Apple Developer Connection Student Program/ADC Tools Sampler CD Disk 3 1999.iso/Metrowerks CodeWarrior/Java Support/Java_Source/Java2/src/javax/swing/JLayeredPane.java

Java Source | 1999-05-28 | 25.7 KB | 718 lines | [TEXT/CWIE]

/*
 * @(#)JLayeredPane.java    1.32 98/08/28
 *
 * Copyright 1997, 1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */
package javax.swing;

import java.awt.Component;
import java.util.Hashtable;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;

import javax.accessibility.*;

/**
 * JLayeredPane adds depth to a JFC/Swing container, allowing components to overlap
 * each other when needed. An Integer object specifies each component's depth in the
 * container, where higher-numbered components sit "on top" of other
 * components.
 * <P>
 * <TABLE ALIGN="RIGHT" BORDER="0">
 * <TR>
 *   <TD ALIGN="CENTER">
 *     <P ALIGN="CENTER"><IMG SRC="doc-files/JLayeredPane-1.gif" WIDTH="269" HEIGHT="264" ALIGN="BOTTOM" BORDER="0">
 *   </TD>
 * </TR>
 * </TABLE>
 * For convenience, JLayeredPane divides the depth-range into several different
 * layers. Putting a component into one of those layers makes it easy to ensure
 * that components overlap properly, without having to worry about specifying
 * numbers for specific depths:
 * <DL>
 *    <DT><FONT SIZE="2">DEFAULT_LAYER</FONT></DT>
 *         <DD>The standard layer, where most components go. This the bottommost
 *         layer.
 *    <DT><FONT SIZE="2">PALETTE_LAYER</FONT></DT>
 *         <DD>The palette layer sits over the default layer. Useful for floating
 *         toolbars and palettes, so they can be positioned above other components.
 *    <DT><FONT SIZE="2">MODAL_LAYER</FONT></DT>
 *         <DD>The layer used for modal dialogs. They will appear on top of any
 *         toolbars, palettes, or standard components in the container.
 *    <DT><FONT SIZE="2">POPUP_LAYER</FONT></DT>
 *         <DD>The popup layer displays above dialogs. That way, the popup windows
 *         associated with combo boxes, tooltips, and other help text will appear
 *         above the component, palette, or dialog that generated them.
 *    <DT><FONT SIZE="2">DRAG_LAYER</FONT></DT>
 *         <DD>When dragging a component, reassigning it to the drag layer ensures
 *         that it is positioned over every other component in the container. When
 *         finished dragging, it can be reassigned to its normal layer.
 * </DL>
 * The JLayeredPane methods <code>moveToFront(Component)</code>,
 * <code>moveToBack(Component)</code> and <code>setPosition</code> can be used
 * to reposition a component within its layer. The <code>setLayer</code> method
 * can also be used to change the component's current layer.
 *
 * <h2>Details</h2>
 * JLayeredPane manages it's list of children like Container, but
 * allows for the definition of a several layers within itself. Children
 * in the same layer are managed exactly like the normal Container object,
 * with the added feature that when children components overlap, children
 * in higher layers display above the children in lower layers.
 * <p>
 * Each layer is a distinct integer number. The layer attribute can be set
 * on a Component by passing an Integer object during the add call.<br>
 * For example:
 * <PRE>
 *     layeredPane.add(child, JLayeredPane.DEFAULT_LAYER);
 * or
 *     layeredPane.add(child, new Integer(10));
 * </PRE>
 * The layer attribute can also be set on a Component by calling<PRE>
 *     layeredPaneParent.setLayer(child, 10)</PRE>
 * on the JLayeredPane that is the parent of component. The layer
 * should be set <i>before</i> adding the child to the parent.
 * <p>
 * Higher number layers display above lower number layers. So, using
 * numbers for the layers and letters for individual components, a
 * representative list order would look like this:<PRE>
 *       5a, 5b, 5c, 2a, 2b, 2c, 1a </PRE>
 * where the leftmost components are closest to the top of the display.
 * <p>
 * A component can be moved to the top or bottom position within its
 * layer by calling <code>moveToFront</code> or <code>moveToBack</code>.
 * <p>
 * The position of a component within a layer can also be specified directly.
 * Valid positions range from 0 up to one less than the number of
 * components in that layer. A value of -1 indicates the bottommost
 * position. A value of 0 indicates the topmost position. Unlike layer
 * numbers, higher position values are <i>lower</i> in the display.
 * <blockquote>
 * <b>Note:</b> This sequence (defined by java.awt.Container) is the reverse
 * of the layer numbering sequence. Usually though, you will use <code>moveToFront</code>,
 * <code>moveToBack</code>, and <code>setLayer</code>.
 * </blockquote>
 * Here are some examples using the method add(Component, layer, position):
 * Calling add(5x, 5, -1) results in:<PRE>
 *       5a, 5b, 5c, 5x, 2a, 2b, 2c, 1a </PRE>
 *
 * Calling add(5z, 5, 2) results in:<PRE>
 *       5a, 5b, 5z, 5c, 5x, 2a, 2b, 2c, 1a </PRE>
 *
 * Calling add(3a, 3, 7) results in:<PRE>
 *       5a, 5b, 5z, 5c, 5x, 3a, 2a, 2b, 2c, 1a </PRE>
 *
 * Using normal paint/event mechanics results in 1a appearing at the bottom
 * and 5a being above all other components.
 * <p>
 * <b>Note:</b> that these layers are simply a logical construct and LayoutManagers
 * will affect all child components of this container without regard for
 * layer settings.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases.  The current serialization support is appropriate
 * for short term storage or RMI between applications running the same
 * version of Swing.  A future release of Swing will provide support for
 * long term persistence.
 *
 * @version 1.32 08/28/98
 * @author David Kloba
 */
public class JLayeredPane extends JComponent implements Accessible {
    /// Watch the values in getObjectForLayer()
    /** Convenience object defining the Default layer. Equivalent to new Integer(0).*/
    public final static Integer DEFAULT_LAYER = new Integer(0);
    /** Convenience object defining the Palette layer. Equivalent to new Integer(100).*/
    public final static Integer PALETTE_LAYER = new Integer(100);
    /** Convenience object defining the Modal layer. Equivalent to new Integer(200).*/
    public final static Integer MODAL_LAYER = new Integer(200);
    /** Convenience object defining the Popup layer. Equivalent to new Integer(300).*/
    public final static Integer POPUP_LAYER = new Integer(300);
    /** Convenience object defining the Drag layer. Equivalent to new Integer(400).*/
    public final static Integer DRAG_LAYER = new Integer(400);
    /** Convenience object defining the Frame Content layer.
      * This layer is normally only use to positon the contentPane and menuBar
      * components of JFrame.
      * Equivalent to new Integer(-30000).
      * @see JFrame
      */
    public final static Integer FRAME_CONTENT_LAYER = new Integer(-30000);

