Drawing Areas

#include "graphapp.h"

void draw_shapes(drawing d, rect r)
{
  setcolour(Red);
  drawrect(r);

  setcolour(Blue);
  fillrect(rect(10,40,80,10));
}

void main(void)
{
  window w;
  drawing d;
  rect r;

  w = newwindow("Rectangles", rect(50,50,150,200),
                StandardWindow);
  setbackground(w, LightGrey);
  r = rect(10,10,100,100);
  d = newdrawing(r, draw_shapes);
  show(w);
  mainloop();
}

• Use newdrawing to create a drawing area.
• Pass a function as a "redraw callback".
• Whenever the drawing needs to be redrawn, that callback is used.
• Use setbackground to change the background colour.
• Use setcolour to change the drawing colour.
• drawrect draws a border inside the rectangle.
• fillrect fills the given rectangle.
• Source code: makedraw.c