[Libreoffice-bugs] [Bug 135910] Transparent objects either possess outlines when none are defined or are completely opaque, depending on export PNG options

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=135910

Mike Kaganski <mikekaganski at hotmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |l.lunak at collabora.com,
                   |                            |quikee at gmail.com,
                   |                            |thb at libreoffice.org

--- Comment #9 from Mike Kaganski <mikekaganski at hotmail.com> ---
The problem is that now, when the painting of objects happens on a clear
transparent vdev, painting the object (e.g. rectangle in case of attachment
164477), happening in two stages (RGB separately, alpha separately), only sees
white background while drawing RGB. AA makes the painting to blend with the
background on edges, which results in the borders of the shape to become light
(and semi-transparent, but the unintended *color* change happens anyway).

I suppose that it should instead somehow see that the pixels it blends with are
completely transparent, and then do not change color, and only apply AA to
transparency. But I don't yet have an idea how to perform that in out weird
separated (RGB / Alpha) graphics.

Thorsten, quikee, Lubos: possibly you have some ideas?

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