gcc/libjava/classpath/javax/swing/tree/VariableHeightLayoutCache.java

/* VariableHeightLayoutCache.java --
   Copyright (C) 2002, 2004, 2006,  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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permission to link this library with independent modules to produce an
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package javax.swing.tree;

import gnu.javax.swing.tree.GnuPath;

import java.awt.Rectangle;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.LinkedList;
import java.util.Set;
import java.util.Vector;

import javax.swing.event.TreeModelEvent;

/**
 * The fixed height tree layout. This class requires the NodeDimensions to be
 * set and ignores the row height property.
 * 
 * @specnote the methods, of this class, returning TreePath, actually returns
 * the derived class GnuPath that provides additional information for optimized
 * painting. See the GnuPath code for details.
 * 
 * @author Audrius Meskauskas
 */
public class VariableHeightLayoutCache
  extends AbstractLayoutCache
{

  private static final Rectangle RECT_CACHE = new Rectangle();

  /**
   * The cached node record.
   */
  class NodeRecord
  {
    NodeRecord(int aRow, int aDepth, Object aNode, Object aParent)
    {
      row = aRow;
      depth = aDepth;
      parent = aParent;
      node = aNode;
      isExpanded = expanded.contains(aNode);
      bounds = new Rectangle(0, -1, 0, 0);
    }
    
    /**
     * The row, where the tree node is displayed.
     */
    final int row;    
    
    /**
     * The nesting depth
     */
    final int depth;
    
    /**
     * The parent of the given node, null for the root node.
     */
    final Object parent;
    
    /**
     * This node.
     */
    final Object node;
    
    /**
     * True for the expanded nodes. The value is calculated in constructor.
     * Using this field saves one hashtable access operation.
     */
    final boolean isExpanded;

    /**
     * The cached bounds of the tree row.
     */
    Rectangle bounds;
    
    /**
     * The path from the tree top to the given node (computed under first
     * demand)
     */
    private TreePath path;
    
    /**
     * Get the path for this node. The derived class is returned, making check
     * for the last child of some parent easier.
     */
    TreePath getPath()
    {
      if (path == null)
        {
          boolean lastChild = false;
          if (parent != null)
            {
              int nc = treeModel.getChildCount(parent);
              if (nc > 0)
                {
                  int n = treeModel.getIndexOfChild(parent, node);
                  if (n == nc - 1)
                    lastChild = true;
                }
            }

          LinkedList<Object> lpath = new LinkedList<Object>();
          NodeRecord rp = this;
          while (rp != null)
            {
              lpath.addFirst(rp.node);
              if (rp.parent != null)
                {
                  Object parent = rp.parent;
                  rp = nodes.get(parent);
                  // Add the root node, even if it is not visible.
                  if (rp == null)
                    lpath.addFirst(parent);
                }
              else
                rp = null;
            }
          path = new GnuPath(lpath.toArray(), lastChild);
        }
      return path;
    }
    
    /**
     * Get the rectangle bounds (compute, if required).
     */
    Rectangle getBounds()
    {
      return bounds;      
    }
  }
  
  /**
   * The set of all expanded tree nodes.
   */
  Set<Object> expanded = new HashSet<Object>();
  
  /**
   * Maps nodes to the row numbers.
   */
  Hashtable<Object,NodeRecord> nodes = new Hashtable<Object,NodeRecord>();
  
  /**
   * Maps row numbers to nodes.
   */
  ArrayList<Object> row2node = new ArrayList<Object>();
  
  /**
   * If true, the row map must be recomputed before using.
   */
  boolean dirty;
  
  /**
   * The cumulative height of all rows.
   */
  int totalHeight;
  
  /**
   * The maximal width.
   */
  int maximalWidth;

  /**
   * Creates the unitialised instance. Before using the class, the row height
   * must be set with the {@link #setRowHeight(int)} and the model must be set
   * with {@link #setModel(TreeModel)}. The node dimensions may not be set.
   */
  public VariableHeightLayoutCache()
  {
    // Nothing to do here.
  } 

  /**
   * Get the total number of rows in the tree. Every displayed node occupies the
   * single row. The root node row is included if the root node is set as
   * visible (false by default).
   * 
   * @return int the number of the displayed rows.
   */
  public int getRowCount()
  {
    if (dirty) update();
    return row2node.size();
  } 
  
  /**
   * Refresh the row map.
   */
  private final void update()
  {
    nodes.clear();
    row2node.clear();
    
    totalHeight = maximalWidth = 0;

    if (treeModel == null)
      return;

    Object root = treeModel.getRoot();
    countRows(root, null, 0, 0);
    dirty = false;
  }
  
