Repaint Issue

Jonas Ådahl jadahl at
Tue Sep 11 05:02:28 PDT 2012

On Tue, Sep 11, 2012 at 1:53 PM, Pekka Paalanen <ppaalanen at> wrote:
> On Tue, 11 Sep 2012 15:44:55 +0530
> Abhijit Potnis <abhijitpotnis at> wrote:
>> Hello,
>> Last few days I have been debugging a repaint issue in Weston. No repaint is
>> triggered until an input event occurs or a Wayland client like simple-shm
>> triggers
>> one.
>> Digging down, I see that struct weston_output.repaint is pointing to my
>> output repaint
>> function implementation. When I run weston and follow thru the logs, the
>> repaint in
>> my back-end implementation gets called when my
>> 1. mouse moves/or an input event is sensed.
>> 2. when a new client is launched.
>> 3. when a client like simple-shm forces a repaint in a loop
>> The intermittent screen repaints are timed long apart. So the screen
>> doesn't get
>> repainted until any one of the above event happens, which force a repaint.
>> Here is a video of the behaviour. I launch simple-shm and then kill it
>> (time 0:05), the
>> screen isn't updated until I move my mouse (time 0:11). When I move the
>> mouse the
>> screen is updated and the residual simple-shm disappears from the screen,
>> which is
>> actually a repaint.
>> Does any body else happen to see such behaviour ?
> Yeah, I've seen similar issues on the DRM and X11 backends. When I
> launch an app by clicking a button in the panel, the new window does not
> appear, until something else causes a repaint. Weston-terminal and
> flower, at least.
> Repaint is supposed to be as-needed only, not periodical, but clearly
> some trigger is missing. Maybe a new surface is not assigned an output
> until redraw, and redraw does not happen until there is damage, and
> damage is not applied, if the window is not mapped? Or something like
> that, chicken-and-egg problem with assigning an output. A wild guess...

I've seen this for popup surfaces as well. It's fixed by strategically
adding a call to the update transform function which will set the
bounding box, which then will trigger assign_output to work properly.
I have a patch fixing my case that I haven't sent yet and it's
possible that it's the same issue with non-popup surfaces.


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