jviewport.java

linux下编程用 编译软件

  }

  public final Insets getInsets(Insets insets)
  {
    if (insets == null)
      return getInsets();
    insets.top = 0;
    insets.bottom = 0;
    insets.left = 0;
    insets.right = 0;
    return insets;
  }
    

  /**
   * Overridden to return <code>false</code>, so the JViewport's paint method
   * gets called instead of directly calling the children. This is necessary
   * in order to get a useful clipping and translation on the children.
   *
   * @return <code>false</code>
   */
  public boolean isOptimizedDrawingEnabled()
  {
    return false;
  }

  public void paint(Graphics g)
  {
    Component view = getView();

    if (view == null)
      return;

    Point pos = getViewPosition();
    Rectangle viewBounds = view.getBounds();
    Rectangle portBounds = getBounds();

    if (viewBounds.width == 0 
        || viewBounds.height == 0
        || portBounds.width == 0
        || portBounds.height == 0)
      return;

    switch (getScrollMode())
      {

      case JViewport.BACKINGSTORE_SCROLL_MODE:
        paintBackingStore(g);
        break;
      case JViewport.BLIT_SCROLL_MODE:
        paintBlit(g);
        break;
      case JViewport.SIMPLE_SCROLL_MODE:
      default:
        paintSimple(g);
        break;
      }
    damaged = false;
  }

  public void addChangeListener(ChangeListener listener)
  {
    listenerList.add(ChangeListener.class, listener);
  }

  public void removeChangeListener(ChangeListener listener)
  {
    listenerList.remove(ChangeListener.class, listener);
  }

  public ChangeListener[] getChangeListeners() 
  {
    return (ChangeListener[]) getListeners(ChangeListener.class);
  }

  /**
   * This method returns the String ID of the UI class of  Separator.
   *
   * @return The UI class' String ID.
   */
  public String getUIClassID()
  {
    return "ViewportUI";
  }

  /**
   * This method resets the UI used to the Look and Feel defaults..
   */
  public void updateUI()
  {
    setUI((ViewportUI) UIManager.getUI(this));
  }            

  /**
   * This method returns the viewport's UI delegate.
   *
   * @return The viewport's UI delegate.
   */
  public ViewportUI getUI()
  {
    return (ViewportUI) ui;
  }

  /**
   * This method sets the viewport's UI delegate.
   *
   * @param ui The viewport's UI delegate.
   */
  public void setUI(ViewportUI ui)
  {
    super.setUI(ui);
  }

  public final void setBorder(Border border)
  {
    if (border != null)
      throw new IllegalArgumentException();
  }

  /**
   * Scrolls the view so that contentRect becomes visible.
   *
   * @param contentRect the rectangle to make visible within the view
   */
  public void scrollRectToVisible(Rectangle contentRect)
  {
    Component view = getView();
    if (view == null)
      return;    
      
    Point pos = getViewPosition();
    Rectangle viewBounds = getView().getBounds();
    Rectangle portBounds = getBounds();
    
    if (isShowing())
      getView().validate();

    // If the bottom boundary of contentRect is below the port
    // boundaries, scroll up as necessary.
    if (contentRect.y + contentRect.height + viewBounds.y > portBounds.height)
      pos.y = contentRect.y + contentRect.height - portBounds.height;
    // If contentRect.y is above the port boundaries, scroll down to
    // contentRect.y.
    if (contentRect.y + viewBounds.y < 0)
      pos.y = contentRect.y;
    // If the right boundary of contentRect is right from the port
    // boundaries, scroll left as necessary.
    if (contentRect.x + contentRect.width + viewBounds.x > portBounds.width)
      pos.x = contentRect.x + contentRect.width - portBounds.width;
    // If contentRect.x is left from the port boundaries, scroll right to
    // contentRect.x.
    if (contentRect.x + viewBounds.x < 0)
      pos.x = contentRect.x;
    setViewPosition(pos);
  }

  /**
   * Returns the accessible context for this <code>JViewport</code>. This
   * will be an instance of {@link AccessibleJViewport}.
   *
   * @return the accessible context for this <code>JViewport</code>
   */
  public AccessibleContext getAccessibleContext()
  {
    if (accessibleContext == null)
      accessibleContext = new AccessibleJViewport();
    return accessibleContext;
  }

