floodfill算法
文章来自：http://blog.sina.com.cn/s/blog_7506816f0100pqzn.html
从国外网站看到几个关于floodfill的code，感觉不错，供大家分享，主要分为以下几种，具体不用介绍，程序一看就明白。
一、4-Way Recursive Method（FloodFill4）
//Recursive 4-way floodfill, crashes if recursion stack is full
void floodFill4(int x, int y, int newColor, int oldColor)
{
if(x >= 0 && x < w && y >= 0 && y < h && screenBuffer[x][y] == oldColor && screenBuffer[x][y] != newColor)
{
screenBuffer[x][y] = newColor; //set color before starting recursion
floodFill4(x + 1, y, newColor, oldColor);
floodFill4(x - 1, y, newColor, oldColor);
floodFill4(x, y + 1, newColor, oldColor);
floodFill4(x, y - 1, newColor, oldColor);
}
} 二、8-Way Recursive Method（FloodFill8）
//Recursive 8-way floodfill, crashes if recursion stack is full
void floodFill8(int x, int y, int newColor, int oldColor)
{
if(x >= 0 && x < w && y >= 0 && y < h && screenBuffer[x][y] == oldColor && screenBuffer[x][y] != newColor)
{
screenBuffer[x][y] = newColor; //set color before starting recursion!
floodFill8(x + 1, y, newColor, oldColor);
floodFill8(x - 1, y, newColor, oldColor);
floodFill8(x, y + 1, newColor, oldColor);
floodFill8(x, y - 1, newColor, oldColor);
floodFill8(x + 1, y + 1, newColor, oldColor);
floodFill8(x - 1, y - 1, newColor, oldColor);
floodFill8(x - 1, y + 1, newColor, oldColor);
floodFill8(x + 1, y - 1, newColor, oldColor);
}
} 三、4-Way Method With Stack（FloodFill4Stack）
//4-way floodfill using our own stack routines
void floodFill4Stack(int x, int y, int newColor, int oldColor)
{
if(newColor == oldColor) return; //avoid infinite loop
emptyStack();
if(!push(x, y)) return;
while(pop(x, y))
{
screenBuffer[x][y] = newColor;
if(x + 1 < w && screenBuffer[x + 1][y] == oldColor)
{
if(!push(x + 1, y)) return;
}
if(x - 1 >= 0 && screenBuffer[x - 1][y] == oldColor)
{
if(!push(x - 1, y)) return;
}
if(y + 1 < h && screenBuffer[x][y + 1] == oldColor)
{
if(!push(x, y + 1)) return;
}
if(y - 1 >= 0 && screenBuffer[x][y - 1] == oldColor)
{
if(!push(x, y - 1)) return;
}
}
} 四、8-Way Method With Stack（FloodFill8Stack）
//8-way floodfill using our own stack routines
void floodFill4Stack(int x, int y, int newColor, int oldColor)
{
if(newColor == oldColor) return; //avoid infinite loop
emptyStack();
if(!push(x, y)) return;
while(pop(x, y))
{
screenBuffer[x][y] = newColor;
if(x + 1 < w && screenBuffer[x + 1][y] == oldColor)
{
if(!push(x + 1, y)) return;
}
if(x - 1 >= 0 && screenBuffer[x - 1][y] == oldColor)
{
if(!push(x - 1, y)) return;
}
if(y + 1 < h && screenBuffer[x][y + 1] == oldColor)
{
if(!push(x, y + 1)) return;
}
if(y - 1 >= 0 && screenBuffer[x][y - 1] == oldColor)
{
if(!push(x, y - 1)) return;
}
if(x + 1 < w && y + 1 < h && screenBuffer[x + 1][y + 1] == oldColor)
{
if(!push(x + 1, y + 1)) return;
}
if(x + 1 < w && y - 1 >= 0 && screenBuffer[x + 1][y - 1] == oldColor)
{
if(!push(x + 1, y - 1)) return;
}
if(x - 1 >= 0 && y + 1 < h && screenBuffer[x - 1][y + 1] == oldColor)
{
if(!push(x - 1, y + 1)) return;
}
