Input and Output

Stream Input and Output

Geometric objects can be written to streams and read from streams. The operators are designed such that output written by << can be read by >>.

Example

The following example generates two points writes them to a file and reads them again.

#include <LEDA/geo/point.h>
#include <LEDA/system/stream.h>

using namespace leda;

int main()
{ 
  point p(2,3), q(3,4);  
  std::cout << p << endl << q << std::endl;

  file_ostream O("points.txt"); 
  O << p << std::endl << q << std::endl;
  
  file_istream I("points.txt");
  point r, s;
  I >> r >> s;

  std::cout << r << std::endl << s << std::endl;

  return 0;
}

Graphical Input and Output

The simplest way to draw a geometric object is to use the operator <<, for example,

	W << r.to_ray();
	W << l.to_line();

The operator >> can be used to read a point, segment, line, ray, circle, or polygon with the mouse, for example,

	W >> p; //p is a point
	W >> s; //s is a segment
	

The reading operations are blocking and wait for mouse clicks. A point is constructed by a single click on the left mouse button, and a segment, line, ray, and circle is constructed by two clicks on the left mouse button.

Remark: In window.h the input operator >> is only defined for floating point objects. To use it for rational objects you must include rat_window.h.

Example

#include <LEDA/graphics/window.h>
#include <LEDA/geo/rat_point.h>
#include <LEDA/geo/point.h>
#include <LEDA/geo/rat_segment.h>
#include <LEDA/geo/segment.h>

using namespace leda;

int main()
{ 
  rat_point rp(60,70);
  rat_segment rs(point(0,0),point(100,100)); 
  
  window W(100,100);
  W.open();

  W << rp.to_point();   
  W << rs.to_segment();

  point p;
  segment s;
  W >> p;
  W >> s;

  W.display();
  W.read_mouse();

  std::cout << p << std::endl << s << std::endl;

  return 0;
}	

See also:

Data Types for 2D Geometry

Window

Mouse Input

Colors

Geometry

Advanced Data types for 2-D geometry

Data Types for 3-D Geometry

Geometry Algorithms

GeoWin