    /** Bound property */
    public final static String LAYER_PROPERTY = "layeredContainerLayer";
    // Hashtable to store layer values for non-JComponent components
    private Hashtable componentToLayer;
    private boolean optimizedDrawingPossible = true;


//////////////////////////////////////////////////////////////////////////////
//// Container Override methods
//////////////////////////////////////////////////////////////////////////////
    /** Create a new JLayeredPane */
    public JLayeredPane() {
        setLayout(null);
    }

    private void validateOptimizedDrawing() {
        boolean layeredComponentFound = false;
        synchronized(getTreeLock()) {
            int i,d;
            Integer layer = null;

            for(i=0,d=getComponentCount();i<d;i++) {
                layer = null;
                if(getComponent(i) instanceof JInternalFrame ||
                   (getComponent(i) instanceof JComponent &&
                    (layer = (Integer)((JComponent)getComponent(i)).getClientProperty(LAYER_PROPERTY)) != null)) {
                    if(layer != null && layer.equals(FRAME_CONTENT_LAYER))
                        continue;
                    layeredComponentFound = true;
                    break;
                }
            }
        }

        if(layeredComponentFound)
            optimizedDrawingPossible = false;
        else
            optimizedDrawingPossible = true;
    }

    protected void addImpl(Component comp, Object constraints, int index) {
        int layer = DEFAULT_LAYER.intValue();
        int pos;

        if(constraints instanceof Integer) {
            layer = ((Integer)constraints).intValue();
            setLayer(comp, layer);
        } else
            layer = getLayer(comp);

        pos = insertIndexForLayer(layer, index);
        super.addImpl(comp, constraints, pos);
        comp.validate();
        comp.repaint();
        validateOptimizedDrawing();
    }

    /**
     * Remove the indexed component from this pane.
     * This is the absolute index, ignoring layers.
     *
     * @param index  an int specifying the component to remove
     * @see #getIndexOf
     */
    public void remove(int index) {
        Component c = getComponent(index);
        super.remove(index);
        validateOptimizedDrawing();
    }

