Aric Stewart : user32: Scroll window fix.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 1b6d127aee1210f8f9436b85bb34a9c416d0aaac
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=1b6d127aee1210f8f9436b85bb34a9c416d0aaac

Author: Aric Stewart <aric at codeweavers.com>
Date:   Tue Feb 13 07:38:06 2007 -0600

user32: Scroll window fix.

Fix the case where the scrolling amount exceeds the window but still
falls within the clipping rect. This generates an additional update
region that needs to be invalidated.

---

 dlls/user32/painting.c  |   19 +++++++++++++++++++
 dlls/user32/tests/win.c |    9 +++++++++
 2 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/dlls/user32/painting.c b/dlls/user32/painting.c
index dbc8cfe..9fe6764 100644
--- a/dlls/user32/painting.c
+++ b/dlls/user32/painting.c
@@ -870,6 +870,25 @@ INT WINAPI ScrollWindowEx( HWND hwnd, INT dx, INT dy,
                 CombineRgn( hrgnWinupd, hrgnWinupd, hrgnTemp, RGN_OR );
             RedrawWindow( hwnd, NULL, hrgnTemp, rdw_flags);
             DeleteObject( hrgnClip );
+
+           /* Catch the case where the scolling amount exceeds the size of the
+            * original window. This generated a second update area that is the
+            * location where the original scrolled content would end up.
+            * This second region is not returned by the ScrollDC and sets
+            * ScrollWindowEx apart from just a ScrollDC.
+            *
+            * This has been verified with testing on windows.
+            */
+            if (abs(dx) > abs(rc.right - rc.left) ||
+                abs(dy) > abs(rc.bottom - rc.top))
+            {
+                SetRectRgn( hrgnTemp, rc.left + dx, rc.top + dy, rc.right+dx, rc.bottom + dy);
+                CombineRgn( hrgnTemp, hrgnTemp, hrgnClip, RGN_AND );
+                CombineRgn( hrgnUpdate, hrgnUpdate, hrgnTemp, RGN_OR );
+
+                if( !bOwnRgn)
+                    CombineRgn( hrgnWinupd, hrgnWinupd, hrgnTemp, RGN_OR );
+            }
         }
         DeleteObject( hrgnTemp );
     } else {
diff --git a/dlls/user32/tests/win.c b/dlls/user32/tests/win.c
index ef456ca..9d07306 100644
--- a/dlls/user32/tests/win.c
+++ b/dlls/user32/tests/win.c
@@ -2991,6 +2991,15 @@ static void test_scrollvalidate( HWND parent)
     CombineRgn( exprgn, exprgn, tmprgn, RGN_OR);
     ok( EqualRgn( exprgn, hrgn), "wrong update region\n");
 
+    SetRect( &rc, 0,40, 100,60);
+    SetRect( &cliprc, 0,0, 100,100);
+    ScrollWindowEx( hwnd1, 0, -25, &rc, &cliprc, hrgn, &rcu, SW_INVALIDATE);
+    SetRectRgn( tmprgn, 0,15,98,35);
+    CombineRgn( exprgn, exprgn, tmprgn, RGN_OR);
+    SetRectRgn( tmprgn, 0, 40, 98, 60);
+    CombineRgn( exprgn, exprgn, tmprgn, RGN_OR);
+    ok( EqualRgn( exprgn, hrgn), "wrong update region in excessive scroll\n");
+
     /* now test ScrollWindowEx with a combination of
      * WS_CLIPCHILDREN style and SW_SCROLLCHILDREN flag */
     /* make hwnd2 the child of hwnd1 */