OpenCV 虚线矩形

转自：http://blog.sina.com.cn/s/blog_4b0020f301010cy8.html

前两天查资料看opencv 画虚线矩形，先收录一下；后面有可能会用得到。不过代码没有测试。

OpenCV2.0提供了一些比较简单的绘图函数，比如绘制 矩形，椭圆，圆，多边形，直线；但都是实线，有时需要用做对比试验，虚线矩形就派上了用场，下面是一种简单的实现。

直接上代码：

void  drawDashRect(CvArr* img,int linelength,int dashlength,CvBlob* blob,CvScalar color,int thickness)
{
int w=cvRound(blob->w);//width
int h=cvRound(blob->h);//height

int tl_x=cvRound(blob->x-blob->w/2);//top left x
int tl_y=cvRound(blob->y-blob->h/2);//top  left y

    int totallength=dashlength+linelength;
int nCountX=w/totallength;//
int nCountY=h/totallength;//

CvPoint start,end;//start and end point of each dash

//draw the horizontal lines
start.y=tl_y;
start.x=tl_x;

end.x=tl_x;
end.y=tl_y;

for (int i=0;i<nCountX;i++)
{
end.x=tl_x+(i+1)*totallength-dashlength;//draw top dash line
   end.y=tl_y;
start.x=tl_x+i*totallength;
start.y=tl_y;
cvLine(img,start,end,color,thickness);   
}
for (int i=0;i<nCountX;i++)
{  
start.x=tl_x+i*totallength;
start.y=tl_y+h;
end.x=tl_x+(i+1)*totallength-dashlength;//draw bottom dash line
end.y=tl_y+h;
cvLine(img,start,end,color,thickness);     
}

for (int i=0;i<nCountY;i++)
{  
start.x=tl_x;
start.y=tl_y+i*totallength;
end.y=tl_y+(i+1)*totallength-dashlength;//draw left dash line
end.x=tl_x;
cvLine(img,start,end,color,thickness);     
}

for (int i=0;i<nCountY;i++)
{  
start.x=tl_x+w;
start.y=tl_y+i*totallength;
end.y=tl_y+(i+1)*totallength-dashlength;//draw right dash line
end.x=tl_x+w;
cvLine(img,start,end,color,thickness);     
}

}