<AWT Dev> 6603887: Where are transparent areas filled with bgColor?

[Clemens Eisserer]

Hi there,

I recently found a strange bug while fixing the
Mozilla-Browser-Plugin, somehow the Java2d/X11 pipeline has problems
with the graybox_error.gif which is shown when an applet fails to
initialize.
The image is a partially transparent gif which is drawn with a
background-color specified. It works for the first time, but at
subsequent blits the transparent pixels which should be white are
black.
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6603887.

I played a bit with Java2D's trace functionality that came out:

1.) First draw, rendered correctly:
sun.java2d.loops.BlitBg::BlitBg(ByteIndexedBm, SrcNoEa, IntRgb)

2.) Seems like the accaleration-blit:
sun.java2d.x11.X11PMBlitLoops$DelegateBlitLoop::Blit(Any, SrcNoEa,
"Integer RGB Pixmap with 1-bit transp")
sun.java2d.loops.Blit::Blit(ByteIndexed, SrcNoEa, IntRgb)
sun.java2d.x11.X11PMBlitBgLoops::BlitBg("Integer RGB Pixmap with 1-bit
transp", SrcNoEa, "Integer RGB Pixmap")

3.) subsequent draws only do:
sun.java2d.x11.X11PMBlitBgLoops::BlitBg("Integer RGB Pixmap with 1-bit
transp", SrcNoEa, "Integer RGB Pixmap")

So the interesing opereations seem to habben in 2.) I guess.

In X11PMLoops I saw the following comment:
    /* do an unmasked copy as we've already filled transparent
       pixels of the source image with the desired color */
    XCopyArea(awt_display, srcDrawable, dstXsdo->drawable, dstGC,
	      srcx, srcy, width, height, dstx, dsty);

So I guess somehow the filling of the transparent colors with the
background-color does something wrong.
However I did not find the code where this happens, so some
navigation-help would be really appiciated ;)

Thank you in advance, lg Clemens