component.java

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    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()
  {
    if (prefSize == null)
      prefSize = (peer != null ? peer.getPreferredSize()
                       : new Dimension(width, height));
    return prefSize;
  }

  /**
   * Returns the component's preferred size.
   *
   * @return the component's preferred size
   * @deprecated use {@link #getPreferredSize()} instead
   */
  public Dimension preferredSize()
  {
    return getPreferredSize();
  }

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

  /**
   * Returns the component's minimum size.
   *
   * @return the component's minimum size
   * @deprecated use {@link #getMinimumSize()} instead
   */
  public Dimension minimumSize()
  {
    return getMinimumSize();
  }

  /**
   * Returns the component's maximum size.
   *
   * @return the component's maximum size
   * @see #getMinimumSize()
   * @see #getPreferredSize()
   * @see LayoutManager
   */
  public Dimension getMaximumSize()
  {
    return new Dimension(Integer.MAX_VALUE, Integer.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()
  {
    // nothing to do unless we're a container
  }

  /**
   * 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()
  {
    doLayout();
  }

  /**
   * 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.valid)
      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();
        if (gfx != null)
          return gfx;
        // create graphics for lightweight:
        Container parent = getParent();
        if (parent != null)
          {
            gfx = parent.getGraphics();
            Rectangle bounds = getBounds();
            gfx.setClip(bounds);
            gfx.translate(bounds.x, bounds.y);
            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)
  {
  }

  /**
   * 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 graphics the graphics context for this update
   * @see #paint(Graphics)
   * @see #repaint()
   */
  public void update(Graphics g)
  {
    paint(g);
  }

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

  /**
   * Repaint this entire component. The <code>update()</code> method
   * on this component will be called as soon as possible.
   *
   * @see #update(Graphics)
   * @see #repaint(long, int, int, int, int)
   */
  public void repaint()
  {
    repaint(0, 0, 0, width, height);
  }

  /**
   * Repaint this entire component. The <code>update()</code> method on this
   * component will be called in approximate the specified number of
   * milliseconds.
   *
   * @param tm milliseconds before this component should be repainted
   * @see #paint(Graphics)
   * @see #repaint(long, int, int, int, int)
   */
  public void repaint(long tm)
  {
    repaint(tm, 0, 0, width, height);
  }

  /**
   * Repaints the specified rectangular region within this component. The
   * <code>update</code> method on this component will be called as soon as
   * possible. The coordinates are relative to this component.
   *
   * @param x the X coordinate of the upper left of the region to repaint
   * @param y the Y coordinate of the upper left of the region to repaint
   * @param w the width of the region to repaint
   * @param h the height of the region to repaint
   * @see #update(Graphics)
   * @see #repaint(long, int, int, int, int)
   */
  public void repaint(int x, int y, int w, int h)
  {
    repaint(0, x, y, w, h);
  }

  /**
   * Repaints the specified rectangular region within this component. The
   * <code>update</code> method on this component will be called in
   * approximately the specified number of milliseconds. The coordinates
   * are relative to this component.
   *
   * @param tm milliseconds before this component should be repainted
   * @param x the X coordinate of the upper left of the region to repaint
   * @param y the Y coordinate of the upper left of the region to repaint
   * @param w the width of the region to repaint
   * @param h the height of the region to repaint
   * @see #update(Graphics)
   */
  public void repaint(long tm, int x, int y, int width, int height)
  {
    // Handle lightweight repainting by forwarding to native parent
    if (isLightweight() && parent != null)
      {
        if (parent != null)
          parent.repaint(tm, x + getX(), y + getY(), width, height);
      }
    else if (peer != null)
      peer.repaint(tm, x, y, width, height);
  }

  /**
   * Prints this component. This method is provided so that printing can be
   * done in a different manner from painting. However, the implementation
   * in this class simply calls the <code>paint()</code> method.
   *
   * @param graphics the graphics context of the print device
   * @see #paint(Graphics)
   */
  public void print(Graphics g)
  {
    paint(g);
  }

  /**
   * Prints this component, including all sub-components. This method is
   * provided so that printing can be done in a different manner from
   * painting. However, the implementation in this class simply calls the
   * <code>paintAll()</code> method.
   *
   * @param graphics the graphics context of the print device
   * @see #paintAll(Graphics)
   */
  public void printAll(Graphics g)
  {
    paintAll(g);
  }

  /**
   * Called when an image has changed so that this component is repainted.
   * This incrementally draws an image as more bits are available, when
   * possible. Incremental drawing is enabled if the system property
   * <code>awt.image.incrementalDraw</code> is not present or is true, in which
   * case the redraw rate is set to 100ms or the value of the system property
   * <code>awt.image.redrawrate</code>.
   *
   * <p>The coordinate system used depends on the particular flags.
   *
   * @param image the image that has been updated
   * @param flags tlags as specified in <code>ImageObserver</code>
   * @param x the X coordinate
   * @param y the Y coordinate
   * @param w the width
   * @param h the height
   * @return true if the image has been fully loaded
   * @see ImageObserver
   * @see Graphics#drawImage(Image, int, int, Color, ImageObserver)
   * @see Graphics#drawImage(Image, int, int, ImageObserver)
   * @see Graphics#drawImage(Image, int, int, int, int, Color, ImageObserver)
   * @see Graphics#drawImage(Image, int, int, int, int, ImageObserver)
   * @see ImageObserver#update(Image, int, int, int, int, int)
   */
  public boolean imageUpdate(Image img, int flags, int x, int y, int w, int h)
  {
    // XXX Implement.
    throw new Error("not implemented");
  }

  /**
   * Creates an image from the specified producer.
   *
   * @param producer the image procedure to create the image from
   * @return the resulting image
   */
  public Image createImage(ImageProducer producer)
  {
    // XXX What if peer or producer is null?
    return peer.createImage(producer);
  }

  /**
   * Creates an image with the specified width and height for use in
   * double buffering. Headless environments do not support images.
   *
   * @param width the width of the image
   * @param height the height of the image
   * @return the requested image, or null if it is not supported
   */
  public Image createImage(int width, int height)
  {
    if (GraphicsEnvironment.isHeadless())
      return null;
    GraphicsConfiguration config = getGraphicsConfiguration();
    return config == null ? null : config.createCompatibleImage(width, height);
  }

  /**
   * Creates an image with the specified width and height for use in
   * double buffering. Headless environments do not support images.
   *
   * @param width the width of the image
   * @param height the height of the image
   * @return the requested image, or null if it is not supported
   * @since 1.4