[OpenJDK 2D-Dev] 6603887: Where are transparent areas filled with bgColor?

[Clemens Eisserer]

Hi Dmitri,

Glad to meet you here!

>    do you see the same issue with Java 6 or is it
>    Java 7 specific?
I see the same issue since the accalerated X11 pipelines were
introduced with Java-1.4 (and up to 1.7.0b19). 1.3.1 always renders
correctly.

For me its not critical at all, I just thought it would be a good
bugfix to contribute. however if you find it, dont hestitate to
correct it ;)

lg Clemens

>
> Clemens Eisserer wrote:
> > 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 ;)
>
>    It happens here during this call:
>      srcDrawable = srcXsdo->GetPixmapWithBg(env, srcXsdo, pixel);
>    Which can be found in X11SurfaceData.c (X11SD_GetPixmapWithBg).
>    Here 'pixel' is the pixel value of the bg color.
>
>    There were some changes in this area recently in jdk7.
>    My guess would be that we don't initialize the bitmask.
>    In the case of a Blit we call (see X11PMBlitLoops.Blit)
>              updateBitmask(src, dst,
>                            src.getColorModel() instanceof IndexColorModel);
>    but I don't see us doing it for the BlitBg.
>
>    So if you do only BlitBg blits from the image the
>    bitmask will never get initialized.
>    Try adding the updateBitmask call to BlitBg and see if it helps..
>
>    Thanks,
>      Dmitri
>
>
>
> >
> > Thank you in advance, lg Clemens
>