gcc/libjava/classpath/javax/swing/RepaintManager.java

/* RepaintManager.java --
   Copyright (C) 2002, 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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permission to link this library with independent modules to produce an
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package javax.swing;

import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.Window;
import java.awt.image.VolatileImage;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;

/**
 * <p>The repaint manager holds a set of dirty regions, invalid components,
 * and a double buffer surface.  The dirty regions and invalid components
 * are used to coalesce multiple revalidate() and repaint() calls in the
 * component tree into larger groups to be refreshed "all at once"; the
 * double buffer surface is used by root components to paint
 * themselves.</p>
 *
 * <p>In general, painting is very confusing in swing. see <a
 * href="http://java.sun.com/products/jfc/tsc/articles/painting/index.html">this
 * document</a> for more details.</p>
 *
 * @author Roman Kennke (kennke@aicas.com)
 * @author Graydon Hoare (graydon@redhat.com)
 */
public class RepaintManager
{
  /**
   * The current repaint managers, indexed by their ThreadGroups.
   */
  private static WeakHashMap currentRepaintManagers;

  /**
   * A rectangle object to be reused in damaged regions calculation.
   */
  private static Rectangle rectCache = new Rectangle();

  /**
   * <p>A helper class which is placed into the system event queue at
   * various times in order to facilitate repainting and layout. There is
   * typically only one of these objects active at any time. When the
   * {@link RepaintManager} is told to queue a repaint, it checks to see if
   * a {@link RepaintWorker} is "live" in the system event queue, and if
   * not it inserts one using {@link SwingUtilities#invokeLater}.</p>
   *
   * <p>When the {@link RepaintWorker} comes to the head of the system
   * event queue, its {@link RepaintWorker#run} method is executed by the
   * swing paint thread, which revalidates all invalid components and
   * repaints any damage in the swing scene.</p>
   */
  private class RepaintWorker
    implements Runnable
  {

    boolean live;

    public RepaintWorker()
    {
      live = false;
    }

    public synchronized void setLive(boolean b) 
    {
      live = b;
    }

    public synchronized boolean isLive()
    {
      return live;
    }

    public void run()
    {
      try
        {
          ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
          RepaintManager rm =
            (RepaintManager) currentRepaintManagers.get(threadGroup);
          rm.validateInvalidComponents();
          rm.paintDirtyRegions();
        }
      finally
        {
          setLive(false);
        }
    }

  }

  /**
   * Compares two components using their depths in the component hierarchy.
   * A component with a lesser depth (higher level components) are sorted
   * before components with a deeper depth (low level components). This is used
   * to order paint requests, so that the higher level components are painted
   * before the low level components get painted.
   *
   * @author Roman Kennke (kennke@aicas.com)
   */
  private class ComponentComparator implements Comparator
  {

    /**
     * Compares two components.
     *
     * @param o1 the first component
     * @param o2 the second component
     *
     * @return a negative integer, if <code>o1</code> is bigger in than
     *         <code>o2</code>, zero, if both are at the same size and a
     *         positive integer, if <code>o1</code> is smaller than
     *         <code>o2</code> 
     */
    public int compare(Object o1, Object o2)
    {
      if (o1 instanceof JComponent && o2 instanceof JComponent)
        {
          JComponent c1 = (JComponent) o1;
          Rectangle d1 = (Rectangle) dirtyComponents.get(c1);
          JComponent c2 = (JComponent) o2;
          Rectangle d2 = (Rectangle) dirtyComponents.get(c2);
          return d2.width * d2.height - d1.width * d1.height;
        }
      throw new ClassCastException("This comparator can only be used with "
                                   + "JComponents");
    }
  }

  /** 
   * A table storing the dirty regions of components.  The keys of this
   * table are components, the values are rectangles. Each component maps
   * to exactly one rectangle.  When more regions are marked as dirty on a
   * component, they are union'ed with the existing rectangle.
   *
   * This is package private to avoid a synthetic accessor method in inner
   * class.
   *
   * @see #addDirtyRegion
   * @see #getDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyClean
   * @see #markCompletelyDirty
   */
  HashMap dirtyComponents;

  /**
   * The comparator used for ordered inserting into the repaintOrder list. 
   */
  private transient Comparator comparator;

