https://git.reactos.org/?p=reactos.git;a=commitdiff;h=5c505d9a9b804a5464f348ebc09265f28d4b75b4
commit 5c505d9a9b804a5464f348ebc09265f28d4b75b4
Author: Doug Lyons <dougly...@douglyons.com>
AuthorDate: Sat Feb 22 23:31:50 2025 -0600
Commit: Hermès Bélusca-Maïto <hermes.belusca-ma...@reactos.org>
CommitDate: Wed Mar 12 12:18:53 2025 +0100
[NTUSER] Handle window update region larger than the current window in clip
region (#7731)
CORE-18206 CORE-18799 CORE-19371
Fixes infinite loop of:
err: Message WM_PAINT count 1 Internal Paint Set? FALSE
The symptom appears in the following scenario (as reported in CORE-18799):
A program (game) runs at a small resolution (e.g. 640 x 480), but the
game window gets invalidated at a larger size (e.g. 1152 x 864 screen
resolution) before switching to the smaller (640 x 480) size.
Because of this, the window's update region is larger than the current
window so only the 640 x 480 region gets validated leaving the remaining
region invalid. This causes the recurring WM_PAINT messages because there
is no way to invalidate the remaining area.
---
win32ss/user/ntuser/winpos.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/win32ss/user/ntuser/winpos.c b/win32ss/user/ntuser/winpos.c
index d06730112be..da895726b7a 100644
--- a/win32ss/user/ntuser/winpos.c
+++ b/win32ss/user/ntuser/winpos.c
@@ -2037,7 +2037,17 @@ co_WinPosSetWindowPos(
}
else if(VisAfter)
{
- REGION_bOffsetRgn(VisAfter, -Window->rcWindow.left,
-Window->rcWindow.top);
+ /* Clip existing update region to new window size */
+ if (Window->hrgnUpdate != NULL)
+ {
+ PREGION RgnUpdate = REGION_LockRgn(Window->hrgnUpdate);
+ if (RgnUpdate)
+ {
+ RgnType = IntGdiCombineRgn(RgnUpdate, RgnUpdate, VisAfter,
RGN_AND);
+ REGION_UnlockRgn(RgnUpdate);
+ }
+ }
+ REGION_bOffsetRgn(VisAfter, -Window->rcWindow.left,
-Window->rcWindow.top);
}
/*
