libjava/classpath/javax/swing/text/ComponentView.java

/* ComponentView.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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permission to link this library with independent modules to produce an
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package javax.swing.text;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;

import javax.swing.SwingUtilities;

/**
 * A {@link View} implementation that is able to render arbitrary
 * {@link Component}s. This uses the attribute
 * {@link StyleConstants#ComponentAttribute} to determine the
 * <code>Component</code> that should be rendered. This <code>Component</code>
 * becomes a direct child of the <code>JTextComponent</code> that contains
 * this <code>ComponentView</code>, so this view must not be shared between
 * multiple <code>JTextComponent</code>s.
 *
 * @author Roman Kennke (kennke@aicas.com)
 * @author original author unknown
 */
public class ComponentView extends View
{

  /**
   * A special container that sits between the component and the hosting
   * container. This is used to propagate invalidate requests and cache
   * the component's layout sizes.
   */
  private class Interceptor
    extends Container
  {
    Dimension min;
    Dimension pref;
    Dimension max;
    float alignX;
    float alignY;

    /**
     * Creates a new instance that hosts the specified component.
     */
    Interceptor(Component c)
    {
      setLayout(null);
      add(c);
      cacheComponentSizes();
    }

    /**
     * Intercepts the normal invalidate call and propagates the invalidate
     * request up using the View's preferenceChanged().
     */
    public void invalidate()
    {
      super.invalidate();
      if (getParent() != null)
        preferenceChanged(null, true, true);
    }

    /**
     * This is overridden to simply cache the layout sizes.
     */
    public void doLayout()
    {
      cacheComponentSizes();
    }

    /**
     * Overridden to also reshape the component itself.
     */
    public void reshape(int x, int y, int w, int h)
    {
      super.reshape(x, y, w, h);
      if (getComponentCount() > 0)
        getComponent(0).setSize(w, h);
      cacheComponentSizes();
    }

    /**
     * Overridden to also show the component.
     */
    public void show()
    {
      super.show();
      if (getComponentCount() > 0)
        getComponent(0).setVisible(true);
    }

    /**
     * Overridden to also hide the component.
     */
    public void hide()
    {
      super.hide();
      if (getComponentCount() > 0)
        getComponent(0).setVisible(false);
    }

    /**
     * Overridden to return the cached value.
     */
    public Dimension getMinimumSize()
    {
      maybeValidate();
      return min;
    }

    /**
     * Overridden to return the cached value.
     */
    public Dimension getPreferredSize()
    {
      maybeValidate();
      return pref;
    }

    /**
     * Overridden to return the cached value.
     */
    public Dimension getMaximumSize()
    {
      maybeValidate();
      return max;
    }

    /**
     * Overridden to return the cached value.
     */
    public float getAlignmentX()
    {
      maybeValidate();
      return alignX;
    }

    /**
     * Overridden to return the cached value.
     */
    public float getAlignmentY()
    {
      maybeValidate();
      return alignY;
    }

    /**
     * Validates the container only when necessary.
     */
    private void maybeValidate()
    {
      if (! isValid())
        validate();
    }

    /**
     * Fetches the component layout sizes into the cache.
     */
    private void cacheComponentSizes()
    {
      if (getComponentCount() > 0)
        {
          Component c = getComponent(0);
          min = c.getMinimumSize();
          pref = c.getPreferredSize();
          max = c.getMaximumSize();
          alignX = c.getAlignmentX();
          alignY = c.getAlignmentY();
        }
    }
  }

  /**
   * The component that is displayed by this view.
   */
  private Component comp;

  /**
   * The intercepting container.
   */
  private Interceptor interceptor;

  /**
   * Creates a new instance of <code>ComponentView</code> for the specified
   * <code>Element</code>.
   *
   * @param elem the element that this <code>View</code> is rendering
   */
  public ComponentView(Element elem)
  {
    super(elem);
  }

  /**
   * Creates the <code>Component</code> that this <code>View</code> is
   * rendering. The <code>Component</code> is determined using
   * the {@link StyleConstants#ComponentAttribute} of the associated
   * <code>Element</code>.
   *
   * @return the component that is rendered
   */
  protected Component createComponent()
  {
    return StyleConstants.getComponent(getElement().getAttributes());
  }

  /**
   * Returns the alignment of this <code>View</code> along the specified axis.
   *
   * @param axis either {@link View#X_AXIS} or {@link View#Y_AXIS}
   *
   * @return the alignment of this <code>View</code> along the specified axis
   */
  public float getAlignment(int axis)
  {
    float align = 0.0F;
    // I'd rather throw an IllegalArgumentException for illegal axis,
    // but the Harmony testsuite indicates fallback to super behaviour.
    if (interceptor != null && (axis == X_AXIS || axis == Y_AXIS))
      {
        if (axis == X_AXIS)
          align = interceptor.getAlignmentX();
        else if (axis == Y_AXIS)
          align = interceptor.getAlignmentY();
        else
          assert false : "Must not reach here";
      }
    else
      align = super.getAlignment(axis);
    return align;
  }

  /**
   * Returns the <code>Component</code> that is rendered by this
   * <code>ComponentView</code>.
   *
   * @return the <code>Component</code> that is rendered by this
   *         <code>ComponentView</code>
   */
  public final Component getComponent()
  {
    return comp;
  }

