The goal of this MR is to set up the minimum necessary infrastructure to display the contents of some simple, software rendered windows. This involves two major steps:
1. Associate a window with a Wayland surface and give it the `xdg_toplevel` role, so that the compositor can display it. We also have to implement the required initial `xdg_surface` configuration sequence to be able to safely (i.e., without the compositor disconnecting us with an error) attach buffers to the surface in step (2).
2. Implement the `window_surface` interface for the Wayland driver. For now we provide a simple (and suboptimal) `window_surface_flush` implementation: for each flush we create a new `wl_shm` buffer, copy the whole window contents (ignoring damaged bounds for now) into it and attach it to the target Wayland surface. In the next MR I will optimize this implementation in multiple ways: a. implement a buffer queue to avoid constantly allocating new buffers b. respect the damaged bounds of the `window_surface` to minimize copying of data from the `window_surface` to the SHM buffer (and also for correctness) c. communicate damaged surface regions to the compositor to (potentially) allow more efficient texture uploads.
With this MR many (software-rendered) applications can now display dynamic content on screen. We can't interact with the apps yet, but we do get to enjoy `notepad` in all its blinking-cursor glory.
Thanks!