The real reason for this bug has been hiding in plain sight on this page
all the time. Note the backtrace above:
#5 0xacf9b466 in ThumbnailGenerator::requestImage(QString const&, QSize*, QSize
const&) ()
from
/usr/lib/arm-linux-gnueabihf/qt5/qml/Ubuntu/Components/libUbuntuComponents.so
This means that the thumbnailer plugin is invoked from
libUbuntuComponents.so, which is provided by ubuntu-ui-toolkit and *not*
from the plugin provided by thumbnailer. And, sure enough, in
modules/Ubuntu/Components/plugin/plugin.cp we find this:
try {
engine->addImageProvider(QLatin1String("thumbnailer"), new
ThumbnailGenerator);
} catch(std::runtime_error &e) {
qDebug() << "Could not create thumbnailer: " << e.what();
}
This same piece of code can also be found in
plugins/Ubuntu/Thumbnailer/plugin.cpp (along with the other two
generators it provides.
A quick test shows that removing the registration code from thumbnailer
makes these threading bugs disappear. Apparently what happens is that if
you register the same image provider into Qt twice, it gets confused and
starts corrupting its own data structures.
A side effect of this fix is that when you tap on a picture in the
gallery app to bring it full screen, pinch-to-zoom no longer works and
there is other weirdness (sometimes the image goes fully black). (As an
aside, why is gallery even using the thumbnailer for this? You need the
entire image for proper zooming so why not just open it directly?)
To get this fixed we need to do the following:
- decide with UI toolkit people on where the correct place for thumbnail image
provider is
- once done we need to verify if the pinching bug still happens and fix it
- land all MRs dealing with the above as one clump
** Also affects: ubuntu-ui-toolkit
Importance: Undecided
Status: New
** Changed in: ubuntu-ui-toolkit
Status: New => Confirmed
** Changed in: ubuntu-ui-toolkit
Importance: Undecided => Critical
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https://bugs.launchpad.net/bugs/1368492
Title:
crash opening image file
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