Version 5.0 The LEDA User Manual

ool write postscript(const CONTAINER& c, ps file& ps, color c1 , color c2 )
The parameters of these two virtual functions are like the parameters of the members
with the same name of geowin redraw, but there is an additional first parameter. This
parameter is a reference to the container of the scene that has to be redrawn.
In update- and redraw- functions and objects the following static member functions of
the GeoWin class can be used:
GeoWin ∗ GeoWin :: get call geowin( )
geo scene GeoWin :: get call scene( )
geo scene GeoWin :: get call input scene( )
The first function returns a pointer to the GeoWin of the calling scene, the second returns
the calling scene and the third (only usable in update functions/ objects) returns the input
scene of the calling scene.
Note that S and R in the following operations are template parameters. S and R have
to be a list, where T is a 2d LEDA kernel type, a d3 point or a d3 rat point. S is the
type of the contents of the input scene, R the type of the contents of the created result
scene. All operations creating result scenes return a pointer to the created result scene.
This section contains three small example programs showing you the usage of the
new scene operations for the creation of result scenes. All example programs compute
the convex hull of a set of points stored in the container of an input scene sc points and
store the computed hull in a result scene sc hull.
template
GeoResultScene∗ GW.new scene(void (∗f update)(const S& , R& ), geo scene sc,
string str, D3 FCN f = NULL)
creates a new result scene with name str. The input
scene for this new result scene will be sc. The update
function will be f update.
The first example program shows the usage of the new scene operation taking an update
function pointer. The update function computes the convex hull of the points stored in
the input scene. The result polygon will be inserted in the container P of the result scene.
#include
#include
using namespace leda;
void convex_hull(const list& L, list& P)
{ P.clear(); P.append(CONVEX_HULL_POLY(L)); }
int main()
{
GeoWin gw;
list LP;