On Tue, Mar 1, 2011 at 7:40 AM, Michal Suchanek <[email protected]> wrote: > Hello, > > I was just wondering about subpixel rendering and how is that going do > be done in Wayland.
There are discussions about this in the archives. My understanding of the problem requires for Wayland to provide the window transformation function and the screen geometry to the app (which way the subpixels run), and then let the app generate a final, transformed, subpixel antialiased bitmap. Wayland would only do straight copies of this bitmap to the display surface since doing any more transforms will mess up the antialiasing. In this case apps (via toolkit libs) need to know how to do subpixel antialiasing for output buffers that may be twisted in 3D space. The projection of the transformed buffer is not necessarily a rectangle and a depth buffer is needed. A legacy mode could be provided where apps only render into rectangles and then Wayland does the transform. The app still needs the screen geometry info to know which way the subpixels run. That info is passed into Freetype. Wayland can decide to do further transforms to this buffer knowing that it will mess up the antialiasing. As far as I know no one is looking at the first case. It would be interesting to see some experimentation with adding improved antialiasing to the various toolkits. A simple way to see the impact of improved antialiasing is a cover flow type display for switching between windows. The windows on the sides have been twisted in 3D space and their projections are now trapezoids. > > In X an application is supposed to ask xrandr about current screen > layout, determine on what screen(s) the window is placed, and use the > subpixel order and screen rotation information to figure out how to > lay out subpixels in antialiased objects. > > To the best of my knowledge no X toolkit does this. Last time I tried > to look there was a global setting of horizontal RGB vs BGR so I > turned off subpixel rendering completely. > > Wayland currently does not support multiscreen but rotation should be > already possible. > > Is there any provision for applications to get the information about > subpixel layout of their windows and is there any toolkit for Wayland > that honors it? Are there any tests in place that would make sure > toolkits render subpixels properly in various situations? > > Or is subpixel rendering considered superfluous and unsupported by wayland? > > Thanks > > Michal > _______________________________________________ > wayland-devel mailing list > [email protected] > http://lists.freedesktop.org/mailman/listinfo/wayland-devel > -- Jon Smirl [email protected] _______________________________________________ wayland-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/wayland-devel
