C++ D2D位图转化为Mat

在Windows下，可以使用Direct2D来创建位图，OpenCV中的Mat是一个矩阵类，可以表示图像。我们可以通过将Direct2D位图转换为GDI+位图，然后使用OpenCV的imread函数将其读入Mat中。

以下是一个示例代码：

#include <d2d1.h>
#include <gdiplus.h>
#include <opencv2/opencv.hpp>

#pragma comment(lib, "d2d1.lib")
#pragma comment(lib, "gdiplus.lib")

using namespace Gdiplus;

int main()
{
    // Initialize Direct2D
    HRESULT hr = CoInitialize(NULL);
    ID2D1Factory* pFactory = NULL;
    hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &pFactory);

    // Create a Direct2D bitmap
    ID2D1Bitmap* pBitmap = NULL;
    D2D1_SIZE_U size = D2D1::SizeU(640, 480);
    hr = pFactory->CreateBitmap(size, D2D1::BitmapProperties(D2D1_PIXEL_FORMAT{ DXGI_FORMAT_R8G8B8A8_UNORM, D2D1_ALPHA_MODE_IGNORE }), &pBitmap);

    // Draw something on the bitmap
    ID2D1RenderTarget* pRenderTarget = NULL;
    hr = pFactory->CreateWicBitmapRenderTarget(pBitmap, &D2D1::RenderTargetProperties(), &pRenderTarget);
    pRenderTarget->BeginDraw();
    pRenderTarget->Clear(D2D1::ColorF(D2D1::ColorF::White));
    ID2D1SolidColorBrush* pBrush = NULL;
    hr = pRenderTarget->CreateSolidColorBrush(D2D1::ColorF(D2D1::ColorF::Red), &pBrush);
    pRenderTarget->DrawLine(D2D1::Point2F(0, 0), D2D1::Point2F(640, 480), pBrush);
    pRenderTarget->DrawLine(D2D1::Point2F(0, 480), D2D1::Point2F(640, 0), pBrush);
    hr = pRenderTarget->EndDraw();

    // Convert Direct2D bitmap to GDI+ bitmap
    IWICImagingFactory* pWICFactory = NULL;
    hr = CoCreateInstance(CLSID_WICImagingFactory, NULL, CLSCTX_INPROC_SERVER, IID_IWICImagingFactory, (LPVOID*)&pWICFactory);
    IWICBitmap* pWICBitmap = NULL;
    hr = pRenderTarget->GetBitmap(&pWICBitmap);
    IWICBitmapSource* pWICBitmapSource = NULL;
    hr = pWICBitmap->QueryInterface(IID_IWICBitmapSource, (LPVOID*)&pWICBitmapSource);
    Gdiplus::Bitmap* pGdiBitmap = new Gdiplus::Bitmap(pWICBitmapSource, NULL);

    // Convert GDI+ bitmap to Mat
    cv::Mat mat = cv::Mat(pGdiBitmap->GetHeight(), pGdiBitmap->GetWidth(), CV_8UC4, pGdiBitmap->GetPixelAddress(0, 0));

    // Show the Mat
    cv::imshow("Mat from Direct2D Bitmap", mat);
    cv::waitKey();

    // Clean up
    delete pGdiBitmap;
    pWICBitmapSource->Release();
    pWICBitmap->Release();
    pRenderTarget->Release();
    pBrush->Release();
    pBitmap->Release();
    pFactory->Release();
    CoUninitialize();

    return 0;
}

在这个示例中，我们首先使用Direct2D创建了一个640x480的位图，并在其中绘制了两条对角线。接下来，我们将Direct2D位图转换为GDI+位图，并使用GDI+位图的像素地址创建了一个OpenCV的Mat对象。最后，我们将Mat对象显示在一个窗口中。

请注意，在将Direct2D位图转换为GDI+位图时，我们使用了Windows Imaging Component (WIC)。WIC是一个功能强大的图像处理库，可以用于在Windows中处理各种图像格式。