opencv 檢測滑鼠的點選和移動
阿新 • • 發佈：2019-02-19
只需要定義一個callback的函式， 然後將這個函式附屬到我們定義的一個opencv的window上即可， 這樣每當滑鼠在視窗處發生動作的時候， 就會呼叫callback函式。 點選滑鼠的時候， callback也會記錄下點選滑鼠的位置。 程式如下：
#include "opencv2/highgui/highgui.hpp" #include <iostream> using namespace std; using namespace cv; void CallBackFunc(int event, int x, int y, int flags, void* userdata) { if ( event == EVENT_LBUTTONDOWN ) { cout << "Left button of the mouse is clicked - position (" << x << ", " << y << ")" << endl; } else if ( event == EVENT_RBUTTONDOWN ) { cout << "Right button of the mouse is clicked - position (" << x << ", " << y << ")" << endl; } else if ( event == EVENT_MBUTTONDOWN ) { cout << "Middle button of the mouse is clicked - position (" << x << ", " << y << ")" << endl; } else if ( event == EVENT_MOUSEMOVE ) { cout << "Mouse move over the window - position (" << x << ", " << y << ")" << endl; } } int main(int argc, char** argv) { // Read image from file Mat img = imread("D:\\psb.JPG"); //if fail to read the image if ( img.empty() ) { cout << "Error loading the image" << endl; return -1; } //Create a window namedWindow("My Window", 1); //set the callback function for any mouse event setMouseCallback("My Window", CallBackFunc, NULL); //show the image imshow("My Window", img); // Wait until user press some key waitKey(0); return 0; }
函式解釋如下：
下面在給一個函式， 用於檢測 一個滑鼠事件配合鍵盤上的某個鍵時候， 會響應， 如下：void setMouseCallback(const string& winname, MouseCallback onMouse, void* userdata = 0) This function sets a callback function to be called every time any mouse events occurs in the specified window. Here is the detailed explanation of the each parameters of the above OpenCV function. winname - Name of the OpenCV window. All mouse events related to this window will be registered onMouse - Name of the callback function. Whenever mouse events related to the above window occur, this callback function will be called. This function should have the signature like the following void FunctionName(int event, int x, int y, int flags, void* userdata) event - Type of the mouse event. These are the entire list of mouse events EVENT_MOUSEMOVE EVENT_LBUTTONDOWN EVENT_RBUTTONDOWN EVENT_MBUTTONDOWN EVENT_LBUTTONUP EVENT_RBUTTONUP EVENT_MBUTTONUP EVENT_LBUTTONDBLCLK EVENT_RBUTTONDBLCLK EVENT_MBUTTONDBLCLK x - x coordinate of the mouse event y - y coordinate of the mouse event flags - Specific condition whenever a mouse event occurs. See the next OpenCV example code for the usage of this parameter. Here is the entire list of enum values which will be possesed by "flags" EVENT_FLAG_LBUTTON EVENT_FLAG_RBUTTON EVENT_FLAG_MBUTTON EVENT_FLAG_CTRLKEY EVENT_FLAG_SHIFTKEY EVENT_FLAG_ALTKEY userdata - Any pointer passes to the "setMouseCallback" function as the 3rd parameter (see below) userdata - This pointer will be passed to the callback function
#include "opencv2/highgui/highgui.hpp" #include <iostream> using namespace std; using namespace cv; void CallBackFunc(int event, int x, int y, int flags, void* userdata) { if ( flags == (EVENT_FLAG_CTRLKEY + EVENT_FLAG_LBUTTON) ) { cout << "Left mouse button is clicked while pressing CTRL key - position (" << x << ", " << y << ")" << endl; } else if ( flags == (EVENT_FLAG_RBUTTON + EVENT_FLAG_SHIFTKEY) ) { cout << "Right mouse button is clicked while pressing SHIFT key - position (" << x << ", " << y << ")" << endl; } else if ( event == EVENT_MOUSEMOVE && flags == EVENT_FLAG_ALTKEY) { cout << "Mouse is moved over the window while pressing ALT key - position (" << x << ", " << y << ")" << endl; } } int main(int argc, char** argv) { // Read image from file Mat img = imread("D:\\psb.JPG"); //if fail to read the image if ( img.empty() ) { cout << "Error loading the image" << endl; return -1; } //Create a window namedWindow("My Window", 1); //set the callback function for any mouse event setMouseCallback("My Window", CallBackFunc, NULL); //show the image imshow("My Window", img); // Wait until user press some key waitKey(0); return 0; }