From 1a6891126636505152d134b91e3a3824b3e615b9 Mon Sep 17 00:00:00 2001
From: Gary Wong <gtw@gnu.org>
Date: Tue, 25 Aug 2009 14:19:01 -0600
Subject: [PATCH] Properly compute the update region when the old region was
 empty.

---
 ChangeLog      |  5 +++++
 window-table.c | 33 +++++++++++++++++++++------------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 038b015..54053bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-08-25  Gary Wong  <gtw@gnu.org>
+
+	* window-table.c (queue_window_update): Properly compute the
+	update region when the old region was empty.
+
 2009-08-24  Gary Wong  <gtw@gnu.org>
 
 	* gwm.c (shutdown_display) [DEBUG]: Call muntrace() only when
diff --git a/window-table.c b/window-table.c
index 047161e..88ce34f 100644
--- a/window-table.c
+++ b/window-table.c
@@ -243,23 +243,32 @@ extern void queue_window_update( struct gwm_window *window,
 				 int cleared ) {
 
     /* FIXME Consider computing the region instead of the bounding box. */
-    
-    if( x < window->update.x ) {
-	window->update.width += window->update.x - x;
-	window->update.x = x;
-    }
 
-    if( y < window->update.y ) {
-	window->update.height += window->update.y - y;
+    if( !window->update.width || !window->update.height ) {
+	/* New update region. */
+	window->update.x = x;
 	window->update.y = y;
-    }
+	window->update.width = width;
+	window->update.height = height;
+    } else {
+	/* Compute the bounding box of the union of the old and new regions. */
+	if( x < window->update.x ) {
+	    window->update.width += window->update.x - x;
+	    window->update.x = x;
+	}
 
-    if( x + width > window->update.x + window->update.width )
-	window->update.width = x + width - window->update.x;
+	if( y < window->update.y ) {
+	    window->update.height += window->update.y - y;
+	    window->update.y = y;
+	}
 
-    if( y + height > window->update.y + window->update.height )
-	window->update.height = y + height - window->update.y;
+	if( x + width > window->update.x + window->update.width )
+	    window->update.width = x + width - window->update.x;
 
+	if( y + height > window->update.y + window->update.height )
+	    window->update.height = y + height - window->update.y;
+    }
+    
     if( !cleared )
 	window->cleared = FALSE;
 
-- 
2.11.4.GIT