使用鼠标在OpenCV视频上绘制线条

Question

我一直在玩OpenCV（我很新），以显示实时相机。接下来我想做的是用鼠标在上面画线。有谁知道如何做到这一点？到目前为止，我所拥有的是：

#include "stdafx.h" 
#include <stdio.h> 
#include "cv.h" 
#include "highgui.h" 

int main(int argc, char **argv) 
{ 
CvCapture *capture = 0; 
IplImage *frame = 0; 
int  key = 0; 

/* initialize camera */ 
capture = cvCaptureFromCAM(0); 

/* always check */ 
if (!capture) { 
    fprintf(stderr, "Cannot open initialize webcam!\n"); 
    return 1; 
} 

/* create a window for the video */ 
cvNamedWindow("Testing", CV_WINDOW_AUTOSIZE); 

while(key != 'q') { 
    /* get a frame */ 
    frame = cvQueryFrame(capture); 

    /* always check */ 
    if(!frame) break; 

    /* display current frame */ 
    cvShowImage("result", frame); 

    /* exit if user press 'q' */ 
    key = cvWaitKey(1); 

} 

/* free memory */ 
cvDestroyWindow("result"); 
cvReleaseCapture(&capture); 

return 0; 
} 

如果有人可以帮我画上实时视频线，或者如果任何人任何提示的人都知道，我会非常感激！谢谢！

Answer 1

你必须更清楚你的意思是通过绘制视频。
一种方法是通过在黑色/空白“遮罩”图像上绘制它们之间的线条来处理鼠标位置，并在显示之前将该图像“应用”到每个视频帧。

Answer 2

要捕获鼠标事件，您需要创建一个回调。此回调将绑定到特定的命名窗口。电话cvSetMouseCallback的文档非常好。回调函数将知道当前位置和按钮点击信息。从那里你可以捕捉鼠标点击点，并使用这些点与cvLine绘制你的框架。

Answer 3

如果有帮助，这是我对多种尺寸的视频绘制矩形码流[使用OpenCV的摄像头上绘图]

#include "stdafx.h" 
#include "opencv2/imgproc/imgproc.hpp" 
#include "opencv2/highgui/highgui.hpp" 
#include <stdlib.h> 
#include <stdio.h> 
#include <iostream> 
#define SSTR(x) dynamic_cast< std::ostringstream & >((std::ostringstream() << std::dec << x)).str() 

using namespace std; 
using namespace cv; 

Rect box; //global structures needed for drawing 
bool drawing_box = false; 
struct mousecallbackstruct{ 
    Mat* src; 
    Mat* overlay; 
    string windowname; 
}; 

Mat srcoverlay,smallsrcoverlay; //an overlay must be created for each window you want to draw on 

void onMouse(int event, int x, int y, int flags, void* param) //it seems the only way to use this is by keeping different globals for different windows - meaning you have to set up all thise ahead of time, and keep track of it and not mix/match windows/frames!! horrible design here. 
{ 
    cout << event; 
    mousecallbackstruct mousestruct; 
    mousestruct = *((mousecallbackstruct*)param); 
    Mat* srcp = mousestruct.src; 
    Mat* overlayp = mousestruct.overlay;      // yeah, yeah, i use 7 lines where I could use 3, so sue me 
    Mat src = *srcp; 
    Mat overlay = *overlayp; 

    if(!src.data){ 
     cout << "your void * cast didn't work :(\n"; 
     return; 
    } 
    switch(event){ 
     case CV_EVENT_MOUSEMOVE: 
      if(drawing_box){ 
       box.width = x-box.x; 
       box.height = y-box.y; 
      } 
      break; 

     case CV_EVENT_LBUTTONDOWN: //start drawing 
      drawing_box = true; 
      box = cvRect(x, y, 0, 0); 
      break; 
     case CV_EVENT_LBUTTONDBLCLK: //double click to clear 
      drawing_box = false; 
      overlay.setTo(cv::Scalar::all(0)); //clear it 
      break; 
     case CV_EVENT_LBUTTONUP: //draw what we created with Lbuttondown 
      drawing_box = false; 
      if(box.width < 0){ 
       box.x += box.width; 
       box.width *= -1; 
      } 
      if(box.height < 0){ 
       box.y += box.height; 
       box.height *= -1; 
      } 
      rectangle(overlay, Point(box.x, box.y), Point(box.x+box.width,box.y+box.height),CV_RGB(100,200,100),4); //draw rectangle. You can change this to line or circle or whatever. Maybe with the Right mouse button. 
      break; 
    } 
} 


