OpenCV 利用滚动条在不缩小的情况下显示大型图片
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 ROIrect_dst = cvRect(0, 0, showWidth, showHeight);cvSetImageROI(dst_img, rect_dst);// 设置源图像的 ROIsrc_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;}
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