Our platform is an underlay platform, on which all HW planes are beneath the primary plane, we call these planes underlay planes. However, current weston only supports the display of the images on overlay planes, which are placed above the primary plane.
In order to enable weston to support the display of the underlay planes, we implemented a set of methods to support the underlay platform based on the ideas in #9 and combined with the current design of weston. What this series does:
Draw through holes on primary plane for the underlay planes, as described in #9, the through holes will allow the images on the underlay planes to be displayed.
Before repainting, calculate the visible and damaged region of through hole, and take the impact of holes into account when updating the visible and damaged region of paint nodes on primary plane.
Since weston does not take the underlay planes into account when preparing planes for views, we improved the process.
Allow the renderer to produce a non-opaque image, because only non-opaque image can make through holes effective. We only allow the renderer to generate non-opaque image when there are holes on primary plane.