[PATCH 1/5] comctl32/listbox: Resize the entire item array at once in SetCount

[Gabriel Ivăncescu]

Signed-off-by: Gabriel Ivăncescu <gabrielopcode at gmail.com>
---

This has been carefully done so that it matches the previous behavior when
LBS_NODATA was used, since SetCount only works with it (so that means it
also implies LBS_OWNERDRAWFIXED and so on).

count was changed to unsigned so that it passes the last test in the patch
series, apparently Windows treats it as unsigned.

 dlls/comctl32/listbox.c | 45 +++++++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 11 deletions(-)

diff --git a/dlls/comctl32/listbox.c b/dlls/comctl32/listbox.c
index c92c2a2..787fc88 100644
--- a/dlls/comctl32/listbox.c
+++ b/dlls/comctl32/listbox.c
@@ -1742,24 +1742,47 @@ static void LISTBOX_ResetContent( LB_DESCR *descr )
 /***********************************************************************
  *           LISTBOX_SetCount
  */
-static LRESULT LISTBOX_SetCount( LB_DESCR *descr, INT count )
+static LRESULT LISTBOX_SetCount( LB_DESCR *descr, UINT count )
 {
-    LRESULT ret;
+    UINT orig_num = descr->nb_items;
 
     if (!(descr->style & LBS_NODATA)) return LB_ERR;
 
-    /* FIXME: this is far from optimal... */
-    if (count > descr->nb_items)
+    if (count > orig_num)
     {
-        while (count > descr->nb_items)
-            if ((ret = LISTBOX_InsertString( descr, -1, 0 )) < 0)
-                return ret;
+        if (!resize_storage(descr, count))
+            return LB_ERRSPACE;
+        memset(&descr->items[orig_num], 0, (count - orig_num) * sizeof(LB_ITEMDATA));
+        descr->nb_items = count;
+
+        LISTBOX_UpdateScroll(descr);
+        LISTBOX_InvalidateItems(descr, orig_num);
+
+        /* If listbox was empty, set focus to the first item */
+        if (orig_num == 0) LISTBOX_SetCaretIndex(descr, 0, FALSE);
     }
-    else if (count < descr->nb_items)
+    else if (count < orig_num)
     {
-        while (count < descr->nb_items)
-            if ((ret = LISTBOX_RemoveItem( descr, (descr->nb_items - 1) )) < 0)
-                return ret;
+        LISTBOX_InvalidateItems(descr, count);
+        descr->nb_items = count;
+
+        if (count == 0) SendMessageW(descr->self, LB_RESETCONTENT, 0, 0);
+        else
+        {
+            descr->anchor_item = min(descr->anchor_item, count - 1);
+
+            resize_storage(descr, count);
+            if (descr->selected_item >= count)
+                descr->selected_item = -1;
+
+            LISTBOX_UpdateScroll(descr);
+
+            /* If we removed the scrollbar, reset the top of the list */
+            if (count <= descr->page_size && orig_num > descr->page_size)
+                LISTBOX_SetTopItem(descr, 0, TRUE);
+
+            descr->focus_item = min(descr->focus_item, count - 1);
+        }
     }
 
     InvalidateRect( descr->self, NULL, TRUE );
-- 
2.19.1