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

/* View.java --
   Copyright (C) 2002, 2004, 2005, 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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General Public License for more details.

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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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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this exception to your version of the library, but you are not
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package javax.swing.text;

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

import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.event.DocumentEvent;

public abstract class View implements SwingConstants
{
  public static final int BadBreakWeight = 0;
  public static final int ExcellentBreakWeight = 2000;
  public static final int ForcedBreakWeight = 3000;
  public static final int GoodBreakWeight = 1000;

  public static final int X_AXIS = 0;
  public static final int Y_AXIS = 1;

  private Element elt;
  private View parent;

  /**
   * Creates a new <code>View</code> instance.
   *
   * @param elem an <code>Element</code> value
   */
  public View(Element elem)
  {
    elt = elem;
  }

  public abstract void paint(Graphics g, Shape s);

  /**
   * Sets the parent for this view. This is the first method that is beeing
   * called on a view to setup the view hierarchy. This is also the last method
   * beeing called when the view is disconnected from the view hierarchy, in
   * this case <code>parent</code> is null.
   *
   * If <code>parent</code> is <code>null</code>, a call to this method also
   * calls <code>setParent</code> on the children, thus disconnecting them from
   * the view hierarchy. That means that super must be called when this method
   * is overridden.
   *
   * @param parent the parent to set, <code>null</code> when this view is
   *        beeing disconnected from the view hierarchy
   */
  public void setParent(View parent)
  {
    if (parent == null)
      {
        int numChildren = getViewCount();
        for (int i = 0; i < numChildren; i++)
          {
            View child = getView(i);
            // It is important that we only reset the parent on views that
            // actually belong to us. In FlowView the child may already be
            // reparented.
            if (child.getParent() == this)
              child.setParent(null);
          }
      }

    this.parent = parent;
  }

  public View getParent()
  {
    return parent;
  }

  public Container getContainer()
  {
    View parent = getParent();
    if (parent == null)
      return null;
    else
      return parent.getContainer();
  }

  public Document getDocument()
  {
    return getElement().getDocument();
  }

  public Element getElement()
  {
    return elt;
  }

  /**
   * Returns the preferred span along the specified axis. Normally the view is
   * rendered with the span returned here if that is possible.
   *
   * @param axis the axis
   *
   * @return the preferred span along the specified axis
   */
  public abstract float getPreferredSpan(int axis);

  /**
   * Returns the resize weight of this view. A value of <code>0</code> or less
   * means this view is not resizeable. Positive values make the view
   * resizeable. The default implementation returns <code>0</code>
   * unconditionally.
   *
   * @param axis the axis
   *
   * @return the resizability of this view along the specified axis
   */
  public int getResizeWeight(int axis)
  {
    return 0;
  }

  /**
   * Returns the maximum span along the specified axis. The default
   * implementation will forward to
   * {@link #getPreferredSpan(int)} unless {@link #getResizeWeight(int)}
   * returns a value > 0, in which case this returns {@link Integer#MIN_VALUE}.
   *
   * @param axis the axis
   *
   * @return the maximum span along the specified axis
   */
  public float getMaximumSpan(int axis)
  {
    float max = Integer.MAX_VALUE;
    if (getResizeWeight(axis) <= 0)
      max = getPreferredSpan(axis);
    return max;
  }

  /**
   * Returns the minimum span along the specified axis. The default
   * implementation will forward to
   * {@link #getPreferredSpan(int)} unless {@link #getResizeWeight(int)}
   * returns a value > 0, in which case this returns <code>0</code>.
   *
   * @param axis the axis
   *
   * @return the minimum span along the specified axis
   */
  public float getMinimumSpan(int axis)
  {
    float min = 0;
    if (getResizeWeight(axis) <= 0)
      min = getPreferredSpan(axis);
    return min;
  }

  public void setSize(float width, float height)
  {
    // The default implementation does nothing.
  }

