graphical libraries usually are incompatible and sometimes even "unusual" for a reason, performance, when you´re processing lots and lots of points per second, the simple act of calling a non inline function is too much overhead. Don´t take me wrong I also believe that a "unique" implementation for points would be great, but such implementation is not trivial. I´m not sure about the internals of your implementation, but I implemented something with a similar interface sometime ago and the overhead caused by the function forwarding was unacceptable. A template solution was the fastest I could get, something like: point<2, int> my_point; If you´re intested in it take a look at http://osl.iu.edu/~tveldhui/ especially in the blitz++ library On 5/20/04, Anis Benylloul <benyelloul@mailbolt.com> wrote:
Hi !
It is very common for graphical libraries to declare some rectangle and point classes. In fact, all of them do that: SDL has SDL_Rect, X has XRectangle and XPoint, Qt has QRect and QPoint, Window$ has POINT and RECT (and POINTF and RECTF), rect, Rect, Rectangle, point, Point2D, Point3D, point<float> ..... etc ....
And you know what ? they all are incompatible, both interface and implementation. Time to have a look at this, heu ?
After few months of work here is what I have:
// Code Start int main() { // point_xy is an implementation type it contains // "some implementation" of the point abtraction // Other implementaions include point_xyz<>, for 3D points typedef geom::point_xy<double> point_xy;
// point<> is a wrapper class, in which you "plug" implementation types // to obtain a working ``point'' typedef geom::point<point_xy> point; // Plug, then save the result in ``point''
point pt=point_xy(3.4, 3.0), pt2=point_xy(0.2, 1.4);
// Cool property access pt.x()++; pt.y()=pt2.rho(); pt.theta()+=3*pt2.y();
// Handy operator overloads pt+=pt2*4;
// std::complex<> is also a possible implementation geom::point< std::complex<double> > pt_cplx=std::complex<double>(4, 6);
pt2=pt_cplx-pt; // Mixed-implementation computations
// point::impl() extracts the implementation out of its wrapper std::complex<double>& impl=pt_cplx.impl();
// Now for Boxes. Boxes are some generalization of rectanlges that are not always // ``flat''
typedef geom::box_xywh<int> box_xywh; // Implementation type .. typedef geom::box<box_xywh> box; // .. being plugged in a wrapper
box bx, bx2;
bx.xmin()=bx2.x2(); bx.width()=bx2.height(); bx.y2()=bx2.height();
// Accessing corners bx.corner< geom::x1, geom::y1>()=pt; // Displace bx.corner< geom::xmin, geom::ymax >()=bx2.corner<geom::x2, geom::y1, geom::z1>();
// Accessing the center bx.center()=bx2.center()+pt; bx2.x1()=bx.center().x();
// ..... } // Code End
So, wadda you say ?
-- Anis Benyelloul
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