Make Aura and compositor stacking methods more intuitive.

ui/gfx/compositor/layer_unittest.cc

 // Copyright (c) 2011 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 "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/path_service.h"
@@ skipping 72 matching lines @@
   }
 
   if (diff_pixels_count != 0) {
     LOG(ERROR) << "Images differ by pixel count: " << diff_pixels_count;
     return false;
   }
 
   return true;
 }
 
+// Returns a comma-separated list of the names of |layer|'s children in
+// bottom-to-top stacking order.
+std::string GetLayerChildrenNames(const Layer& layer) {
+  std::string names;
+  for (std::vector<Layer*>::const_iterator it = layer.children().begin();
+       it != layer.children().end(); ++it) {
+    if (!names.empty())
+      names += ",";
+    names += (*it)->name();
+  }
+  return names;
+}
+
 
 // There are three test classes in here that configure the Compositor and
 // Layer's slightly differently:
 // - LayerWithNullDelegateTest uses TestCompositor and NullLayerDelegate as the
 //   LayerDelegate. This is typically the base class you want to use.
 // - LayerWithDelegateTest uses TestCompositor and does not set a LayerDelegate
 //   on the delegates.
 // - LayerWithRealCompositorTest when a real compositor is required for testing.
 //    - Slow because they bring up a window and run the real compositor. This
 //      is typically not what you want.
@@ skipping 937 matching lines @@
 
   l1->SetVisible(true);
   EXPECT_TRUE(l1->IsDrawn());
   EXPECT_TRUE(l2->IsDrawn());
   EXPECT_FALSE(l3->IsDrawn());
 #if defined(USE_WEBKIT_COMPOSITOR)
   EXPECT_EQ(1.f, l1->web_layer().opacity());
 #endif
 }
 
+// Checks that stacking-related methods behave as advertised.
+TEST_F(LayerWithNullDelegateTest, Stacking) {
+  scoped_ptr<Layer> root(new Layer(Layer::LAYER_HAS_NO_TEXTURE));
+  scoped_ptr<Layer> l1(new Layer(Layer::LAYER_HAS_TEXTURE));
+  scoped_ptr<Layer> l2(new Layer(Layer::LAYER_HAS_TEXTURE));
+  scoped_ptr<Layer> l3(new Layer(Layer::LAYER_HAS_TEXTURE));
+  l1->set_name("1");
+  l2->set_name("2");
+  l3->set_name("3");
+  root->Add(l3.get());
+  root->Add(l2.get());
+  root->Add(l1.get());
+
+  // Layers' children are stored in bottom-to-top order.
+  EXPECT_EQ("3,2,1", GetLayerChildrenNames(*root.get()));
+
+  root->StackAtTop(l3.get());
+  EXPECT_EQ("2,1,3", GetLayerChildrenNames(*root.get()));
+
+  root->StackAtTop(l1.get());
+  EXPECT_EQ("2,3,1", GetLayerChildrenNames(*root.get()));
+
+  root->StackAtTop(l1.get());
+  EXPECT_EQ("2,3,1", GetLayerChildrenNames(*root.get()));
+
+  root->StackAbove(l2.get(), l3.get());
+  EXPECT_EQ("3,2,1", GetLayerChildrenNames(*root.get()));
+
+  root->StackAbove(l1.get(), l3.get());
+  EXPECT_EQ("3,1,2", GetLayerChildrenNames(*root.get()));
+
+  root->StackAbove(l2.get(), l1.get());
+  EXPECT_EQ("3,1,2", GetLayerChildrenNames(*root.get()));
+}
+
 // Checks that the invalid rect assumes correct values when setting bounds.
 // TODO(vollick): for USE_WEBKIT_COMPOSITOR, use WebKit's dirty rect.
 TEST_F(LayerWithNullDelegateTest,
        NOT_APPLICABLE_TO_WEBKIT_COMPOSITOR(SetBoundsInvalidRect)) {
   scoped_ptr<Layer> l1(CreateTextureLayer(gfx::Rect(0, 0, 200, 200)));
   compositor()->SetRootLayer(l1.get());
 
   // After a draw the invalid rect should be empty.
   Draw();
   EXPECT_TRUE(l1->invalid_rect().IsEmpty());
@@ skipping 230 matching lines @@
   l0->Add(l11.get());
   DrawTree(l0.get());
   SkBitmap bitmap;
   ASSERT_TRUE(ReadPixels(&bitmap));
   ASSERT_FALSE(bitmap.empty());
   // WritePNGFile(bitmap, ref_img);
   EXPECT_TRUE(IsSameAsPNGFile(bitmap, ref_img));
 }
 
 } // namespace ui