  /**
   * Returns the alignment of this view along the baseline of the parent view.
   * An alignment of <code>0.0</code> will align this view with the left edge
   * along the baseline, an alignment of <code>0.5</code> will align it
   * centered to the baseline, an alignment of <code>1.0</code> will align
   * the right edge along the baseline.
   *
   * The default implementation returns 0.5 unconditionally.
   *
   * @param axis the axis
   *
   * @return the alignment of this view along the parents baseline for the
   *         specified axis
   */
  public float getAlignment(int axis)
  {
    return 0.5f;
  }

  public AttributeSet getAttributes()
  {
    return getElement().getAttributes();
  }

  public boolean isVisible()
  {
    return true;
  }

  public int getViewCount()
  {
    return 0;
  }

  public View getView(int index)
  {
    return null;
  }

  public ViewFactory getViewFactory()
  {
    View parent = getParent();
    return parent != null ? parent.getViewFactory() : null;
  }

  /**
   * Replaces a couple of child views with new child views. If
   * <code>length == 0</code> then this is a simple insertion, if
   * <code>views == null</code> this only removes some child views.
   *
   * @param offset the offset at which to replace
   * @param length the number of child views to be removed
   * @param views the new views to be inserted, may be <code>null</code>
   */
  public void replace(int offset, int length, View[] views)
  {
    // Default implementation does nothing.
  }

  public void insert(int offset, View view)
  {
    View[] array = { view };
    replace(offset, 1, array);
  }

  public void append(View view)
  {
    View[] array = { view };
    int offset = getViewCount();
    replace(offset, 0, array);
  }

  public void removeAll()
  {
    replace(0, getViewCount(), null);
  }

  public void remove(int index)
  {
    replace(index, 1, null);
  }

  public View createFragment(int p0, int p1)
  {
    // The default implementation doesn't support fragmentation.
    return this;
  }

  public int getStartOffset()
  {
    return getElement().getStartOffset();
  }

  public int getEndOffset()
  {
    return getElement().getEndOffset();
  }

  public Shape getChildAllocation(int index, Shape a)
  {
    return null;
  }

  /**
   * @since 1.4
   */
  public int getViewIndex(float x, float y, Shape allocation)
  {
    return -1;
  }

  /**
   * @since 1.4
   */
  public String getToolTipText(float x, float y, Shape allocation)
  {
    int index = getViewIndex(x, y, allocation);

    String text = null;
    if (index >= 0)
      {
        allocation = getChildAllocation(index, allocation);
        Rectangle r = allocation instanceof Rectangle ? (Rectangle) allocation
                                                      : allocation.getBounds();
        if (r.contains(x, y))
          text = getView(index).getToolTipText(x, y, allocation);
      }
    return text;
  }

  /**
   * @since 1.3
   */
  public Graphics getGraphics()
  {
    return getContainer().getGraphics();
  }

  public void preferenceChanged(View child, boolean width, boolean height)
  {
    View p = getParent();
    if (p != null)
      p.preferenceChanged(this, width, height);
  }

  public int getBreakWeight(int axis, float pos, float len)
  {
    int weight = BadBreakWeight;
    if (len > getPreferredSpan(axis))
      weight = GoodBreakWeight;
    return weight;
  }

  public View breakView(int axis, int offset, float pos, float len)
  {
    return this;
  }

  /**
   * @since 1.3
   */
  public int getViewIndex(int pos, Position.Bias b)
  {
    return -1;
  }

  /**
   * Receive notification about an insert update to the text model.
   *
   * The default implementation of this method does the following:
   * <ul>
   * <li>Call {@link #updateChildren} if the element that this view is
   * responsible for has changed. This makes sure that the children can
   * correctly represent the model.<li>
   * <li>Call {@link #forwardUpdate}. This forwards the DocumentEvent to
   * the child views.<li>
   * <li>Call {@link #updateLayout}. Gives the view a chance to either
   * repair its layout, reschedule layout or do nothing at all.</li>
   * </ul>
   *
   * @param ev the DocumentEvent that describes the change
   * @param shape the shape of the view
   * @param vf the ViewFactory for creating child views
   */
  public void insertUpdate(DocumentEvent ev, Shape shape, ViewFactory vf)
  {
    if (getViewCount() > 0)
      {
        Element el = getElement();
        DocumentEvent.ElementChange ec = ev.getChange(el);
        if (ec != null)
          {
            if (! updateChildren(ec, ev, vf))
              ec = null;
          }
        forwardUpdate(ec, ev, shape, vf);
        updateLayout(ec, ev, shape);
      }
  }

