Add Vector2d classes that represent offsets, instead of using Point.

ui/gfx/vector2d_f.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/vector2d_f.h"
+
+#include <cmath>
+
+#include "base/stringprintf.h"
+
+namespace gfx {
+
+Vector2dF::Vector2dF()
+    : x_(0),
+      y_(0) {
+}
+
+Vector2dF::Vector2dF(float x, float y)
+    : x_(x),
+      y_(y) {
+}
+
+std::string Vector2dF::ToString() const {
+  return base::StringPrintf("[%f %f]", x_, y_);
+}
+
+bool Vector2dF::IsZero() const {
+  return x_ == 0 && y_ == 0;
+}
+
+void Vector2dF::Add(const Vector2dF& other) {
+  x_ += other.x_;
+  y_ += other.y_;
+}
+
+void Vector2dF::Subtract(const Vector2dF& other) {
+  x_ -= other.x_;
+  y_ -= other.y_;
+}
+
+double Vector2dF::LengthSquared() const {
+  return static_cast<double>(x_) * x_ + static_cast<double>(y_) * y_;
+}
+
+float Vector2dF::Length() const {
+  return static_cast<float>(std::sqrt(LengthSquared()));
+}
+
+void Vector2dF::Scale(float x_scale, float y_scale) {
+  x_ *= x_scale;
+  y_ *= y_scale;
+}
+
+}  // namespace gfx