Name: paC48320 Date: 09/18/97


The implementation of java.awt.Component.getGraphics()
appears to be incorrect. This method is supposed to return
a Graphics object whose clipping rectangle is set
to the intersection of the component's bounding
box with the bounding boxes of its parent container(s).
It fails to do this for lightweight components
because of an apparent typo in the code. As a result,
output drawn into the Graphics object does not get
clipped to the boundaries of the component's window
ancestry, if the ancestry is comprised of lightweight
components. This bug affects all platforms and appears
in all releases of the JDK. The code and the one
line fix are attached below.

========================= java.awt.Component.java =================

/**
 * Creates a graphics context for this component. This method will
 * return <code>null</code> if this component is currently not on
 * the screen.
 * @return A graphics context for this component, or <code>null</code>
 * if it has none.
 * @see java.awt.Component#paint
 * @since JDK1.0
 */
public Graphics getGraphics() {
    if (peer instanceof java.awt.peer.LightweightPeer) {
        // This is for a lightweight component, need to
        // translate coordinate spaces and clip relative
        // to the parent.
        Graphics g = parent.getGraphics();
        g.translate(x,y);
////////g.setClip(0, 0, width, height); <---------WRONG
        g.clipRect(0, 0, width, height); <---------RIGHT
        return g;
    } else {
        ComponentPeer peer = this.peer;
        return (peer != null) ? peer.getGraphics() : null;
    }
}

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company - IBM , email - ###@###.###
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