ui: Create the gfx::QuadF class.

ui/gfx/vector2d_f.h

Index: ui/gfx/vector2d_f.h
diff --git a/ui/gfx/vector2d_f.h b/ui/gfx/vector2d_f.h
index e2baa0cc4a6201cefcfe1689ec2fd24586046f19..e78c68821b7f2f18d85decfccc30a7ba61a9bddd 100644
--- a/ui/gfx/vector2d_f.h
+++ b/ui/gfx/vector2d_f.h
@@ -76,6 +76,12 @@ inline Vector2dF operator-(const Vector2dF& lhs, const Vector2dF& rhs) {
   return result;
 }
 
+// Return the cross product of two vectors.
+UI_EXPORT double CrossProduct(const Vector2dF& lhs, const Vector2dF& rhs);

[Peter Kasting, 2012/11/02 18:09:37]

Isn't the cross product a vector?

[danakj, 2012/11/02 18:34:10]

http://mathworld.wolfram.com/CrossProduct.html

See: "In two dimensions, the analog of the cross product..."

[Peter Kasting, 2012/11/02 20:41:46]

Maybe we should name the 2d "cross product" "Determinant"?  That might be
clearer, since a 2d "cross product" is just surprising.

[danakj, 2012/11/02 20:44:00]

Well, determinant is only an operation on matrices. If you search for two
dimension cross product you find a few references to this. In particular, in the
description of the Graham Scan algorithm, you also find it. It's a bit of a toss
up, but I do like this one a bit more for these reasons.

+
+// Return the dot product of two vectors.
+UI_EXPORT double DotProduct(const Vector2dF& lhs, const Vector2dF& rhs);
+
 }  // namespace gfx
 
 #endif // UI_GFX_VECTOR2D_F_H_