OpenCV 利用滚动条在不缩小的情况下显示大型图片

叁歲伎倆 2022-09-28 11:40 159阅读 0赞

最近由于项目需要，要在不缩小的情况下显示一张2500\*2000大小的图片，找到了一篇博客写的非常好，是邹老师写于2011年的：  
http://blog.csdn.net/chenyusiyuan/article/details/6565424

我正在试着把它翻译成C++风格，用Mat类型，实现后会再发出来

原贴代码，简单修改并加上了一些注释，在VS2010上运行成功：

// Image_ScrollBar.cpp : Defines the entry point for the console application.  
    //  
    #include <opencv2/highgui/highgui.hpp>  
    #include <opencv2/imgproc/imgproc_c.h>  
    
    #include <iostream>  
    #include <vector>  
    
    using namespace std;  
    
    
    double mx = 0, my = 0;  
    int dx = 0, dy = 0, horizBar_x = 0, vertiBar_y = 0;  
    bool clickVertiBar = false, clickHorizBar = false, needScroll = false;  
    CvRect rect_bar_horiz, rect_bar_verti;  
    
    void help()  
    {  
    	printf(  
    		"/n"  
    		"This program demonstrated the use of the cvSetMouseCallback /n"  
    		"for viewing large image with scroll bar in a small window/n"  
    		"created by OpenCV highgui model. (chenyusiyuan, 2011-06-24)/n"  
    		"Call:/n"  
    		"./Image_ScrollBar [<img_filename default im.jpg> <window_width default 1400> <window_height default 700>]/n/n"  
    		);  
    }  
    
    
    void mouse_callback( int event, int x, int y, int flags, void* param )  
    {  
    	if (needScroll)  
    	{  
    		switch( event )   
    		{  
    		case CV_EVENT_LBUTTONDOWN:  
    			mx = x, my = y;  
    			dx = 0, dy = 0;  
    			// 按下左键时光标定位在水平滚动条区域内  
    			if (x >= rect_bar_horiz.x && x <= rect_bar_horiz.x+rect_bar_horiz.width  
    				&& y >= rect_bar_horiz.y && y<= rect_bar_horiz.y+rect_bar_horiz.height)  
    			{  
    				clickHorizBar = true;  
    			}  
    			// 按下左键时光标定位在垂直滚动条区域内  
    			if (x >= rect_bar_verti.x && x <= rect_bar_verti.x+rect_bar_verti.width  
    				&& y >= rect_bar_verti.y && y<= rect_bar_verti.y+rect_bar_verti.height)  
    			{  
    				clickVertiBar = true;  
    			}  
    			break;   
    		case CV_EVENT_MOUSEMOVE:   
    			if (clickHorizBar)  
    			{  
    				dx = fabs(x-mx) > 1 ? (int)(x-mx) : 0;  
    				dy = 0;  
    			}  
    			if (clickVertiBar)  
    			{  
    				dx = 0;  
    				dy = fabs(y-my) > 1 ? (int)(y-my) : 0;  
    			}  
    			mx = x, my = y;  
    			break;    
    		case CV_EVENT_LBUTTONUP:   
    			mx = x, my = y;  
    			dx = 0, dy = 0;  
    			clickHorizBar = false;  
    			clickVertiBar = false;  
    			break;    
    		default:  
    			dx = 0, dy = 0;  
    			break;  
    		}  
    	}  
    }  
    
    void myShowImageScroll(char* title, IplImage* src_img,   
    	int winWidth = 1400, int winHeight = 700) // 显示窗口大小默认为 1400×700  
    {  
    	IplImage* dst_img;  
    	CvRect  rect_dst,   // 窗口中有效的图像显示区域  
    		rect_src;   // 窗口图像对应于源图像中的区域  
    	int imgWidth = src_img->width,   
    		imgHeight = src_img->height,  
    		barWidth = 25;  // 滚动条的宽度（像素）  
    	double  scale_w = (double)imgWidth/(double)winWidth,    // 源图像与窗口的宽度比值  用以判断是否超出显示范围
    		scale_h = (double)imgHeight/(double)winHeight;            // 源图像与窗口的高度比值  用以判断是否超出显示范围
    
    	if(scale_w<1)                                                                     //如果小于1 说明原图比窗口小，窗口的宽度将重新赋值
    		winWidth = imgWidth+barWidth;  
    	if(scale_h<1)                                                                     //如果小于1 说明原图比窗口小，窗口的高度将重新赋值
    		winHeight = imgHeight+barWidth;  
    
    	int showWidth = winWidth, showHeight = winHeight; // 窗口中有效的图像显示区域的宽和高  
    	int src_x = 0, src_y = 0;                                                      // 源图像中 rect_src 的左上角位置  
    	int horizBar_width = 0, horizBar_height = 0,                   //定义并初始化垂直于水平滑块的宽高
    		vertiBar_width = 0, vertiBar_height = 0;  
    
