From 277243a09e74992c63094142a8b806e87ab4c3f0 Mon Sep 17 00:00:00 2001
From: jesus <jesus@lazarus-ide.org>
Date: Wed, 14 Dec 2005 16:03:42 +0000
Subject: [PATCH] UnionRect now looks to empty source rects

git-svn-id: trunk@8318 -
---
 lcl/include/winapi.inc | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/lcl/include/winapi.inc b/lcl/include/winapi.inc
index 12ee19d1ab..9be28b167f 100644
--- a/lcl/include/winapi.inc
+++ b/lcl/include/winapi.inc
@@ -1355,11 +1355,18 @@ end;
 function UnionRect(var DestRect: TRect;
   const SrcRect1, SrcRect2: TRect): Boolean;
 begin
-  Result := True;
-  DestRect.Left := Min(SrcRect1.Left, SrcRect2.Left);
-  DestRect.Top := Min(SrcRect1.Top, SrcRect2.Top);
-  DestRect.Right := Max(SrcRect1.Right, SrcRect2.Right);
-  DestRect.Bottom := Max(SrcRect1.Bottom, SrcRect2.Bottom);
+  if IsRectEmpty(SrcRect1) then
+    DestRect := SrcRect2
+  else
+  if IsRectEmpty(SrcRect2) then
+    DestRect := SrcRect1
+  else begin
+    DestRect.Left := Min(SrcRect1.Left, SrcRect2.Left);
+    DestRect.Top := Min(SrcRect1.Top, SrcRect2.Top);
+    DestRect.Right := Max(SrcRect1.Right, SrcRect2.Right);
+    DestRect.Bottom := Max(SrcRect1.Bottom, SrcRect2.Bottom);
+  end;
+  Result := not IsRectEmpty(DestRect);
 end;
 
 //##apiwiz##epi##   // Do not remove