void cpdf_rect (int pdf document, float x-coor, float y-coor, float width, float height [, int mode])
The cpdf_rect() function draws a rectangle with its lower left corner at point (x-coor, y-coor). This width is set to widgth. This height is set to height.
The optional parameter mode determines the unit length. If it's 0 or omitted the default unit as specified for the page is used. Otherwise the coordinates are measured in postscript points disregarding the current unit.