We need to use a GLXFBConfig which matches the depth of the window
pixmap's depth. So far it used the GLXFBConfig of the GL context.
This worked fine for RGBA windows, but failed for RGB windows on e.g.
some NVIDIA drivers.
After this change the FBConfig of the context is completely ignored,
instead it tries to find a good FBConfig for a given depth.
Whenever a FBConfig for a given depth is found it's inserted in a
cache shared between all WindowThumbnails so that we don't have the
X roundtrips all the time.
BUG: 334241
REVIEW: 118110
Introduces a new optional dependency to EGL. If EGL is found the
WindowThumbnail gets compiled with EGL support. The EGL support is
unlike Qt's XCB plugin not mutual exclusive to the GLX backend, thus
it's possible to compile with EGL and GLX at the same time.
By that this implementation is prepared for the case that Qt supports
EGL or GLX through runtime selection.
In practice EGL support is only useful if Qt is compiled with GLESv2.
In that case the corebindingsplugin gets linked against Qt5::Gui_GLESv2
to get the dependency to GLES.
The implementation makes use of the EGL_KHR_image extension
(or EGL_KHR_image_base and EGL_KHR_Image_pixmap) and
the GL_OES_EGL_image extension to bind the X pixmap to an EGLImageKHR.
REVIEW: 116627
New qquick item in PlasmaCore to render a live updating window
thumbnail. The implementation uses XCB to redirect the specified
window using the composite extension. This means a running compositor
is not required. Through the damage extension the item tracks changes
to the window and triggers updates of the texture. Furthermore the
item tracks geometry changes of the window to recreate the window
pixmap.
If the pixmap of the window is valid, a texture is generated from it
using the glx texture from pixmap extension. For this a new optional
dependency for glx is added. On platform where glx is not available
(e.g. Windows, Linux with OpenGL ES) this will not get compiled and
the window's icon is used instead as a fallback.
REVIEW: 112142
