[mutter] wayland/xdg-shell: Intersect set geometry with subsurface tree geometry

[Jonas Ådahl <jadahl src gnome org>]

commit c7db234c11ed79de602aeab464771ec00eb4f30b
Author: Robert Mader <robert mader posteo de>
Date:   Sat Aug 18 19:41:15 2018 +0200

    wayland/xdg-shell: Intersect set geometry with subsurface tree geometry
    
    Currently xdg-shell applies a geometry set with set_window_geometry
    unconditionally. But the specification requires:
    
    > When applied, the effective window geometry will be
    > the set window geometry clamped to the bounding rectangle of the
    > combined geometry of the surface of the xdg_surface and the
    > associated subsurfaces.
    
    This is especially important to implement viewporter and
    transformation.

 src/wayland/meta-wayland-legacy-xdg-shell.c |  5 +++--
 src/wayland/meta-wayland-shell-surface.c    | 17 +++++++++++++++++
 src/wayland/meta-wayland-shell-surface.h    |  4 ++++
 src/wayland/meta-wayland-xdg-shell.c        |  5 +++--
 4 files changed, 27 insertions(+), 4 deletions(-)
---
diff --git a/src/wayland/meta-wayland-legacy-xdg-shell.c b/src/wayland/meta-wayland-legacy-xdg-shell.c
index e871be972..fdae10e25 100644
--- a/src/wayland/meta-wayland-legacy-xdg-shell.c
+++ b/src/wayland/meta-wayland-legacy-xdg-shell.c
@@ -1304,8 +1304,9 @@ meta_wayland_zxdg_surface_v6_commit (MetaWaylandSurfaceRole  *surface_role,
 
   if (pending->has_new_geometry)
     {
-      /* If we have new geometry, use it. */
-      priv->geometry = pending->new_geometry;
+      meta_wayland_shell_surface_determine_geometry (shell_surface,
+                                                     &pending->new_geometry,
+                                                     &priv->geometry);
       priv->has_set_geometry = TRUE;
     }
   else if (!priv->has_set_geometry)
diff --git a/src/wayland/meta-wayland-shell-surface.c b/src/wayland/meta-wayland-shell-surface.c
index c1e2bd7c1..88bfc21a5 100644
--- a/src/wayland/meta-wayland-shell-surface.c
+++ b/src/wayland/meta-wayland-shell-surface.c
@@ -64,6 +64,23 @@ meta_wayland_shell_surface_calculate_geometry (MetaWaylandShellSurface *shell_su
   *out_geometry = geometry;
 }
 
+void
+meta_wayland_shell_surface_determine_geometry (MetaWaylandShellSurface *shell_surface,
+                                               MetaRectangle           *set_geometry,
+                                               MetaRectangle           *out_geometry)
+{
+  MetaRectangle bounding_geometry = { 0 };
+  MetaRectangle intersected_geometry = { 0 };
+
+  meta_wayland_shell_surface_calculate_geometry (shell_surface,
+                                                 &bounding_geometry);
+
+  meta_rectangle_intersect (set_geometry, &bounding_geometry,
+                            &intersected_geometry);
+
+  *out_geometry = intersected_geometry;
+}
+
 void
 meta_wayland_shell_surface_set_window (MetaWaylandShellSurface *shell_surface,
                                        MetaWindow              *window)
diff --git a/src/wayland/meta-wayland-shell-surface.h b/src/wayland/meta-wayland-shell-surface.h
index fbed72908..39a5e4a50 100644
--- a/src/wayland/meta-wayland-shell-surface.h
+++ b/src/wayland/meta-wayland-shell-surface.h
@@ -64,6 +64,10 @@ void meta_wayland_shell_surface_managed (MetaWaylandShellSurface *shell_surface,
 void meta_wayland_shell_surface_calculate_geometry (MetaWaylandShellSurface *shell_surface,
                                                     MetaRectangle           *out_geometry);
 
+void meta_wayland_shell_surface_determine_geometry (MetaWaylandShellSurface *shell_surface,
+                                                    MetaRectangle           *set_geometry,
+                                                    MetaRectangle           *out_geometry);
+
 void meta_wayland_shell_surface_set_window (MetaWaylandShellSurface *shell_surface,
                                             MetaWindow              *window);
 
diff --git a/src/wayland/meta-wayland-xdg-shell.c b/src/wayland/meta-wayland-xdg-shell.c
index 41cdfc86b..b5f347095 100644
--- a/src/wayland/meta-wayland-xdg-shell.c
+++ b/src/wayland/meta-wayland-xdg-shell.c
@@ -1369,8 +1369,9 @@ meta_wayland_xdg_surface_commit (MetaWaylandSurfaceRole  *surface_role,
 
   if (pending->has_new_geometry)
     {
-      /* If we have new geometry, use it. */
-      priv->geometry = pending->new_geometry;
+      meta_wayland_shell_surface_determine_geometry (shell_surface,
+                                                     &pending->new_geometry,
+                                                     &priv->geometry);
       priv->has_set_geometry = TRUE;
     }
   else if (!priv->has_set_geometry)