/*
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* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
/**
* 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.
* The <code>JComponent</code> class
* invokes methods from this class in order to delegate operations
* (painting, layout calculations, etc.) that may vary depending on the
* look and feel installed. <b>Client programs should not invoke methods
* on this class directly.</b>
*
* @see javax.swing.JComponent
* @see javax.swing.UIManager
*
*/
public abstract class ComponentUI {
/**
* Sole constructor. (For invocation by subclass constructors,
* typically implicit.)
*/
public ComponentUI() {
}
/**
* Configures the specified component appropriately for the look and feel.
* This method is invoked when the <code>ComponentUI</code> 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:
* <ol>
* <li>Install default property values for color, fonts, borders,
* icons, opacity, etc. on the component. Whenever possible,
* property values initialized by the client program should <i>not</i>
* be overridden.
* <li>Install a <code>LayoutManager</code> on the component if necessary.
* to detect and respond to component property changes appropriately.
* <li>Install keyboard UI (mnemonics, traversal, etc.) on the component.
* <li>Initialize any appropriate instance data.
* </ol>
* @param c the component where this UI delegate is being installed
*
* @see #uninstallUI
* @see javax.swing.JComponent#setUI
* @see javax.swing.JComponent#updateUI
*/
}
/**
* Reverses configuration which was done on the specified component during
* <code>installUI</code>. This method is invoked when this
* <code>UIComponent</code> instance is being removed as the UI delegate
* for the specified component. This method should undo the
* configuration performed in <code>installUI</code>, being careful to
* leave the <code>JComponent</code> instance in a clean state (no
* extraneous listeners, look-and-feel-specific property objects, etc.).
* This should include the following:
* <ol>
* <li>Remove any UI-set borders from the component.
* <li>Remove any UI-set layout managers on the component.
* <li>Remove any UI-added sub-components from the component.
* <li>Remove any UI-installed keyboard UI from the component.
* <li>Nullify any allocated instance data objects to allow for GC.
* </ol>
* @param 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 #installUI
* @see javax.swing.JComponent#updateUI
*/
}
/**
* Paints the specified component appropriately for the look and feel.
* This method is invoked from the <code>ComponentUI.update</code> method when
* the specified component is being painted. Subclasses should override
* this method and use the specified <code>Graphics</code> object to
* render the content of the component.
*
* @param g the <code>Graphics</code> context in which to paint
* @param 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 #update
*/
}
/**
* Notifies this UI delegate that it is time to paint the specified
* component. This method is invoked by <code>JComponent</code>
* when the specified component is being painted.
*
* <p>By default this method fills the specified component with
* its background color if its {@code opaque} property is {@code true},
* and then immediately calls {@code paint}. In general this method need
* not be overridden by subclasses; all look-and-feel rendering code should
* reside in the {@code paint} method.
*
* @param g the <code>Graphics</code> context in which to paint
* @param 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 #paint
* @see javax.swing.JComponent#paintComponent
*/
if (c.isOpaque()) {
g.setColor(c.getBackground());
}
paint(g, c);
}
/**
* Returns the specified component's preferred size appropriate for
* the look and feel. If <code>null</code> 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 <code>null</code>.
*
* @param 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
*
* @see javax.swing.JComponent#getPreferredSize
* @see java.awt.LayoutManager#preferredLayoutSize
*/
return null;
}
/**
* Returns the specified component's minimum size appropriate for
* the look and feel. If <code>null</code> 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 <code>getPreferredSize</code> and returns that value.
*
* @param 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
*
* @return a <code>Dimension</code> object or <code>null</code>
*
* @see javax.swing.JComponent#getMinimumSize
* @see java.awt.LayoutManager#minimumLayoutSize
* @see #getPreferredSize
*/
return getPreferredSize(c);
}
/**
* Returns the specified component's maximum size appropriate for
* the look and feel. If <code>null</code> 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 <code>getPreferredSize</code> and returns that value.
*
* @param 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
* @return a <code>Dimension</code> object or <code>null</code>
*
* @see javax.swing.JComponent#getMaximumSize
* @see java.awt.LayoutManager2#maximumLayoutSize
*/
return getPreferredSize(c);
}
/**
* Returns <code>true</code> if the specified <i>x,y</i> location is
* contained within the look and feel's defined shape of the specified
* component. <code>x</code> and <code>y</code> are defined to be relative
* to the coordinate system of the specified component. Although
* a component's <code>bounds</code> is constrained to a rectangle,
* this method provides the means for defining a non-rectangular
* shape within those bounds for the purpose of hit detection.
*
* @param c the component where the <i>x,y</i> location is being queried;
* this argument is often ignored,
* but might be used if the UI object is stateless
* and shared by multiple components
* @param x the <i>x</i> coordinate of the point
* @param y the <i>y</i> coordinate of the point
*
* @see javax.swing.JComponent#contains
* @see java.awt.Component#contains
*/
return c.inside(x, y);
}
/**
* Returns an instance of the UI delegate for the specified component.
* Each subclass must provide its own static <code>createUI</code>
* method 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.
*/
throw new Error("ComponentUI.createUI not implemented.");
}
/**
* Returns the baseline. The baseline is measured from the top of
* the component. This method is primarily meant for
* <code>LayoutManager</code>s to align components along their
* baseline. A return value less than 0 indicates this component
* does not have a reasonable baseline and that
* <code>LayoutManager</code>s should not align this component on
* its baseline.
* <p>
* This method returns -1. Subclasses that have a meaningful baseline
* should override appropriately.
*
* @param c <code>JComponent</code> baseline is being requested for
* @param width the width to get the baseline for
* @param height the height to get the baseline for
* @throws NullPointerException if <code>c</code> is <code>null</code>
* @throws IllegalArgumentException if width or height is < 0
* @return baseline or a value < 0 indicating there is no reasonable
* baseline
* @see javax.swing.JComponent#getBaseline(int,int)
* @since 1.6
*/
if (c == null) {
throw new NullPointerException("Component must be non-null");
}
throw new IllegalArgumentException(
"Width and height must be >= 0");
}
return -1;
}
/**
* Returns an enum indicating how the baseline of he component
* changes as the size changes. This method is primarily meant for
* layout managers and GUI builders.
* <p>
* This method returns <code>BaselineResizeBehavior.OTHER</code>.
* Subclasses that support a baseline should override appropriately.
*
* @param c <code>JComponent</code> to return baseline resize behavior for
* @return an enum indicating how the baseline changes as the component
* size changes
* @throws NullPointerException if <code>c</code> is <code>null</code>
* @see javax.swing.JComponent#getBaseline(int, int)
* @since 1.6
*/
JComponent c) {
if (c == null) {
throw new NullPointerException("Component must be non-null");
}
}
/**
* Returns the number of accessible children in the object. If all
* of the children of this object implement <code>Accessible</code>,
* 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 call
* <code>Component.AccessibleAWTComponent.getAccessibleChildrenCount()</code> instead
* of this method.
*
* @see #getAccessibleChild
* @return the number of accessible children in the object
*/
return SwingUtilities.getAccessibleChildrenCount(c);
}
/**
* Returns the <code>i</code>th <code>Accessible</code> child 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.
*
* <p>
*
* Note: As of v1.3, it is recommended that developers call
* <code>Component.AccessibleAWTComponent.getAccessibleChild()</code> instead of
* this method.
*
* @see #getAccessibleChildrenCount
* @param i zero-based index of child
* @return the <code>i</code>th <code>Accessible</code> child of the object
*/
return SwingUtilities.getAccessibleChild(c, i);
}
}