void iimshow(mousecallbackstruct* mystructp){ //this is where we add the text/drawing created in the mouse handler to the actual image (since mouse handler events do not coincide with the drawing events) 

    mousecallbackstruct mystruct = *mystructp; //custom struct made for the mouse callback - very handy for other functions too 
    Mat overlay, src; 
    Mat* srcp = mystruct.src; 
    Mat* overlayp = mystruct.overlay; 
    src = *srcp;        // yeah, yeah, i use 9 lines where I could use 3, so sue me 
    overlay = *overlayp; 
    string name = mystruct.windowname; 
    Mat added,imageROI; 

    try{ 
     //cout << "tch:" << overlay.rows << "," << src.rows << ";" << overlay.cols << "," << src.cols << ";" << src.channels() << "," << overlay.channels() <<"," << src.type() << "," << overlay.type() << "\n"; 
     if(overlay.data && overlay.rows == src.rows && overlay.cols == src.cols && overlay.channels() == src.channels()){ //basic error checking 
      add(src,overlay,added); 
     }else{ 
      //try to resize it 
      imageROI= overlay(Rect(0,0,src.cols,src.rows)); 
      add(src,imageROI,added); 
     } 

     imshow(name,added);// the actual draw moment 

    }catch(...){ //if resize didn't work then this should catch it and you can see what didn't match up 
     cout << "Error. Mismatch:" << overlay.rows << "," << src.rows << ";" << overlay.cols << "," << src.cols << ";" << src.channels() << "," << overlay.channels() <<"," << src.type() << "," << overlay.type() << "\n"; 
     imshow(name + "overlay",overlay); 
     imshow(name+"source",src); 
    } 
} 

int _tmain(int argc, _TCHAR* argv[]){ 

    VideoCapture cap(0); // open the default camera 
    if(!cap.isOpened()) { // check if we succeeded 
     cout << "NO camera found \n"; 
     return -1; 
    } 

    Mat src,smallsrc,overlay; 
    cap >> src; //grab 1 frame to build our preliminary Mats and overlays 

    srcoverlay.create(src.rows,src.cols,src.type()); //create overlays 
    smallsrcoverlay.create(src.rows,src.cols,src.type()); 
    srcoverlay.setTo(cv::Scalar::all(0)); //clear it 
    smallsrcoverlay.setTo(cv::Scalar::all(0)); //clear it 

    namedWindow("smallsrc", CV_WINDOW_AUTOSIZE); 
    namedWindow("source", CV_WINDOW_AUTOSIZE); //these must be created early for the setmousecallback, AND you have to know what Mats will be using them and not switch them around :(
    moveWindow("smallsrc",1000,100); //create a small original capture off to the side of screen 

    ////////////// for each window/mat that uses a mouse handler, you must create one of these structures for it and pass it into the mouse handler, and add a global mat for overlays (at top of code) 
    mousecallbackstruct srcmousestruct,smallsrcmousestruct; //these get passed into the mouse callback function. Hopefully they update their contents automatically for the callback? :(
    srcmousestruct.overlay = &srcoverlay; //fill our custom struct 
    srcmousestruct.src = &src; 
    srcmousestruct.windowname = "source"; 

    smallsrcmousestruct.overlay = &smallsrcoverlay; //the small window 
    smallsrcmousestruct.src = &smallsrc; 
    smallsrcmousestruct.windowname = "smallsrc"; 

    setMouseCallback(smallsrcmousestruct.windowname, onMouse, (void*)&smallsrcmousestruct); //the actual 'set mouse callback' call 
    setMouseCallback(srcmousestruct.windowname, onMouse, (void*)&srcmousestruct); 

    for(;;){ //main loop 
     /// Load an image 
     cap >> src; 

     if(!src.data) 
     { return -1; } 

     resize(src,smallsrc,Size(),.5,.5); //smaller scale window of original 

     overlay = *srcmousestruct.overlay; 
     src = *srcmousestruct.src; 

     iimshow(&srcmousestruct); //my imshow replacement. uses structs 
     iimshow(&smallsrcmousestruct); 

     if(waitKey(30) == 27) cin.get(); //esc pauses 
    } 
    cin.get(); 
    return 0; 
}