[PATCH] xwayland-input: Don't assume all input is children of the focused window

[Olivier Fourdan]

Hi Jasper,

I was working on the same issue 
(https://bugzilla.redhat.com/show_bug.cgi?id=1188289) but did not think 
about translating the coordinates!

I applied your patch along with the patch for mutter (on mutter 3.14.3 
as found in F21) not to map the cow but that does not work very well.

It works, as long as the window is not moved, as soon as the toplevel 
window is moved, the translated coordinates seem correct but the window 
returned by miSpriteTrace() is not, e.g. I get the "mutter guard window" 
instead of the actual expected window.

Oddly enough the coordinates of the toplevel xwindow (as seen with 
xprop) are not updated after the move, so that miSpriteTrace() picks the 
wrong window - Maybe I am missing some other patch in mutter, I'll check 
that.

That being said, I don't think it's a good idea to make a disruptive 
change in Xwayland that requires code change in the Wayland compositors, 
what about Weston or the other Wayland compositors out there, we can't 
really expect all of them to change their code in a synchronously with 
Xwayland.

We discussed that with ajax and halfline and the the idea would be 
rather to check if the cow exists and is mapped (e.g. as in mutter 
before your patch) then use the current code, otherwise, translate the 
coordinates as you did.

i.e. something like that:

--- a/hw/xwayland/xwayland-input.c
+++ b/hw/xwayland/xwayland-input.c
@@ -32,6 +32,9 @@
  #include <xkbsrv.h>
  #include <xserver-properties.h>
  #include <inpututils.h>
+#ifdef COMPOSITE
+#include "compint.h"
+#endif

  static void
  xwl_pointer_control(DeviceIntPtr device, PtrCtrl *ctrl)
@@ -628,8 +631,25 @@ xwl_xy_to_window(ScreenPtr screen, SpritePtr 
sprite, int x, int y)
      }

      if (xwl_seat->focus_window) {
-        sprite->spriteTraceGood = 2;
-        sprite->spriteTrace[1] = xwl_seat->focus_window->window;
+#ifdef COMPOSITE
+        CompScreenPtr cs;
+
+        /* The compositor may have mapped the COW.
+         * If this is the case, translating to the root coordinates to 
search
+         * for the window will give us the COW which we don't want, so 
use the
+         * seat's focused window with relative coordinates instead.
+         */
+        cs = GetCompScreen(screen);
+        if (cs->pOverlayWin && cs->pOverlayWin->mapped) {
+           sprite->spriteTraceGood = 2;
+           sprite->spriteTrace[1] = xwl_seat->focus_window->window;
+           return miSpriteTrace(sprite, x, y);
+        }
+#endif
+        /* convert to root coordinates */
+        x += xwl_seat->focus_window->window->drawable.x;
+        y += xwl_seat->focus_window->window->drawable.y;
+        sprite->spriteTraceGood = 1;
          return miSpriteTrace(sprite, x, y);
      }
      else {


But we still need to make sure it works reliably with translated 
coordinates.

Cheers,
Olivier

On 18/02/15 21:41, Jasper St. Pierre wrote:
> Some toolkits implement comboboxes or menus or other things through
> O-R windows, which aren't children of the focused window. In order to
> properly get input on them during grab conditions, we need to trace the
> whole input tree, not just the focused window down.
>
> Signed-off-by: Jasper St. Pierre <jstpierre at mecheye.net>
> ---
>   hw/xwayland/xwayland-input.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
> index 5e20418..8b96bd2 100644
> --- a/hw/xwayland/xwayland-input.c
> +++ b/hw/xwayland/xwayland-input.c
> @@ -654,8 +654,10 @@ xwl_xy_to_window(ScreenPtr screen, SpritePtr sprite, int x, int y)
>       }
>
>       if (xwl_seat->focus_window) {
> -        sprite->spriteTraceGood = 2;
> -        sprite->spriteTrace[1] = xwl_seat->focus_window->window;
> +        /* convert to root coordinates */
> +        x += xwl_seat->focus_window->window->drawable.x;
> +        y += xwl_seat->focus_window->window->drawable.y;
> +        sprite->spriteTraceGood = 1;
>           return miSpriteTrace(sprite, x, y);
>       }
>       else {
>