Java 1.2 How-To/JavaHowTo.iso/3rdParty/jbuilder/unsupported/JDK1.2beta3/SOURCE/SRC.ZIP/java/awt/swing/JLayeredPane.java

Java Source | 1998-03-20 | 18.2 KB | 528 lines

/*
 * @(#)JLayeredPane.java    1.23 98/02/02
 *
 * Copyright (c) 1997 Sun Microsystems, Inc. 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.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 *
 */
package java.awt.swing;

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

import java.awt.accessibility.*;

/**
 * <P>
 * 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 children in higher layers display above
 * the children in lower layers.
 * Each layer is a distinct integer number.
 * <P>
 * The layer attribute can be set on a Component by passing an Integer object
 * during the add call. For example:
 * <PRE>
 *     layeredPane.add(child, JLayeredPane.DEFAULT_LAYER);
 * or
 *     layeredPane.add(child, new Integer(10));
 * </PRE>
 *
 * <P>
 * The layer attribute can also be set on a Component by calling
 * <PRE>
 *     layeredPaneParent.setLayer(child, 10)
 * </PRE>
 * on the JLayeredPane that will be the parent of component. The layer
 * should be set before adding the child to the parent.
 * <P>
 * <PRE>
 * Higher number layers display above lower number layers.
 * Where numbers are the layers and letter indicate individual components:
 * A represenative list order looks like this:
 *       5a, 5b, 5c, 2a, 2b, 2c, 1a
 * Using the method add(Component, layer, position):
 * Calling add(5x, 5, -1) results in:
 *       5a, 5b, 5c, 5x, 2a, 2b, 2c, 1a
 * Calling add(5z, 5, 2) results in:
 *       5a, 5b, 5z, 5c, 5x, 2a, 2b, 2c, 1a
 * Calling add(3a, 3, 7) results in:
 *       5a, 5b, 5z, 5c, 5x, 3a, 2a, 2b, 2c, 1a
 * Using normal paint/event mechanics results in 1a appearing at the bottom
 * and 5a being above all other components.
 * </PRE>
 * Note that these layers are simply a logical construct and LayoutManagers
 * will affect all child components of this container without regard for
 * layer settings.
 * <p>
 * Warning: 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 Swing1.0 applications.  It will
 * not be possible to load serialized Swing1.0 objects with future releases
 * of Swing.  The JDK1.2 release of Swing will be the compatibility
 * baseline for the serialized form of Swing objects.
 *
 * @version 1.23 02/02/98
 * @author David Kloba
 */
public class JLayeredPane extends JComponent implements Accessible {
    /// Watch the values in getObjectForLayer()
    /** Convience object defining the Default layer. Equivalent to new Integer(0).*/
    public final static Integer DEFAULT_LAYER = new Integer(0);
    /** Convience object defining the Palette layer. Equivalent to new Integer(100).*/
    public final static Integer PALETTE_LAYER = new Integer(100);
    /** Convience object defining the Modal layer. Equivalent to new Integer(200).*/
    public final static Integer MODAL_LAYER = new Integer(200);
    /** Convience object defining the Popup layer. Equivalent to new Integer(300).*/
    public final static Integer POPUP_LAYER = new Integer(300);
    /** Convience object defining the Drag layer. Equivalent to new Integer(400).*/
    public final static Integer DRAG_LAYER = new Integer(400);
    /** Convience 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);

    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
//////////////////////////////////////////////////////////////////////////////
    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();
    }

    public void remove(int index) {
        Component c = getComponent(index);
        super.remove(index);
        validateOptimizedDrawing();
    }

    /**
     * Overridden to return false.  The children of a LayeredPane can overlap.
     * @see JComponent#isOptimizedDrawingEnabled
     */
    public boolean isOptimizedDrawingEnabled() {
        return optimizedDrawingPossible;
    }


//////////////////////////////////////////////////////////////////////////////
//// New methods for managing layers
//////////////////////////////////////////////////////////////////////////////
    /** This method will set the layer property on a JComponent, it
      * does not cause any side effects like setLayer(). (painting, add/remove, etc)
      * Normally you should use the instance method 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);
    }

    /** This method will get the layer property on a JComponent, it
      * does not cause any side effects like setLayer(). (painting, add/remove, etc)
      * Normally you should use the instance method getLayer().
      */
    public static int getLayer(JComponent c) {
    Integer i;
    if((i = (Integer)c.getClientProperty(LAYER_PROPERTY)) != null)
        return i.intValue();
    return DEFAULT_LAYER.intValue();
    }

    /** Convience method for searching above <b>c</b> in the
      * component heirarchy and returns the first JLayeredPane it
      * finds. Will return null, in case a JLayeredPane cannot be found.
      * Note that all JFrames have a JLayeredPane as their rootPane.
      */
    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 <b>c</b>. Should be called before
      * adding to parent.
      */
    public void setLayer(Component c, int layer)  {
        setLayer(c, layer, -1);
    }

    /** Sets the layer attribute on <b>c</b>.
      */
    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(LAYER_PROPERTY, 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 this Component <b>c</b>.*/
    public int getLayer(Component c) {
        Integer i;
        if(c instanceof JComponent)
            i = (Integer)((JComponent)c).getClientProperty(LAYER_PROPERTY);
        else
            i = (Integer)getComponentToLayer().get(LAYER_PROPERTY);

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

    /** Returns the index of this Component <b>c</b>.
      * This is the absolute index, ignoring layers.
      */
    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 position 0 within it's current layer. */
    public void moveToFront(Component c) {
        setPosition(c, 0);
    }

    /** Moves the component to position -1 within it's current layer. */
    public void moveToBack(Component c) {
        setPosition(c, getComponentCountInLayer(getLayer(c)));
    }

    /** Moves the component to <b>position</b> within it's current layer. */
    public void setPosition(Component c, int position) {
        setLayer(c, getLayer(c), position);
    }

    /** Relative position with the component's layer. */
    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 not 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 not children.
      */
    public int lowestLayer() {
        int count = getComponentCount();
        if(count > 0)
            return getLayer(getComponent(count-1));
        return 0;
    }

    /** Returns the number of children currently in <b>layer</b>.
      */
    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 <b>layer</b>.
      */
    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;
    }

    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
//////////////////////////////////////////////////////////////////////////////

    protected Hashtable getComponentToLayer() {
        if(componentToLayer == null)
            componentToLayer = new Hashtable(4);
        return componentToLayer;
    }

    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.
      */
    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;
    }

/////////////////
// 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>
     * Warning: 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 Swing1.0 applications.  It will
     * not be possible to load serialized Swing1.0 objects with future releases
     * of Swing.  The JDK1.2 release of Swing will be the compatibility
     * baseline for the serialized form of Swing objects.
     */
    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;
    }
    }
}