Use the new GTK_CROSSING_ACTIVE crossing events to update
the im context focus when the window becomes active or
inactive. IBus requires this, since it has only a single,
global focus location.
Fixes: #2390
Emit crossing events when the active window changes.
We don't want to emit GTK_CROSSING_FOCUS events, since
every window has its own focus location (focus does not
jump from window to window), so we use the new
GTK_CROSSING_ACTIVE type of crossing event for this.
Document the different crossing event kinds that we use,
and add GTK_CROSSING_ACTIVE. We are going to use it in
the future when the active window changes.
If GLES support is enabled on Windows, force GLES mode if we are running
on a ARM64 version of Windows (i.e. Windows 10 for ARM).
This is required as ARM64 versions of Windows only provide a software
implementation of OpenGL 1.1/1.2, which is not enough for our purposes.
Thus, we could make instead use the GLES support provided via Google's
libANGLE (which emulates OpenGL/ES 3 with Direct3D 9/11), so that we
can run GtkGLArea programs under OpenGL/ES in ARM64 versions of Windows.
Note that eventually we could update the libepoxy build files for Windows
to not check nor enable WGL when building for ARM64 Windows, as the WGL
items do not work, although they do build.
We need to use GL_BGRA instead of GL_RGBA when doing glReadPixels() on
EGL on Windows (ANGLE) so that the red and blue bits won't be displayed
inverted.
Also fix the logic where we determine whether to bit blit or redraw
everything.
Some implementations of the ES 1.00 shader (such as Google's ANGLE) do
not like the 'f' suffix for floats, so just drop it, as it should be
harmless to drop.
This is for adding a EGL-based renderer which is done via the ANGLE
project, which translate EGL calls to Direct3D 9/11. This is done as a
possible solution to issue #105, especially for cases where the needed
full GL extensions to map OpenGL to Direct3D is unavailable or
unreliable, or when the OpenGL implementation from the graphics drivers
are problematic.
To enable this, do the following:
-Build ANGLE and ensure the ANGLE libEGL.dll and libGLESv2.dll are
available. A sufficiently-recent ANGLE is needed for things to
work correctly--note that the copy of ANGLE that is included in
qtbase-5.10.1 is sufficient. ANGLE is licensed under a BSD 3-clause
license.
-Build libepoxy on Windows with EGL support enabled.
-Currently, prior to running GTK+ programs, the GDK_DEBUG envvar needs
to be set with gl-gles as at least one of the flags.
Known issues:
-Only OpenGL ES 3 is supported, ANGLE's ES 2 does not support the needed
extensions, notably GL_OES_vertex_array_object, but its ES 3 support is
sufficient.
-There is no autodetection or fallback mechanism to enable using
EGL/Angle automatically yet. There are no plans to do this in this
commit.
...EGL support needs to be explicitly enabled during the build of
libepoxy on Windows as it is not enabled by default on Windows.
With this, we can add an EGL renderer for Windows that make use of
Google's libANGLE, which is a library that translates OpenGL/ES calls
to Direct3D 9/11, which will provide better hardware compatibility
on Windows and would act as one of the foundations to resolve issue #105.
