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, 3 insertions, 3 deletions

diff --git a/ui/base/dragdrop/drag_utils_win.cc b/ui/base/dragdrop/drag_utils_win.cc
index f7d05ee..9a3ab56 100644
--- a/ui/base/dragdrop/drag_utils_win.cc
+++ b/ui/base/dragdrop/drag_utils_win.cc
@@ -21,7 +21,7 @@ namespace drag_utils {
 
 static void SetDragImageOnDataObject(HBITMAP hbitmap,
                                      const gfx::Size& size,
-                                     const gfx::Point& cursor_offset,
+                                     const gfx::Vector2d& cursor_offset,
                                      IDataObject* data_object) {
   base::win::ScopedComPtr<IDragSourceHelper> helper;
   HRESULT rv = CoCreateInstance(CLSID_DragDropHelper, 0, CLSCTX_INPROC_SERVER,
@@ -31,7 +31,7 @@ static void SetDragImageOnDataObject(HBITMAP hbitmap,
     sdi.sizeDragImage = size.ToSIZE();
     sdi.crColorKey = 0xFFFFFFFF;
     sdi.hbmpDragImage = hbitmap;
-    sdi.ptOffset = cursor_offset.ToPOINT();
+    sdi.ptOffset = gfx::PointAtOffsetFromOrigin(cursor_offset).ToPOINT();
     helper->InitializeFromBitmap(&sdi, data_object);
   }
 }
@@ -56,7 +56,7 @@ static HBITMAP CreateHBITMAPFromSkBitmap(const SkBitmap& sk_bitmap) {
 
 void SetDragImageOnDataObject(const gfx::ImageSkia& image_skia,
                               const gfx::Size& size,
-                              const gfx::Point& cursor_offset,
+                              const gfx::Vector2d& cursor_offset,
                               ui::OSExchangeData* data_object) {
   DCHECK(data_object && !size.IsEmpty());
   // InitializeFromBitmap() doesn't expect an alpha channel and is confused