified component. This method should undo the configuration performed in installUI, being careful to leave the JComponent instance in a clean state (no extraneous listeners, look-and-feel-specific property objects, etc.). This should include the following:

1. Remove any UI-set borders from the component.
2. Remove any UI-set layout managers on the component.
3. Remove any UI-added sub-components from the component.
4. Remove any UI-added event/property listeners from the component.
5. Remove any UI-installed keyboard UI from the component.
6. Nullify any allocated instance data objects to allow for GC.

Overrides:

uninstallUI in class ComponentUI

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:

• ComponentUI.installUI(JComponent)
• JComponent.updateUI()

installDefaults

protected void installDefaults(JLabel c)

Installs default properties.

Parameters:

c - an instance of JLabel

installListeners

protected void installListeners(JLabel c)

Registers listeners.

Parameters:

c - an instance of JLabel

installComponents

protected void installComponents(JLabel c)

Registers components.

Parameters:

c - an instance of JLabel

installKeyboardActions

protected void installKeyboardActions(JLabel l)

Registers keyboard actions.

Parameters:

l - an instance of JLabel

uninstallDefaults

protected void uninstallDefaults(JLabel c)

Uninstalls default properties.

Parameters:

c - an instance of JLabel

uninstallListeners

protected void uninstallListeners(JLabel c)

Unregisters listeners.

Parameters:

c - an instance of JLabel

uninstallComponents

protected void uninstallComponents(JLabel c)

Unregisters components.

Parameters:

c - an instance of JLabel

uninstallKeyboardActions

protected void uninstallKeyboardActions(JLabel c)

Unregisters keyboard actions.

Parameters:

c - an instance of JLabel

createUI

public static ComponentUI createUI(JComponent c)

Returns an instance of BasicLabelUI.

Parameters:

c - a component

Returns:

an instance of BasicLabelUI

propertyChange

public void propertyChange(PropertyChangeEvent e)

Description copied from interface: PropertyChangeListener

This method gets called when a bound property is changed.

Specified by:

propertyChange in interface PropertyChangeListener

Parameters:

e - A PropertyChangeEvent object describing the event source and the property that has changed.