ipc: expose surface_content_rect in get_tree

[jbms]

Expose the actual view geometry (as set by the client via xdg-shell set_window_geometry) in the IPC get_tree output as 'surface_content_rect'.

This is useful for clients using protocols like ext-image-copy-capture-v1 to capture foreign windows. Since the capture contains the full window surface (including Client-Side Decorations, shadows, etc.), the client needs to know the offset of the actual window content within the captured image. The surface_content_rect field exposes this offset (x, y) and size (width, height) relative to the surface.

[dawsers]

view->geometry always has {x, y} = {0, 0}, it is mainly used to know the rounded size of the content, so I think it will not serve for this purpose. If you want the offset of the content, the container has container->pending->content_* variables. These are in double precision, and then rounded with care to submit view_configure() events.

[jbms]

I think the geometry field exposed via IPC always has x=0 and y=0, but I believe view->geometry is correct and may have a non-zero x/y coordinate when using client side decorations.

[dawsers]

OK, so you don't want coordinates to capture a part of the frame buffer like you would do with grim, you are expecting to get the buffer submitted by a client.

[dawsers]

Is this for your project? Do you want to use the client buffer to create a static image for your suspended applications? If that is the case, I will merge it, but I have no way to test this otherwise. Most applications simply get the whole frame buffer and use rect or window_rect to get the part of the buffer they want