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Flood fill algorithm using C graphics

Given a rectangle, your task to fill this rectangle using flood fill algorithm.
Examples:

Input : rectangle(left = 50, top = 50, right= 100, bottom = 100)
        flood( x = 55, y = 55, new_color = 12, old_color = 0)
Output : 


Input : rectangle(left = 50, top = 50, right= 200, bottom = 400)
        flood( x = 51, y = 51, new_color = 6, old_color = 0)
Output :


Flood fill algorithm fills new color until the
old color match.

Flood fill algorithm:-

// A recursive function to replace previous
// color 'oldcolor' at  '(x, y)' and all 
// surrounding pixels of (x, y) with new 
// color 'newcolor' and
floodfill(x, y, newcolor, oldcolor)
1) If x or y is outside the screen, then
   return.
2) If color of getpixel(x, y) is same as
   oldcolor, then 
3) Recur for top, bottom, right and left.
    floodFill(x+1, y, newcolor, oldcolor);
    floodFill(x-1, y, newcolor, oldcolor);
    floodFill(x, y+1, newcolor, oldcolor);
    floodFill(x, y-1, newcolor, oldcolor); 
// program to fill polygon using floodfill
// algorithm
#include <graphics.h>
#include <stdio.h>
  
// flood fill algorithm
void flood(int x, int y, int new_col, int old_col)
{
    // check current pixel is old_color or not
    if (getpixel(x, y) == old_col) {
  
        // put new pixel with new color
        putpixel(x, y, new_col);
  
        // recursive call for bottom pixel fill
        flood(x + 1, y, new_col, old_col);
  
        // recursive call for top pixel fill
        flood(x - 1, y, new_col, old_col);
  
        // recursive call for right pixel fill
        flood(x, y + 1, new_col, old_col);
  
        // recursive call for left pixel fill
        flood(x, y - 1, new_col, old_col);
    }
}
  
int main()
{
    int gd, gm = DETECT;
  
    // initialize graph
    initgraph(&gd, &gm, "");
  
    // rectangle coordinate
    int top, left, bottom, right;
  
    top = left = 50;
    bottom = right = 300;
  
    // rectangle for print rectangle
    rectangle(left, top, right, bottom);
  
    // filling start cordinate
    int x = 51;
    int y = 51;
  
    // new color to fill
    int newcolor = 12;
  
    // new color which you want to fill
    int oldcolor = 0;
  
    // call for fill rectangle
    flood(x, y, newcolor, oldcolor);
    getch();
  
    return 0;
}

Output:-




This article is attributed to GeeksforGeeks.org

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