  /**
   * Receive notification about a remove update to the text model.
   *
   * The default implementation of this method does the following:
   * <ul>
   * <li>Call {@link #updateChildren} if the element that this view is
   * responsible for has changed. This makes sure that the children can
   * correctly represent the model.<li>
   * <li>Call {@link #forwardUpdate}. This forwards the DocumentEvent to
   * the child views.<li>
   * <li>Call {@link #updateLayout}. Gives the view a chance to either
   * repair its layout, reschedule layout or do nothing at all.</li>
   * </ul>
   *
   * @param ev the DocumentEvent that describes the change
   * @param shape the shape of the view
   * @param vf the ViewFactory for creating child views
   */
  public void removeUpdate(DocumentEvent ev, Shape shape, ViewFactory vf)
  {
    Element el = getElement();
    DocumentEvent.ElementChange ec = ev.getChange(el);
    if (ec != null)
      {
        if (! updateChildren(ec, ev, vf))
          ec = null;
      }
    forwardUpdate(ec, ev, shape, vf);
    updateLayout(ec, ev, shape);
  }

  /**
   * Receive notification about a change update to the text model.
   *
   * The default implementation of this method does the following:
   * <ul>
   * <li>Call {@link #updateChildren} if the element that this view is
   * responsible for has changed. This makes sure that the children can
   * correctly represent the model.<li>
   * <li>Call {@link #forwardUpdate}. This forwards the DocumentEvent to
   * the child views.<li>
   * <li>Call {@link #updateLayout}. Gives the view a chance to either
   * repair its layout, reschedule layout or do nothing at all.</li>
   * </ul>
   *
   * @param ev the DocumentEvent that describes the change
   * @param shape the shape of the view
   * @param vf the ViewFactory for creating child views
   */
  public void changedUpdate(DocumentEvent ev, Shape shape, ViewFactory vf)
  {
    if (getViewCount() > 0)
      {
        Element el = getElement();
        DocumentEvent.ElementChange ec = ev.getChange(el);
        if (ec != null)
          {
            if (! updateChildren(ec, ev, vf))
              ec = null;
          }
        forwardUpdate(ec, ev, shape, vf);
        updateLayout(ec, ev, shape);
      }
  }

  /**
   * Updates the list of children that is returned by {@link #getView}
   * and {@link #getViewCount}.
   *
   * Element that are specified as beeing added in the ElementChange record are
   * assigned a view for using the ViewFactory. Views of Elements that
   * are specified as beeing removed are removed from the list.
   *
   * @param ec the ElementChange record that describes the change of the
   *           element
   * @param ev the DocumentEvent describing the change of the document model
   * @param vf the ViewFactory to use for creating new views
   *
   * @return whether or not the child views represent the child elements of
   *         the element that this view is responsible for. Some views may
   *         create views that are responsible only for parts of the element
   *         that they are responsible for and should then return false.
   *
   * @since 1.3
   */
  protected boolean updateChildren(DocumentEvent.ElementChange ec,
                                   DocumentEvent ev,
                                   ViewFactory vf)
  {
    Element[] added = ec.getChildrenAdded();
    Element[] removed = ec.getChildrenRemoved();
    int index = ec.getIndex();

