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

Previously Point served two purposes, to be a position in 2d space, and also
an offset from the origin. This introduces a Vector2d class to represent an
offset, allowing typesafety checks for geometric operations.

The following are now the case:

Point +/- Vector = Point
- A point plus/minus an offset gives you a point at a position offset by the
vector.

Vector +/- Vector = Vector
- Two offsets can be added together to make a new offset.

Point - Point = Vector
- Subtracting one point from another gives you the offset between the two
points.

We add some new methods to perform these operations:

Rect::OffsetFromOrigin() gives the offset between the position of the rect
and the origin.

Point::OffsetFromOrigin() gives the offset between the point and the origin.

PointAtOffsetFromOrigin(Vector2d) converts a Vector2d to a Point at the given
offset away from the origin.

Rect::Offset(), Point::Add(), and Point::Subtract() now receive a Vector2d
instead of a point.

BUG=147395
R=sky

Review URL: https://codereview.chromium.org/11269022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@165198 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 13 insertions, 4 deletions

diff --git a/ui/gfx/point_f.h b/ui/gfx/point_f.h
index d6cded9..3e69bd7 100644
--- a/ui/gfx/point_f.h
+++ b/ui/gfx/point_f.h
@@ -9,11 +9,12 @@
 
 #include "ui/base/ui_export.h"
 #include "ui/gfx/point_base.h"
+#include "ui/gfx/vector2d_f.h"
 
 namespace gfx {
 
 // A floating version of gfx::Point.
-class UI_EXPORT PointF : public PointBase<PointF, float> {
+class UI_EXPORT PointF : public PointBase<PointF, float, Vector2dF> {
  public:
   PointF();
   PointF(float x, float y);
@@ -39,16 +40,24 @@ inline bool operator!=(const PointF& lhs, const PointF& rhs) {
   return !(lhs == rhs);
 }
 
-inline PointF operator+(PointF lhs, PointF rhs) {
+inline PointF operator+(const PointF& lhs, const Vector2dF& rhs) {
   return lhs.Add(rhs);
 }
 
-inline PointF operator-(PointF lhs, PointF rhs) {
+inline PointF operator-(const PointF& lhs, const Vector2dF& rhs) {
   return lhs.Subtract(rhs);
 }
 
+inline Vector2dF operator-(const PointF& lhs, const PointF& rhs) {
+  return lhs.OffsetFrom(rhs);
+}
+
+inline PointF PointAtOffsetFromOrigin(const Vector2dF& offset_from_origin) {
+  return PointF(offset_from_origin.x(), offset_from_origin.y());
+}
+
 #if !defined(COMPILER_MSVC)
-extern template class PointBase<PointF, float>;
+extern template class PointBase<PointF, float, Vector2dF>;
 #endif
 
 }  // namespace gfx