Make scroll offset type of float in cc

ui/gfx/geometry/scroll_offset.h

+// Copyright 2014 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.
+
+#ifndef UI_GFX_GEOMETRY_SCROLL_OFFSET_H_
+#define UI_GFX_GEOMETRY_SCROLL_OFFSET_H_
+
+#include "ui/gfx/geometry/safe_integer_conversions.h"
+#include "ui/gfx/geometry/vector2d.h"
+#include "ui/gfx/gfx_export.h"
+
+namespace gfx {
+
+class GFX_EXPORT ScrollOffset {

[danakj, 2014/09/25 22:01:27]

Please add PrintTo like we have for other geometry types so EXPECT_EQ works. See
https://codereview.chromium.org/368903003/ for where this was added.

[Yufeng Shen (Slow to review), 2014/09/26 20:19:08]

Done.

+ public:
+  ScrollOffset() : x_(0), y_(0) {}

[danakj, 2014/09/25 22:01:27]

Can you add some unit tests for this class, similar to what exists for Vector2d?

[Yufeng Shen (Slow to review), 2014/09/26 20:19:08]

Done.

+  ScrollOffset(double x, double y) : x_(x), y_(y) {}
+  explicit ScrollOffset(const Vector2dF& v) : x_(v.x()), y_(v.y()) {}
+  explicit ScrollOffset(const Vector2d& v) : x_(v.x()), y_(v.y()) {}
+
+  double x() const { return x_; }
+  void set_x(double x) { x_ = x; }
+
+  double y() const { return y_; }
+  void set_y(double y) { y_ = y; }
+
+  // True if both components are 0.
+  bool IsZero() const;
+
+  // Add the components of the |other| ScrollOffset to the current ScrollOffset.
+  void Add(const ScrollOffset& other);
+  // Subtract the components of the |other| ScrollOffset from the current
+  // ScrollOffset.
+  void Subtract(const ScrollOffset& other);
+
+  void operator+=(const ScrollOffset& other) { Add(other); }
+  void operator-=(const ScrollOffset& other) { Subtract(other); }
+
+  void SetToMin(const ScrollOffset& other) {
+    x_ = x_ <= other.x_ ? x_ : other.x_;
+    y_ = y_ <= other.y_ ? y_ : other.y_;
+  }
+
+  void SetToMax(const ScrollOffset& other) {
+    x_ = x_ >= other.x_ ? x_ : other.x_;
+    y_ = y_ >= other.y_ ? y_ : other.y_;
+  }
+
+  void Scale(double scale) { Scale(scale, scale); }
+  void Scale(double x_scale, double y_scale) {
+    x_ *= x_scale;
+    y_ *= y_scale;
+  }
+
+  Vector2d ToFlooredVector2d() const {

[danakj, 2014/09/25 22:01:27]

Sorry, can I take this back? ._. Now that I see how it looks like this, I think
you were right before. Can you move them back out, but give them a name to
better scope them, like ScrollOffsetToFlooredVector2d() and
ScrollOffsetToVector2dF()>?

[Yufeng Shen (Slow to review), 2014/09/26 20:19:08]

Done.

+    return Vector2d(ToFlooredInt(x_), ToFlooredInt(y_));
+  }
+
+  Vector2dF ToVector2dF() const { return Vector2dF(x_, y_); }
+
+ private:
+  double x_;
+  double y_;
+};
+
+inline bool operator==(const ScrollOffset& lhs, const ScrollOffset& rhs) {
+  return lhs.x() == rhs.x() && lhs.y() == rhs.y();
+}
+
+inline bool operator!=(const ScrollOffset& lhs, const ScrollOffset& rhs) {
+  return lhs.x() != rhs.x() || lhs.y() != rhs.y();
+}
+
+inline ScrollOffset operator-(const ScrollOffset& v) {
+  return ScrollOffset(-v.x(), -v.y());
+}
+
+inline ScrollOffset operator+(const ScrollOffset& lhs,
+                              const ScrollOffset& rhs) {
+  ScrollOffset result = lhs;
+  result.Add(rhs);
+  return result;
+}
+
+inline ScrollOffset operator-(const ScrollOffset& lhs,
+                              const ScrollOffset& rhs) {
+  ScrollOffset result = lhs;
+  result.Add(-rhs);
+  return result;
+}
+
+}  // namespace gfx
+
+#endif  // UI_GFX_GEOMETRY_SCROLL_OFFSET_H_