Implement transform snapping for gfx::Transforms.

ui/gfx/transform_util_unittest.cc

 // Copyright (c) 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 "ui/gfx/transform_util.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/point.h"
+#include "ui/gfx/point3_f.h"
+#include "ui/gfx/rect.h"
 
 namespace gfx {
 namespace {
 
 TEST(TransformUtilTest, GetScaleTransform) {
   const Point kAnchor(20, 40);
   const float kScale = 0.5f;
 
   Transform scale = GetScaleTransform(kAnchor, kScale);
 
   const int kOffset = 10;
   for (int sign_x = -1; sign_x <= 1; ++sign_x) {
     for (int sign_y = -1; sign_y <= 1; ++sign_y) {
       Point test(kAnchor.x() + sign_x * kOffset,
                  kAnchor.y() + sign_y * kOffset);
       scale.TransformPoint(&test);
 
       EXPECT_EQ(Point(kAnchor.x() + sign_x * kOffset * kScale,
                       kAnchor.y() + sign_y * kOffset * kScale),
                 test);
     }
   }
 }
 
+TEST(TransformUtilTest, SnapTransform) {

[Ian Vollick, 2013/10/21 18:36:30]

Need tests for snapping scale and translation.

[avallee, 2013/10/23 14:48:23]

Done.

+  gfx::Transform result(gfx::Transform::kSkipInitialization);
+  gfx::Transform transform;
+  transform.RotateAboutZAxis(89.99);
+
+  Rect viewport(1920, 1200);
+  bool snapped = SnapTransform(&result, transform, viewport);
+
+  EXPECT_TRUE(snapped) << "Viewport should snap for this rotation.";
+}
+
+TEST(TransformUtilTest, SnapTransformDistantViewport) {
+  const int kOffset = 5000;
+  gfx::Transform result(gfx::Transform::kSkipInitialization);
+  gfx::Transform transform;
+
+  transform.RotateAboutZAxis(89.99);
+
+  Rect viewport(1920 + kOffset, 1200 + kOffset);
+  bool snapped = SnapTransform(&result, transform, viewport);
+
+  EXPECT_FALSE(snapped) << "Distant viewport shouldn't snap by more than 1px.";
+}
+
+TEST(TransformUtilTest, NoSnapTransform) {
+  gfx::Transform result(gfx::Transform::kSkipInitialization);
+  gfx::Transform transform;
+  const int kOffset = 5000;
+
+  transform.RotateAboutZAxis(89.9);
+
+  Rect viewport(1920 + kOffset, 1200 + kOffset);
+  bool snapped = SnapTransform(&result, transform, viewport);
+
+  EXPECT_FALSE(snapped) << "Viewport should not snap for this rotation.";
+}
+
 }  // namespace
 }  // namespace gfx