One of the annoying things about EGL headers is that they include
platform headers by default, e.g. on X11, it's Xlib.h, etc.
The problem with Xlib.h is that it uses the define compiler directive to
declare constants and those constants have very generic names, e.g.
'None', which typically conflict with enums, etc.
In order to work around bad things coming from Xlib.h, we include
fixx11.h file that contains some workarounds to redefine some Xlib's
types.
There's a flag or rather two flags (EGL_NO_PLATFORM_SPECIFIC_TYPES and
EGL_NO_X11) that are cross-vendor and they can be used to prevent EGL
headers from including platform specific headers, such as Xlib.h [1]
The benefit of setting those two flags is that you can simply include
EGL/egl.h or epoxy/egl.h and the world won't explode due to Xlib.h
MESA_EGL_NO_X11_HEADERS is set to support older versions of Mesa.
[1] https://github.com/KhronosGroup/EGL-Registry/pull/111
This makes our QPlatformOpenGLContext private subclass simpler.
As a slightly unrelated change, this patch also fixes a bug where our
platform opengl context may return a wrong surface format if surfaceless
contexts are unsupported.
The main advantage of SPDX license identifiers over the traditional
license headers is that it's more difficult to overlook inappropriate
licenses for kwin, for example GPL 3. We also don't have to copy a
lot of boilerplate text.
In order to create this change, I ran licensedigger -r -c from the
toplevel source directory.
Summary:
With recent Mesa updates (19.2.1), MESA_EGL_NO_X11_HEADERS doesn't have
any effect. So, let's include fixx11h.h instead.
Test Plan: I am able to build kwin once again.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D24840
Summary:
Depending on whether the underlying platform supports offscreen surfaces,
QOffscreenSurface may create an invisible QWindow. In our case that's the
case, for each offscreen surface a native window is created. This may
lead to some funky results related to window decorations, see bug 407612.
There are several ways to implement offscreen surfaces - either use pbuffers
or utilize a surfaceless context extension. For the sake of simplicity
this change sticks with pbuffers, but it's a good idea to support both
methods.
CCBUG: 407612
Reviewers: #kwin, romangg
Reviewed By: #kwin, romangg
Subscribers: romangg, alexeymin, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D22150
