cursor-renderer: Add API to allow inhibiting HW cursor

There may be reasons to temporarly inhibit the HW cursor under certain
circumstances. Allow adding such inhibitations by adding API to the
cursor renderer to allow API users to add generic inhibitors with
whatever logic is deemed necessary.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/357

src/backends/meta-cursor-renderer.c

@@ -35,6 +35,9 @@
 
 #include "meta-stage-private.h"
 
+G_DEFINE_INTERFACE (MetaHwCursorInhibitor, meta_hw_cursor_inhibitor,
+                    G_TYPE_OBJECT)
+
 struct _MetaCursorRendererPrivate
 {
   float current_x;
@@ -44,6 +47,8 @@ struct _MetaCursorRendererPrivate
   MetaOverlay *stage_overlay;
   gboolean handled_by_backend;
   guint post_paint_func_id;
+
+  GList *hw_cursor_inhibitors;
 };
 typedef struct _MetaCursorRendererPrivate MetaCursorRendererPrivate;
 
@@ -55,6 +60,21 @@ static guint signals[LAST_SIGNAL];
 
 G_DEFINE_TYPE_WITH_PRIVATE (MetaCursorRenderer, meta_cursor_renderer, G_TYPE_OBJECT);
 
+static gboolean
+meta_hw_cursor_inhibitor_is_cursor_sprite_inhibited (MetaHwCursorInhibitor *inhibitor,
+                                                     MetaCursorSprite      *cursor_sprite)
+{
+  MetaHwCursorInhibitorInterface *iface =
+    META_HW_CURSOR_INHIBITOR_GET_IFACE (inhibitor);
+
+  return iface->is_cursor_sprite_inhibited (inhibitor, cursor_sprite);
+}
+
+static void
+meta_hw_cursor_inhibitor_default_init (MetaHwCursorInhibitorInterface *iface)
+{
+}
+
 void
 meta_cursor_renderer_emit_painted (MetaCursorRenderer *renderer,
                                    MetaCursorSprite   *cursor_sprite)
@@ -283,3 +303,45 @@ meta_cursor_renderer_get_cursor (MetaCursorRenderer *renderer)
 
   return priv->displayed_cursor;
 }
+
+void
+meta_cursor_renderer_add_hw_cursor_inhibitor (MetaCursorRenderer    *renderer,
+                                              MetaHwCursorInhibitor *inhibitor)
+{
+  MetaCursorRendererPrivate *priv =
+    meta_cursor_renderer_get_instance_private (renderer);
+
+  priv->hw_cursor_inhibitors = g_list_prepend (priv->hw_cursor_inhibitors,
+                                               inhibitor);
+}
+
+void
+meta_cursor_renderer_remove_hw_cursor_inhibitor (MetaCursorRenderer    *renderer,
+                                                 MetaHwCursorInhibitor *inhibitor)
+{
+  MetaCursorRendererPrivate *priv =
+    meta_cursor_renderer_get_instance_private (renderer);
+
+  priv->hw_cursor_inhibitors = g_list_remove (priv->hw_cursor_inhibitors,
+                                              inhibitor);
+}
+
+gboolean
+meta_cursor_renderer_is_hw_cursors_inhibited (MetaCursorRenderer *renderer,
+                                              MetaCursorSprite   *cursor_sprite)
+{
+  MetaCursorRendererPrivate *priv =
+    meta_cursor_renderer_get_instance_private (renderer);
+  GList *l;
+
+  for (l = priv->hw_cursor_inhibitors; l; l = l->next)
+    {
+      MetaHwCursorInhibitor *inhibitor = l->data;
+
+      if (meta_hw_cursor_inhibitor_is_cursor_sprite_inhibited (inhibitor,
+                                                               cursor_sprite))
+        return TRUE;
+    }
+
+  return FALSE;
+}

src/backends/meta-cursor-renderer.h

@@ -30,6 +30,18 @@
 #include <meta/screen.h>
 #include "meta-cursor.h"
 
+#define META_TYPE_HW_CURSOR_INHIBITOR (meta_hw_cursor_inhibitor_get_type ())
+G_DECLARE_INTERFACE (MetaHwCursorInhibitor, meta_hw_cursor_inhibitor,
+                     META, HW_CURSOR_INHIBITOR, GObject)
+
+struct _MetaHwCursorInhibitorInterface
+{
+  GTypeInterface parent_iface;
+
+  gboolean (* is_cursor_sprite_inhibited) (MetaHwCursorInhibitor *inhibitor,
+                                           MetaCursorSprite      *cursor_sprite);
+};
+
 #define META_TYPE_CURSOR_RENDERER (meta_cursor_renderer_get_type ())
 G_DECLARE_DERIVABLE_TYPE (MetaCursorRenderer, meta_cursor_renderer,
                           META, CURSOR_RENDERER, GObject);
@@ -55,6 +67,15 @@ void meta_cursor_renderer_force_update (MetaCursorRenderer *renderer);
 
 MetaCursorSprite * meta_cursor_renderer_get_cursor (MetaCursorRenderer *renderer);
 
+void meta_cursor_renderer_add_hw_cursor_inhibitor (MetaCursorRenderer    *renderer,
+                                                   MetaHwCursorInhibitor *inhibitor);
+
+void meta_cursor_renderer_remove_hw_cursor_inhibitor (MetaCursorRenderer    *renderer,
+                                                      MetaHwCursorInhibitor *inhibitor);
+
+gboolean meta_cursor_renderer_is_hw_cursors_inhibited (MetaCursorRenderer *renderer,
+                                                       MetaCursorSprite   *cursor_sprite);
+
 ClutterRect meta_cursor_renderer_calculate_rect (MetaCursorRenderer *renderer,
                                                  MetaCursorSprite   *cursor_sprite);
 

src/backends/native/meta-cursor-renderer-native.c

@@ -587,6 +587,10 @@ should_have_hw_cursor (MetaCursorRenderer *renderer,
   if (!cursor_sprite)
     return FALSE;
 
+  if (meta_cursor_renderer_is_hw_cursors_inhibited (renderer,
+                                                    cursor_sprite))
+    return FALSE;
+
   for (l = gpus; l; l = l->next)
     {
       MetaGpuKms *gpu_kms = l->data;