if(x - 1 >= 0 && y - 1 >= 0 && screenBuffer[x - 1][y - 1] == oldColor)
{
if(!push(x - 1, y - 1)) return;
}
}
} 五、 Recursive Scanline Floodfill Algorithm(floodFillScanline)
//stack friendly and fast floodfill algorithm
void floodFillScanline(int x, int y, int newColor, int oldColor)
{
if(oldColor == newColor) return;
if(screenBuffer[x][y] != oldColor) return;
int y1;
//draw current scanline from start position to the top
y1 = y;
while(y1 < h && screenBuffer[x][y1] == oldColor)
{
screenBuffer[x][y1] = newColor;
y1++;
}
//draw current scanline from start position to the bottom
y1 = y - 1;
while(y1 >= 0 && screenBuffer[x][y1] == oldColor)
{
screenBuffer[x][y1] = newColor;
y1--;
}
//test for new scanlines to the left
y1 = y;
while(y1 < h && screenBuffer[x][y1] == newColor)
{
if(x > 0 && screenBuffer[x - 1][y1] == oldColor)
{
floodFillScanline(x - 1, y1, newColor, oldColor);
}
y1++;
}
y1 = y - 1;
while(y1 >= 0 && screenBuffer[x][y1] == newColor)
{
if(x > 0 && screenBuffer[x - 1][y1] == oldColor)
{
floodFillScanline(x - 1, y1, newColor, oldColor);
}
y1--;
}
//test for new scanlines to the right
y1 = y;
while(y1 < h && screenBuffer[x][y1] == newColor)
{
if(x < w - 1 && screenBuffer[x + 1][y1] == oldColor)
{
floodFillScanline(x + 1, y1, newColor, oldColor);
}
y1++;
}
y1 = y - 1;
while(y1 >= 0 && screenBuffer[x][y1] == newColor)
{
if(x < w - 1 && screenBuffer[x + 1][y1] == oldColor)
{
floodFillScanline(x + 1, y1, newColor, oldColor);
}
y1--;
}
} 六、Scanline Floodfill Algorithm With Stack(floodFillScanlineStack)
//The scanline floodfill algorithm using our own stack routines, faster
void floodFillScanlineStack(int x, int y, int newColor, int oldColor)
{
if(oldColor == newColor) return;
emptyStack();
int y1;
bool spanLeft, spanRight;
if(!push(x, y)) return;
while(pop(x, y))
{
y1 = y;
while(y1 >= 0 && screenBuffer[x][y1] == oldColor) y1--;
y1++;
spanLeft = spanRight = 0;
while(y1 < h && screenBuffer[x][y1] == oldColor )
{
screenBuffer[x][y1] = newColor;
if(!spanLeft && x > 0 && screenBuffer[x - 1][y1] == oldColor)
{
if(!push(x - 1, y1)) return;
spanLeft = 1;
}
else if(spanLeft && x > 0 && screenBuffer[x - 1][y1] != oldColor)
{
spanLeft = 0;
}
if(!spanRight && x < w - 1 && screenBuffer[x + 1][y1] == oldColor)
{
if(!push(x + 1, y1)) return;
spanRight = 1;
}
else if(spanRight && x < w - 1 && screenBuffer[x + 1][y1] != oldColor)
{
spanRight = 0;
}
y1++;
}
}
} 另外还有几个辅助函数的源码：
bool pop(int&x, int &y)
{
if(stackPointer > 0)
{
int p = stack[stackPointer];
x = p / h;
y = p % h;
stackPointer--;
return 1;
}
else
{
return 0;
}
}
bool push(int x, int y)
{
if(stackPointer < stackSize - 1)
{
stackPointer++;
stack[stackPointer] = h * x + y;
return 1;
}
else
{
return 0;
}
}
void emptyStack()
{
int x, y;
while(pop(x, y));
}
void clearScreenBuffer(ColorRGB color)
{
for(int x = 0; x < w; x++)
for(int y = 0; y < h; y++)
{
screenBuffer[x][y] = RGBtoINT(color);
}
}
作者： kezunhai 出处： http://blog.csdn.net/kezunhai 欢迎转载或分享，但请务必声明文章出处。