Flood Fill C Program Using graphics.h

Flood Fill Algorithm

Sometimes we want to fill in (or recolor) an area that is not defined within a single color boundary. Here is a figure describing the situation.

We can paint such areas by replacing a specified interior color instead of searching for a boundary color value. This approach is called a flood-fill algorithm. We can use either a 4-connected or 8-connected approach,

Follow The Instructions To Successfully Run The Program In Dev-Cpp/CodeBlock:

Whenever you #include <graphics.h> in a program, you must instruct the linker to 
link in certain libraries. The command to do so from Dev-C++ is Alt-P. Choose the 
Parameters tab from the pop-up window and type the following into the Linker area:

-lbgi
-lgdi32
-lcomdlg32
-luuid
-loleaut32
-lole32

Code

#include <stdio.h>
#include <graphics.h>


/* oc = old color and fc = fill color */
void floodfill(int x, int y, int fc, int oc)
{
    int c = getpixel(x, y);
    if (c == oc) {
        putpixel(x, y, fc);
        floodfill(x, y + 1, fc, oc);
        floodfill(x, y - 1, fc, oc);
        floodfill(x - 1, y, fc, oc);
        floodfill(x + 1, y, fc, oc);
    }
}

int main()
{
    int arr[] = {10, 10, 100,10, 10, 100, 10, 10};
    initwindow(300,300,"FloodFill");
    drawpoly(4, arr);
    
    delay(3000);
    
    floodfill(40, 40, 4, 0);
    
    while(!kbhit());
    
    return 0;
}

Output