Function output_capture_constraints 

pub fn output_capture_constraints(
    output: &Output,
    renderer: Option<&GlesRenderer>,
    render_node_path: &str,
) -> Option<BufferConstraints>

Buffer constraints for capturing output: its current mode’s size, the shm formats both render paths can serve, and — with a GLES renderer — the renderer’s dmabuf render formats so a client buffer can be blitted to on the GPU.