The BufferInterface used nested calls of wl_shm_buffer_begin_access
and allowed multiple different BufferInterfaces to be in a block
between wl_shm_buffer_begin_access and wl_shm_buffer_end_access.
But this is not allowed: nesting is only possible if it accesses
the same buffer!
This resulted in an abort when we accessed two BufferInterfaces
at the same time. The added test case aborts in the previous
version.
The fix now changes the semantic of the method. The BufferInterface
doesn't hold the QImage any more, but creates a new one every time
::data is invoked. The QImage is created with a custom cleanup
function which calls to wl_shm_buffer_end_access. It ensures that
we don't call into wl_shm_buffer_begin_access as long as there is
a valid QImage for any other BufferInterface still around and
instead returns a null QImage.
Thus a user of a BufferInterface::data should destroy the returned
QImage as soon as it's no longer needed or create a deep copy if
it needs to be kept around.
The Buffers are exclusively hold by ShmPool. The user of a Buffer is not
supposed to delete it as a no longer used Buffer should be reused by the
ShmPool.
To make it obvious that the ownership of the pointer is not passed to the
user the return type is changed to QWeakPointer. This also allows the
ShmPool to destroy Buffers as needed.
Framework style build system which generates two libraries:
* KF5WaylandClient
* KF5WaylandServer
autotests are adjusted to compile again. They need to be changed to
use the libraries once the export header gets generated.
