OpenCv——5鼠标绘制矩形

1.目的：鼠标绘制矩形

2.关键API介绍：setMouseCallback,为指定窗口设定鼠标回调函数

rectangle矩形绘制

3.main函数

Rect rect_angle = Rect(0, 0, 0, 0);
	Mat src(600, 800, CV_8UC3);
	Mat temple;
	src = Scalar::all(0);
	namedWindow(namewindow);
	setMouseCallback(namewindow, onMousle, (void*)&src);
	while (1) 
	{

		src.copyTo(temple);
		if (drawingbox)
		{

			DrawRectangle(temple, rect_angle);

		}
		imshow(namewindow, temple);
		if (waitKey(10) == 27)break;
	}
	return 0;
}

其中onMouse为鼠标回调函数

4.关键点

在onMouse函数中各鼠标移动、鼠标左击时、鼠标左击后的设定

另需考虑当鼠标从右向左移动时rect_tangle.width/rect_tangle.height为负的情况。

颜色通过rng产生随机数

onmouse函数

void onMousle(int event, int x, int y, int flags, void* userdata)
{
	Mat&image = *(Mat*)userdata;
	switch (event)
	{ 
		case EVENT_MOUSEMOVE:
	{
		if (drawingbox)
		{
			rect_angle.width = x - rect_angle.x;
			rect_angle.height = y - rect_angle.y;
		}
	}
	break;
		case EVENT_LBUTTONDOWN:
		{
			drawingbox = true;
			rect_angle = Rect(x, y, 0, 0);
		}
		break;
		case EVENT_LBUTTONUP:
		{
			drawingbox = false;
			if (rect_angle.width < 0)
			{
				rect_angle.x += rect_angle.width;
				rect_angle.width *= -1;
			}
			if (rect_angle.height < 0)
			{
				rect_angle.y+= rect_angle.height;
				rect_angle.height *= -1;
			}
			DrawRectangle(image, rect_angle);
		}
		break;
	}
}

绘制图像函数

void DrawRectangle(Mat& image,Rect box)
{
	rectangle(image, box.tl(), box.br(), Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255)));

}

5.结果展示

总体代码

#include
#include 

#define namewindow "窗口名字"

using namespace cv;
using namespace std;

Rect rect_angle;
bool drawingbox=false;
RNG rng;

void onMousle(int event, int x, int y, int flags, void* userdata);
void DrawRectangle(Mat& image, Rect box);

int main()
{
     
	Rect rect_angle = Rect(0, 0, 0, 0);
	Mat src(600, 800, CV_8UC3);
	Mat temple;
	src = Scalar::all(0);
	namedWindow(namewindow);
	setMouseCallback(namewindow, onMousle, (void*)&src);
	while (1) 
	{

		src.copyTo(temple);
		if (drawingbox)
		{

			DrawRectangle(temple, rect_angle);

		}
		imshow(namewindow, temple);
		if (waitKey(10) == 27)break;
	}
	return 0;
}

void onMousle(int event, int x, int y, int flags, void* userdata)
{
	Mat&image = *(Mat*)userdata;
	switch (event)
	{ 
		case EVENT_MOUSEMOVE:
	{
		if (drawingbox)
		{
			rect_angle.width = x - rect_angle.x;
			rect_angle.height = y - rect_angle.y;
		}
	}
	break;
		case EVENT_LBUTTONDOWN:
		{
			drawingbox = true;
			rect_angle = Rect(x, y, 0, 0);
		}
		break;
		case EVENT_LBUTTONUP:
		{
			drawingbox = false;
			if (rect_angle.width < 0)
			{
				rect_angle.x += rect_angle.width;
				rect_angle.width *= -1;
			}
			if (rect_angle.height < 0)
			{
				rect_angle.y+= rect_angle.height;
				rect_angle.height *= -1;
			}
			DrawRectangle(image, rect_angle);
		}
		break;
	}
}
void DrawRectangle(Mat& image,Rect box)
{
	rectangle(image, box.tl(), box.br(), Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255)));

}