03-HighGUI图形用户界面初步

文章目录

HighGUI

HighGUI

HighGUI为高层GUI图形用户界面模块，包含媒体输入输出，视频捕捉，图像和视频编码解码，图形交互界面的接口等内容。
1、图像输入，输出，保存；
2、滑动条（Trackbar）使用；
3、OpenCV中鼠标操作；

图像输入，输出，保存；

1、Mat类是用于保存图像以及其他矩阵数据的数据结构，默认尺寸为0；
2、imread() :

2、imshow() :

3、imwrite():

4、push_back():

demo:

#include<opencv2/opencv.hpp>
#include <vector>

using namespace std;
using namespace cv;

void createAlphaMat(Mat &mat)
{
	for (int row = 0; row < mat.rows; row++)
	{
		for (int col = 0; col < mat.cols; col++)
		{
			Vec4b &rgba = mat.at<Vec4b>(row, col);
			rgba[0] = UCHAR_MAX;  //0xff;
			rgba[1] = saturate_cast<uchar>((float(mat.cols - col)) / ((float)mat.cols) * UCHAR_MAX);
			rgba[2] = saturate_cast<uchar>((float(mat.rows - row)) / ((float)mat.rows) * UCHAR_MAX);
			rgba[3] = saturate_cast<uchar>(0.5 * (rgba[1] + rgba[2]));
		}
	}
}
int main()
{
	Mat mat(480, 640, CV_8UC4); //创建带alpha通道的Mat；
	createAlphaMat(mat);    //像素值填充

	vector<int> compression_params;
	//compression_params.push_back(IMWRITE_PNG_COMPRESSION);
	compression_params.push_back(9);

	try {
		imwrite("透明alpha图.png", mat, compression_params);
		imshow("PNG图", mat);
		waitKey(0);
	}
	catch (runtime_error & ex)
	{
		fprintf(stderr, "图像转换成PNG格式发生错误： %s\n", ex.what());
		return -1; 
	}

	return 0;
}

Trackbar

1、Trackbar依附于窗口而存在，必须与回调函数搭配使用：回调函数类型必须为 void XXXX(int ,void*)；

2、getTrackbarPos() : 返回当前轨迹条位置；

鼠标操作

1、指定鼠标操作消息回调函数为： SetMouseCallback();

鼠标操作 demo:

#include <opencv2/opencv.hpp>

using namespace cv;

#define WINDOW_NAME "程序窗口"

void onMouseHandle(int event, int x, int y, int flags, void* param);
void DrawRectangle(Mat & img, Rect box);
void ShowHelpText();

Rect g_rectangle;
bool g_bDrawingBox = false;
RNG rng(12345);


int main(int argc, char** argv)
{
   
	g_rectangle = Rect(-1, -1, 0, 0);
	Mat srcImage(600, 800, CV_8UC3), tempImage;

	namedWindow(WINDOW_NAME);
	setMouseCallback(WINDOW_NAME, onMouseHandle,(void *) &srcImage);

	while (1)
	{
   
		srcImage.copyTo(tempImage);
		if (g_bDrawingBox) DrawRectangle(tempImage, g_rectangle);

		imshow(WINDOW_NAME, tempImage);
		
		if (waitKey(10) == 27)  //ESC退出
		{
   
			break;
		}
	}

	return 0;
}




void onMouseHandle(int event, int x, int y, int flags, void* param) 
{
   
	Mat &image = *(cv::Mat *) param;
	switch (event)
	{
   
		case EVENT_MOUSEMOVE:
			{
   
				if (g_bDrawingBox)
				{
   
					g_rectangle.width = x - g_rectangle.x;
					g_rectangle.height = y - g_rectangle.y;
				}
			}
			break;
		case EVENT_LBUTTONDOWN:
			{
   
				g_bDrawingBox = true;
				g_rectangle = Rect(x, y, 0, 0);  //记录起始点
			}
			break;
		case EVENT_LBUTTONUP:
			{
   
				g_bDrawingBox = false;
				if (g_rectangle.width < 0)
				{
   
					g_rectangle.x += g_rectangle.width;
					g_rectangle.width *= -1;
				}
				if (g_rectangle.height < 0)
				{
   
					g_rectangle.y += g_rectangle.y;
					g_rectangle.height *= -1;
				}
				DrawRectangle(image, g_rectangle);
			}
			break;

		default:
			break;
	}
}

void DrawRectangle(Mat & img, Rect box)
{
   
	rectangle(img, box, Scalar(rng.uniform(0, 255), rng.uniform(0, 255), rng.uniform(0, 255)));//随机颜色
}
void ShowHelpText()
{
   

}