Re:Programming the Linux Framebuffer
by vardump on Thursday February 01, 2018 @05:08AM
(#16280685)
Current GPU implementations often support multiple arbitrary "framebuffers" layered on top of each other. Similar to hardware sprites from 8/16-bit era or like more recent hardware "mouse cursor". With the exception they can cover whole screen.
So you can have multiple framebuffers in the same time with arbitrary color formats (like 8-bit grayscale, 16/32-bit (A)RGB, YUV2, etc.). Bilinear scaling, alpha-blending and mirroring/90/180/270 degree rotations are often supported as well.
It's important to understand these framebuffers are not composited anywhere else, but are actually scanned to the display device in real time, on the fly.
Traditional framebuffer can of course be emulated by setting a single layer to cover full screen without alpha-blending.
So you can have multiple framebuffers in the same time with arbitrary color formats (like 8-bit grayscale, 16/32-bit (A)RGB, YUV2, etc.). Bilinear scaling, alpha-blending and mirroring/90/180/270 degree rotations are often supported as well.
It's important to understand these framebuffers are not composited anywhere else, but are actually scanned to the display device in real time, on the fly.
Traditional framebuffer can of course be emulated by setting a single layer to cover full screen without alpha-blending.