dwrite: Collect and sort positional lookups.

dlls/dwrite/dwrite_private.h

@@ -76,6 +76,33 @@ static inline const char *debugstr_matrix(const DWRITE_MATRIX *m)
         m->dx, m->dy);
 }
 
+static inline BOOL dwrite_array_reserve(void **elements, size_t *capacity, size_t count, size_t size)
+{
+    size_t new_capacity, max_capacity;
+    void *new_elements;
+
+    if (count <= *capacity)
+        return TRUE;
+
+    max_capacity = ~(SIZE_T)0 / size;
+    if (count > max_capacity)
+        return FALSE;
+
+    new_capacity = max(4, *capacity);
+    while (new_capacity < count && new_capacity <= max_capacity / 2)
+        new_capacity *= 2;
+    if (new_capacity < count)
+        new_capacity = max_capacity;
+
+    if (!(new_elements = heap_realloc(*elements, new_capacity * size)))
+        return FALSE;
+
+    *elements = new_elements;
+    *capacity = new_capacity;
+
+    return TRUE;
+}
+
 static inline const char *debugstr_tag(DWORD tag)
 {
     return debugstr_an((char *)&tag, 4);