component.java

gcc的组建

          {
            Rectangle oldBounds = new Rectangle(oldx, oldy, oldwidth,
                                                oldheight);
            Rectangle newBounds = new Rectangle(x, y, width, height);
            Rectangle destroyed = oldBounds.union(newBounds);
            if (!destroyed.isEmpty())
              parent.repaint(0, destroyed.x, destroyed.y, destroyed.width,
                             destroyed.height);
          }
      }

    // Only post event if this component is visible and has changed size.
    if (isShowing ()
        && (oldx != x || oldy != y))
      {
        ComponentEvent ce = new ComponentEvent(this,
                                               ComponentEvent.COMPONENT_MOVED);
        getToolkit().getSystemEventQueue().postEvent(ce);
      }
    if (isShowing ()
        && (oldwidth != width || oldheight != height))
      {
        ComponentEvent ce = new ComponentEvent(this,
                                               ComponentEvent.COMPONENT_RESIZED);
        getToolkit().getSystemEventQueue().postEvent(ce);
      }
  }

  /**
   * Sets the bounding rectangle for this component to the specified
   * rectangle. Note that these coordinates are relative to the parent, not
   * to the screen.
   *
   * @param r the new bounding rectangle
   * @throws NullPointerException if r is null
   * @see #getBounds()
   * @see #setLocation(Point)
   * @see #setSize(Dimension)
   * @since 1.1
   */
  public void setBounds(Rectangle r)
  {
    setBounds (r.x, r.y, r.width, r.height);
  }

  /**
   * Gets the x coordinate of the upper left corner. This is more efficient
   * than getBounds().x or getLocation().x.
   *
   * @return the current x coordinate
   * @since 1.2
   */
  public int getX()
  {
    return x;
  }

  /**
   * Gets the y coordinate of the upper left corner. This is more efficient
   * than getBounds().y or getLocation().y.
   *
   * @return the current y coordinate
   * @since 1.2
   */
  public int getY()
  {
    return y;
  }

  /**
   * Gets the width of the component. This is more efficient than
   * getBounds().width or getSize().width.
   *
   * @return the current width
   * @since 1.2
   */
  public int getWidth()
  {
    return width;
  }

  /**
   * Gets the height of the component. This is more efficient than
   * getBounds().height or getSize().height.
   *
   * @return the current width
   * @since 1.2
   */
  public int getHeight()
  {
    return height;
  }

  /**
   * Returns the bounds of this component. This allows reuse of an existing
   * rectangle, if r is non-null.
   *
   * @param r the rectangle to use, or null
   * @return the bounds
   */
  public Rectangle getBounds(Rectangle r)
  {
    if (r == null)
      r = new Rectangle();
    r.x = x;
    r.y = y;
    r.width = width;
    r.height = height;
    return r;
  }

  /**
   * Returns the size of this component. This allows reuse of an existing
   * dimension, if d is non-null.
   *
   * @param d the dimension to use, or null
   * @return the size
   */
  public Dimension getSize(Dimension d)
  {
    if (d == null)
      d = new Dimension();
    d.width = width;
    d.height = height;
    return d;
  }

  /**
   * Returns the location of this component. This allows reuse of an existing
   * point, if p is non-null.
   *
   * @param p the point to use, or null
   * @return the location
   */
  public Point getLocation(Point p)
  {
    if (p == null)
      p = new Point();
    p.x = x;
    p.y = y;
    return p;
  }

  /**
   * Tests if this component is opaque. All "heavyweight" (natively-drawn)
   * components are opaque. A component is opaque if it draws all pixels in
   * the bounds; a lightweight component is partially transparent if it lets
   * pixels underneath show through. Subclasses that guarantee that all pixels
   * will be drawn should override this.
   *
   * @return true if this is opaque
   * @see #isLightweight()
   * @since 1.2
   */
  public boolean isOpaque()
  {
    return ! isLightweight();
  }