    	needScroll = scale_w>1.0 || scale_h>1.0 ? true : false;  
    	// 若图像大于设定的窗口大小，则显示滚动条  
    	if(needScroll)  
    	{  
    		dst_img = cvCreateImage(cvSize(winWidth, winHeight),src_img->depth, src_img->nChannels);  
    		cvZero(dst_img);  
    		// 源图像宽度大于窗口宽度，则显示水平滚动条  
    		if(scale_w > 1.0)  //宽度超出了
    		{  
    			showHeight = winHeight - barWidth;  
    			horizBar_width = (int)((double)winWidth/scale_w);  
    			horizBar_height = winHeight-showHeight;  
    			horizBar_x = min(  
    				max(0,horizBar_x+dx),  
    				winWidth-horizBar_width);  
    			rect_bar_horiz = cvRect(  
    				horizBar_x,   
    				showHeight+1,   
    				horizBar_width,   
    				horizBar_height);  
    			// 显示水平滚动条  
    			cvRectangleR(dst_img, rect_bar_horiz, cvScalarAll(255), -1);  
    		}   
    		// 源图像高度大于窗口高度，则显示垂直滚动条  
    		if(scale_h > 1.0)  //高度超出了
    		{  
    			showWidth = winWidth - barWidth;  
    			vertiBar_width = winWidth-showWidth;  
    			vertiBar_height = (int)((double)winHeight/scale_h);  
    			vertiBar_y = min(  
    				max(0,vertiBar_y+dy),   
    				winHeight-vertiBar_height);  
    			rect_bar_verti = cvRect(  
    				showWidth+1,   
    				vertiBar_y,   
    				vertiBar_width,   
    				vertiBar_height);   //确定垂直滚动条的白色部分的大小
    			// 显示垂直滚动条  
    			cvRectangleR(dst_img, rect_bar_verti, cvScalarAll(255), -1);  
    		}  
    
    		showWidth = min(showWidth,imgWidth);  
    		showHeight = min(showHeight,imgHeight);  
    		// 设置窗口显示区的 ROI  
    		rect_dst = cvRect(0, 0, showWidth, showHeight);  
    		cvSetImageROI(dst_img, rect_dst);  
    		// 设置源图像的 ROI  
    		src_x = (int)((double)horizBar_x*scale_w);  
    		src_y = (int)((double)vertiBar_y*scale_h);  
    		src_x = min(src_x, imgWidth-showWidth);  
    		src_y = min(src_y, imgHeight-showHeight);  
    		rect_src = cvRect(src_x, src_y, showWidth, showHeight);  
    		cvSetImageROI(src_img, rect_src);  
    		// 将源图像内容复制到窗口显示区  
    		cvCopy(src_img, dst_img);  
    
    		cvResetImageROI(dst_img);  
    		cvResetImageROI(src_img);  
    		// 显示图像和滚动条  
    		cvShowImage(title,dst_img);  
    
    		cvReleaseImage(&dst_img);  
    	}  
    	// 源图像小于设定窗口，则直接显示图像，无滚动条  
    	else  
    	{  
    		cvShowImage(title, src_img);  
    	}     
    }  
    
    int main(int argc, char** argv)  
    {  
    	help();  
    	const char* filename = argc > 1 ? argv[1] : "1.bmp";  
    	int width = 1200, height = 800;  
    	if (4==argc)  
    	{  
    		sscanf( argv[2], "%u", &width );  
    		sscanf( argv[3], "%u", &height );  
    	}  
    
    	cvNamedWindow("Image Scroll Bar", 1);  
    	cvSetMouseCallback("Image Scroll Bar", mouse_callback);  
    
    	IplImage* image = cvLoadImage( filename, CV_LOAD_IMAGE_COLOR );  
    	if( !image )  
    	{  
    		fprintf( stderr, "Can not load %s and/or %s/n"  
    			"Usage: Image_ScrollBar [<img_filename default im.jpg>]/n",  
    			filename );  
    		exit(-1);  
    	}  
    
    	while(1)  
    	{  
    		myShowImageScroll("Image Scroll Bar", image, width, height);  
    
    		int KEY = cvWaitKey(10);  
    		if( (char) KEY == 27 )  
    			break;  
    
    	}  
    	cvDestroyWindow("Image Scroll Bar");  
    
    	return 0;  
    }

![这里写图片描述][0a6c56db53322f1d6dabe21bbd6f60a0.png]

[0a6c56db53322f1d6dabe21bbd6f60a0.png]: /images/20220708/39e79fe5c9614b628a0bcf117ee7baaf.png