  /**
   * Recursively counts all rows in the tree.
   */
  private final int countRows(Object node, Object parent, int depth, int y)
  {
    boolean visible = node != treeModel.getRoot() || rootVisible;
    int row = row2node.size();
    if (visible)
      {
        row2node.add(node);
      }
    NodeRecord nr = new NodeRecord(row, depth, node, parent);
    NodeDimensions d = getNodeDimensions();
    Rectangle r = RECT_CACHE;
    if (d != null)
      r = d.getNodeDimensions(node, row, depth, nr.isExpanded, r);
    else
      r.setBounds(0, 0, 0, 0);

    if (! visible)
      r.y = -1;
    else
      r.y = Math.max(0, y);

    if (isFixedRowHeight())
      r.height = getRowHeight();

    nr.bounds.setBounds(r);
    nodes.put(node, nr);

    if (visible)
      y += r.height;

    int sc = treeModel.getChildCount(node);
    int deeper = depth + 1;
    if (expanded.contains(node))
      {
        for (int i = 0; i < sc; i++)
          {
            Object child = treeModel.getChild(node, i);
            y = countRows(child, node, deeper, y);
          }
      }
    return y;
  }

  /**
   * Discard the bound information for the given path.
   * 
   * @param path the path, for that the bound information must be recomputed.
   */
  public void invalidatePathBounds(TreePath path)
  {
    NodeRecord r = nodes.get(path.getLastPathComponent());
    if (r != null)
      r.bounds = null;
  } 

  /**
   * Mark all cached information as invalid.
   */
  public void invalidateSizes()
  {
    dirty = true;
  } 

  /**
   * Set the expanded state of the given path. The expansion states must be
   * always updated when expanding and colapsing the tree nodes. Otherwise 
   * other methods will not work correctly after the nodes are collapsed or
   * expanded.
   *
   * @param path the tree path, for that the state is being set.
   * @param isExpanded the expanded state of the given path.
   */
  public void setExpandedState(TreePath path, boolean isExpanded)
  {
    if (isExpanded)
      {
        int length = path.getPathCount();
        for (int i = 0; i < length; i++)
          expanded.add(path.getPathComponent(i));
      }
    else
      expanded.remove(path.getLastPathComponent());

    dirty = true;
  }
  
  /**
   * Get the expanded state for the given tree path.
   * 
   * @return true if the given path is expanded, false otherwise.
   */
  public boolean isExpanded(TreePath path)
  {
    return expanded.contains(path.getLastPathComponent());
  } 

  /**
   * Get bounds for the given tree path.
   * 
   * @param path the tree path
   * @param rect the rectangle that will be reused to return the result.
   * @return Rectangle the bounds of the last line, defined by the given path.
   */
  public Rectangle getBounds(TreePath path, Rectangle rect)
  {
    if (path == null)
      return null;
    if (dirty)
      update();

    Object last = path.getLastPathComponent();
    Rectangle result = null;
    NodeRecord r = nodes.get(last);
    if (r != null)
      {
        // The RI allows null arguments for rect, in which case a new Rectangle
        // is created.
        result = rect;
        if (result == null)
          result = new Rectangle(r.bounds);
        else
          result.setBounds(r.bounds);
      }
    return result;
  } 

  /**
   * Get the path, the last element of that is displayed in the given row.
   * 
   * @param row the row
   * @return TreePath the path
   */
  public TreePath getPathForRow(int row)
  {
    if (dirty)
      update();

    TreePath path = null;
    // Search row in the nodes map. TODO: This is inefficient, optimize this.
    Enumeration<NodeRecord> nodesEnum = nodes.elements();
    while (nodesEnum.hasMoreElements() && path == null)
      {
        NodeRecord record = nodesEnum.nextElement();
        if (record.row == row)
          path = record.getPath();
      }
    return path;
  } 

  /**
   * Get the row, displaying the last node of the given path.
   * 
   * @param path the path
   * @return int the row number or -1 if the end of the path is not visible.
   */
  public int getRowForPath(TreePath path)
  {
    if (path == null)
      return -1;

    if (dirty)
      update();

    NodeRecord r = nodes.get(path.getLastPathComponent());
    if (r == null)
      return - 1;
    else
      return r.row;
  } 

  /**
   * Get the path, closest to the given point.
   * 
   * @param x the point x coordinate
   * @param y the point y coordinate
   * @return the tree path, closest to the the given point
   */
  public TreePath getPathClosestTo(int x, int y)
  {
    if (dirty)
      update();

