[PATCH xserver] composite: Propagate damagedDescendants when reparented

[Peter Harris]

If a window that is fully covered by an automatic-redirected descendant
(even implicitly, eg. via BackingStores) is reparented, the automatic
updates could be broken if the new parent is not marked as having
damaged descendants.

Fix this issue by propagating the damagedDescendants flag whenever a
window is reparented.

Signed-off-by: Peter Harris <pharris at opentext.com>
---
 composite/compalloc.c  | 21 +++++++++++++--------
 composite/compint.h    |  2 ++
 composite/compwindow.c |  5 +++++
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/composite/compalloc.c b/composite/compalloc.c
index 05ffc7e85..433dc820a 100644
--- a/composite/compalloc.c
+++ b/composite/compalloc.c
@@ -67,6 +67,18 @@ compBlockHandler(ScreenPtr pScreen, void *pTimeout)
     cs->BlockHandler = NULL;
 }
 
+void
+compMarkAncestors(WindowPtr pWin)
+{
+    pWin = pWin->parent;
+    while (pWin) {
+        if (pWin->damagedDescendants)
+            return;
+        pWin->damagedDescendants = TRUE;
+        pWin = pWin->parent;
+    }
+}
+
 static void
 compReportDamage(DamagePtr pDamage, RegionPtr pRegion, void *closure)
 {
@@ -81,14 +93,7 @@ compReportDamage(DamagePtr pDamage, RegionPtr pRegion, void *closure)
     }
     cw->damaged = TRUE;
 
-    /* Mark the ancestors */
-    pWin = pWin->parent;
-    while (pWin) {
-        if (pWin->damagedDescendants)
-            break;
-        pWin->damagedDescendants = TRUE;
-        pWin = pWin->parent;
-    }
+    compMarkAncestors(pWin);
 }
 
 static void
diff --git a/composite/compint.h b/composite/compint.h
index f05c2d8a5..89f6507b9 100644
--- a/composite/compint.h
+++ b/composite/compint.h
@@ -236,6 +236,8 @@ Bool
 compReallocPixmap(WindowPtr pWin, int x, int y,
                   unsigned int w, unsigned int h, int bw);
 
+void compMarkAncestors(WindowPtr pWin);
+
 /*
  * compinit.c
  */
diff --git a/composite/compwindow.c b/composite/compwindow.c
index f88238146..e74ce661a 100644
--- a/composite/compwindow.c
+++ b/composite/compwindow.c
@@ -432,6 +432,7 @@ compReparentWindow(WindowPtr pWin, WindowPtr pPriorParent)
 {
     ScreenPtr pScreen = pWin->drawable.pScreen;
     CompScreenPtr cs = GetCompScreen(pScreen);
+    CompWindowPtr cw = GetCompWindow(pWin);
 
     pScreen->ReparentWindow = cs->ReparentWindow;
     /*
@@ -469,6 +470,10 @@ compReparentWindow(WindowPtr pWin, WindowPtr pPriorParent)
         (*pScreen->ReparentWindow) (pWin, pPriorParent);
     cs->ReparentWindow = pScreen->ReparentWindow;
     pScreen->ReparentWindow = compReparentWindow;
+
+    if (pWin->damagedDescendants || (cw && cw->damaged))
+        compMarkAncestors(pWin);
+
     compCheckTree(pWin->drawable.pScreen);
 }
 
-- 
2.14.1