最近，因工作需要，在YUV图像上画直线；

算法1步骤：

1.已知直线的起点和终点；

2. 利用布雷森汉姆算法在两点间画直线；

3. 将该直线上的点的颜色在YUV图像上画出。

布雷森汉姆算法原理参考wiki: http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm

yuv图像转换原理参考：http://en.wikipedia.org/wiki/Yuv

参考代码：

unsigned char breshenham(unsigned char* imgdata, int width, int height, nPoint startPoint, nPoint endPoint, nColor color)

{

if (!imgdata)

{

return -1;

}

if (width < 0 || height < 0 )

{

return -1;

}

if (startPoint.x<0 || startPoint.x > width || startPoint.y < 0 || startPoint.y > height || endPoint.x < 0 || endPoint.x > width || endPoint.y < 0 || endPoint.y > height)

{

return -1;

}

int imgSize = width*height;

int x0 = startPoint.x, x1 = endPoint.x;

int y0 = startPoint.y, y1 = endPoint.y;

int dy = abs(y1 - y0);

int dx = abs(x1 - x0);

bool steep = dy>dx ?true:false;

if (steep)

{

swap(x0, y0);

swap(x1, y1);

}

if (x0 > x1)

{

swap(x0, x1);

swap(y0, y1);

}

int deltax = x1 - x0;

int deltay = abs(y1 - y0);

int error = deltax/2;

int ystep;

int y = y0;

if (y0 < y1)

ystep = 1;

else

ystep = -1;

for (int x = x0; x < x1; x++)

{

if (steep)

{

imgdata[x*width + y] = color.r;

imgdata[imgSize + x/2*width/2 + y/2] = color.g;

imgdata[imgSize + imgSize/4 + x/2*width/2 + y/2] = color.b;

}

else

{

imgdata[y*width + x] = color.r;

imgdata[imgSize + y/2*width/2 + x/2] = color.g;

imgdata[imgSize + imgSize/4 + y/2*width/2 + x/2] = color.b;

}

error -= deltay;

if (error < 0)

{

y += ystep;

error += deltax;

}

}

return 1;

}

算法2步骤：

1.已知直线的起点和终点；

2. 利用super vector bresenham算法在两点间画直线；

3. 将该直线上的点的颜色在YUV图像上画出。

super vector bresenham 算法原理参考wiki: http://lifc.univ-fcomte.fr/home/~ededu/projects/bresenham/

yuv图像转换原理参考：http://en.wikipedia.org/wiki/Yuv

void superVectorBresenham(unsigned char* imgData, int width, int height, nPoint startPoint, nPoint endPoint, nColor color)

{

if (!imgData)

{

return ;

}

if (width<0 || height<0)

{

return;

}

if (startPoint.x < 0 || startPoint.x > width || startPoint.y < 0 || startPoint.y > height ||

endPoint.x < 0 || endPoint.x >width || endPoint.y < 0 || endPoint.y > height)

{

return;

}

int imgSize = width*height;

int yStep, xStep;

int error, errorPrev;

int y = startPoint.y, x = startPoint.x;

int ddy, ddx;

int dx = endPoint.x - startPoint.x;

int dy = endPoint.y - startPoint.y;

//StartPoint()

imgData[y*width + x] = color.r;

imgData[imgSize + y/2*width/2 + x/2] = uData;

imgData[imgSize + imgSize/4 + y/2*width/2 + x/2] = vData;

if (dy < 0)

{

yStep = -1;

dy = -dy;

}

else

yStep = 1;

if (dx < 0)

{

xStep = -1;

dx = -dx;

}

else

xStep = 1;

ddx = 2*dx;

ddy = 2*dy;

if (ddx >= ddy)

{

errorPrev = error = dx;

for (int i=0; i

{

x += xStep;

error += ddy;

if (error > ddx)

{

y += yStep;

error -= ddx;

if (error + errorPrev < ddx)

{//POINT(y-ystep, x)

int tmpY = y - yStep;

imgData[tmpY*width + x] = color.r;

imgData[imgSize + tmpY/2*width/2 + x/2] = color.g;

imgData[imgSize + imgSize/4 + tmpY/2*width/2 + x/2] = color.b;

}

else if (error + errorPrev > ddx)

{

//POINT(y, x-xstep)

int tmpX = x - xStep;

imgData[y*width + tmpX] = color.r;

imgData[imgSize + y/2*width/2 + tmpX/2] = color.g;

imgData[imgSize + imgSize/4 + y/2*width/2 + tmpX/2] = color.b;

}

else

{

//POINT(y-ystep, x)

int tmpY = y - yStep;

imgData[tmpY*width + x] = color.r;

imgData[imgSize + tmpY/2*width/2 + x/2] = color.g;

imgData[imgSize + imgSize/4 + tmpY/2*width/2 + x/2] = color.b;

//POINT(y, x-xstep)

int tmpX = x - xStep;

imgData[y*width + tmpX] = color.r;

imgData[imgSize + y/2*width/2 + tmpX/2] = color.g;

imgData[imgSize + imgSize/4 + y/2*width/2 + tmpX/2] = color.b;

}

}

//POINT(y,x)

imgData[y*width + x] = color.r;

imgData[imgSize + y/2*width/2 + x/2] = color.g;

imgData[imgSize + imgSize/4 + y/2*width/2 + x/2] = color.b;

errorPrev = error;

}

}

else

{

errorPrev = error = dy;

for (int i=0; i

{

y += yStep;

error += ddx;

if (error > ddy)

{

x += xStep;

error -= ddy;

if (error + errorPrev < ddy)

{

//POINT(y, x-xstep)

int tmpX = x - xStep;

imgData[y*width + tmpX] = color.r;

imgData[imgSize + y/2*width/2 + tmpX/2] = color.g;

imgData[imgSize + imgSize/4 + y/2*width/2 + tmpX/2] = color.b;

}

else if (error + errorPrev > ddy)

{

//POINT(y-ystep, x)

int tmpY = y - yStep;

imgData[tmpY*width + x] = color.r;

imgData[imgSize + tmpY/2*width/2 + x/2] = color.g;

imgData[imgSize + imgSize/4 + tmpY/2*width/2 + x/2] = color.b;

}

else

{

//POINT(y, x-xstep)

int tmpX = x - xStep;

imgData[y*width + tmpX] = color.r;

imgData[imgSize + y/2*width/2 + tmpX/2] = color.g;

imgData[imgSize + imgSize/4 + y/2*width/2 + tmpX/2] = color.b;

//POINT(y-ystep, x)

int tmpY = y - yStep;

imgData[tmpY*width + x] = color.r;

imgData[imgSize + tmpY/2*width/2 + x/2] = color.g;

imgData[imgSize + imgSize/4 + tmpY/2*width/2 + x/2] = color.b;

}

}

//POINT(y, x)

imgData[y*width + x] = color.r;

imgData[imgSize + y/2*width/2 + x/2] = color.g;

imgData[imgSize + imgSize/4 + y/2*width/2 + x/2] = color.b;

errorPrev = error;

}

}

}