O, I get it! Thank you for your explanation!
On Wed, Apr 27, 2011 at 8:22 PM, Dave Hylands <[email protected]> wrote: > Hi Philip, > > Replying to all this time. > > On Wed, Apr 27, 2011 at 4:24 PM, siqiao chen <[email protected]> wrote: > > Hello, Could I ask how do I enable double buffer support in FrameBuffer > > device? > > I think I could manually increase xres_virtual/yres_virtual to 2 times of > > the display size in video driver and swap xoffset/yoffset after VSync. > But > > could I know if this is the right way to do double buffering or this > > function is already built-in? > > You're on the right track. You only need to double xres_virtual or > yres_virtual, not both. > > Let's suppose that your display is 800x480. Then your display driver > needs to size the framebuffer to be 800x960, and you'd use > FBIOPAN_DISPLAY to toggle between 0,0 and 0,480. > > The driver has to support the double sized framebuffer and the pan > command (or maybe you can modify yoffset directly? I haven't tried > this approach myself). > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.davehylands.com >
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