    View[] newChildren = null;
    if (added != null)
      {
        newChildren = new View[added.length];
        for (int i = 0; i < added.length; ++i)
          newChildren[i] = vf.create(added[i]);
      }
    int numRemoved = removed != null ? removed.length : 0;
    replace(index, numRemoved, newChildren);

    return true;
  }

  /**
   * Forwards the DocumentEvent to child views that need to get notified
   * of the change to the model. This calles {@link #forwardUpdateToView}
   * for each View that must be forwarded to.
   *
   * If <code>ec</code> is not <code>null</code> (this means there have been
   * structural changes to the element that this view is responsible for) this
   * method should recognize this and don't notify newly added child views.
   *
   * @param ec the ElementChange describing the element changes (may be
   *           <code>null</code> if there were no changes)
   * @param ev the DocumentEvent describing the changes to the model
   * @param shape the current allocation of the view
   * @param vf the ViewFactory used to create new Views
   *
   * @since 1.3
   */
  protected void forwardUpdate(DocumentEvent.ElementChange ec,
                               DocumentEvent ev, Shape shape, ViewFactory vf)
  {
    int count = getViewCount();
    if (count > 0)
      {
        // Determine start index.
        int startOffset = ev.getOffset();
        int startIndex = getViewIndex(startOffset, Position.Bias.Backward);

        // For REMOVE events we have to forward the event to the last element,
        // for the case that an Element has been removed that represente
        // the offset.
        if (startIndex == -1 && ev.getType() == DocumentEvent.EventType.REMOVE
            && startOffset >= getEndOffset())
          {
            startIndex = getViewCount() - 1;
          }

        // When startIndex is on a view boundary, forward event to the
        // previous view too.
        if (startIndex >= 0)
          {
            View v = getView(startIndex);
            if (v != null)
              {
                if (v.getStartOffset() == startOffset && startOffset > 0)
                  startIndex = Math.max(0, startIndex - 1);
              }
          }
        startIndex = Math.max(0, startIndex);

        // Determine end index.
        int endIndex = startIndex;
        if (ev.getType() != DocumentEvent.EventType.REMOVE)
          {
            endIndex = getViewIndex(startOffset + ev.getLength(),
                                    Position.Bias.Forward);
            if (endIndex < 0)
              endIndex = getViewCount() - 1;
          }

        // Determine hole that comes from added elements (we don't forward
        // the event to newly added views.
        int startAdded = endIndex + 1;
        int endAdded = startAdded;
        Element[] added = (ec != null) ? ec.getChildrenAdded() : null;
        if (added != null && added.length > 0)
          {
            startAdded = ec.getIndex();
            endAdded = startAdded + added.length - 1;
          }

        // Forward event to all views between startIndex and endIndex,
        // and leave out all views in the hole.
        for (int i = startIndex; i <= endIndex; i++)
          {
            // Skip newly added child views.
            if (! (i >= startAdded && i <= endAdded))
              {
                View child = getView(i);
                if (child != null)
                  {
                    Shape childAlloc = getChildAllocation(i, shape);
                    forwardUpdateToView(child, ev, childAlloc, vf);
                  }
              }
          }
      }
  }

  /**
   * Forwards an update event to the given child view. This calls
   * {@link #insertUpdate}, {@link #removeUpdate} or {@link #changedUpdate},
   * depending on the type of document event.
   *
   * @param view the View to forward the event to
   * @param ev the DocumentEvent to forward
   * @param shape the current allocation of the View
   * @param vf the ViewFactory used to create new Views
   *
   * @since 1.3
   */
  protected void forwardUpdateToView(View view, DocumentEvent ev, Shape shape,
                                     ViewFactory vf)
  {
    DocumentEvent.EventType type = ev.getType();
    if (type == DocumentEvent.EventType.INSERT)
      view.insertUpdate(ev, shape, vf);
    else if (type == DocumentEvent.EventType.REMOVE)
      view.removeUpdate(ev, shape, vf);
    else if (type == DocumentEvent.EventType.CHANGE)
      view.changedUpdate(ev, shape, vf);
  }

