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>

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

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);

composite/compint.h

@@ -315,10 +315,7 @@ void
 compCopyWindow (WindowPtr pWin, DDXPointRec ptOldOrg, RegionPtr prgnSrc);
 
 void
-compWindowUpdate (WindowPtr pWin);
+compPaintChildrenToWindow (WindowPtr pWin);
-
-void
-compScreenUpdate (ScreenPtr pScreen);
 
 WindowPtr
 CompositeRealChildHead (WindowPtr pWin);

composite/compwindow.c

@@ -720,13 +720,11 @@ compWindowUpdateAutomatic (WindowPtr pWin)
     DamageEmpty (cw->damage);
 }
 
-void
+static void
-compWindowUpdate (WindowPtr pWin)
+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)
 {

dix/window.c

@@ -298,6 +298,10 @@ SetWindowToDefaults(WindowPtr pWin)
 #ifdef ROOTLESS
     pWin->rootlessUnhittable = FALSE;
 #endif
+
+#ifdef COMPOSITE
+    pWin->damagedDescendants = FALSE;
+#endif
 }
 
 static void

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;
 
 /*