    /**
     * Returns false if components in the pane can overlap, which makes
     * optimized drawing impossible. Otherwise, returns true.
     *
     * @return false if components can overlap, else true
     * @see JComponent#isOptimizedDrawingEnabled
     */
    public boolean isOptimizedDrawingEnabled() {
        return optimizedDrawingPossible;
    }


//////////////////////////////////////////////////////////////////////////////
//// New methods for managing layers
//////////////////////////////////////////////////////////////////////////////
    /** Sets the layer property on a JComponent. This method does not cause
      * any side effects like setLayer() (painting, add/remove, etc).
      * Normally you should use the instance method setLayer(), in order to
      * get the desired side-effects (like repainting).
      *
      * @param c      the JComponent to move
      * @param layer  an int specifying the layer to move it to
      * @see #setLayer
      */
    public static void putLayer(JComponent c, int layer) {
        /// MAKE SURE THIS AND setLayer(Component c, int layer, int position)  are SYNCED
        Integer layerObj;

        layerObj = new Integer(layer);
        c.putClientProperty(LAYER_PROPERTY, layerObj);
    }

    /** Gets the layer property for a JComponent, it
      * does not cause any side effects like setLayer(). (painting, add/remove, etc)
      * Normally you should use the instance method getLayer().
      *
      * @param c  the JComponent to check
      * @return   an int specifying the component's layer
      */
    public static int getLayer(JComponent c) {
        Integer i;
        if((i = (Integer)c.getClientProperty(LAYER_PROPERTY)) != null)
            return i.intValue();
        return DEFAULT_LAYER.intValue();
    }

    /** Convenience method that returns the first JLayeredPane which
      * contains the specified component. Note that all JFrames have a
      * JLayeredPane at their root, so any component in a JFrame will
      * have a JLayeredPane parent.
      *
      * @param c the Component to check
      * @return the JLayeredPane that contains the component, or
      *         null if no JLayeredPane is found in the component
      *         hierarchy
      * @see JFrame
      * @see JRootPane
      */
    public static JLayeredPane getLayeredPaneAbove(Component c) {
        if(c == null) return null;

        Component parent = c.getParent();
        while(parent != null && !(parent instanceof JLayeredPane))
            parent = parent.getParent();
        return (JLayeredPane)parent;
    }

    /** Sets the layer attribute on the specified component,
      * making it the bottommost component in that layer.
      * Should be called before adding to parent.
      *
      * @param c     the Component to set the layer for
      * @param layer an int specifying the layer to set, where
      *              lower numbers are closer to the bottom
      */
    public void setLayer(Component c, int layer)  {
        setLayer(c, layer, -1);
    }

    /** Sets the layer attribute for the specified component and
      * also sets its position within that layer.
      *
      * @param c         the Component to set the layer for
      * @param layer     an int specifying the layer to set, where
      *                  lower numbers are closer to the bottom
      * @param position  an int specifying the position within the
      *                  layer, where 0 is the topmost position and -1
      *                  is the bottommost position
      */
    public void setLayer(Component c, int layer, int position)  {
        Integer layerObj;
        layerObj = getObjectForLayer(layer);

        if(layer == getLayer(c) && position == getPosition(c)) {
            if(c instanceof JComponent)
                repaint(((JComponent)c)._bounds);
            else
                repaint(c.getBounds());
            return;
        }

        /// MAKE SURE THIS AND putLayer(JComponent c, int layer) are SYNCED
        if(c instanceof JComponent)
            ((JComponent)c).putClientProperty(LAYER_PROPERTY, layerObj);
        else
            getComponentToLayer().put((Component)c, layerObj);

        if(c.getParent() == null || c.getParent() != this)      {
            if(c instanceof JComponent)
                repaint(((JComponent)c)._bounds);
            else
                repaint(c.getBounds());
            return;
        }

        // Remove the Component and re-add after re-setting the layer
        // this is necessary now because I have no access to the
        // components[] in Container, to reorder things.
        remove(c);

        // ALERT passing NULL here for the constraints may be bad
        // the current hacks to fix this smell bad right now.
        // Cannot override
        add(c, null, position);
        if(c instanceof JComponent)
            repaint(((JComponent)c)._bounds);
        else
            repaint(c.getBounds());
    }

    /**
     * Returns the layer attribute for the specified Component.
     *
     * @param c  the Component to check
     * @return an int specifying the component's current layer
     */
    public int getLayer(Component c) {
        Integer i;
        if(c instanceof JComponent)
            i = (Integer)((JComponent)c).getClientProperty(LAYER_PROPERTY);
        else
            i = (Integer)getComponentToLayer().get((Component)c);

        if(i == null)
            return DEFAULT_LAYER.intValue();
        return i.intValue();
    }