  /**
   * Return whether the component is lightweight. That means the component has
   * no native peer, but is displayable. This applies to subclasses of
   * Component not in this package, such as javax.swing.
   *
   * @return true if the component has a lightweight peer
   * @see #isDisplayable()
   * @since 1.2
   */
  public boolean isLightweight()
  {
    return peer instanceof LightweightPeer;
  }

  /**
   * Returns the component's preferred size.
   *
   * @return the component's preferred size
   * @see #getMinimumSize()
   * @see LayoutManager
   */
  public Dimension getPreferredSize()
  {
    return preferredSize();
  }

  /**
   * Returns the component's preferred size.
   *
   * @return the component's preferred size
   * @deprecated use {@link #getPreferredSize()} instead
   */
  public Dimension preferredSize()
  {
    if (prefSize == null)
      if (peer == null)
	return new Dimension(width, height);
      else 
        prefSize = peer.getPreferredSize();
    return prefSize;
  }

  /**
   * Returns the component's minimum size.
   *
   * @return the component's minimum size
   * @see #getPreferredSize()
   * @see LayoutManager
   */
  public Dimension getMinimumSize()
  {
    return minimumSize();
  }

  /**
   * Returns the component's minimum size.
   *
   * @return the component's minimum size
   * @deprecated use {@link #getMinimumSize()} instead
   */
  public Dimension minimumSize()
  {
    if (minSize == null)
      minSize = (peer != null ? peer.getMinimumSize()
                 : new Dimension(width, height));
    return minSize;
  }

  /**
   * Returns the component's maximum size.
   *
   * @return the component's maximum size
   * @see #getMinimumSize()
   * @see #getPreferredSize()
   * @see LayoutManager
   */
  public Dimension getMaximumSize()
  {
    return new Dimension(Short.MAX_VALUE, Short.MAX_VALUE);
  }

  /**
   * Returns the preferred horizontal alignment of this component. The value
   * returned will be between {@link #LEFT_ALIGNMENT} and
   * {@link #RIGHT_ALIGNMENT}, inclusive.
   *
   * @return the preferred horizontal alignment of this component
   */
  public float getAlignmentX()
  {
    return CENTER_ALIGNMENT;
  }

  /**
   * Returns the preferred vertical alignment of this component. The value
   * returned will be between {@link #TOP_ALIGNMENT} and
   * {@link #BOTTOM_ALIGNMENT}, inclusive.
   *
   * @return the preferred vertical alignment of this component
   */
  public float getAlignmentY()
  {
    return CENTER_ALIGNMENT;
  }

  /**
   * Calls the layout manager to re-layout the component. This is called
   * during validation of a container in most cases.
   *
   * @see #validate()
   * @see LayoutManager
   */
  public void doLayout()
  {
    layout ();
  }

  /**
   * Calls the layout manager to re-layout the component. This is called
   * during validation of a container in most cases.
   *
   * @deprecated use {@link #doLayout()} instead
   */
  public void layout()
  {
    // Nothing to do unless we're a container.
  }

  /**
   * Called to ensure that the layout for this component is valid. This is
   * usually called on containers.
   *
   * @see #invalidate()
   * @see #doLayout()
   * @see LayoutManager
   * @see Container#validate()
   */
  public void validate()
  {
    valid = true;
  }

  /**
   * Invalidates this component and all of its parent components. This will
   * cause them to have their layout redone. This is called frequently, so
   * make it fast.
   */
  public void invalidate()
  {
    valid = false;
    prefSize = null;
    minSize = null;
    if (parent != null && parent.isValid())
      parent.invalidate();
  }

  /**
   * Returns a graphics object for this component. Returns <code>null</code>
   * if this component is not currently displayed on the screen.
   *
   * @return a graphics object for this component
   * @see #paint(Graphics)
   */
  public Graphics getGraphics()
  {
    if (peer != null)
      {
        Graphics gfx = peer.getGraphics();
        // Create peer for lightweights.
        if (gfx == null && parent != null)
          {
            gfx = parent.getGraphics();
            Rectangle bounds = getBounds();
            gfx.setClip(bounds);
            gfx.translate(bounds.x, bounds.y);
            return gfx;
          }
        gfx.setFont(font);
        return gfx;
      }
    return null;
  }

