OpenCv學習：繪製形狀與文字

第六課 繪製形狀與文字

1.cv::Point、cv::Scalar
Point表示2D平面上一個點

	Point p;
		p.x=10;
		p.y=8;
		//p=Point(10,8);
		//Scalar表示四元素向量
		Scalar(a,b,c);//RGB三通道，第四個爲透明度alpha通道

2.繪製線、矩形、圓、橢圓

	void MyLines()
	{
		Point p1 = Point(20,30);
		Point p2;
		p2.x = 300;
		p2.y= 300;
		Scalar color=Scalar(0,0,255);
		line(src, p1, p2, color, 1, LINE_8);
	}
	void MyRectangle()
	{
		Rect rect = Rect(200, 100, 100, 100);//起始位置和寬高
		Scalar color = Scalar(255,255,0);
		rectangle(src, rect, color, 2, LINE_8);//背景圖，矩形，顏色，線寬
	}
	void MyEllipse()
	{
		Scalar color = Scalar(255,0,0);
		//背景，中心，長短半徑，角度即傾斜程度，顏色，線寬，線型,90°方向畫0到360一圈橢圓
		ellipse(src, Point(src.cols / 2, src.rows / 2), Size(src.cols / 4, src.rows / 8), 90, 0, 360, color, 2, LINE_8);
	}
	void MyCircle()
	{
		Scalar color = Scalar(25, 23, 255);
		Point center = Point(src.cols / 2, src.rows / 2);
		//背景，圓心，半徑，顏色，線寬，線型
		circle(src,center,150,color,2,8);

3.隨機生成

void RandomLineDemo()
	{
		RNG rng(12345);
		Point pt1, pt2;
		Mat dst = Mat::zeros(src.size(), src.type());
		namedWindow("output", CV_WINDOW_AUTOSIZE);
		for (int i = 0; i < 10000; i++)
		{
			pt1.x = rng.uniform(0, src.cols);
			pt2.x = rng.uniform(0, src.cols);
			pt1.y = rng.uniform(0, src.rows);
			pt2.y = rng.uniform(0, src.rows);
			Scalar color = Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255));
			if (waitKey(1)>0)
			{
				break;
			}
			line(dst, pt1, pt2, color, 1, 8);
			imshow("output", dst);
		}
	}

4.繪製文本

	putText(src, "Hello", Point(300, 300), CV_FONT_BLACK, 1, Scalar(255, 255, 0), 2, 8);