    /**
     * Returns the index of the specified Component.
     * This is the absolute index, ignoring layers.
     * Index numbers, like position numbers, have the topmost component
     * at index zero. Larger numbers are closer to the bottom.
     *
     * @param c  the Component to check
     * @return an int specifying the component's index
     */
    public int getIndexOf(Component c) {
        int i, count;

        count = getComponentCount();
        for(i = 0; i < count; i++) {
            if(c == getComponent(i))
                return i;
        }
        return -1;
    }
    /**
     * Moves the component to the top of the components in it's current layer
     * (position 0).
     *
     * @param c the Component to move
     * @see #setPosition(Component, int)
     */
    public void moveToFront(Component c) {
        setPosition(c, 0);
    }

    /**
     * Moves the component to the bottom of the components in it's current layer
     * (position -1).
     *
     * @param c the Component to move
     * @see #setPosition(Component, int)
     */
    public void moveToBack(Component c) {
        setPosition(c, getComponentCountInLayer(getLayer(c)));
    }

    /**
     * Moves the component to <code>position</code> within it's current layer,
     * where 0 is the topmost position within the layer and -1 is the bottommost
     * position.
     * <p>
     * <b>Note:</b> Position numbering is defined by java.awt.Container, and
     * is the opposite of layer numbering. Lower position numbers are closer
     * to the top (0 is topmost), and higher position numbers are closer to
     * the bottom.
     *
     * @param c         the Component to move
     * @param position  an int in the range -1..N-1, where N is the number of
     *                  components in the component's current layer
     */
    public void setPosition(Component c, int position) {
        setLayer(c, getLayer(c), position);
    }

    /**
     * Get the relative position of the component within its layer.
     *
     * @param c  the Component to check
     * @return an int giving the component's position, where 0 is the
     *         topmost position and the highest index value = the count
     *         count of components at that layer, minus 1
     *
     * @see #getComponentCountInLayer
     */
    public int getPosition(Component c) {
        int i, count, startLayer, curLayer, startLocation, pos = 0;

        count = getComponentCount();
        startLocation = getIndexOf(c);

        if(startLocation == -1)
            return -1;

        startLayer = getLayer(c);
        for(i = startLocation - 1; i >= 0; i--) {
            curLayer = getLayer(getComponent(i));
            if(curLayer == startLayer)
                pos++;
            else
                return pos;
        }
        return pos;
    }

    /** Returns the highest layer value from all current children.
      * Returns 0 if there are no children.
      *
      * @return an int indicating the layer of the topmost component in the
      *         pane, or zero if there are no children
      */
    public int highestLayer() {
        if(getComponentCount() > 0)
            return getLayer(getComponent(0));
        return 0;
    }

    /** Returns the lowest layer value from all current children.
      * Returns 0 if there are no children.
      *
      * @return an int indicating the layer of the bottommost component in the
      *         pane, or zero if there are no children
      */
    public int lowestLayer() {
        int count = getComponentCount();
        if(count > 0)
            return getLayer(getComponent(count-1));
        return 0;
    }

    /**
     * Returns the number of children currently in the specified layer.
     *
     * @param layer  an int specifying the layer to check
     * @return an int specifying the number of components in that layer
     */
    public int getComponentCountInLayer(int layer) {
        int i, count, curLayer;
        int layerCount = 0;

        count = getComponentCount();
        for(i = 0; i < count; i++) {
            curLayer = getLayer(getComponent(i));
            if(curLayer == layer) {
                layerCount++;
            /// Short circut the counting when we have them all
            } else if(layerCount > 0 || curLayer < layer) {
                break;
            }
        }

        return layerCount;
    }

    /**
     * Returns an array of the components in the specified layer.
     *
     * @param layer  an int specifying the layer to check
     * @return an array of Components contained in that layer
     */
    public Component[] getComponentsInLayer(int layer) {
        int i, count, curLayer;
        int layerCount = 0;
        Component[] results;

        results = new Component[getComponentCountInLayer(layer)];
        count = getComponentCount();
        for(i = 0; i < count; i++) {
            curLayer = getLayer(getComponent(i));
            if(curLayer == layer) {
                results[layerCount++] = getComponent(i);
            /// Short circut the counting when we have them all
            } else if(layerCount > 0 || curLayer < layer) {
                break;
            }
        }

        return results;
    }

    /**
     * Paints this JLayeredPane within the specified graphics context.
     *
     * @param g  the Graphics context within which to paint
     */
    public void paint(Graphics g) {
        if(isOpaque()) {
            Rectangle r = g.getClipBounds();
            Color c = getBackground();
            if(c == null)
                c = Color.lightGray;
            g.setColor(c);
            g.fillRect(r.x, r.y, r.width, r.height);
        }
        super.paint(g);
    }