  /**
   * Returns the font metrics for the specified font in this component.
   *
   * @param font the font to retrieve metrics for
   * @return the font metrics for the specified font
   * @throws NullPointerException if font is null
   * @see #getFont()
   * @see Toolkit#getFontMetrics(Font)
   */
  public FontMetrics getFontMetrics(Font font)
  {
    return peer == null ? getToolkit().getFontMetrics(font)
      : peer.getFontMetrics(font);
  }

  /**
   * Sets the cursor for this component to the specified cursor. The cursor
   * is displayed when the point is contained by the component, and the
   * component is visible, displayable, and enabled. This is inherited by
   * subcomponents unless they set their own cursor.
   *
   * @param cursor the new cursor for this component
   * @see #isEnabled()
   * @see #isShowing()
   * @see #getCursor()
   * @see #contains(int, int)
   * @see Toolkit#createCustomCursor(Image, Point, String)
   */
  public void setCursor(Cursor cursor)
  {
    this.cursor = cursor;
    if (peer != null)
      peer.setCursor(cursor);
  }

  /**
   * Returns the cursor for this component. If not set, this is inherited
   * from the parent, or from Cursor.getDefaultCursor().
   *
   * @return the cursor for this component
   */
  public Cursor getCursor()
  {
    if (cursor != null)
      return cursor;
    return parent != null ? parent.getCursor() : Cursor.getDefaultCursor();
  }

  /**
   * Tests if the cursor was explicitly set, or just inherited from the parent.
   *
   * @return true if the cursor has been set
   * @since 1.4
   */
  public boolean isCursorSet()
  {
    return cursor != null;
  }

  /**
   * Paints this component on the screen. The clipping region in the graphics
   * context will indicate the region that requires painting. This is called
   * whenever the component first shows, or needs to be repaired because
   * something was temporarily drawn on top. It is not necessary for
   * subclasses to call <code>super.paint(g)</code>. Components with no area
   * are not painted.
   *
   * @param g the graphics context for this paint job
   * @see #update(Graphics)
   */
  public void paint(Graphics g)
  {
    // This is a callback method and is meant to be overridden by subclasses
    // that want to perform custom painting.
  }

  /**
   * Updates this component. This is called in response to
   * <code>repaint</code>. This method fills the component with the
   * background color, then sets the foreground color of the specified
   * graphics context to the foreground color of this component and calls
   * the <code>paint()</code> method. The coordinates of the graphics are
   * relative to this component. Subclasses should call either
   * <code>super.update(g)</code> or <code>paint(g)</code>.
   *
   * @param g the graphics context for this update
   *
   * @see #paint(Graphics)
   * @see #repaint()
   *
   * @specnote In contrast to what the spec says, tests show that the exact
   *           behaviour is to clear the background on lightweight and
   *           top-level components only. Heavyweight components are not
   *           affected by this method and only call paint().
   */
  public void update(Graphics g)
  {
    // Tests show that the clearing of the background is only done in
    // two cases:
    // - If the component is lightweight (yes this is in contrast to the spec).
    // or
    // - If the component is a toplevel container.
    if (isLightweight() || getParent() == null)
      {
        Rectangle clip = g.getClipBounds();
        if (clip == null)
          g.clearRect(0, 0, width, height);
        else
          g.clearRect(clip.x, clip.y, clip.width, clip.height);
      }
    paint(g);
  }

  /**
   * Paints this entire component, including any sub-components.
   *
   * @param g the graphics context for this paint job
   * 
   * @see #paint(Graphics)
   */
  public void paintAll(Graphics g)
  {
    if (! visible)
      return;
    paint(g);
  }

  /**