<div dir="ltr">The description for wl_surface.damage should be shortened to a minimal indication that this is for back-compatibility only and that refer to the buffer_damage request. Something like "identical to buffer_damage if the buffer and surface coordinates are equal, otherwise the behaviour is undefined". </div><div class="gmail_extra"> <div class="gmail_quote">On Fri, Nov 6, 2015 at 11:08 AM, Jasper St. Pierre <<a href="mailto:jstpierre@mecheye.net" target="_blank">jstpierre@mecheye.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">To help clear things up, I think we should deprecate the wl_surface.damage request and document that the coordinates are effectively undefined -- for legacy reasons, if you see wl_surface.damage, it should be considered a damage for the entire surface. <div class="HOEnZb"><div class="h5"> On Fri, Nov 6, 2015 at 10:55 AM, Derek Foreman <<a href="mailto:derekf@osg.samsung.com">derekf@osg.samsung.com</a>> wrote: > wl_surface.damage uses surface local co-ordinates. > > Buffer scale and buffer transforms came along, and EGL surfaces > have no understanding of them. > > Theoretically, clients pass damage rectangles - in Y-inverted surface > co-ordinates) to EGLSwapBuffersWithDamage, and the EGL implementation > passed them on to wayland. However, for this to work the EGL > implementation must be able to flip those rectangles into the space > the compositor is expecting, but it's unable to do so because it > doesn't know the height of the transformed buffer. > > So, currently, EGLSwapBuffersWithDamage is unusable and EGLSwapBuffers > has to pass (0,0) - (INT32_MAX, INT32_MAX) damage to function. > > wl_surface.buffer_damage allows damage to be registered on a surface > in buffer co-ordinates, avoiding this problem. > > Credit where it's due, these ideas are not entirely my own: > Over a year ago the idea of changing damage co-ordinates to buffer > co-ordinates was suggested (by Jason Ekstrand), and it was at least > partially rejected and abandoned. At the time it was also suggested > (by Pekka Paalanen) that adding a new wl_surface.buffer_damage request > was another option. > > Signed-off-by: Derek Foreman <<a href="mailto:derekf@osg.samsung.com">derekf@osg.samsung.com</a>> > --- > > Necro-posting on: > <a href="http://lists.freedesktop.org/archives/wayland-devel/2014-February/013440.html" rel="noreferrer" target="_blank">http://lists.freedesktop.org/archives/wayland-devel/2014-February/013440.html</a> > and > <a href="http://lists.freedesktop.org/archives/wayland-devel/2014-February/013442.html" rel="noreferrer" target="_blank">http://lists.freedesktop.org/archives/wayland-devel/2014-February/013442.html</a> > > This came up on IRC again the other day, and it's still an unsolved problem... > I'm posting this as RFC to see if anyone's interested in it - I'll do an > implementation if we can get an agreement on the protocol text. > > protocol/wayland.xml | 44 ++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 42 insertions(+), 2 deletions(-) > > diff --git a/protocol/wayland.xml b/protocol/wayland.xml > index 9c22d45..1cb2f66 100644 > --- a/protocol/wayland.xml > +++ b/protocol/wayland.xml > @@ -176,7 +176,7 @@ > </event> > </interface> > > - <interface name="wl_compositor" version="3"> > + <interface name="wl_compositor" version="4"> > <description summary="the compositor singleton"> > A compositor. This object is a singleton global. The > compositor is in charge of combining the contents of multiple > @@ -986,7 +986,7 @@ > </event> > </interface> > > - <interface name="wl_surface" version="3"> > + <interface name="wl_surface" version="4"> > <description summary="an onscreen surface"> > A surface is a rectangular area that is displayed on the screen. > It has a location, size and pixel contents. > @@ -1327,6 +1327,46 @@ > </description> > <arg name="scale" type="int"/> > </request> > + > +  > + <request name="buffer_damage" since="4"> > + <description summary="mark part of the surface damaged using buffer co-ordinates"> > + This request is used to describe the regions where the pending > + buffer is different from the current surface contents, and where > + the surface therefore needs to be repainted. The pending buffer > + must be set by wl_surface.attach before sending damage. The > + compositor ignores the parts of the damage that fall outside of > + the surface. > + > + Damage is double-buffered state, see wl_surface.commit. > + > + The damage rectangle is specified in buffer coordinates. > + > + The initial value for pending damage is empty: no damage. > + wl_surface.damage adds pending damage: the new pending damage > + is the union of old pending damage and the given rectangle. > + > + wl_surface.commit assigns pending damage as the current damage, > + and clears pending damage. The server will clear the current > + damage as it repaints the surface. > + > + This request differs from wl_surface.damage in only one way - it > + takes damage in buffer co-ordinates instead of surface local > + co-ordinates. This is desirable because EGL implementations > + are unaware of buffer scale and buffer transform and can only > + provide damage in buffer co-ordinates. Damage in buffer > + co-ordinates is required for EGLSwapBuffersWithDamage to work > + efficiently. > + > + Mixing wl_surface.buffer_damage and wl_surface.damage requests > + on the same surface will result in undefined behaviour. > + </description> > + > + <arg name="x" type="int"/> > + <arg name="y" type="int"/> > + <arg name="width" type="int"/> > + <arg name="height" type="int"/> > + </request> > </interface> > > <interface name="wl_seat" version="5"> > -- > 2.6.1 > > _______________________________________________ > wayland-devel mailing list > <a href="mailto:wayland-devel@lists.freedesktop.org">wayland-devel@lists.freedesktop.org</a> > <a href="http://lists.freedesktop.org/mailman/listinfo/wayland-devel" rel="noreferrer" target="_blank">http://lists.freedesktop.org/mailman/listinfo/wayland-devel</a> </div></div>-- Jasper <div class="HOEnZb"><div class="h5">_______________________________________________ wayland-devel mailing list <a href="mailto:wayland-devel@lists.freedesktop.org">wayland-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/wayland-devel" rel="noreferrer" target="_blank">http://lists.freedesktop.org/mailman/listinfo/wayland-devel</a> </div></div></blockquote></div> </div>