  /**
   * A single, shared instance of the helper class. Any methods which mark
   * components as invalid or dirty eventually activate this instance. It
   * is added to the event queue if it is not already active, otherwise
   * reused.
   *
   * @see #addDirtyRegion
   * @see #addInvalidComponent
   */
  private RepaintWorker repaintWorker;

  /** 
   * The set of components which need revalidation, in the "layout" sense.
   * There is no additional information about "what kind of layout" they
   * need (as there is with dirty regions), so it is just a vector rather
   * than a table.
   *
   * @see #addInvalidComponent
   * @see #removeInvalidComponent
   * @see #validateInvalidComponents
   */
  private ArrayList invalidComponents;

  /** 
   * Whether or not double buffering is enabled on this repaint
   * manager. This is merely a hint to clients; the RepaintManager will
   * always return an offscreen buffer when one is requested.
   * 
   * @see #isDoubleBufferingEnabled
   * @see #setDoubleBufferingEnabled
   */
  private boolean doubleBufferingEnabled;

  /**
   * The offscreen buffers. This map holds one offscreen buffer per
   * Window/Applet and releases them as soon as the Window/Applet gets garbage
   * collected.
   */
  private WeakHashMap offscreenBuffers;

  /**
   * Indicates if the RepaintManager is currently repainting an area.
   */
  private boolean repaintUnderway;

  /**
   * This holds buffer commit requests when the RepaintManager is working.
   * This maps Component objects (the top level components) to Rectangle
   * objects (the area of the corresponding buffer that must be blitted on
   * the component).
   */
  private HashMap commitRequests;

  /**
   * The maximum width and height to allocate as a double buffer. Requests
   * beyond this size are ignored.
   *
   * @see #paintDirtyRegions
   * @see #getDoubleBufferMaximumSize
   * @see #setDoubleBufferMaximumSize
   */
  private Dimension doubleBufferMaximumSize;


  /**
   * Create a new RepaintManager object.
   */
  public RepaintManager()
  {
    dirtyComponents = new HashMap();
    invalidComponents = new ArrayList();
    repaintWorker = new RepaintWorker();
    doubleBufferMaximumSize = new Dimension(2000,2000);
    doubleBufferingEnabled = true;
    offscreenBuffers = new WeakHashMap();
    repaintUnderway = false;
    commitRequests = new HashMap();
  }

  /**
   * Returns the <code>RepaintManager</code> for the current thread's
   * thread group. The default implementation ignores the
   * <code>component</code> parameter and returns the same repaint manager
   * for all components.
   *
   * @param component a component to look up the manager of
   *
   * @return the current repaint manager for the calling thread's thread group
   *         and the specified component
   *
   * @see #setCurrentManager
   */
  public static RepaintManager currentManager(Component component)
  {
    if (currentRepaintManagers == null)
      currentRepaintManagers = new WeakHashMap();
    ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
    RepaintManager currentManager =
      (RepaintManager) currentRepaintManagers.get(threadGroup);
    if (currentManager == null)
      {
        currentManager = new RepaintManager();
        currentRepaintManagers.put(threadGroup, currentManager);
      }
    return currentManager;
  }

  /**
   * Returns the <code>RepaintManager</code> for the current thread's
   * thread group. The default implementation ignores the
   * <code>component</code> parameter and returns the same repaint manager
   * for all components.
   *
   * This method is only here for backwards compatibility with older versions
   * of Swing and simply forwards to {@link #currentManager(Component)}.
   *
   * @param component a component to look up the manager of
   *
   * @return the current repaint manager for the calling thread's thread group
   *         and the specified component
   *
   * @see #setCurrentManager
   */
  public static RepaintManager currentManager(JComponent component)
  {
    return currentManager((Component)component);
  }

  /**
   * Sets the repaint manager for the calling thread's thread group.
   *
   * @param manager the repaint manager to set for the current thread's thread
   *        group
   *
   * @see #currentManager(Component)
   */
  public static void setCurrentManager(RepaintManager manager)
  {
    if (currentRepaintManagers == null)
      currentRepaintManagers = new WeakHashMap();

    ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
    currentRepaintManagers.put(threadGroup, manager);
  }

