path: root/src/classes/com/sun/opengl/impl/packrect/RectanglePacker.java

/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
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 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
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 * - Redistribution in binary form must reproduce the above copyright
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 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
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 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
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 * 
 * You acknowledge that this software is not designed or intended for use
 * in the design, construction, operation or maintenance of any nuclear
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 * Sun gratefully acknowledges that this software was originally authored
 * and developed by Kenneth Bradley Russell and Christopher John Kline.
 */

package com.sun.opengl.impl.packrect;

import java.util.*;

/** Packs rectangles supplied by the user (typically representing
    image regions) into a larger backing store rectangle (typically
    representing a large texture). Supports automatic compaction of
    the space on the backing store, and automatic expansion of the
    backing store, when necessary. */

public class RectanglePacker {
  private BackingStoreManager manager;
  private Object backingStore;
  private LevelSet levels;
  private float EXPANSION_FACTOR = 0.5f;
  private float SHRINK_FACTOR = 0.3f;

  private int initialWidth;
  private int initialHeight;

  private int maxWidth  = -1;
  private int maxHeight = -1;

  static class RectHComparator implements Comparator {
    public int compare(Object o1, Object o2) {
      Rect r1 = (Rect) o1;
      Rect r2 = (Rect) o2;
      return r2.h() - r1.h();
    }

    public boolean equals(Object obj) {
      return this == obj;
    }
  }
  private static final Comparator rectHComparator = new RectHComparator();

  public RectanglePacker(BackingStoreManager manager,
                         int initialWidth,
                         int initialHeight) {
    this.manager = manager;
    levels = new LevelSet(initialWidth, initialHeight);
    this.initialWidth = initialWidth;
    this.initialHeight = initialHeight;
  }

  public Object getBackingStore() {
    if (backingStore == null) {
      backingStore = manager.allocateBackingStore(levels.w(), levels.h());
    }

    return backingStore;
  }

  /** Sets up a maximum width and height for the backing store. These
      are optional and if not specified the backing store will grow as
      necessary. Setting up a maximum width and height introduces the
      possibility that additions will fail; these are handled with the
      BackingStoreManager's allocationFailed notification. */
  public void setMaxSize(int maxWidth, int maxHeight) {
    this.maxWidth  = maxWidth;
    this.maxHeight = maxHeight;
  }

  /** Decides upon an (x, y) position for the given rectangle (leaving
      its width and height unchanged) and places it on the backing
      store. May provoke re-layout of other Rects already added. */
  public void add(Rect rect) {
    // Allocate backing store if we don't have any yet
    if (backingStore == null)
      backingStore = manager.allocateBackingStore(levels.w(), levels.h());

    int attemptNumber = 0;
    boolean tryAgain = false;

    do {
      // Try to allocate
      if (levels.add(rect))
        return;

      // Try to allocate with horizontal compaction
      if (levels.compactAndAdd(rect, backingStore, manager))
        return;

      // Let the manager have a chance at potentially evicting some entries
      tryAgain = manager.preExpand(rect, attemptNumber++);
    } while (tryAgain);

    compactImpl(rect);

    // Retry the addition of the incoming rectangle
    add(rect);
    // Done
  }

  /** Removes the given rectangle from this RectanglePacker. */
  public void remove(Rect rect) {
    levels.remove(rect);
  }

  /** Visits all Rects contained in this RectanglePacker. */
  public void visit(RectVisitor visitor) {
    levels.visit(visitor);
  }

  /** Returns the vertical fragmentation ratio of this
      RectanglePacker. This is defined as the ratio of the sum of the
      heights of all completely empty Levels divided by the overall
      used height of the LevelSet. A high vertical fragmentation ratio
      indicates that it may be profitable to perform a compaction. */
  public float verticalFragmentationRatio() {
    return levels.verticalFragmentationRatio();
  }

  /** Forces a compaction cycle, which typically results in allocating
      a new backing store and copying all entries to it. */
  public void compact() {
    compactImpl(null);
  }

  // The "cause" rect may be null
  private void compactImpl(Rect cause) {
    // Have to either expand, compact or both. Need to figure out what
    // direction to go. Prefer to expand vertically. Expand
    // horizontally only if rectangle being added is too wide. FIXME:
    // may want to consider rebalancing the width and height to be
    // more equal if it turns out we keep expanding in the vertical
    // direction.
    boolean done = false;
    int newWidth = levels.w();
    int newHeight = levels.h();
    LevelSet nextLevelSet = null;
    int attemptNumber = 0;
    boolean needAdditionFailureNotification = false;

    while (!done) {
      if (cause != null) {
        if (cause.w() > newWidth) {
          newWidth = cause.w();
        } else {
          newHeight = (int) (newHeight * (1.0f + EXPANSION_FACTOR));
        }
      }