  /**
   * Updates the layout.
   *
   * @param ec the ElementChange that describes the changes to the element
   * @param ev the DocumentEvent that describes the changes to the model
   * @param shape the current allocation for this view
   *
   * @since 1.3
   */
  protected void updateLayout(DocumentEvent.ElementChange ec,
                              DocumentEvent ev, Shape shape)
  {
    if (ec != null && shape != null)
      {
        preferenceChanged(null, true, true);
        Container c = getContainer();
        if (c != null)
          c.repaint();
      }
  }

  /**
   * Maps a position in the document into the coordinate space of the View.
   * The output rectangle usually reflects the font height but has a width
   * of zero.
   *
   * @param pos the position of the character in the model
   * @param a the area that is occupied by the view
   * @param b either {@link Position.Bias#Forward} or
   *        {@link Position.Bias#Backward} depending on the preferred
   *        direction bias. If <code>null</code> this defaults to
   *        <code>Position.Bias.Forward</code>
   *
   * @return a rectangle that gives the location of the document position
   *         inside the view coordinate space
   *
   * @throws BadLocationException if <code>pos</code> is invalid
   * @throws IllegalArgumentException if b is not one of the above listed
   *         valid values
   */
  public abstract Shape modelToView(int pos, Shape a, Position.Bias b)
    throws BadLocationException;

  /**
   * Maps a region in the document into the coordinate space of the View.
   *
   * @param p1 the beginning position inside the document
   * @param b1 the direction bias for the beginning position
   * @param p2 the end position inside the document
   * @param b2 the direction bias for the end position
   * @param a the area that is occupied by the view
   *
   * @return a rectangle that gives the span of the document region
   *         inside the view coordinate space
   *
   * @throws BadLocationException if <code>p1</code> or <code>p2</code> are
   *         invalid
   * @throws IllegalArgumentException if b1 or b2 is not one of the above
   *         listed valid values
   */
  public Shape modelToView(int p1, Position.Bias b1,
                           int p2, Position.Bias b2, Shape a)
    throws BadLocationException
  {
    if (b1 != Position.Bias.Forward && b1 != Position.Bias.Backward)
      throw new IllegalArgumentException
        ("b1 must be either Position.Bias.Forward or Position.Bias.Backward");
    if (b2 != Position.Bias.Forward && b2 != Position.Bias.Backward)
      throw new IllegalArgumentException
        ("b2 must be either Position.Bias.Forward or Position.Bias.Backward");

    Shape s1 = modelToView(p1, a, b1);
    // Special case for p2 == end index.
    Shape s2;
    if (p2 != getEndOffset())
      {
        s2 = modelToView(p2, a, b2);
      }
    else
      {
        try
          {
            s2 = modelToView(p2, a, b2);
          }
        catch (BadLocationException ex)
          {
            // Assume the end rectangle to be at the right edge of the
            // view.
            Rectangle aRect = a instanceof Rectangle ? (Rectangle) a
                                                     : a.getBounds();
            s2 = new Rectangle(aRect.x + aRect.width - 1, aRect.y, 1,
                               aRect.height);
          }
      }

    // Need to modify the rectangle, so we create a copy in all cases.
    Rectangle r1 = s1.getBounds();
    Rectangle r2 = s2 instanceof Rectangle ? (Rectangle) s2
                                           : s2.getBounds();

    // For multiline view, let the resulting rectangle span the whole view.
    if (r1.y != r2.y)
      {
        Rectangle aRect = a instanceof Rectangle ? (Rectangle) a
                                                 : a.getBounds();
        r1.x = aRect.x;
        r1.width = aRect.width;
      }

    return SwingUtilities.computeUnion(r2.x, r2.y, r2.width, r2.height, r1);
  }

  /**
   * Maps a position in the document into the coordinate space of the View.
   * The output rectangle usually reflects the font height but has a width
   * of zero.
   *
   * This method is deprecated and calls
   * {@link #modelToView(int, Position.Bias, int, Position.Bias, Shape)} with
   * a bias of {@link Position.Bias#Forward}.
   *
   * @param pos the position of the character in the model
   * @param a the area that is occupied by the view
   *
   * @return a rectangle that gives the location of the document position
   *         inside the view coordinate space
   *
   * @throws BadLocationException if <code>pos</code> is invalid
   *
   * @deprecated Use {@link #modelToView(int, Shape, Position.Bias)} instead.
   */
  public Shape modelToView(int pos, Shape a) throws BadLocationException
  {
    return modelToView(pos, a, Position.Bias.Forward);
  }

