Applications that use the VMR7 use the graphics card’s overlay surface. When using the overlay surface the video is not actually composited onto a window by the operating system but is handled by the graphics hardware. The operating system does however need to let the graphics hardware know where to render the video. To do this a color key is specified. The color key that is used is R254, B255, G254. This key causes the background of the video render area to be a very dark shade of blue. It looks black to the naked eye but is really very dark blue. The graphics HW can then look for this shade of blue in the frame buffer and replace it with the video.
When the translucent start button’s glow extends beyond the confines of the task bar it interacts with the colors of the background window. The operating system then attempts to blend the colors of the glow and the background window together. This causes the background color of the video window to change just enough to confuse the graphics HW. The area where the glow appears is no longer the expected dark blue and so the graphics hardware does not render video to this location. This causes the effect of a shadow or dark area around the Windows start button.
Raksta ID: 2543412. Pēdējo reizi pārskatīts: 2011. gada 6. maijs. Pārskatījums: 1