// FILE: canvas.cpp
// written for the course 2172, 1999
//
#include "canvas.h"
// for the definition of setw
#include <iomanip.h>

// constructor
// create a (xsize x ysize) canvas
canvas::canvas(int xsize, int ysize ) :x(xsize),y(ysize){
   
   if (x<=0 || y<=0) return;

   _bottom = new pixel*[y];
   _top = new pixel*[y];
    
   for(int i=0;i<y;i++) {
     _bottom[i] = new pixel[x];
     _top[i] = new pixel[x];
  }
}

// destructor
// deallocate the top and bottom canvasses
canvas::~canvas() {

   for(int i=0;i<y;i++) {
     delete [] _bottom[i];
     delete [] _top[i];
   }

   delete [] _bottom;
   delete [] _top;
}

// properties
int canvas::width() const { return x; }
int canvas::height() const { return y; }
color canvas::get_color(int i, int j) const { return _top[i][j].get_color(); }

// copy all pixels of top into bottom
void canvas::save_canvas() {
  
  for(int i=0;i<y;i++) {
    for(int j=0;j<x;j++) {
      _bottom[i][j] = _top[i][j];
    }
  }
}

// draw p=<_x,_y> with color c and id 
// if p is out of the grid, do not crash
void canvas::draw_point(int _x,int _y,const color& c,long id) {

  if (_x>=0 && _x<x && _y>=0 && _y<y) {
    if (c==clear) {
      _top[_y][_x] = _bottom[_y][_x];
    } else {
      _top[_y][_x].set_color(c);
    }
    _top[_y][_x].set_id(id);
  }
}

// use the simple minded (and sometimes incorrect) floodfill 
// algorithm to fill the interior of the bounded region
// the boundary is the id "border"
// the point must be inside the canvas, otherwise it fills nothing
void canvas::fill_area(int ox, int oy,long border,const color& c) {

  if (ox <0 || ox >= x || oy < 0 || oy >= y) return;
 
  if(border !=_top[oy][ox].get_id()) {
     if (c == clear) {
       _top[oy][ox] = _bottom[oy][ox];
     } else {
       _top[oy][ox].set_color(c);
     }

     _top[oy][ox].set_id(border);

     fill_area(ox+1,oy,border,c);
     fill_area(ox-1,oy,border,c);
     fill_area(ox,oy+1,border,c);
     fill_area(ox,oy-1,border,c);
  } 
}

// write a text ppm file
ostream& canvas::dump_text_PPM(ostream& os) const {
  
   os << "P3" << endl
      << "# created by the \"draw\" scripted drawing program" << endl
      << "# developed for the course CSI2172 " << endl
      << "# University of Ottawa, 1999" << endl
      << x << ' ' << y << " 255 " << endl;

   int fc = 0;
   for(int i=y-1;i>=0;i--) {
     for(int j=0;j<x;j++) {
       os << setw(3) <<_top[i][j].get_color().red() << ' ' 
          << setw(3) <<_top[i][j].get_color().green() << ' '
          << setw(3) <<_top[i][j].get_color().blue() << "  ";
       if (fc++ > 4) {
         fc = 0;
         os << endl;
       }
     }
   }
  return os;
}

// write a binary ppm file
ostream& canvas::dump_binary_PPM(ostream& os) const {
 
   os << "P6" << endl
      << "# created by the \"draw\" scripted drawing program" << endl
      << "# developed for the course CSI2172 " << endl
      << "# University of Ottawa, 1999" << endl
      << x << ' ' << y << " 255" << endl;

   for(int i=y-1;i>=0;i--) {
     for(int j=0;j<x;j++) {
       os.put((char)_top[i][j].get_color().red());
       os.put((char)_top[i][j].get_color().green()); 
       os.put((char)_top[i][j].get_color().blue());
     }
   }

  return os;
}

// draw a line between <x1,y1> and <x2,y2> using the
// well known Bresenheim drwaing algortihm
// which does as many calculations as many pixels it
// draws
// (see any elementary computer graphics book)
void canvas::draw_line(int x1, int y1, int x2, int y2,
   const color& c, long id) {

   int width = x2 - x1, 
       height = y2 - y1,
       awidth = width>=0?width:-width,
       aheight = height>=0?height:-height;

   int e; // error term

   if (awidth>=aheight) {
     e = awidth;
     int j = y1;
     for(int i=0; i <= awidth;i++) {
       draw_point(x1+(width>0?1:-1)*i,j,c,id);
       e += 2*aheight;
       if (e >= 2*awidth) {
         e -= 2*awidth;
         j = height>0?j+1:j-1;
       }
     } // for
   } else { // dx/dy
     e=aheight;
     int i = x1;
     for(int j=0; j <= aheight;j++) {
       draw_point(i,y1+(height>0?1:-1)*j,c,id);
       e += 2*awidth;
       if (e>= 2*aheight) {
         e -= 2*aheight;
         i = width>0?i+1:i-1;
       }
     } // for
   }
}