comctl32/listbox: Fix mouse wheel scrolling for multi-column listboxes.

Multi-column listboxes scroll horizontally, so each wheel tick must go an entire page at a time instead of an item at a time. But we have to limit the amount of scrolling in this case to avoid "jumping over" columns, if the window is too small. Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=22253Signed-off-by: Gabriel Ivăncescu <gabrielopcode@gmail.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

comctl32/listbox: Fix mouse wheel scrolling for multi-column listboxes.
1f378751 · Gabriel Ivăncescu · Alexandre Julliard · e97ec060 · 1f378751
Commit 1f378751 authored Jun 05, 2019 by Gabriel Ivăncescu Committed by Alexandre Julliard Jun 14, 2019
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Showing with 15 additions and 4 deletions

listbox.c dlls/comctl32/listbox.c +15 -4

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--- a/dlls/comctl32/listbox.c
+++ b/dlls/comctl32/listbox.c
@@ -2068,7 +2068,7 @@ static LRESULT LISTBOX_HandleHScroll( LB_DESCR *descr, WORD scrollReq, WORD pos 

 static LRESULT LISTBOX_HandleMouseWheel(LB_DESCR *descr, SHORT delta )
 {
-    UINT pulScrollLines = 3;
+    INT pulScrollLines = 3;

    SystemParametersInfoW(SPI_GETWHEELSCROLLLINES,0, &pulScrollLines, 0);

@@ -2082,9 +2082,20 @@ static LRESULT LISTBOX_HandleMouseWheel(LB_DESCR *descr, SHORT delta )
    if (descr->wheel_remain && pulScrollLines)
    {
        int cLineScroll;
-        pulScrollLines = min((UINT) descr->page_size, pulScrollLines);
-        cLineScroll = pulScrollLines * (float)descr->wheel_remain / WHEEL_DELTA;
-        descr->wheel_remain -= WHEEL_DELTA * cLineScroll / (int)pulScrollLines;
+        if (descr->style & LBS_MULTICOLUMN)
+        {
+            pulScrollLines = min(descr->width / descr->column_width, pulScrollLines);
+            pulScrollLines = max(1, pulScrollLines);
+            cLineScroll = pulScrollLines * descr->wheel_remain / WHEEL_DELTA;
+            descr->wheel_remain -= WHEEL_DELTA * cLineScroll / pulScrollLines;
+            cLineScroll *= descr->page_size;
+        }
+        else
+        {
+            pulScrollLines = min(descr->page_size, pulScrollLines);
+            cLineScroll = pulScrollLines * descr->wheel_remain / WHEEL_DELTA;
+            descr->wheel_remain -= WHEEL_DELTA * cLineScroll / pulScrollLines;
+        }
        LISTBOX_SetTopItem( descr, descr->top_item - cLineScroll, TRUE );
    }
    return 0;