composite: Inhibit window background paint with manual subwindow redi…

…rection

The composite extension spec says that window background painting
should be inhibited when the subwindow redirection mode is set to
manual.

This eliminates the ugly flashing effect when compiz unredirects a
fullscreen window.

Signed-off-by: Ville Syrjälä <ville.syrjala@nokia.com>
Reviewed-by: Owen Taylor <otaylor@fishsoup.net>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

composite/compalloc.c

@@ -434,6 +434,7 @@ compRedirectSubwindows (ClientPtr pClient, WindowPtr pWin, int update)
 	 * critical output
 	 */
 	DamageExtSetCritical (pClient, TRUE);
+	pWin->inhibitBGPaint = TRUE;
     }
     return Success;
 }
@@ -466,6 +467,7 @@ compFreeClientSubwindows (WindowPtr pWin, XID id)
 		 */
 		DamageExtSetCritical (pClient, FALSE);
 		csw->update = CompositeRedirectAutomatic;
+		pWin->inhibitBGPaint = FALSE;
 		if (pWin->mapped)
 		    (*pWin->drawable.pScreen->ClearToBackground)(pWin, 0, 0, 0, 0, TRUE);
 	    }

include/windowstr.h

@@ -169,6 +169,7 @@ typedef struct _Window {
 #endif
 #ifdef COMPOSITE
     unsigned		damagedDescendants:1;	/* some descendants are damaged */
+    unsigned		inhibitBGPaint:1;	/* paint the background? */
 #endif
 } WindowRec;
 

mi/miexpose.c

@@ -575,6 +575,10 @@ miPaintWindow(WindowPtr pWin, RegionPtr prgn, int what)
 	tile_x_off = pWin->drawable.x - draw_x_off;
 	tile_y_off = pWin->drawable.y - draw_y_off;
 	fill = pWin->background;
+#ifdef COMPOSITE
+	if (pWin->inhibitBGPaint)
+	    return;
+#endif
 	switch (pWin->backgroundState) {
 	case None:
 	    return;