Qt获取Windows系统窗口内容图片

创建并获取窗口句柄

	view->show();
    view->createWinId();
    auto wid = view->winId();

获取图片

    // 三秒钟之后
    QTimer::singleShot(3000, [wid]() {
        auto&& image = GetGDIBitmap((HWND)wid);
		// 保存
        image.save("test.png");
    });

主要实现

#pragma once
#include <QImage>
#include <wtypes.h>

QImage BitmapToQImage(HBITMAP&);
QImage GetGDIBitmap(HWND);

// 获取窗体句柄窗口的图像
inline QImage GetGDIBitmap(HWND hd)
{
    // 获取窗口大小
    RECT rect;
    GetWindowRect(hd, &rect);
    int width = rect.right - rect.left;
    int height = rect.bottom - rect.top;
    // 创建设备上下文
    HDC hdc = GetDC(hd);
    HDC hdcMem = CreateCompatibleDC(hdc);
    // 创建位图
    HBITMAP hBitmap = CreateCompatibleBitmap(hdc, width, height);
    // 选择位图
    HBITMAP hOldBitmap = (HBITMAP)SelectObject(hdcMem, hBitmap);
    // 拷贝图像
    BitBlt(hdcMem, 0, 0, width, height, hdc, 0, 0, SRCCOPY);
    // 释放资源
    SelectObject(hdcMem, hOldBitmap);
    DeleteDC(hdcMem);
    ReleaseDC(hd, hdc);
    // 转换为QImage
    QImage image = BitmapToQImage(hBitmap);
    DeleteObject(hBitmap);
    return image;
}

//将HBITMAP转为QImage
inline QImage BitmapToQImage(HBITMAP& hBitmap)
{
    BITMAP bitmap;
    GetObject(hBitmap, sizeof(BITMAP), &bitmap);
    QImage img(bitmap.bmWidth, bitmap.bmHeight, QImage::Format_ARGB32);
    HDC hdc = CreateCompatibleDC(NULL);
    HBITMAP hBitOld = (HBITMAP)SelectObject(hdc, hBitmap);
    for (int i = 0; i < bitmap.bmHeight; i++) {
        QRgb* line = (QRgb*)img.scanLine(i);
        for (int j = 0; j < bitmap.bmWidth; j++) {
            COLORREF clr = GetPixel(hdc, j, i);
            line[j] = qRgba(GetRValue(clr), GetGValue(clr), GetBValue(clr), 255);
        }
    }
    SelectObject(hdc, hBitOld);
    DeleteDC(hdc);
    return img;
}