  /**
   * Add a component to the {@link #invalidComponents} vector. If the
   * {@link #repaintWorker} class is not active, insert it in the system
   * event queue.
   *
   * @param component The component to add
   *
   * @see #removeInvalidComponent
   */
  public void addInvalidComponent(JComponent component)
  {
    Component ancestor = component;

    while (ancestor != null
           && (! (ancestor instanceof JComponent)
               || ! ((JComponent) ancestor).isValidateRoot() ))
      ancestor = ancestor.getParent();

    if (ancestor != null
        && ancestor instanceof JComponent
        && ((JComponent) ancestor).isValidateRoot())
      component = (JComponent) ancestor;

    if (invalidComponents.contains(component))
      return;

    synchronized (invalidComponents)
      {
        invalidComponents.add(component);
      }

    if (! repaintWorker.isLive())
      {
        repaintWorker.setLive(true);
        SwingUtilities.invokeLater(repaintWorker);
      }
  }

  /**
   * Remove a component from the {@link #invalidComponents} vector.
   *
   * @param component The component to remove
   *
   * @see #addInvalidComponent
   */
  public void removeInvalidComponent(JComponent component)
  {
    synchronized (invalidComponents)
      {
        invalidComponents.remove(component);
      }
  }

  /**
   * Add a region to the set of dirty regions for a specified component.
   * This involves union'ing the new region with any existing dirty region
   * associated with the component. If the {@link #repaintWorker} class
   * is not active, insert it in the system event queue.
   *
   * @param component The component to add a dirty region for
   * @param x The left x coordinate of the new dirty region
   * @param y The top y coordinate of the new dirty region
   * @param w The width of the new dirty region
   * @param h The height of the new dirty region
   *
   * @see #addDirtyRegion
   * @see #getDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyClean
   * @see #markCompletelyDirty
   */
  public void addDirtyRegion(JComponent component, int x, int y,
                             int w, int h)
  {
    if (w <= 0 || h <= 0 || !component.isShowing())
      return;

    component.computeVisibleRect(rectCache);
    SwingUtilities.computeIntersection(x, y, w, h, rectCache);

    if (! rectCache.isEmpty())
      {
        if (dirtyComponents.containsKey(component))
          {
            SwingUtilities.computeUnion(rectCache.x, rectCache.y,
                                        rectCache.width, rectCache.height,
                                   (Rectangle) dirtyComponents.get(component));
          }
        else
          {
            synchronized (dirtyComponents)
              {
                dirtyComponents.put(component, rectCache.getBounds());
              }
          }

        if (! repaintWorker.isLive())
          {
            repaintWorker.setLive(true);
            SwingUtilities.invokeLater(repaintWorker);
          }
      }
  }

  /**
   * Get the dirty region associated with a component, or <code>null</code>
   * if the component has no dirty region.
   *
   * @param component The component to get the dirty region of
   *
   * @return The dirty region of the component
   *
   * @see #dirtyComponents
   * @see #addDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyClean
   * @see #markCompletelyDirty
   */
  public Rectangle getDirtyRegion(JComponent component)
  {
    Rectangle dirty = (Rectangle) dirtyComponents.get(component);
    if (dirty == null)
      dirty = new Rectangle();
    return dirty;
  }
  
  /**
   * Mark a component as dirty over its entire bounds.
   *
   * @param component The component to mark as dirty
   *
   * @see #dirtyComponents
   * @see #addDirtyRegion
   * @see #getDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyClean
   */
  public void markCompletelyDirty(JComponent component)
  {
    Rectangle r = component.getBounds();
    addDirtyRegion(component, r.x, r.y, r.width, r.height);
    component.isCompletelyDirty = true;
  }

  /**
   * Remove all dirty regions for a specified component
   *
   * @param component The component to mark as clean
   *
   * @see #dirtyComponents
   * @see #addDirtyRegion
   * @see #getDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyDirty
   */
  public void markCompletelyClean(JComponent component)
  {
    synchronized (dirtyComponents)
      {
        dirtyComponents.remove(component);
      }
    component.isCompletelyDirty = false;
  }

  /**
   * Return <code>true</code> if the specified component is completely
   * contained within its dirty region, otherwise <code>false</code>
   *
   * @param component The component to check for complete dirtyness
   *
   * @return Whether the component is completely dirty
   *
   * @see #dirtyComponents
   * @see #addDirtyRegion
   * @see #getDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyClean
   */
  public boolean isCompletelyDirty(JComponent component)
  {
    if (! dirtyComponents.containsKey(component))
      return false;
    return component.isCompletelyDirty;
  }