  /**
   * Returns the maximum span of this <code>View</code> along the specified
   * axis.
   *
   * This will return {@link Component#getMaximumSize()} for the specified
   * axis.
   *
   * @return the maximum span of this <code>View</code> along the specified
   *         axis
   */
  public float getMaximumSpan(int axis)
  {
    if (axis != X_AXIS && axis != Y_AXIS)
      throw new IllegalArgumentException("Illegal axis");
    float span = 0;
    if (interceptor != null)
      {
        if (axis == X_AXIS)
          span = interceptor.getMaximumSize().width;
        else if (axis == Y_AXIS)
          span = interceptor.getMaximumSize().height;
        else
          assert false : "Must not reach here";
      }
    return span;
  }

  public float getMinimumSpan(int axis)
  {
    if (axis != X_AXIS && axis != Y_AXIS)
      throw new IllegalArgumentException("Illegal axis");
    float span = 0;
    if (interceptor != null)
      {
        if (axis == X_AXIS)
          span = interceptor.getMinimumSize().width;
        else if (axis == Y_AXIS)
          span = interceptor.getMinimumSize().height;
        else
          assert false : "Must not reach here";
      }
    return span;
  }

  public float getPreferredSpan(int axis)
  {
    if (axis != X_AXIS && axis != Y_AXIS)
      throw new IllegalArgumentException("Illegal axis");
    float span = 0;
    if (interceptor != null)
      {
        if (axis == X_AXIS)
          span = interceptor.getPreferredSize().width;
        else if (axis == Y_AXIS)
          span = interceptor.getPreferredSize().height;
        else
          assert false : "Must not reach here";
      }
    return span;
  }

  public Shape modelToView(int pos, Shape a, Position.Bias b)
    throws BadLocationException
  {
    int p0 = getStartOffset();
    int p1 = getEndOffset();
    if (pos >= p0 && pos <= p1)
      {
        Rectangle viewRect = a.getBounds();
        if (pos == p1)
          viewRect.x += viewRect.width;
        viewRect.width = 0;
        return viewRect;
      }
    else
      throw new BadLocationException("Illegal position", pos);
  }

  /**
   * The real painting behavour is performed by normal component painting,
   * triggered by the text component that hosts this view. This method does
   * not paint by itself. However, it sets the size of the component according
   * to the allocation that is passed here.
   *
   * @param g the graphics context
   * @param a the allocation of the child
   */
  public void paint(Graphics g, Shape a)
  {
    if (interceptor != null)
      {
        Rectangle r = a instanceof Rectangle ? (Rectangle) a : a.getBounds();
        interceptor.setBounds(r.x, r.y, r.width, r.height);
      }
  }

  /**
   * This sets up the component when the view is added to its parent, or
   * cleans up the view when it is removed from its parent.
   *
   * When this view is added to a parent view, the component of this view
   * is added to the container that hosts this view. When <code>p</code> is
   * <code>null</code>, then the view is removed from it's parent and we have
   * to also remove the component from it's parent container.
   *
   * @param p the parent view or <code>null</code> if this view is removed
   *        from it's parent
   */
  public void setParent(final View p)
  {
    super.setParent(p);
    if (SwingUtilities.isEventDispatchThread())
      setParentImpl();
    else
      SwingUtilities.invokeLater
      (new Runnable()
       {
         public void run()
         {
           Document doc = getDocument();
           try
             {
               if (doc instanceof AbstractDocument)
                 ((AbstractDocument) doc).readLock();
               setParentImpl();
               Container host = getContainer();
               if (host != null)
                 {
                   preferenceChanged(null, true, true);
                   host.repaint();
                 }
             }
           finally
             {
               if (doc instanceof AbstractDocument)
                 ((AbstractDocument) doc).readUnlock();
             }
         }
       });
  }

  /**
   * The implementation of {@link #setParent}. This is package private to
   * avoid a synthetic accessor method.
   */
  void setParentImpl()
  {
    View p = getParent();
    if (p != null)
      {
        Container c = getContainer();
        if (c != null)
          {
            if (interceptor == null)
              {
                // Create component and put it inside the interceptor.
                Component created = createComponent();
                if (created != null)
                  {
                    comp = created;
                    interceptor = new Interceptor(comp);
                  }
              }
            if (interceptor != null)
              {
                // Add the interceptor to the hosting container.
                if (interceptor.getParent() == null)
                  c.add(interceptor, this);
              }
          }
      }
    else
      {
        if (interceptor != null)
          {
            Container parent = interceptor.getParent();
            if (parent != null)
              parent.remove(interceptor);
          }
      }
  }

  /**
   * Maps coordinates from the <code>View</code>'s space into a position
   * in the document model.
   *
   * @param x the x coordinate in the view space
   * @param y the y coordinate in the view space
   * @param a the allocation of this <code>View</code>
   * @param b the bias to use
   *
   * @return the position in the document that corresponds to the screen
   *         coordinates <code>x, y</code>
   */
  public int viewToModel(float x, float y, Shape a, Position.Bias[] b)
  {
    int pos;
    // I'd rather do the following. The harmony testsuite indicates
    // that a simple cast is performed.
    //Rectangle r = a instanceof Rectangle ? (Rectangle) a : a.getBounds();
    Rectangle r = (Rectangle) a;
    if (x < r.x + r.width / 2)
      {
        b[0] = Position.Bias.Forward;
        pos = getStartOffset();
      }
    else
      {
        b[0] = Position.Bias.Backward;
        pos = getEndOffset();
      }
    return pos;
  }
}