composite: Support updating an arbitrary subtree

Rename compUpdateWindow to compPaintWindowToParent and split the child
walk to compPaintChildrenToWindow. Calling compPaintChildrenToWindow
allows an arbitrary subtree to be updated, instead of having to update
all the windows. This will be used to make sure all the descendants are
copied to the parent when the parent window contents need to be accessed
in IncludeInferios sub-window mode.

WindowRec has a new member 'damagedDescendants' that is used to keep
track of which subtrees need updating. When a window is damaged,
'damagedDescendants' will be set for all the ancestors, and when a
subtree is updated, the tree walk can be stopped early if no damaged
descendants are present.

CompScreenRec no longer needs the 'damaged' member since the root
window's 'damagedDescendants' provides the same information.

Signed-off-by: Ville Syrjälä <ville.syrjala@nokia.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

6 files changed, 38 insertions, 13 deletions

diff --git a/composite/compalloc.c b/composite/compalloc.c
index b2e3f7165..e4064f6b1 100644
--- a/composite/compalloc.c
+++ b/composite/compalloc.c
@@ -47,11 +47,11 @@
 
 #include "compint.h"
 
-void
+static void
 compScreenUpdate (ScreenPtr pScreen)
 {
     compCheckTree (pScreen);
-    compWindowUpdate (pScreen->root);
+    compPaintChildrenToWindow (pScreen->root);
 }
 
 static void
@@ -84,6 +84,15 @@ compReportDamage (DamagePtr pDamage, RegionPtr pRegion, void *closure)
         pScreen->BlockHandler = compBlockHandler;
     }
     cw->damaged = TRUE;
+
+    /* Mark the ancestors */
+    pWin = pWin->parent;
+    while (pWin) {
+	if (pWin->damagedDescendants)
+	    break;
+	pWin->damagedDescendants = TRUE;
+	pWin = pWin->parent;
+    }
 }
 
 static void
diff --git a/composite/compinit.c b/composite/compinit.c
index 74689be1f..90ee66c88 100644
--- a/composite/compinit.c
+++ b/composite/compinit.c
@@ -145,7 +145,7 @@ compGetImage (DrawablePtr pDrawable,
 
     pScreen->GetImage = cs->GetImage;
     if (pDrawable->type == DRAWABLE_WINDOW)
-	compScreenUpdate (pScreen);
+	compPaintChildrenToWindow ((WindowPtr) pDrawable);
     (*pScreen->GetImage) (pDrawable, sx, sy, w, h, format, planemask, pdstLine);
     cs->GetImage = pScreen->GetImage;
     pScreen->GetImage = compGetImage;
@@ -161,7 +161,7 @@ static void compSourceValidate(DrawablePtr pDrawable,
 
     pScreen->SourceValidate = cs->SourceValidate;
     if (pDrawable->type == DRAWABLE_WINDOW && subWindowMode == IncludeInferiors)
-	compScreenUpdate (pScreen);
+	compPaintChildrenToWindow ((WindowPtr) pDrawable);
     if (pScreen->SourceValidate)
 	(*pScreen->SourceValidate) (pDrawable, x, y, width, height,
 				    subWindowMode);
diff --git a/composite/compint.h b/composite/compint.h
index 681f651e9..57e0b5dea 100644
--- a/composite/compint.h
+++ b/composite/compint.h
@@ -315,10 +315,7 @@ void
 compCopyWindow (WindowPtr pWin, DDXPointRec ptOldOrg, RegionPtr prgnSrc);
 
 void
-compWindowUpdate (WindowPtr pWin);
-
-void
-compScreenUpdate (ScreenPtr pScreen);
+compPaintChildrenToWindow (WindowPtr pWin);
 
 WindowPtr
 CompositeRealChildHead (WindowPtr pWin);
diff --git a/composite/compwindow.c b/composite/compwindow.c
index 22d237481..2440f1897 100644
--- a/composite/compwindow.c
+++ b/composite/compwindow.c
@@ -720,13 +720,11 @@ compWindowUpdateAutomatic (WindowPtr pWin)
     DamageEmpty (cw->damage);
 }
 
-void
-compWindowUpdate (WindowPtr pWin)
+static void
+compPaintWindowToParent (WindowPtr pWin)
 {
-    WindowPtr	pChild;
+    compPaintChildrenToWindow (pWin);
 
-    for (pChild = pWin->lastChild; pChild; pChild = pChild->prevSib)
-	compWindowUpdate (pChild);
     if (pWin->redirectDraw != RedirectDrawNone)
     {
 	CompWindowPtr	cw = GetCompWindow(pWin);
@@ -739,6 +737,20 @@ compWindowUpdate (WindowPtr pWin)
     }
 }
 
+void
+compPaintChildrenToWindow (WindowPtr pWin)
+{
+    WindowPtr pChild;
+
+    if (!pWin->damagedDescendants)
+	return;
+
+    for (pChild = pWin->lastChild; pChild; pChild = pChild->prevSib)
+	compPaintWindowToParent (pChild);
+
+    pWin->damagedDescendants = FALSE;
+}
+
 WindowPtr
 CompositeRealChildHead (WindowPtr pWin)
 {
diff --git a/dix/window.c b/dix/window.c
index d140ddade..9be70649a 100644
--- a/dix/window.c
+++ b/dix/window.c
@@ -298,6 +298,10 @@ SetWindowToDefaults(WindowPtr pWin)
 #ifdef ROOTLESS
     pWin->rootlessUnhittable = FALSE;
 #endif
+
+#ifdef COMPOSITE
+    pWin->damagedDescendants = FALSE;
+#endif
 }
 
 static void
diff --git a/include/windowstr.h b/include/windowstr.h
index 0b66ebbcc..4a7a0f488 100644
--- a/include/windowstr.h
+++ b/include/windowstr.h
@@ -167,6 +167,9 @@ typedef struct _Window {
 #ifdef ROOTLESS
     unsigned		rootlessUnhittable:1;	/* doesn't hit-test */
 #endif
+#ifdef COMPOSITE
+    unsigned		damagedDescendants:1;	/* some descendants are damaged */
+#endif
 } WindowRec;
 
 /*