  /**
   * Forward repaint to parent to make sure only one paint is performed by the
   * RepaintManager.
   *
   * @param tm number of milliseconds to defer the repaint request
   * @param x the X coordinate of the upper left corner of the dirty area
   * @param y the Y coordinate of the upper left corner of the dirty area
   * @param w the width of the dirty area
   * @param h the height of the dirty area
   */
  public void repaint(long tm, int x, int y, int w, int h)
  {
    Component parent = getParent();
    if (parent != null)
      {
        parent.repaint(tm, x + getX(), y + getY(), w, h);
      }
  }

  protected void addImpl(Component comp, Object constraints, int index)
  {
    if (getComponentCount() > 0)
      remove(getComponents()[0]);
    
    super.addImpl(comp, constraints, index);
  }

  protected void fireStateChanged()
  {
    ChangeListener[] listeners = getChangeListeners();
    for (int i = 0; i < listeners.length; ++i)
      listeners[i].stateChanged(changeEvent);
  }

  /**
   * Creates a {@link ViewListener} that is supposed to listen for
   * size changes on the view component.
   *
   * @return a ViewListener instance
   */
  protected ViewListener createViewListener()
  {
    return new ViewListener();
  }

  /**
   * Creates the LayoutManager that is used for this viewport. Override
   * this method if you want to use a custom LayoutManager.
   *
   * @return a LayoutManager to use for this viewport
   */
  protected LayoutManager createLayoutManager()
  {
    return new ViewportLayout();
  }

  /**
   * Computes the parameters for the blitting scroll method. <code>dx</code>
   * and <code>dy</code> specifiy the X and Y offset by which the viewport
   * is scrolled. All other arguments are output parameters and are filled by
   * this method.
   *
   * <code>blitFrom</code> holds the position of the blit rectangle in the
   * viewport rectangle before scrolling, <code>blitTo</code> where the blitArea
   * is copied to.
   *
   * <code>blitSize</code> holds the size of the blit area and
   * <code>blitPaint</code> is the area of the view that needs to be painted.
   *
   * This method returns <code>true</code> if blitting is possible and
   * <code>false</code> if the viewport has to be repainted completetly without
   * blitting.
   *
   * @param dx the horizontal delta
   * @param dy the vertical delta
   * @param blitFrom the position from where to blit; set by this method
   * @param blitTo the position where to blit area is copied to; set by this
   *        method
   * @param blitSize the size of the blitted area; set by this method
   * @param blitPaint the area that needs repainting; set by this method
   *
   * @return <code>true</code> if blitting is possible,
   *         <code>false</code> otherwise
   */
  protected boolean computeBlit(int dx, int dy, Point blitFrom, Point blitTo,
                                Dimension blitSize, Rectangle blitPaint)
  {
    if ((dx != 0 && dy != 0) || damaged)
      // We cannot blit if the viewport is scrolled in both directions at
      // once.
      return false;

    Rectangle portBounds = SwingUtilities.calculateInnerArea(this, getBounds());

    // Compute the blitFrom and blitTo parameters.
    blitFrom.x = portBounds.x;
    blitFrom.y = portBounds.y;
    blitTo.x = portBounds.x;
    blitTo.y = portBounds.y;

    if (dy > 0)
      {
        blitFrom.y = portBounds.y + dy;
      }
    else if (dy < 0)
      {
        blitTo.y = portBounds.y - dy;
      }
    else if (dx > 0)
      {
        blitFrom.x = portBounds.x + dx;
      }
    else if (dx < 0)
      {
        blitTo.x = portBounds.x - dx;
      }

    // Compute size of the blit area.
    if (dx != 0)
      {
        blitSize.width = portBounds.width - Math.abs(dx);
        blitSize.height = portBounds.height;
      }
    else if (dy != 0)
      {
        blitSize.width = portBounds.width;
        blitSize.height = portBounds.height - Math.abs(dy);
      }

