[PATCH v2 4/4] composite: Copy the window contents back from the pixmap

[ville.syrjala at nokia.com]

From: Ville Syrjälä <ville.syrjala at nokia.com>

Since extra expose events are no longer generated during window
unredirection, the window contents must be preserved by the server.
So copy the window contents back from the pixmap. The copy can only
be done after the clips have been recomputed, so delay the copy and
the pixmap destruction until ValidateTree is done. Window borders are
restored by HandleExposures and thus don't need to be copied back.

Signed-off-by: Ville Syrjälä <ville.syrjala at nokia.com>
---
 composite/compalloc.c  |   47 +++++++++++++++++++++++++++++++++++++++++------
 composite/compint.h    |    5 ++++-
 composite/compwindow.c |   16 ++++++++++++----
 3 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/composite/compalloc.c b/composite/compalloc.c
index 233fb10..1683ee9 100644
--- a/composite/compalloc.c
+++ b/composite/compalloc.c
@@ -206,6 +206,34 @@ compRedirectWindow (ClientPtr pClient, WindowPtr pWin, int update)
     return Success;
 }
 
+void
+compRestoreWindow (WindowPtr pWin, PixmapPtr pPixmap)
+{
+    ScreenPtr pScreen = pWin->drawable.pScreen;
+    WindowPtr pParent = pWin->parent;
+
+    if (pParent->drawable.depth == pWin->drawable.depth) {
+	GCPtr pGC = GetScratchGC (pWin->drawable.depth, pScreen);
+	int bw = (int) pWin->borderWidth;
+	int x = bw;
+	int y = bw;
+	int w = pWin->drawable.width;
+	int h = pWin->drawable.height;
+
+	if (pGC) {
+	    ChangeGCVal val;
+	    val.val = IncludeInferiors;
+	    ChangeGC (NullClient, pGC, GCSubwindowMode, &val);
+	    ValidateGC(&pWin->drawable, pGC);
+	    (*pGC->ops->CopyArea) (&pPixmap->drawable,
+				   &pWin->drawable,
+				   pGC,
+				   x, y, w, h, 0, 0);
+	    FreeScratchGC (pGC);
+	}
+    }
+}
+
 /*
  * Free one of the per-client per-window resources, clearing
  * redirect and the per-window pointer as appropriate
@@ -213,10 +241,12 @@ compRedirectWindow (ClientPtr pClient, WindowPtr pWin, int update)
 void
 compFreeClientWindow (WindowPtr pWin, XID id)
 {
+    ScreenPtr		pScreen = pWin->drawable.pScreen;
     CompWindowPtr	cw = GetCompWindow (pWin);
     CompClientWindowPtr	ccw, *prev;
     Bool		anyMarked = FALSE;
     WindowPtr		pLayerWin;
+    PixmapPtr           pPixmap = NULL;
 
     if (!cw)
 	return;
@@ -236,8 +266,10 @@ compFreeClientWindow (WindowPtr pWin, XID id)
 	if (pWin->mapped)
 	    anyMarked = compMarkWindows (pWin, &pLayerWin);
     
-	if (pWin->redirectDraw != RedirectDrawNone)
-	    compFreePixmap (pWin);
+	if (pWin->redirectDraw != RedirectDrawNone) {
+	    pPixmap = (*pScreen->GetWindowPixmap) (pWin);
+	    compSetParentPixmap (pWin);
+	}
 
 	if (cw->damage)
 	    DamageDestroy (cw->damage);
@@ -258,6 +290,11 @@ compFreeClientWindow (WindowPtr pWin, XID id)
 
     if (anyMarked)
 	compHandleMarkedWindows (pWin, pLayerWin);
+
+    if (pPixmap) {
+	compRestoreWindow (pWin, pPixmap);
+	(*pScreen->DestroyPixmap) (pPixmap);
+    }
 }
 
 /*
@@ -589,10 +626,10 @@ compAllocPixmap (WindowPtr pWin)
 }
 
 void
-compFreePixmap (WindowPtr pWin)
+compSetParentPixmap (WindowPtr pWin)
 {
     ScreenPtr	    pScreen = pWin->drawable.pScreen;
-    PixmapPtr	    pRedirectPixmap, pParentPixmap;
+    PixmapPtr	    pParentPixmap;
     CompWindowPtr   cw = GetCompWindow (pWin);
 
     if (cw->damageRegistered)
@@ -608,11 +645,9 @@ compFreePixmap (WindowPtr pWin)
      * parent exposed area; regions beyond the parent cause crashes
      */
     RegionCopy(&pWin->borderClip, &cw->borderClip);
-    pRedirectPixmap = (*pScreen->GetWindowPixmap) (pWin);
     pParentPixmap = (*pScreen->GetWindowPixmap) (pWin->parent);
     pWin->redirectDraw = RedirectDrawNone;
     compSetPixmap (pWin, pParentPixmap);
-    (*pScreen->DestroyPixmap) (pRedirectPixmap);
 }
 
 /*
diff --git a/composite/compint.h b/composite/compint.h
index 80083b0..b2fc541 100644
--- a/composite/compint.h
+++ b/composite/compint.h
@@ -214,7 +214,10 @@ Bool
 compAllocPixmap (WindowPtr pWin);
 
 void
-compFreePixmap (WindowPtr pWin);
+compSetParentPixmap (WindowPtr pWin);
+
+void
+compRestoreWindow (WindowPtr pWin, PixmapPtr pPixmap);
 
 Bool
 compReallocPixmap (WindowPtr pWin, int x, int y,
diff --git a/composite/compwindow.c b/composite/compwindow.c
index 4dab135..b84c437 100644
--- a/composite/compwindow.c
+++ b/composite/compwindow.c
@@ -160,8 +160,13 @@ compCheckRedirect (WindowPtr pWin)
     {
 	if (should)
 	    return compAllocPixmap (pWin);
-	else
-	    compFreePixmap (pWin);
+	else {
+	    ScreenPtr pScreen = pWin->drawable.pScreen;
+	    PixmapPtr pPixmap = (*pScreen->GetWindowPixmap) (pWin);
+	    compSetParentPixmap (pWin);
+	    compRestoreWindow (pWin, pPixmap);
+	    (*pScreen->DestroyPixmap) (pPixmap);
+	}
     }
     return TRUE;
 }
@@ -569,8 +574,11 @@ compDestroyWindow (WindowPtr pWin)
     while ((csw = GetCompSubwindows (pWin)))
 	FreeResource (csw->clients->id, RT_NONE);
 
-    if (pWin->redirectDraw != RedirectDrawNone)
-	compFreePixmap (pWin);
+    if (pWin->redirectDraw != RedirectDrawNone) {
+	PixmapPtr pPixmap = (*pScreen->GetWindowPixmap) (pWin);
+	compSetParentPixmap (pWin);
+	(*pScreen->DestroyPixmap) (pPixmap);
+    }
     ret = (*pScreen->DestroyWindow) (pWin);
     cs->DestroyWindow = pScreen->DestroyWindow;
     pScreen->DestroyWindow = compDestroyWindow;
-- 
1.7.2.2