  /**
   * Validate all components which have been marked invalid in the {@link
   * #invalidComponents} vector.
   */
  public void validateInvalidComponents()
  {
    // We don't use an iterator here because that would fail when there are
    // components invalidated during the validation of others, which happens
    // quite frequently. Instead we synchronize the access a little more.
    while (invalidComponents.size() > 0)
      {
        Component comp;
        synchronized (invalidComponents)
          {
            comp = (Component) invalidComponents.remove(0);
          }
        // Validate the validate component.
        if (! (comp.isVisible() && comp.isShowing()))
          continue;
        comp.validate();
      }
  }

  /**
   * Repaint all regions of all components which have been marked dirty in
   * the {@link #dirtyComponents} table.
   */
  public void paintDirtyRegions()
  {
    // Short cicuit if there is nothing to paint.
    if (dirtyComponents.size() == 0)
      return;

    synchronized (dirtyComponents)
      {
        // We sort the components by their size here. This way we have a good
        // chance that painting the bigger components also paints the smaller
        // components and we don't need to paint them twice.
        ArrayList repaintOrder = new ArrayList(dirtyComponents.size());
        repaintOrder.addAll(dirtyComponents.keySet());
        if (comparator == null)
          comparator = new ComponentComparator();
        Collections.sort(repaintOrder, comparator);
        repaintUnderway = true;
        for (Iterator i = repaintOrder.iterator(); i.hasNext();)
          {
            JComponent comp = (JComponent) i.next();
            // If a component is marked completely clean in the meantime, then skip
            // it.
            Rectangle damaged = (Rectangle) dirtyComponents.get(comp);
            if (damaged == null || damaged.isEmpty())
              continue;
            comp.paintImmediately(damaged);
            dirtyComponents.remove(comp);
          }
        repaintUnderway = false;
        commitRemainingBuffers();
      }
  }

  /**
   * Get an offscreen buffer for painting a component's image. This image
   * may be smaller than the proposed dimensions, depending on the value of
   * the {@link #doubleBufferMaximumSize} property.
   *
   * @param component The component to return an offscreen buffer for
   * @param proposedWidth The proposed width of the offscreen buffer
   * @param proposedHeight The proposed height of the offscreen buffer
   *
   * @return A shared offscreen buffer for painting
   */
  public Image getOffscreenBuffer(Component component, int proposedWidth,
                                  int proposedHeight)
  {
    Component root = SwingUtilities.getRoot(component);
    Image buffer = (Image) offscreenBuffers.get(root);
    if (buffer == null 
        || buffer.getWidth(null) < proposedWidth 
        || buffer.getHeight(null) < proposedHeight)
      {
        int width = Math.max(proposedWidth, root.getWidth());
        width = Math.min(doubleBufferMaximumSize.width, width);
        int height = Math.max(proposedHeight, root.getHeight());
        height = Math.min(doubleBufferMaximumSize.height, height);
        buffer = component.createImage(width, height);
        offscreenBuffers.put(root, buffer);
      }
    return buffer;
  }

  /**
   * Blits the back buffer of the specified root component to the screen. If
   * the RepaintManager is currently working on a paint request, the commit
   * requests are queued up and committed at once when the paint request is
   * done (by {@link #commitRemainingBuffers}). This is package private because
   * it must get called by JComponent.
   *
   * @param root the component, either a Window or an Applet instance
   * @param area the area to paint on screen
   */
  void commitBuffer(Component root, Rectangle area)
  {
    // We synchronize on dirtyComponents here because that is what
    // paintDirtyRegions also synchronizes on while painting.
    synchronized (dirtyComponents)
      {
        // If the RepaintManager is not currently painting, then directly
        // blit the requested buffer on the screen.
        if (! repaintUnderway)
          {
            Graphics g = root.getGraphics();
            Image buffer = (Image) offscreenBuffers.get(root);
            Rectangle clip = g.getClipBounds();
            if (clip != null)
              area = SwingUtilities.computeIntersection(clip.x, clip.y,
                                                        clip.width, clip.height,
                                                        area);
            int dx1 = area.x;
            int dy1 = area.y;
            int dx2 = area.x + area.width;
            int dy2 = area.y + area.height;
            // Make sure we have a sane clip at this point.
            g.clipRect(area.x, area.y, area.width, area.height);