    // As the rows have arbitrary height, we need to iterate.
    NodeRecord best = null;
    NodeRecord r;
    Enumeration<NodeRecord> en = nodes.elements();
    
    int dist = Integer.MAX_VALUE;

    while (en.hasMoreElements() && dist > 0)
      {
        r = en.nextElement();
        if (best == null)
          {
            best = r;
            dist = distance(r.getBounds(), x, y);
          }
        else
          {
            int rr = distance(r.getBounds(), x, y);
            if (rr < dist)
              {
                best = r;
                dist = rr;
              }
          }
      }

    if (best == null)
      return null;
    else
      return best.getPath();
  } 
  
  /**
   * Get the closest distance from this point till the given rectangle. Only
   * vertical distance is taken into consideration.
   */
  int distance(Rectangle r, int x, int y)
  {
    if (y < r.y)
      return r.y - y;
    else if (y > r.y + r.height - 1)
      return y - (r.y + r.height - 1);
    else
      return 0;
  }

  /**
   * Get the number of the visible childs for the given tree path. If the node
   * is not expanded, 0 is returned. Otherwise, the number of children is
   * obtained from the model as the number of children for the last path
   * component.
   * 
   * @param path the tree path
   * @return int the number of the visible childs (for row).
   */
  public int getVisibleChildCount(TreePath path)  
  {
    if (! isExpanded(path) || treeModel == null)
      return 0; 
    else
      return treeModel.getChildCount(path.getLastPathComponent());
  } 

  /**
   * Get the enumeration over all visible paths that start from the given
   * parent path.
   * 
   * @param parentPath the parent path
   * @return the enumeration over pathes
   */
  public Enumeration<TreePath> getVisiblePathsFrom(TreePath parentPath)
  {
    if (dirty)
      update();
    Vector<TreePath> p = new Vector<TreePath>(parentPath.getPathCount());
    Object node;
    NodeRecord nr;

    for (int i = 0; i < parentPath.getPathCount(); i++)
      {
        node = parentPath.getPathComponent(i);
        nr = nodes.get(node);
        if (nr != null && nr.row >= 0)
          p.add((TreePath) node);
      }
    return p.elements();
  }

  /**
   * Return the expansion state of the given tree path. The expansion state
   * must be previously set with the 
   * {@link #setExpandedState(TreePath, boolean)}
   * 
   * @param path the path being checked
   * @return true if the last node of the path is expanded, false otherwise.
   */
  public boolean getExpandedState(TreePath path)
  {
    return expanded.contains(path.getLastPathComponent());
  }

  /**
   * The listener method, called when the tree nodes are changed.
   * 
   * @param event the change event
   */
  public void treeNodesChanged(TreeModelEvent event)
  {
    dirty = true;
  } 

  /**
   * The listener method, called when the tree nodes are inserted.
   * 
   * @param event the change event
   */
  public void treeNodesInserted(TreeModelEvent event)
  {
    dirty = true;
  } 

  /**
   * The listener method, called when the tree nodes are removed.
   * 
   * @param event the change event
   */
  public void treeNodesRemoved(TreeModelEvent event)
  {
    dirty = true;
  } 

  /**
   * Called when the tree structure has been changed. 
   * 
   * @param event the change event
   */
  public void treeStructureChanged(TreeModelEvent event)
  {
    dirty = true;
  } 
  
  /**
   * Set the tree model that will provide the data.
   */
  public void setModel(TreeModel newModel)
  {
    treeModel = newModel;
    dirty = true;
    if (treeModel != null)
      {
        // The root node is expanded by default.
        expanded.add(treeModel.getRoot());
      }
  }
  
  /**
   * Inform the instance if the tree root node is visible. If this method
   * is not called, it is assumed that the tree root node is not visible.
   * 
   * @param visible true if the tree root node is visible, false
   * otherwise.
   */
  public void setRootVisible(boolean visible)
  {
    rootVisible = visible;
    dirty = true;
  }

  /**
   * Get the sum of heights for all rows.
   */
  public int getPreferredHeight()
  {
    if (dirty)
      update();
    int height = 0;
    int rowCount = getRowCount();
    if (rowCount > 0)
      {
        NodeRecord last = nodes.get(row2node.get(rowCount - 1));
        height = last.bounds.y + last.bounds.height;
      }
    return height;
  }

  /**
   * Get the maximal width.
   */
  public int getPreferredWidth(Rectangle value)
  {
    if (dirty)
      update();
    
    maximalWidth = 0;
    Enumeration<NodeRecord> en = nodes.elements();
    while (en.hasMoreElements())
      {
        NodeRecord nr = en.nextElement();
        if (nr != null)
          {
            Rectangle r = nr.getBounds();
            int width = r.x + r.width;
            if (width > maximalWidth)
              maximalWidth = width;
          }
      }
    return maximalWidth;
  }

  /**
   * Sets the node dimensions and invalidates the cached layout.
   *
   * @param dim the dimensions to set
   */
  public void setNodeDimensions(NodeDimensions dim)
  {
    super.setNodeDimensions(dim);
    dirty = true;
  }

  /**
   * Sets the row height and marks the layout as invalid.
   *
   * @param height the row height to set
   */
  public void setRowHeight(int height)
  {
    super.setRowHeight(height);
    dirty = true;
  }
}