Remove root layer specialness in calculateDrawTransforms

This patch is step 2 in removing root layer specialness. The previous patch removed root
layer specialness from code outside of CCLayerTreeHostCommon, this patch removes it from
within CCLayerTreeHostCommon.

One subtle semantics change occurs with this patch, that only affects tests and not
real-world code: The root renderSurface now re-parents the root layer's drawTransform. In
practice, the root layer's drawTransform is always an identity matrix, so it does not
matter.

BUG=154442


Review URL: https://chromiumcodereview.appspot.com/11017044

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@164723 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 24 insertions, 1 deletions

diff --git a/cc/test/layer_test_common.cc b/cc/test/layer_test_common.cc
index 1a41eec..72546dd 100644
--- a/cc/test/layer_test_common.cc
+++ b/cc/test/layer_test_common.cc
@@ -7,6 +7,7 @@
 #include "cc/test/layer_test_common.h"
 
 #include "cc/draw_quad.h"
+#include "cc/math_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace LayerTestCommon {
@@ -14,13 +15,35 @@ namespace LayerTestCommon {
 // Align with expected and actual output
 const char* quadString = "    Quad: ";
 
+bool floatRectCanBeSafelyRoundedToIntRect(const cc::FloatRect& r)
+{
+    // Ensure that range of float values is not beyond integer range.
+    if (!r.isExpressibleAsIntRect())
+        return false;
+
+    // Ensure that the values are actually integers.
+    if (floorf(r.x()) == r.x()
+        && floorf(r.y()) == r.y()
+        && floorf(r.width()) == r.width()
+        && floorf(r.height()) == r.height())
+        return true;
+
+    return false;
+}
+
 void verifyQuadsExactlyCoverRect(const cc::QuadList& quads,
                                  const cc::IntRect& rect) {
     cc::Region remaining(rect);
 
     for (size_t i = 0; i < quads.size(); ++i) {
         cc::DrawQuad* quad = quads[i];
-        cc::IntRect quadRect = cc::IntRect(quad->quadRect());
+        cc::FloatRect floatQuadRect = cc::MathUtil::mapClippedRect(quad->sharedQuadState()->quadTransform, cc::FloatRect(quad->quadRect()));
+
+        // Before testing for exact coverage in the integer world, assert that rounding
+        // will not round the rect incorrectly.
+        ASSERT_TRUE(floatRectCanBeSafelyRoundedToIntRect(floatQuadRect));
+
+        cc::IntRect quadRect = enclosingIntRect(floatQuadRect);
 
         EXPECT_TRUE(rect.contains(quadRect)) << quadString << i;
         EXPECT_TRUE(remaining.contains(quadRect)) << quadString << i;