            // Make sure the coordinates are inside the buffer, everything else
            // might lead to problems.
            // TODO: This code should not really be necessary, however, in fact
            // we have two issues here:
            // 1. We shouldn't get repaint requests in areas outside the buffer
            //    region in the first place. This still happens for example
            //    when a component is inside a JViewport, and the component has
            //    a size that would reach beyond the window size.
            // 2. Graphics.drawImage() should not behave strange when trying
            //    to draw regions outside the image.
            int bufferWidth = buffer.getWidth(root);
            int bufferHeight = buffer.getHeight(root);
            dx1 = Math.min(bufferWidth, dx1);
            dy1 = Math.min(bufferHeight, dy1);
            dx2 = Math.min(bufferWidth, dx2);
            dy2 = Math.min(bufferHeight, dy2);
            g.drawImage(buffer, dx1, dy1, dx2, dy2,
                                dx1, dy1, dx2, dy2, root);
            g.dispose();
          }
        // Otherwise queue this request up, until all the RepaintManager work
        // is done.
        else
          {
            if (commitRequests.containsKey(root))
              SwingUtilities.computeUnion(area.x, area.y, area.width,
                                          area.height,
                                         (Rectangle) commitRequests.get(root));
            else
              commitRequests.put(root, area);
          }
      }
  }

  /**
   * Commits the queued up back buffers to screen all at once.
   */
  private void commitRemainingBuffers()
  {
    // We synchronize on dirtyComponents here because that is what
    // paintDirtyRegions also synchronizes on while painting.
    synchronized (dirtyComponents)
      {
        Set entrySet = commitRequests.entrySet();
        Iterator i = entrySet.iterator();
        while (i.hasNext())
          {
            Map.Entry entry = (Map.Entry) i.next();
            Component root = (Component) entry.getKey();
            Rectangle area = (Rectangle) entry.getValue();
            commitBuffer(root, area);
            i.remove();
          }
      }
  }

  /**
   * Creates and returns a volatile offscreen buffer for the specified
   * component that can be used as a double buffer. The returned image
   * is a {@link VolatileImage}. Its size will be <code>(proposedWidth,
   * proposedHeight)</code> except when the maximum double buffer size
   * has been set in this RepaintManager.
   *
   * @param comp the Component for which to create a volatile buffer
   * @param proposedWidth the proposed width of the buffer
   * @param proposedHeight the proposed height of the buffer
   *
   * @since 1.4
   *
   * @see VolatileImage
   */
  public Image getVolatileOffscreenBuffer(Component comp, int proposedWidth,
                                          int proposedHeight)
  {
    int maxWidth = doubleBufferMaximumSize.width;
    int maxHeight = doubleBufferMaximumSize.height;
    return comp.createVolatileImage(Math.min(maxWidth, proposedWidth),
                                    Math.min(maxHeight, proposedHeight));
  }
  

  /**
   * Get the value of the {@link #doubleBufferMaximumSize} property.
   *
   * @return The current value of the property
   *
   * @see #setDoubleBufferMaximumSize
   */
  public Dimension getDoubleBufferMaximumSize()
  {
    return doubleBufferMaximumSize;
  }

  /**
   * Set the value of the {@link #doubleBufferMaximumSize} property.
   *
   * @param size The new value of the property
   *
   * @see #getDoubleBufferMaximumSize
   */
  public void setDoubleBufferMaximumSize(Dimension size)
  {
    doubleBufferMaximumSize = size;
  }

  /**
   * Set the value of the {@link #doubleBufferingEnabled} property.
   *
   * @param buffer The new value of the property
   *
   * @see #isDoubleBufferingEnabled
   */
  public void setDoubleBufferingEnabled(boolean buffer)
  {
    doubleBufferingEnabled = buffer;
  }

  /**
   * Get the value of the {@link #doubleBufferingEnabled} property.
   *
   * @return The current value of the property
   *
   * @see #setDoubleBufferingEnabled
   */
  public boolean isDoubleBufferingEnabled()
  {
    return doubleBufferingEnabled;
  }
  
  public String toString()
  {
    return "RepaintManager";
  }
}