1. HighGUI
- 媒体输入输出
- 视频捕捉
- 图像和视频的编、解码
- 图形交互界面接口
常用类：VideoCapture
1.1. TrackBar的创建和使用
1.1.1. 创建TrackBar
CV_EXPORTS int createTrackbar(const String& trackbarname, const String& winname,
int* value, int count,
TrackbarCallback onChange = 0,
void* userdata = 0);
- trackbarname:轨迹条名称
- winname:窗口名称，表示轨迹条附加到哪个窗口上
- value:滑块的初始位置
- count:轨迹条的最大值
- onChange:回调函数指针，每当滑块位置改变，会调用这个函数
/** @brief Callback function for Trackbar see cv::createTrackbar @param pos current position of the specified trackbar. @param userdata The optional parameter. */ typedef void (*TrackbarCallback)(int pos, void* userdata); - userdata:用户数据，用来作为回调函数的参数
1.1.2. 例子
#include<opencv2/opencv.hpp>
#define WINDOW_NAME "[线性混合示例]"
using namespace cv;
const int g_nMaxAlphaValue = 100;
int g_nAlphaValueSlider;
double g_dAlphaValue;
double g_dBetaValue;
Mat g_srcImg1;
Mat g_srcImg2;
Mat g_dstImg;
void on_Trackbar(int, void*)
{
g_dAlphaValue = (double)g_nAlphaValueSlider / g_nMaxAlphaValue;
//beta值等于1-alpha
g_dBetaValue = 1.0 - g_dAlphaValue;
//根据alpha和beta进行线性混合
cv::addWeighted(g_srcImg1, g_dAlphaValue, g_srcImg2, g_dBetaValue, 0.0, g_dstImg);
imshow(WINDOW_NAME, g_dstImg);
}
#define _CRT_SECURE_NO_WARNINGS
int main()
{
//读取图片
g_srcImg1 = imread("E:\\temp\\1.jpg");
g_srcImg2 = imread("E:\\temp\\2.jpg");
g_nAlphaValueSlider = 70;
namedWindow(WINDOW_NAME, 1);
char trackbarName[50];
sprintf_s(trackbarName, "透明值 %d", g_nMaxAlphaValue);
cv::createTrackbar(trackbarName, WINDOW_NAME,&g_nAlphaValueSlider,g_nMaxAlphaValue,on_Trackbar);
//on_Trackbar(g_nAlphaValueSlider, 0);
//
waitKey(0);
}
效果：
1.2. 鼠标操作
和TrackBar的操作类似，opencv提供的窗口鼠标交互也是通过回调函数实现。
1.2.1. 设定回调函数
/** @example samples/cpp/create_mask.cpp
This program demonstrates using mouse events and how to make and use a mask image (black and white) .
*/
/** @brief Sets mouse handler for the specified window
@param winname Name of the window.
@param onMouse Callback function for mouse events. See OpenCV samples on how to specify and use the callback.
@param userdata The optional parameter passed to the callback.
*/
CV_EXPORTS void setMouseCallback(const String& winname, MouseCallback onMouse, void* userdata = 0);
回调函数原型：
/** @brief Callback function for mouse events. see cv::setMouseCallback
@param event one of the cv::MouseEventTypes constants.
@param x The x-coordinate of the mouse event.
@param y The y-coordinate of the mouse event.
@param flags one of the cv::MouseEventFlags constants.
@param userdata The optional parameter.
*/
typedef void (*MouseCallback)(int event, int x, int y, int flags, void* userdata);
注意：参数x、y是图像坐标系的坐标 参数：
- event:鼠标事件
//! Mouse Events see cv::MouseCallback enum MouseEventTypes { EVENT_MOUSEMOVE = 0, //!< indicates that the mouse pointer has moved over the window. EVENT_LBUTTONDOWN = 1, //!< indicates that the left mouse button is pressed. EVENT_RBUTTONDOWN = 2, //!< indicates that the right mouse button is pressed. EVENT_MBUTTONDOWN = 3, //!< indicates that the middle mouse button is pressed. EVENT_LBUTTONUP = 4, //!< indicates that left mouse button is released. EVENT_RBUTTONUP = 5, //!< indicates that right mouse button is released. EVENT_MBUTTONUP = 6, //!< indicates that middle mouse button is released. EVENT_LBUTTONDBLCLK = 7, //!< indicates that left mouse button is double clicked. EVENT_RBUTTONDBLCLK = 8, //!< indicates that right mouse button is double clicked. EVENT_MBUTTONDBLCLK = 9, //!< indicates that middle mouse button is double clicked. EVENT_MOUSEWHEEL = 10,//!< positive and negative values mean forward and backward scrolling, respectively. EVENT_MOUSEHWHEEL = 11 //!< positive and negative values mean right and left scrolling, respectively. }; - x:鼠标当前的x坐标
- y:鼠标当前的y坐标
- userdata：用户数据
1.2.2. 例子
在opencv图形窗口中用鼠标绘制矩形框：
#include<opencv2/opencv.hpp>
using namespace cv;
#define WINDOW_NAME "[程序窗口]"
//全局函数声明
void on_MouseHandle(int event, int x, int y, int flags, void* param);
void DrawRectangle(cv::Mat& img, cv::Rect box);
void ShowHelpText();
Rect g_rectangle;
bool g_bDrawingBox = false;
RNG g_rng(12345);
int main()
{
g_rectangle = Rect(-1, -1, 0, 0);
Mat srcImage(600, 800, CV_8UC3), tempImage;
srcImage.copyTo(tempImage);
g_rectangle = Rect(-1, -1, 0, 0);
srcImage = Scalar::all(0);
namedWindow(WINDOW_NAME);
cv::setMouseCallback(WINDOW_NAME, on_MouseHandle, (void*)&srcImage);
while (1)
{
srcImage.copyTo(tempImage);
if (g_bDrawingBox) {
DrawRectangle(tempImage, g_rectangle);
}
imshow(WINDOW_NAME, tempImage);
if (waitKey(10) == 27) {
//ESC
break;
}
}
return 0;
}
void on_MouseHandle(int event, int x, int y, int flags, void* param)
{
Mat& img = *(cv::Mat*)param;
switch (event)
{
case EVENT_MOUSEMOVE:
if (g_bDrawingBox) {
//记录长和宽
g_rectangle.width = x - g_rectangle.x;
g_rectangle.height = y - g_rectangle.y;
}
break;
case EVENT_LBUTTONDOWN:
g_bDrawingBox = true;
g_rectangle = cv::Rect(x, y, 0, 0);
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.height;
g_rectangle.height *= -1;
}
DrawRectangle(img, g_rectangle);
break;
default:
break;
}
}
void DrawRectangle(cv::Mat& img, cv::Rect box)
{
cv::rectangle(img, box.tl(), box.br(), Scalar(g_rng.uniform(0, 255), g_rng.uniform(0, 255), g_rng.uniform(0, 255)));
}
void ShowHelpText()
{
}
效果：
