Transform animations should not collapse by default when interpolating

cc/test/geometry_test_utils.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/test/geometry_test_utils.h"
 
 #include "base/logging.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 // NOTE: even though transform data types use double precision, we only check
 // for equality within single-precision error bounds because many transforms
 // originate from single-precision data types such as quads/rects/etc.
 
 void ExpectTransformationMatrixEq(const gfx::Transform& expected,
                                   const gfx::Transform& actual) {
-  EXPECT_FLOAT_EQ((expected).matrix().get(0, 0), (actual).matrix().get(0, 0));
-  EXPECT_FLOAT_EQ((expected).matrix().get(1, 0), (actual).matrix().get(1, 0));
-  EXPECT_FLOAT_EQ((expected).matrix().get(2, 0), (actual).matrix().get(2, 0));
-  EXPECT_FLOAT_EQ((expected).matrix().get(3, 0), (actual).matrix().get(3, 0));
-  EXPECT_FLOAT_EQ((expected).matrix().get(0, 1), (actual).matrix().get(0, 1));
-  EXPECT_FLOAT_EQ((expected).matrix().get(1, 1), (actual).matrix().get(1, 1));
-  EXPECT_FLOAT_EQ((expected).matrix().get(2, 1), (actual).matrix().get(2, 1));
-  EXPECT_FLOAT_EQ((expected).matrix().get(3, 1), (actual).matrix().get(3, 1));
-  EXPECT_FLOAT_EQ((expected).matrix().get(0, 2), (actual).matrix().get(0, 2));
-  EXPECT_FLOAT_EQ((expected).matrix().get(1, 2), (actual).matrix().get(1, 2));
-  EXPECT_FLOAT_EQ((expected).matrix().get(2, 2), (actual).matrix().get(2, 2));
-  EXPECT_FLOAT_EQ((expected).matrix().get(3, 2), (actual).matrix().get(3, 2));
-  EXPECT_FLOAT_EQ((expected).matrix().get(0, 3), (actual).matrix().get(0, 3));
-  EXPECT_FLOAT_EQ((expected).matrix().get(1, 3), (actual).matrix().get(1, 3));
-  EXPECT_FLOAT_EQ((expected).matrix().get(2, 3), (actual).matrix().get(2, 3));
-  EXPECT_FLOAT_EQ((expected).matrix().get(3, 3), (actual).matrix().get(3, 3));
+  for (int row = 0; row < 4; ++row) {
+    for (int col = 0; col < 4; ++col) {
+      EXPECT_FLOAT_EQ(expected.matrix().get(row, col),
+                      actual.matrix().get(row, col));
+    }
+  }
+}
+
+void ExpectTransformationMatrixNear(const gfx::Transform& expected,
+                                    const gfx::Transform& actual,
+                                    float abs_error) {
+  for (int row = 0; row < 4; ++row) {
+    for (int col = 0; col < 4; ++col) {
+      EXPECT_NEAR(expected.matrix().get(row, col),
+                  actual.matrix().get(row, col), abs_error);
+    }
+  }
 }
 
 gfx::Transform Inverse(const gfx::Transform& transform) {
   gfx::Transform result(gfx::Transform::kSkipInitialization);
   bool inverted_successfully = transform.GetInverse(&result);
   DCHECK(inverted_successfully);
   return result;
 }
 
 }  // namespace cc