      // Clamp to maximum values
      needAdditionFailureNotification = false;
      if (maxWidth > 0 && newWidth > maxWidth) {
        newWidth = maxWidth;
        needAdditionFailureNotification = true;
      }
      if (maxHeight > 0 && newHeight > maxHeight) {
        newHeight = maxHeight;
        needAdditionFailureNotification = true;
      }

      nextLevelSet = new LevelSet(newWidth, newHeight);
      
      // Make copies of all existing rectangles
      List/*<Rect>*/ newRects = new ArrayList/*<Rect>*/();
      for (Iterator i1 = levels.iterator(); i1.hasNext(); ) {
        Level level = (Level) i1.next();
        for (Iterator i2 = level.iterator(); i2.hasNext(); ) {
          Rect cur = (Rect) i2.next();
          Rect newRect = new Rect(0, 0, cur.w(), cur.h(), null);
          cur.setNextLocation(newRect);
          // Hook up the reverse mapping too for easier replacement
          newRect.setNextLocation(cur);
          newRects.add(newRect);
        }
      }
      // Sort them by decreasing height (note: this isn't really
      // guaranteed to improve the chances of a successful layout)
      Collections.sort(newRects, rectHComparator);
      // Try putting all of these rectangles into the new level set
      done = true;
      for (Iterator iter = newRects.iterator(); iter.hasNext(); ) {
        if (!nextLevelSet.add((Rect) iter.next())) {
          done = false;
          break;
        }
      }

      if (done && cause != null) {
        // Try to add the new rectangle as well
        if (nextLevelSet.add(cause)) {
          // We're OK
        } else {
          done = false;
        }
      }

      // Don't send addition failure notifications if we're only doing
      // a compaction
      if (!done && needAdditionFailureNotification && cause != null) {
        manager.additionFailed(cause, attemptNumber);
      }
      ++attemptNumber;
    }

    // See whether the implicit compaction that just occurred has
    // yielded excess empty space.
    if (nextLevelSet.getUsedHeight() > 0 &&
        nextLevelSet.getUsedHeight() < nextLevelSet.h() * SHRINK_FACTOR) {
      int shrunkHeight = Math.max(initialHeight,
                                  (int) (nextLevelSet.getUsedHeight() * (1.0f + EXPANSION_FACTOR)));
      if (maxHeight > 0 && shrunkHeight > maxHeight) {
        shrunkHeight = maxHeight;
      }
      nextLevelSet.setHeight(shrunkHeight);
    }

    // If we temporarily added the new rectangle to the new LevelSet,
    // take it out since we don't "really" add it here but in add(), above
    if (cause != null) {
      nextLevelSet.remove(cause);
    }

    // OK, now we have a new layout and a mapping from the old to the
    // new locations of rectangles on the backing store. Allocate a
    // new backing store, move the contents over and deallocate the
    // old one.
    Object newBackingStore = manager.allocateBackingStore(nextLevelSet.w(),
                                                          nextLevelSet.h());
    manager.beginMovement(backingStore, newBackingStore);
    for (Iterator i1 = levels.iterator(); i1.hasNext(); ) {
      Level level = (Level) i1.next();
      for (Iterator i2 = level.iterator(); i2.hasNext(); ) {
        Rect cur = (Rect) i2.next();
        manager.move(backingStore, cur,
                     newBackingStore, cur.getNextLocation());
      }
    }
    // Replace references to temporary rectangles with original ones
    nextLevelSet.updateRectangleReferences();
    manager.endMovement(backingStore, newBackingStore);
    // Now delete the old backing store
    manager.deleteBackingStore(backingStore);
    // Update to new versions of backing store and LevelSet
    backingStore = newBackingStore;
    levels = nextLevelSet;
  }

  /** Clears all Rects contained in this RectanglePacker. */
  public void clear() {
    levels.clear();
  }

  /** Disposes the backing store allocated by the
      BackingStoreManager. This RectanglePacker may no longer be used
      after calling this method. */
  public void dispose() {
    if (backingStore != null)
      manager.deleteBackingStore(backingStore);
    backingStore = null;
    levels = null;
  }
}