glamor: Implement GetSupportedModifiers

Implement function added in DRI3 v1.1.

A newest version of libepoxy (>= 1.4.4) is required as earlier
versions use a problematic version of Khronos
EXT_image_dma_buf_import_modifiers spec.

v4: Only send scanout-supported modifiers if flipping is possible
v5: Fix memory corruption in XWayland (uninitialized pointer)

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>

2 files changed, 41 insertions, 0 deletions

diff --git a/present/present.c b/present/present.c
index 42e5fb4fc..080cafcba 100644
--- a/present/present.c
+++ b/present/present.c
@@ -614,6 +614,44 @@ present_check_flip_window (WindowPtr window)
     }
 }
 
+Bool
+present_can_window_flip(WindowPtr window)
+{
+    ScreenPtr                   screen = window->drawable.pScreen;
+    PixmapPtr                   window_pixmap;
+    WindowPtr                   root = screen->root;
+    present_screen_priv_ptr     screen_priv = present_screen_priv(screen);
+
+    if (!screen_priv)
+        return FALSE;
+
+    if (!screen_priv->info)
+        return FALSE;
+
+    /* Check to see if the driver supports flips at all */
+    if (!screen_priv->info->flip)
+        return FALSE;
+
+    /* Make sure the window hasn't been redirected with Composite */
+    window_pixmap = screen->GetWindowPixmap(window);
+    if (window_pixmap != screen->GetScreenPixmap(screen) &&
+        window_pixmap != screen_priv->flip_pixmap &&
+        window_pixmap != present_flip_pending_pixmap(screen))
+        return FALSE;
+
+    /* Check for full-screen window */
+    if (!RegionEqual(&window->clipList, &root->winSize)) {
+        return FALSE;
+    }
+
+    /* Does the window match the pixmap exactly? */
+    if (window->drawable.x != 0 || window->drawable.y != 0) {
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
 /*
  * Called when the wait fence is triggered; just gets the current msc/ust and
  * calls present_execute again. That will re-check the fence and pend the
diff --git a/present/present.h b/present/present.h
index 6542dc385..ade838bda 100644
--- a/present/present.h
+++ b/present/present.h
@@ -135,4 +135,7 @@ typedef void (*present_complete_notify_proc)(WindowPtr window,
 extern _X_EXPORT void
 present_register_complete_notify(present_complete_notify_proc proc);
 
+extern _X_EXPORT Bool
+present_can_window_flip(WindowPtr window);
+
 #endif /* _PRESENT_H_ */