windows截图

 Screenshot.h:

#include <Windows.h>
#include <opencv2/opencv.hpp>

class Screenshot
{
public:
    Screenshot();
    double static getZoom();
    cv::Mat getScreenshot();
    cv::Mat getScreenshot(int x, int y, int width, int height);

private:
    int m_width;
    int m_height;
    HDC m_screenDC;
    HDC m_compatibleDC;
    HBITMAP m_hBitmap;
    LPVOID m_screenshotData = nullptr;
};

Screenshot.cpp:

#include "Screenshot.h"
using cv::Mat;

Screenshot::Screenshot()
{
    double zoom = getZoom();
    m_width = GetSystemMetrics(SM_CXSCREEN) * zoom;
    m_height = GetSystemMetrics(SM_CYSCREEN) * zoom;
    m_screenshotData = new char[m_width * m_height * 4];
    memset(m_screenshotData, 0, m_width);

    // 获取屏幕 DC
    m_screenDC = GetDC(NULL);
    m_compatibleDC = CreateCompatibleDC(m_screenDC);

    // 创建位图
    m_hBitmap = CreateCompatibleBitmap(m_screenDC, m_width, m_height);
    SelectObject(m_compatibleDC, m_hBitmap);
}

/* 获取整个屏幕的截图 */
Mat Screenshot::getScreenshot()
{
    // 得到位图的数据
    BitBlt(m_compatibleDC, 0, 0, m_width, m_height, m_screenDC, 0, 0, SRCCOPY);
    GetBitmapBits(m_hBitmap, m_width * m_height * 4, m_screenshotData);

    // 创建图像
    Mat screenshot(m_height, m_width, CV_8UC4, m_screenshotData);
    cv::cvtColor(screenshot, screenshot, CV_BGRA2BGR);
    return screenshot;
}

/** @brief 获取指定范围的屏幕截图
 * @param x 图像左上角的 X 坐标
 * @param y 图像左上角的 Y 坐标
 * @param width 图像宽度
 * @param height 图像高度
 */
Mat Screenshot::getScreenshot(int x, int y, int width, int height)
{
    Mat screenshot = getScreenshot();
    return screenshot(cv::Rect(x, y, width, height));
}

/* 获取屏幕缩放值 */
double Screenshot::getZoom()
{
    // 获取窗口当前显示的监视器
    HWND hWnd = GetDesktopWindow();
    HMONITOR hMonitor = MonitorFromWindow(hWnd, MONITOR_DEFAULTTONEAREST);

    // 获取监视器逻辑宽度
    MONITORINFOEX monitorInfo;
    monitorInfo.cbSize = sizeof(monitorInfo);
    GetMonitorInfo(hMonitor, &monitorInfo);
    int cxLogical = (monitorInfo.rcMonitor.right - monitorInfo.rcMonitor.left);

    // 获取监视器物理宽度
    DEVMODE dm;
    dm.dmSize = sizeof(dm);
    dm.dmDriverExtra = 0;
    EnumDisplaySettings(monitorInfo.szDevice, ENUM_CURRENT_SETTINGS, &dm);
    int cxPhysical = dm.dmPelsWidth;

    return cxPhysical * 1.0 / cxLogical;
}

main.cpp:

#include "Screenshot.h"
int main(int argc, char* argv[])
{
	Screenshot screenshot;
	Mat frame = screenshot.getScreenshot();
    return 0;
}