//////////////////////////////////////////////////////////////////////////////
//// Implementation Details
//////////////////////////////////////////////////////////////////////////////

    /**
     * Returns the hashtable that maps components to layers.
     *
     * @return the Hashtable used to map components to their layers
     */
    protected Hashtable getComponentToLayer() {
        if(componentToLayer == null)
            componentToLayer = new Hashtable(4);
        return componentToLayer;
    }

    /**
     * Returns the Integer object associated with a specified layer.
     *
     * @param layer an int specifying the layer
     * @return an Integer object for that layer
     */
    protected Integer getObjectForLayer(int layer) {
        Integer layerObj;
        switch(layer) {
        case 0:
            layerObj = DEFAULT_LAYER;
            break;
        case 100:
            layerObj = PALETTE_LAYER;
            break;
        case 200:
            layerObj = MODAL_LAYER;
            break;
        case 300:
            layerObj = POPUP_LAYER;
            break;
        case 400:
            layerObj = DRAG_LAYER;
            break;
        default:
            layerObj = new Integer(layer);
        }
        return layerObj;
    }

    /**
     * Primative method that determines the proper location to
     * insert a new child based on layer and position requests.
     *
     * @param layer     an int specifying the layer
     * @param position  an int specifying the position within the layer
     * @return an int giving the (absolute) insertion-index
     *
     * @see #getIndexOf
     */
    protected int insertIndexForLayer(int layer, int position) {
        int i, count, curLayer;
        int layerStart = -1;
        int layerEnd = -1;

        count = getComponentCount();
        for(i = 0; i < count; i++) {
            curLayer = getLayer(getComponent(i));
            if(layerStart == -1 && curLayer == layer) {
                layerStart = i;
            }
            if(curLayer < layer ) {
                if(i == 0) {
                    // layer is greater than any current layer
                    // [ ASSERT(layer > highestLayer()) ]
                    layerStart = 0;
                    layerEnd = 0;
                } else {
                    layerEnd = i;
                }
                break;
            }
        }

        // layer requested is lower than any current layer
        // [ ASSERT(layer < lowestLayer()) ]
        // put it on the bottom of the stack
        if(layerStart == -1 && layerEnd == -1)
            return count;

        // In the case of a single layer entry handle the degenerative cases
        if(layerStart != -1 && layerEnd == -1)
            layerEnd = count;

        if(layerEnd != -1 && layerStart == -1)
            layerStart = layerEnd;

        // If we are adding to the bottom, return the last element
        if(position == -1)
            return layerEnd;

        // Otherwise make sure the requested position falls in the
        // proper range
        if(position > -1 && layerStart + position <= layerEnd)
            return layerStart + position;

        // Otherwise return the end of the layer
        return layerEnd;
    }


    /**
     * Returns a string representation of this JLayeredPane. This method
     * is intended to be used only for debugging purposes, and the
     * content and format of the returned string may vary between
     * implementations. The returned string may be empty but may not
     * be <code>null</code>.
     * <P>
     * Overriding paramString() to provide information about the
     * specific new aspects of the JFC components.
     *
     * @return  a string representation of this JLayeredPane.
     */
    protected String paramString() {
        String optimizedDrawingPossibleString = (optimizedDrawingPossible ?
                         "true" : "false");

    return super.paramString() +
        ",optimizedDrawingPossible=" + optimizedDrawingPossibleString;
    }

/////////////////
// Accessibility support
////////////////

    /**
     * Get the AccessibleContext associated with this JComponent
     *
     * @return the AccessibleContext of this JComponent
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJLayeredPane();
        }
        return accessibleContext;
    }

    /**
     * The class used to obtain the accessible role for this object.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases.  The current serialization support is appropriate
     * for short term storage or RMI between applications running the same
     * version of Swing.  A future release of Swing will provide support for
     * long term persistence.
     */
    protected class AccessibleJLayeredPane extends AccessibleJComponent {

        /**
         * Get the role of this object.
         *
         * @return an instance of AccessibleRole describing the role of the
         * object
         * @see AccessibleRole
         */
        public AccessibleRole getAccessibleRole() {
            return AccessibleRole.LAYERED_PANE;
        }
    }
}