    // Compute the blitPaint parameter.
    blitPaint.setBounds(portBounds);
    if (dy > 0)
      {
        blitPaint.y = portBounds.y + portBounds.height - dy;
        blitPaint.height = dy;
      }
    else if (dy < 0)
      {
        blitPaint.height = -dy;
      }
    if (dx > 0)
      {
        blitPaint.x = portBounds.x + portBounds.width - dx;
        blitPaint.width = dx;
      }
    else if (dx < 0)
      {
        blitPaint.width = -dx;
      }

    return true;
  }

  /**
   * Paints the viewport in case we have a scrollmode of
   * {@link #SIMPLE_SCROLL_MODE}.
   *
   * This simply paints the view directly on the surface of the viewport.
   *
   * @param g the graphics context to use
   */
  void paintSimple(Graphics g)
  {
    Point pos = getViewPosition();
    Component view = getView();
    boolean translated = false;
    try
      {
        g.translate(-pos.x, -pos.y);
        translated = true;
        view.paint(g);
      } 
    finally
      {
        if (translated)
          g.translate (pos.x, pos.y);
      }
  }

  /**
   * Paints the viewport in case we have a scroll mode of
   * {@link #BACKINGSTORE_SCROLL_MODE}.
   *
   * This method uses a backing store image to paint the view to, which is then
   * subsequently painted on the screen. This should make scrolling more
   * smooth.
   *
   * @param g the graphics context to use
   */
  void paintBackingStore(Graphics g)
  {
    // If we have no backing store image yet or the size of the component has
    // changed, we need to rebuild the backing store.
    if (backingStoreImage == null || sizeChanged)
      {
        backingStoreImage = createImage(getWidth(), getHeight());
        sizeChanged = false;
        Graphics g2 = backingStoreImage.getGraphics();
        paintSimple(g2);
        g2.dispose();
      }
    // Otherwise we can perform the blitting on the backing store image:
    // First we move the part that remains visible after scrolling, then
    // we only need to paint the bit that becomes newly visible.
    else
      {
        Graphics g2 = backingStoreImage.getGraphics();
        Point viewPosition = getViewPosition();
        int dx = viewPosition.x - lastPaintPosition.x;
        int dy = viewPosition.y - lastPaintPosition.y;
        boolean canBlit = computeBlit(dx, dy, cachedBlitFrom, cachedBlitTo,
                                      cachedBlitSize, cachedBlitPaint);
        if (canBlit)
          {
            // Copy the part that remains visible during scrolling.
            g2.copyArea(cachedBlitFrom.x, cachedBlitFrom.y,
                        cachedBlitSize.width, cachedBlitSize.height,
                        cachedBlitTo.x - cachedBlitFrom.x,
                        cachedBlitTo.y - cachedBlitFrom.y);
            // Now paint the part that becomes newly visible.
            g2.setClip(cachedBlitPaint.x, cachedBlitPaint.y,
                       cachedBlitPaint.width, cachedBlitPaint.height);
            paintSimple(g2);
          }
        // If blitting is not possible for some reason, fall back to repainting
        // everything.
        else
          {
            paintSimple(g2);
          }
        g2.dispose();
      }
    // Actually draw the backingstore image to the graphics context.
    g.drawImage(backingStoreImage, 0, 0, this);
    // Update the lastPaintPosition so that we know what is already drawn when
    // we paint the next time.
    lastPaintPosition.setLocation(getViewPosition());
  }

  /**
   * Paints the viewport in case we have a scrollmode of
   * {@link #BLIT_SCROLL_MODE}.
   *
   * This paints the viewport using a backingstore and a blitting algorithm.
   * Only the newly exposed area of the view is painted from the view painting
   * methods, the remainder is copied from the backing store.
   *
   * @param g the graphics context to use
   */
  void paintBlit(Graphics g)
  {
    // We cannot perform blitted painting as it is described in Sun's API docs.
    // There it is suggested that this painting method should blit directly
    // on the parent window's surface. This is not possible because when using
    // Swing's double buffering (at least our implementation), it would
    // immediatly be painted when the buffer is painted on the screen. For this
    // to work we would need a kind of hole in the buffer image. And honestly
    // I find this method not very elegant.
    // The alternative, blitting directly on the buffer image, is also not
    // possible because the buffer image gets cleared everytime when an opaque
    // parent component is drawn on it.

    // What we do instead is falling back to the backing store approach which
    // is in fact a mixed blitting/backing store approach where the blitting
    // is performed on the backing store image and this is then drawn to the
    // graphics context. This is very robust and works independent of the
    // painting mechanism that is used by Swing. And it should have comparable
    // performance characteristics as the blitting method.
    paintBackingStore(g);
  }
}