Double buffer support in Framebuffer?
siqiaochen at gmail.com
Thu Apr 28 00:47:08 EDT 2011
O, I get it! Thank you for your explanation!
On Wed, Apr 27, 2011 at 8:22 PM, Dave Hylands <dhylands at gmail.com> wrote:
> Hi Philip,
> Replying to all this time.
> On Wed, Apr 27, 2011 at 4:24 PM, siqiao chen <siqiaochen at gmail.com> 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.
> > 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
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