path: root/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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02110-1301 USA.

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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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terms of your choice, provided that you also meet, for each linked
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package javax.swing;

import java.awt.Component;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.Rectangle;
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.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 Graydon Hoare (graydon@redhat.com)
 */
public class RepaintManager
{
  /**
   * The current repaint managers, indexed by their ThreadGroups.
   */
  static WeakHashMap currentRepaintManagers;
  
  /**
   * <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>
   */
  protected 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()
    {
      ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
      RepaintManager rm =
        (RepaintManager) currentRepaintManagers.get(threadGroup);
      setLive(false);
      rm.validateInvalidComponents();
      rm.paintDirtyRegions();
    }

  }

  /**
   * 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 higher in the
     *         hierarchy than <code>o2</code>, zero, if both are at the same
     *         level and a positive integer, if <code>o1</code> is deeper in
     *         the hierarchy than <code>o2</code> 
     */
    public int compare(Object o1, Object o2)
    {
      if (o1 instanceof JComponent && o2 instanceof JComponent)
        {
          JComponent c1 = (JComponent) o1;
          JComponent c2 = (JComponent) o2;
          return getDepth(c1) - getDepth(c2);
        }
      else
        throw new ClassCastException("This comparator can only be used with "
                                     + "JComponents");
    }

    /**
     * Computes the depth for a given JComponent.
     *
     * @param c the component to compute the depth for
     *
     * @return the depth of the component
     */
    private int getDepth(JComponent c)
    {
      Component comp = c;
      int depth = 0;
      while (comp != null)
        {
          comp = comp.getParent();
          depth++;
        }
      return depth;
    }
  }

  /** 
   * 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.
   *
   * @see #addDirtyRegion
   * @see #getDirtyRegion
   * @see #isCompletelyDirty
   * @see #markCompletelyClean
   * @see #markCompletelyDirty
   */
  HashMap dirtyComponents;

  HashMap workDirtyComponents;

  /**
   * Stores the order in which the components get repainted.
   */
  ArrayList repaintOrder;
  ArrayList workRepaintOrder;

  /**
   * The comparator used for ordered inserting into the repaintOrder list. 
   */
  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
   */
  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
   */
  ArrayList invalidComponents;
  ArrayList workInvalidComponents;

  /** 
   * 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
   */
  boolean doubleBufferingEnabled;

  /** 
   * The current offscreen buffer. This is reused for all requests for
   * offscreen drawing buffers. It grows as necessary, up to {@link
   * #doubleBufferMaximumSize}, but there is only one shared instance.
   *
   * @see #getOffscreenBuffer
   * @see #doubleBufferMaximumSize
   */
  Image doubleBuffer;

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


  /**
   * Create a new RepaintManager object.
   */
  public RepaintManager()
  {
    dirtyComponents = new HashMap();
    workDirtyComponents = new HashMap();
    repaintOrder = new ArrayList();
    workRepaintOrder = new ArrayList();
    invalidComponents = new ArrayList();
    workInvalidComponents = new ArrayList();
    repaintWorker = new RepaintWorker();
    doubleBufferMaximumSize = new Dimension(2000,2000);
    doubleBufferingEnabled = true;
  }

  /**
   * 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 synchronized void addInvalidComponent(JComponent component)
  {
    Component ancestor = component.getParent();

    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;

    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 synchronized void removeInvalidComponent(JComponent component)
  {
    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 synchronized void addDirtyRegion(JComponent component, int x, int y,
                                          int w, int h)
  {
    if (w == 0 || h == 0 || !component.isShowing())
      return;
    Rectangle r = new Rectangle(x, y, w, h);
    if (dirtyComponents.containsKey(component))
      r = r.union((Rectangle)dirtyComponents.get(component));
    else
      insertInRepaintOrder(component);
    dirtyComponents.put(component, r);
    if (! repaintWorker.isLive())
      {
        repaintWorker.setLive(true);
        SwingUtilities.invokeLater(repaintWorker);
      }
  }

  /**
   * Inserts a component into the repaintOrder list in an ordered fashion,
   * using a binary search.
   *
   * @param c the component to be inserted
   */
  private void insertInRepaintOrder(JComponent c)
  {
    if (comparator == null)
      comparator = new ComponentComparator();
    int insertIndex = Collections.binarySearch(repaintOrder, c, comparator);
    if (insertIndex < 0)
      insertIndex = -(insertIndex + 1);
    repaintOrder.add(insertIndex, c);
  }

  /**
   * 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 (this)
      {
        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()
  {
    // In order to keep the blocking of application threads minimal, we switch
    // the invalidComponents field with the workInvalidComponents field and
    // work with the workInvalidComponents field.
    synchronized(this)
    {
      ArrayList swap = invalidComponents;
      invalidComponents = workInvalidComponents;
      workInvalidComponents = swap;
    }
    for (Iterator i = workInvalidComponents.iterator(); i.hasNext(); )
      {
        JComponent comp = (JComponent) i.next();
        if (! (comp.isVisible() && comp.isShowing()))
          continue;
        comp.validate();
      }
    workInvalidComponents.clear();
  }

  /**
   * Repaint all regions of all components which have been marked dirty in
   * the {@link #dirtyComponents} table.
   */
  public synchronized void paintDirtyRegions()
  {
    // In order to keep the blocking of application threads minimal, we switch
    // the dirtyComponents field with the workdirtyComponents field and the
    // repaintOrder field with the workRepaintOrder field and work with the
    // work* fields.
    synchronized(this)
    {
      ArrayList swap = workRepaintOrder;
      workRepaintOrder = repaintOrder;
      repaintOrder = swap;
      HashMap swap2 = workDirtyComponents;
      workDirtyComponents = dirtyComponents;
      dirtyComponents = swap2;
    }
    for (Iterator i = workRepaintOrder.iterator(); i.hasNext();)
      {
        JComponent comp = (JComponent) i.next();
        // If a component is marked completely clean in the meantime, then skip
        // it.
        Rectangle damaged = (Rectangle) workDirtyComponents.get(comp);
        if (damaged == null || damaged.isEmpty())
          continue;
        comp.paintImmediately(damaged);
      }
    workRepaintOrder.clear();
    workDirtyComponents.clear();
  }

  /**
   * 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
   *
   * @see #doubleBuffer
   */
  public Image getOffscreenBuffer(Component component, int proposedWidth,
                                  int proposedHeight)
  {
    if (doubleBuffer == null 
        || (((doubleBuffer.getWidth(null) < proposedWidth) 
             || (doubleBuffer.getHeight(null) < proposedHeight))
            && (proposedWidth < doubleBufferMaximumSize.width)
            && (proposedHeight < doubleBufferMaximumSize.height)))
      {
        doubleBuffer = component.createImage(proposedWidth, proposedHeight);
      }
    return doubleBuffer;
  }

  /**
   * 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";
  }
}