[PATCH 2/2] user32/listbox: Optimize SetCount partly

[Gabriel Ivăncescu]

Signed-off-by: Gabriel Ivăncescu <gabrielopcode at gmail.com>
---
 dlls/user32/listbox.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/dlls/user32/listbox.c b/dlls/user32/listbox.c
index c8bd148..a8de8d3 100644
--- a/dlls/user32/listbox.c
+++ b/dlls/user32/listbox.c
@@ -1763,18 +1763,31 @@ static LRESULT LISTBOX_SetCount( LB_DESCR *descr, INT count )
         return LB_ERR;
     }
 
-    /* FIXME: this is far from optimal... */
     if (count > descr->nb_items)
     {
-        while (count > descr->nb_items)
-            if ((ret = LISTBOX_InsertString( descr, -1, 0 )) < 0)
-                return ret;
+        INT num = descr->nb_items;
+        if ((ret = LISTBOX_InitStorage(descr, count - num)) != LB_OKAY)
+            return ret;
+        memset(&descr->items[num], 0, (count - num) * sizeof(*descr->items));
+        descr->nb_items = count;
+
+        LISTBOX_UpdateScroll(descr);
+        LISTBOX_InvalidateItems(descr, num);
+
+        /* If listbox was empty, set focus to the first item */
+        if (count == 1) LISTBOX_SetCaretIndex(descr, 0, FALSE);
     }
     else if (count < descr->nb_items)
     {
+        /* FIXME: This is not really optimal */
+        DWORD oldstyle = descr->style;
+        LISTBOX_SetRedraw(descr, FALSE);
+
         while (count < descr->nb_items)
             if ((ret = LISTBOX_RemoveItem( descr, (descr->nb_items - 1) )) < 0)
-                return ret;
+                break;
+        if (!(oldstyle & LBS_NOREDRAW)) LISTBOX_SetRedraw(descr, TRUE);
+        if (ret < 0) return ret;
     }
 
     InvalidateRect( descr->self, NULL, TRUE );
-- 
1.9.1