Attention everyone, This could affect a range of KDE apps and libraries in various ways.
Bug 332335 - "Links fade to pitch black when mouse hovering over them" https://bugs.kde.org/show_bug.cgi?id=332335 reports a nasty painting problem that was found when hovering over a Plasma ToolButton in KDevelop on the Apple OS X platform. Screenshot: http://bugsfiles.kde.org/attachment.cgi?id=85991 I also discovered the problem in the KBounce game, reported it [1] and, being a KDE Games programmer, investigated it and found the cause. See also [2], which might relate to this. I think the cause is to do with using QPainter::CompositionMode_DestinationIn to "blend in" an opaque pixmap and make it look semi-transparent on top of the main picture. KBounce creates an opaque message-box pixmap of a color that matches the graphics theme, attempts to make it semi-transparent, then writes black (or dark color) text on it. But on Apple OS X the box comes out black, making the text invisible and the game unplayable for most people. If I comment out the CompositionMode references, the messages appear OK, but on an opaque message-box. I can fix the problem completely by using QPainter::setOpacity() to make the box semi-transparent, instead of CompositionMode. It seems that the problem with Plasma ToolButton (see above) has the same cause. Code references to Plasma::ToolButton::paint() and KBounceGameWidget::generateOverlay(): http://api.kde.org/4.x-api/kdelibs-apidocs/plasma/html/toolbutton_8cpp_source.html#l00329https://projects.kde.org/projects/kde/kdegames/kbounce/repository/revisions/master/entry/gamewidget.cpp lines 390 to 398 But THAT IS NOT ALL … To see if there were other possible occurrences of black-on-black problems in KDE on Apple OS X, I went into LXR and here is what I found … http://lxr.kde.org/ident?_i=CompositionMode_DestinationIn&_remember=1 which shows 146 INSTANCES of using CompositionMode_DestinationIn, across a broad range of KDE applications and libraries … Amongst the KDE Games references, KFourInLine seems to work OK on Apple OS X, but KPat definitely has some transient black-on-black glitches when animating highlights. The KPat code also includes the following interesting comment: 0166 // Using QPainter::setOpacity is currently very inefficient, so to 0167 // paint a semitransparent pixmap, we have to do some fiddling. Is QPainter::setOpacity more efficient now? I do not have the time or the ability to investigate all the references on my own and I have some more urgent KDE portability problems to chase up [3]. So what can we do about this? Any ideas? All the best, Ian W. [1] Bug 333429 - Black on black messages in Apple OS X make KBounce unplayable https://bugs.kde.org/show_bug.cgi?id=333429 [2] Bug 330242 - Strange graphical glitches in Dolphin when the Terminal pane is open and transparency is enabled in Konsole. https://bugs.kde.org/show_bug.cgi?id=330242 [3] https://trac.macports.org/wiki/KDEProblems/KDETickets https://trac.macports.org/wiki/KDEProblems These are some new wiki pages where we are collecting portability issues re KDE on the Apple OS X platform, following recent discussions on this list. >> Visit http://mail.kde.org/mailman/listinfo/kde-devel#unsub to unsubscribe <<
