Hi Melvin! On Tue, Sep 17, 2019 at 01:57:09PM +0200, Melvin Vermeeren wrote: > Hi, > > I have looked around in a bunch of sources and have come to the conclusion > that this is most probably a bug in the bundled chromium version of Qt 5.11.1 > Looking around For Chromium it is difficult to track bugs due to its size and > due to many users making bogus bug reports, but over the years there have been > multiple issues where Chromium print(-preview) results in blank pages. > > The changelog of Qt 5.12.x does also not list anything significant related to > printing, further supporting this theory. I have also confirmed Qt 5.12.0 > resolves the issue. > > > There are two ways to fix this issue as I see it now: > > 1. Hard: Figure out the difference between Chromium 65.0.3325.230 (Qt 5.11.1 - > Qt 5.11.3) and Chromium 69.0.3497.128 (Qt 5.12.0), find upstream bug reports > in Chromium and see if there are any relevant patches and/or commits. Then > attempt to backport these to fix the bug. > > 2. Easy: update to QtWebEngine 5.12.0, keep build depends as Qt 5.11.x. Take > the earliest Debian 5.12.x release, before build depends were updated, and > downgrade to 5.12.0 so the diff is as small as possible. This builds fine in a > buster environment and works as expected. The only "issue" is applications > still say "QtWebEngine 5.11.3" in their about as they aren't recompiled. Thanks for your analysis. We are going to update the whole Qt to 5.12 soon in unstable. Regarding Buster, the second variant will not be possible for many reasons. First reason: the diff is huge and it is impossible to review it manually, which is required for a stable release update. Second reason: while newer Qt WebEngine can build fine against older Qt, the version mismatch can cause issues in other applications. In Ubuntu, I tried to build Qt WebEngine 5.9.8 with Qt 5.9.5 (same series!), and several KDE applications started getting this error (when building or running tests): > CMake Error at /usr/lib/x86_64-linux-gnu/cmake/Qt5WebEngineCore/Qt5WebEngineCoreConfig.cmake:101 (find_package): > Could not find a configuration file for package "Qt5Quick" that is > compatible with requested version "5.9.8". > > The following configuration files were considered but not accepted: > > /usr/lib/x86_64-linux-gnu/cmake/Qt5Quick/Qt5QuickConfig.cmake, version: 5.9.5 So the only way to fix this issue in Buster is the first (hard) variant. -- Dmitry Shachnev
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