Class ComponentUI

public ComponentUI()

Constructs a new UI delegate.

public boolean contains(JComponent c,
                        int x,
                        int y)

Determines whether a click into the component at a specified location is considered as having hit the component. The default implementation checks whether the point falls into the component’s bounding rectangle. Some subclasses might want to override this, for example in the case of a rounded button.

Parameters:

c - the component for which this delegate performs services.

x - the x coordinate of the point, relative to the local coordinate system of the component. Zero would be be component’s left edge, irrespective of the location inside its parent.

y - the y coordinate of the point, relative to the local coordinate system of the component. Zero would be be component’s top edge, irrespective of the location inside its parent.

public static ComponentUI createUI(JComponent c)

Creates a delegate object for the specified component. Users should use the createUI method of a suitable subclass. The implementation of ComponentUI always throws an error.

Parameters:

c - the component for which a UI delegate is requested.

public Accessible getAccessibleChild(JComponent c,
                                     int i)

Returns the specified accessible child of the component. The default implementation delegates the inquiry to the AccessibleContext of c.

Parameters:

c - the component whose i-th accessible child is requested.

i - the index of the accessible child, starting at zero.

public int getAccessibleChildrenCount(JComponent c)

Counts the number of accessible children in the component. The default implementation delegates the inquiry to the AccessibleContext of c.

Parameters:

c - the component whose accessible children are to be counted.

public Dimension getMaximumSize(JComponent c)

Determines the maximum size of a component. The default implementation calls getPreferredSize(JComponent), but subclasses might want to override this.

Parameters:

c - the component for which this delegate performs services.

Returns:

the maximum size, or null to indicate that c’s layout manager should be asked to calculate the maximum size.

public Dimension getMinimumSize(JComponent c)

Determines the minimum size of a component. The default implementation calls getPreferredSize(JComponent), but subclasses might want to override this.

Parameters:

c - the component for which this delegate performs services.

Returns:

the minimum size, or null to indicate that c’s layout manager should be asked to calculate the minimum size.

public Dimension getPreferredSize(JComponent c)

Determines the preferred size of a component. The default implementation returns null, which means that c’s layout manager should be asked to calculate the preferred size.

Parameters:

c - the component for which this delegate performs services.

Returns:

the preferred size, or null to indicate that c’s layout manager should be asked for the preferred size.

public void installUI(JComponent c)

Sets up the specified component so it conforms the the design guidelines of the implemented look and feel. When the look and feel changes, a ComponentUI delegate is created. The delegate object then receives an installUI message.

This method should perform the following tasks:

• Set visual properties such as borders, fonts, colors, or icons. However, no change should be performed for those properties whose values have been directly set by the client application. To allow the distinction, LookAndFeels are expected to use values that implement the UIResource marker interface, such as BorderUIResource or ColorUIResource.
• If necessary, install a LayoutManager.
• Embed custom sub-components. For instance, the UI delegate for a JSplitPane might install a special component for the divider.
• Register event listeners.
• Set up properties related to keyborad navigation, such as mnemonics or focus traversal policies.

Parameters:

c - the component for which this delegate will provide services.

See Also:

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

public void paint(Graphics g,
                  JComponent c)

Paints the component according to the design guidelines of the look and feel. Most subclasses will want to override this method.

Parameters:

g - the graphics for painting.

c - the component for which this delegate performs services.

public void uninstallUI(JComponent c)

Puts the specified component into the state it had before installUI(JComponent) was called.

Parameters:

c - the component for which this delegate has provided services.

See Also:

installUI(JComponent), JComponent.setUI(ComponentUI), JComponent.updateUI()

public void update(Graphics g,
                   JComponent c)

Fills the specified component with its background color (unless the opaque property is false) before calling paint(Graphics,JComponent).

It is unlikely that a subclass needs to override this method. The actual rendering should be performed by the paint(Graphics,JComponent) method.

Parameters:

g - the graphics for painting.

c - the component for which this delegate performs services.

See Also:

paint(Graphics,JComponent), JComponent.paintComponent(Graphics)