On Fri, 08 Nov 2013 18:04:33 -0800 Bill Spitzak <[email protected]> wrote:
> > > Rafael Antognolli wrote: > > On Fri, Nov 08, 2013 at 10:59:07AM -0800, Bill Spitzak wrote: > >> > >> Pekka Paalanen wrote: > >>> Hi all, > >>> > >>> this is the v2 of the crop and scale extension, as RFC. > >> I get the impression that the result of crop+scale is supposed to be > >> exactly > >> the same as though the client made a second buffer of the scale size, > >> scaled > >> the crop region from the first buffer to this second buffer, then attached > >> it with the normal wayland mechanism. Correct? > > > > From what I understood, the visual result might be that, but it's not > > what should go on inside the renderer. > > Sounds right. My main concern was that the scale width+height completely > replaces all uses of the buffer width+height in the visible compositor > api (the buffer width+height is needed to figure out where the memory > for the crop region is, but should be ignored otherwise). This thread is about protocol. It says nothing about Weston's internal implementation details. > >> So that compositors are allowed to only keep the cropped area of a buffer, > > > > IMHO the compositor would keep the entire buffer, just like it already > > does. > > I'm probably using shm too much but I thought it would be a savings if > the compositor could upload only the crop region to an EGL texture from > an shm buffer, and then immediately release the buffer. > > I suppose it could upload the entire thing but then scaling the > subrectangle either requires a copy to another texture, or what I think > is an unrequired EGL extension. Scaling the entire thing but scissoring > the output does not produce the correct filtering at the edges. No, there is no copy or EGL extension needed. > >> You need to define what happens if the crop region extends outside the > >> buffer. > > > > It's defined as "undefined/dirty" pixels, isn't it? I think that's good > > enough for now, at least. > > I think making the crop larger than the buffer will be useful, > especially to fit your video into a slightly-different shaped window > (this will happen if the scale factor is not an integer). It may be > useful for letterboxing as well, but that will require the client to add > black pixels on the edges so the user does not just see the edge of the > video smeared to fill the area. No, sampling outside of a buffer is a non-fatal client mistake. - pq _______________________________________________ wayland-devel mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/wayland-devel