  /**
   * 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 abstract int viewToModel(float x, float y, Shape a, Position.Bias[] b);

  /**
   * Maps coordinates from the <code>View</code>'s space into a position
   * in the document model. This method is deprecated and only there for
   * compatibility.
   *
   * @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>
   *
   * @return the position in the document that corresponds to the screen
   *         coordinates <code>x, y</code>
   *
   * @deprecated Use {@link #viewToModel(float, float, Shape, Position.Bias[])}
   *             instead.
   */
  public int viewToModel(float x, float y, Shape a)
  {
    Position.Bias[] biasRet = new Position.Bias[1];
    biasRet[0] = Position.Bias.Forward;
    return viewToModel(x, y, a, biasRet);
  }

  /**
   * Dumps the complete View hierarchy. This method can be used for debugging
   * purposes.
   */
  protected void dump()
  {
    // Climb up the hierarchy to the parent.
    View parent = getParent();
    if (parent != null)
      parent.dump();
    else
      dump(0);
  }

  /**
   * Dumps the view hierarchy below this View with the specified indentation
   * level.
   *
   * @param indent the indentation level to be used for this view
   */
  void dump(int indent)
  {
    for (int i = 0; i < indent; ++i)
      System.out.print('.');
    System.out.println(this + "(" + getStartOffset() + "," + getEndOffset() + ": " + getElement());

    int count = getViewCount();
    for (int i = 0; i < count; ++i)
      getView(i).dump(indent + 1);
  }

  /**
   * Returns the document position that is (visually) nearest to the given
   * document position <code>pos</code> in the given direction <code>d</code>.
   *
   * @param pos the document position
   * @param b the bias for <code>pos</code>
   * @param a the allocation for this view
   * @param d the direction, must be either {@link SwingConstants#NORTH},
   *        {@link SwingConstants#SOUTH}, {@link SwingConstants#WEST} or
   *        {@link SwingConstants#EAST}
   * @param biasRet an array of {@link Position.Bias} that can hold at least
   *        one element, which is filled with the bias of the return position
   *        on method exit
   *
   * @return the document position that is (visually) nearest to the given
   *         document position <code>pos</code> in the given direction
   *         <code>d</code>
   *
   * @throws BadLocationException if <code>pos</code> is not a valid offset in
   *         the document model
   * @throws IllegalArgumentException if <code>d</code> is not a valid direction
   */
  public int getNextVisualPositionFrom(int pos, Position.Bias b,
                                       Shape a, int d,
                                       Position.Bias[] biasRet)
    throws BadLocationException
  {
    int ret = pos;
    Rectangle r;
    View parent;

    switch (d)
    {
      case EAST:
        // TODO: take component orientation into account?
        // Note: If pos is below zero the implementation will return
        // pos + 1 regardless of whether that value is a correct offset
        // in the document model. However this is what the RI does.
        ret = Math.min(pos + 1, getEndOffset());
        break;
      case WEST:
        // TODO: take component orientation into account?
        ret = Math.max(pos - 1, getStartOffset());
        break;
      case NORTH:
        // Try to find a suitable offset by examining the area above.
        parent = getParent();
        r =  parent.modelToView(pos, a, b).getBounds();
        ret = parent.viewToModel(r.x, r.y - 1, a, biasRet);
        break;
      case SOUTH:
        // Try to find a suitable offset by examining the area below.
        parent = getParent();
        r =  parent.modelToView(pos, a, b).getBounds();
        ret = parent.viewToModel(r.x + r.width, r.y + r.height, a, biasRet);
        break;
      default:
        throw new IllegalArgumentException("Illegal value for d");
    }

    return ret;
  }
}