[PATCH v2 0/1] MR7736: server: Fix the accumulation method when merging WM_MOUSEWHEEL message.

[Akihiro Sagawa (＠sgwaki)]

Otherwise, two MK_RBUTTON messages become MK_SHIFT.

--
  v2: server: Fix the accumulation method when merging WM_MOUSEWHEEL message.

https://gitlab.winehq.org/wine/wine/-/merge_requests/7736

[PATCH v2 1/1] server: Fix the accumulation method when merging WM_MOUSEWHEEL message.

[Akihiro Sagawa]

From: Akihiro Sagawa

---
 server/queue.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/server/queue.c b/server/queue.c
index 520659d377c..282523b21a3 100644
--- a/server/queue.c
+++ b/server/queue.c
@@ -823,11 +823,16 @@ static struct message *find_mouse_message( struct thread_input *input, const str
 static int merge_mousewheel( struct thread_input *input, const struct message *msg )
 {
     struct message *prev;
+    int delta;

if (!(prev = find_mouse_message( input, msg ))) return 0;
     if (prev->x != msg->x || prev->y != msg->y) return 0; /* don't merge if cursor has moved */

-    prev->wparam += msg->wparam; /* accumulate wheel delta */
+    /* accumulate wheel delta */
+    delta = GET_WHEEL_DELTA_WPARAM(prev->wparam) + GET_WHEEL_DELTA_WPARAM(msg->wparam);
+    if (delta < MINSHORT || delta > MAXSHORT) return 0;
+
+    prev->wparam  = MAKEWPARAM(GET_KEYSTATE_WPARAM(msg->wparam), delta);
     prev->lparam  = msg->lparam;
     prev->x       = msg->x;
     prev->y       = msg->y;