Makes tile-creation lazy

cc/resources/picture_layer_tiling_unittest.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/picture_layer_tiling.h"
 
 #include "cc/test/fake_picture_layer_tiling_client.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
 
 namespace cc {
 namespace {
 
 class PictureLayerTilingIteratorTest : public testing::Test {
  public:
   PictureLayerTilingIteratorTest() {}
   virtual ~PictureLayerTilingIteratorTest() {}
 
   void Initialize(gfx::Size tile_size,
                   float contents_scale,
                   gfx::Size layer_bounds) {
     client_.SetTileSize(tile_size);
-    tiling_ = PictureLayerTiling::Create(contents_scale);
-    tiling_->SetClient(&client_);
-    tiling_->SetLayerBounds(layer_bounds);
+    tiling_ = PictureLayerTiling::Create(contents_scale,
+                                         layer_bounds,
+                                         &client_);
+  }
+
+  void VerifyTilesExistOnlyInLiveRect(gfx::Rect live_tiles_rect) {

[enne (OOO), 2013/04/10 20:25:30]

This function is named oddly.  Maybe SetLiveRectAndVerifyTiles would be a better
name.  The name as-is makes it sound like it should be const.

[whunt, 2013/04/10 20:52:30]

sure.

+
+    tiling_->SetLiveTilesRect(live_tiles_rect);
+    for (TilingData::Iterator iter(&tiling_->tiling_data(),

[enne (OOO), 2013/04/10 20:25:30]

Shouldn't you iterate over all tiles and not just the live tiles rect?

[whunt, 2013/04/10 20:52:30]

Yes, it should be iterating over the content rect, I thought it was.  hmmm...

[enne (OOO), 2013/04/10 21:21:24]

No, it's more than that.  I'm saying that you need to iterate over the tile map
and not over a rect.

+                                             live_tiles_rect);
+          iter;
+          ++iter) {
+      Tile* tile = tiling_->TileAt(iter.index_x(), iter.index_y());
+        EXPECT_EQ(tile != NULL,
+                  live_tiles_rect.Intersects(tile->content_rect()));
+    }
   }
 
   void VerifyTilesExactlyCoverRect(
       float rect_scale,
       gfx::Rect request_rect,
       gfx::Rect expect_rect) {
     EXPECT_TRUE(request_rect.Contains(expect_rect));
 
     // Iterators are not valid if this ratio is too large (i.e. the
     // tiling is too high-res for a low-res destination rect.)  This is an
@@ skipping 39 matching lines @@
     VerifyTilesExactlyCoverRect(rect_scale, dest_rect, clamped_rect);
   }
 
  protected:
   FakePictureLayerTilingClient client_;
   scoped_ptr<PictureLayerTiling> tiling_;
 
   DISALLOW_COPY_AND_ASSIGN(PictureLayerTilingIteratorTest);
 };
 
+TEST_F(PictureLayerTilingIteratorTest, LiveTilesExactlyCoverLiveTileRect) {
+  Initialize(gfx::Size(100, 100), 1, gfx::Size(1099, 801));
+  VerifyTilesExistOnlyInLiveRect(gfx::Rect(100, 100));
+  VerifyTilesExistOnlyInLiveRect(gfx::Rect(101, 99));
+  VerifyTilesExistOnlyInLiveRect(gfx::Rect(1099, 1));
+  VerifyTilesExistOnlyInLiveRect(gfx::Rect(1, 801));
+  VerifyTilesExistOnlyInLiveRect(gfx::Rect(1099, 1));
+  VerifyTilesExistOnlyInLiveRect(gfx::Rect(201, 800));
+}
+
 TEST_F(PictureLayerTilingIteratorTest, IteratorCoversLayerBoundsNoScale) {
   Initialize(gfx::Size(100, 100), 1, gfx::Size(1099, 801));
   VerifyTilesExactlyCoverRect(1, gfx::Rect());
   VerifyTilesExactlyCoverRect(1, gfx::Rect(0, 0, 1099, 801));
   VerifyTilesExactlyCoverRect(1, gfx::Rect(52, 83, 789, 412));
 
   // With borders, a size of 3x3 = 1 pixel of content.
   Initialize(gfx::Size(3, 3), 1, gfx::Size(10, 10));
   VerifyTilesExactlyCoverRect(1, gfx::Rect(0, 0, 1, 1));
   VerifyTilesExactlyCoverRect(1, gfx::Rect(0, 0, 2, 2));
@@ skipping 257 matching lines @@
   gfx::Rect in(40, 50, 100, 200);
   gfx::Rect bounds(0, 0, 10, 10);
   int64 target_area = 400 * 400;
   gfx::Rect out = PictureLayerTiling::ExpandRectEquallyToAreaBoundedBy(
       in, target_area, bounds);
   EXPECT_TRUE(out.IsEmpty());
 }
 
 }  // namespace
 }  // namespace cc