GTK applications don't work anymore under unity8

[Sebastien Bacher]

Using current vivid, GTK application don't render anymore. GTK didn't change and that was working earlier in the cycle...

step to reproduce:
- get a vivid install with unity8
- install a gtk application, e.g gedit
- edit /usr/share/applications/gedit.desktop and add X-Ubuntu-Touch=true
- log into unity8
- click on gedit in the dash

Note that the GTK backend works under the Mir test server

Log from the application contains

"gdk_mir_display_create_window_impl window=0x14b6240 location=(0, 0) size=(650, 500)
gdk_mir_window_impl_set_role window=0x14b6240
gdk_mir_window_impl_register_dnd window=0x14b6240
gdk_mir_display_request_selection_notification
gdk_mir_window_impl_register_dnd window=0x14b6240
gdk_mir_window_impl_register_dnd window=0x14b6240
gdk_mir_window_impl_register_dnd window=0x14b6240
gdk_mir_window_impl_set_title window=0x14b6240
gdk_mir_display_supports_selection_notification
gdk_mir_display_request_selection_notification
gdk_mir_window_impl_register_dnd window=0x14b6240
gdk_mir_window_impl_focus window=0x14b6240"

[Sebastien Bacher (seb128)]

Downgrading qtmir to https://launchpad.net/ubuntu/+source/qtmir/0.4.4+15.04.20141124-0ubuntu1 makes e.g eog run, that suggest that the issue is with that component and not with mir or gtk

[Sebastien Bacher (seb128)]

(gedit seems to have issues there but testing with eog works)

[Gerry Boland (gerboland)]

Seems the qmake->cmake transition broke this, digging into why

[Gerry Boland (gerboland)]

Update with what I've got so far. qmake->cmake change did cause this, mainly some subtlety with GL and GLES mixing has been broken.

Surprisingly If I build on desktop with -DUSE_OPENGLES=1, everything works! So some build configuration needs changing

[Gerry Boland (gerboland)]

Yeah, I'm puzzled. On desktop, configuring with -DUSE_OPENGLES=1 has everything working. Qt is compiled with GL support on desktop, so this fact confuses me. With that configure flag, Qt does notified it has a GLES context, perhaps it is smart enough to then just use the right shaders & commands. Or else MESA is being forgiving at switching between GL and GLES.

Comparing the apitrace of the old qmake build versus a newer cmake build, this is the main change:

- glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0)
- glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2048, 1024, 0, GL_BGRA, GL_UNSIGNED_BYTE, NULL)
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_BGRA, 2048, 1024, 0, GL_BGRA, GL_UNSIGNED_BYTE, NULL)

Source of this line is the Scenegraph renderer:

void Atlas::bind(QSGTexture::Filtering filtering)

        glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, 0);

m_internalFormat is wrong after cmake change - it is GL_BGRA, which is the default if a non-GLES context is current.

I compared the build commands between qmake and cmake: http://pastebin.ubuntu.com/9699667/
which shows me that the newer cmake is setting QT_USING_OPENGL and QTMIR_USE_OPENGL (as we'd expect), but qmake was not setting these. qmake worked, perhaps by accident

[Launchpad Janitor (janitor)]

This bug was fixed in the package qtmir - 0.4.4+15.04.20150206-0ubuntu1

---------------
qtmir (0.4.4+15.04.20150206-0ubuntu1) vivid; urgency=medium

  [ Gerry Boland ]
  * Explicitly setting GL-mode breaks GTK app rendering. Removing the
    hack appears to just work (LP: #1401968)

  [ Michał Sawicz ]
  * Add moot autopkgtest to run the standard unit tests

  [ Albert Astals Cid ]
  * Fix demo shell import name

  [ Daniel d'Andrada ]
  * Don't suspend&resume the main stage app when switching focus from
    side to main stage
 -- Ubuntu daily release <email address hidden> Fri, 06 Feb 2015 10:23:19 +0000