Replacing SkTDArray with SkAutoSTArray to reduce memory allocation overhead in SkTileGrid::search

src/core/SkTileGrid.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTileGrid.h"
 
@@ skipping 73 matching lines @@
     tileEndX = SkPin32(tileEndX, tileStartX+1, fXTileCount);
     tileStartY = SkPin32(tileStartY, 0, fYTileCount - 1);
     tileEndY = SkPin32(tileEndY, tileStartY+1, fYTileCount);
 
     int queryTileCount = (tileEndX - tileStartX) * (tileEndY - tileStartY);
     SkASSERT(queryTileCount);
     if (queryTileCount == 1) {
         *results = this->tile(tileStartX, tileStartY);
     } else {
         results->reset();
-        SkTDArray<int> curPositions;
-        curPositions.setCount(queryTileCount);
-        // Note: Reserving space for 1024 tile pointers on the stack. If the
-        // malloc becomes a bottleneck, we may consider increasing that number.
-        // Typical large web page, say 2k x 16k, would require 512 tiles of
-        // size 256 x 256 pixels.
-        SkAutoSTArray<1024, SkTDArray<void *>*> storage(queryTileCount);
+        SkAutoSTArray<kStackAllocationTileCount, int> curPositions(queryTileCount);
+        SkAutoSTArray<kStackAllocationTileCount, SkTDArray<void *>*> storage(queryTileCount);
         SkTDArray<void *>** tileRange = storage.get();
         int tile = 0;
         for (int x = tileStartX; x < tileEndX; ++x) {
             for (int y = tileStartY; y < tileEndY; ++y) {
                 tileRange[tile] = &this->tile(x, y);
                 curPositions[tile] = tileRange[tile]->count() ? 0 : kTileFinished;
                 ++tile;
             }
         }
         void *nextElement;
@@ skipping 14 matching lines @@
 }
 
 void SkTileGrid::rewindInserts() {
     SkASSERT(fClient);
     for (int i = 0; i < fTileCount; ++i) {
         while (!fTileData[i].isEmpty() && fClient->shouldRewind(fTileData[i].top())) {
             fTileData[i].pop();
         }
     }
 }