user32/listbox: Implement LBS_NODATA for single-selection listboxes.

The LBS_NODATA style's purpose is to drastically improve performance and memory usage on very large lists, since they should function as virtual lists. Thus, don't store any data for single-selection listboxes (descr->items always NULL). Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=32374Signed-off-by: Gabriel Ivăncescu <gabrielopcode@gmail.com> Signed-off-by: Huw Davies <huw@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

user32/listbox: Implement LBS_NODATA for single-selection listboxes.
8a9ff9fb · Gabriel Ivăncescu · Alexandre Julliard · 9f586534 · 8a9ff9fb
Commit 8a9ff9fb authored Feb 20, 2019 by Gabriel Ivăncescu Committed by Alexandre Julliard Feb 21, 2019
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Showing with 16 additions and 8 deletions

listbox.c dlls/user32/listbox.c +16 -8

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--- a/dlls/user32/listbox.c
+++ b/dlls/user32/listbox.c
@@ -18,7 +18,7 @@
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 *
 * TODO:
- *    - LBS_NODATA
+ *    - LBS_NODATA for multi-selection listboxes
 */

 #include <string.h>
@@ -130,17 +130,20 @@ static BOOL resize_storage(LB_DESCR *descr, UINT items_size)
        items_size + LB_ARRAY_GRANULARITY * 2 < descr->items_size)
    {
        items_size = (items_size + LB_ARRAY_GRANULARITY - 1) & ~(LB_ARRAY_GRANULARITY - 1);
-        items = heap_realloc(descr->items, items_size * sizeof(LB_ITEMDATA));
-        if (!items)
+        if ((descr->style & (LBS_NODATA | LBS_MULTIPLESEL | LBS_EXTENDEDSEL)) != LBS_NODATA)
        {
-            SEND_NOTIFICATION(descr, LBN_ERRSPACE);
-            return FALSE;
+            items = heap_realloc(descr->items, items_size * sizeof(LB_ITEMDATA));
+            if (!items)
+            {
+                SEND_NOTIFICATION(descr, LBN_ERRSPACE);
+                return FALSE;
+            }
+            descr->items = items;
        }
        descr->items_size = items_size;
-        descr->items = items;
    }

-    if ((descr->style & LBS_NODATA) && items_size > descr->nb_items)
+    if ((descr->style & LBS_NODATA) && descr->items && items_size > descr->nb_items)
    {
        memset(&descr->items[descr->nb_items], 0,
               (items_size - descr->nb_items) * sizeof(LB_ITEMDATA));
@@ -185,6 +188,8 @@ static void insert_item_data(LB_DESCR *descr, UINT index, WCHAR *str, ULONG_PTR 
 {
    LB_ITEMDATA *item;

+    if (!descr->items) return;
+
    item = descr->items + index;
    if (index < descr->nb_items)
        memmove(item + 1, item, (descr->nb_items - index) * sizeof(LB_ITEMDATA));
@@ -199,6 +204,8 @@ static void remove_item_data(LB_DESCR *descr, UINT index)
 {
    LB_ITEMDATA *item;

+    if (!descr->items) return;
+
    item = descr->items + index;
    if (index < descr->nb_items)
        memmove(item, item + 1, (descr->nb_items - index) * sizeof(LB_ITEMDATA));
@@ -1772,7 +1779,8 @@ static void LISTBOX_ResetContent( LB_DESCR *descr )
 {
    INT i;

-    for(i = descr->nb_items - 1; i>=0; i--) LISTBOX_DeleteItem( descr, i);
+    if (!(descr->style & LBS_NODATA))
+        for (i = descr->nb_items - 1; i >= 0; i--) LISTBOX_DeleteItem(descr, i);
    HeapFree( GetProcessHeap(), 0, descr->items );
    descr->nb_items      = 0;
    descr->top_item      = 0;