D2D如何加载PNG图片

在Direct2D (D2D) 中加载PNG图片通常需要借助Windows Imaging Component (WIC)，因为D2D本身并不直接支持所有格式的图片。以下是一般的步骤[^1]：

1. **创建WIC Bitmap Factory**:

   ComPtr<IFactory> wicFactory;
   ThrowIfFailed(CreateWICComponentFactory(__uuidof(CComPtr<IFactory>), &wicFactory));

2. **加载PNG文件**:

   ComPtr<IWICStreamSource> streamSource;
   ThrowIfFailed(wicFactory->CreateStreamFromFile(L"image.png", IID_PPV_ARGS(&streamSource)));

   ComPtr<IWICImagingFactory> imagingFactory;
   ThrowIfFailed(CreateWICComponentFactory(__uuidof(IWICImagingFactory), &imagingFactory));

   ComPtr<IWICBitmapDecoder> decoder;
   ThrowIfFailed(imagingFactory->CreateDecoderFromStream(streamSource, nullptr, WICDecodeMetadataCacheOnLoad, &decoder));

3. **解码并获取位图**:

   ComPtr<IWICBitmapFrameDecode> frame;
   ThrowIfFailed(decoder->GetFrame(0, &frame));

   ComPtr<ID2D1Bitmap1> d2dBitmap;
   D2D1创建位图参数 bitmapOptions;
   bitmapOptions.pixelFormat = D2D1_PIXEL_FORMAT_B8G8R8A8_UNORM;
   ThrowIfFailed(frame->CopyIntoBitmap(d2dContext.Get(), &bitmapOptions, &d2dBitmap));

4. **使用ID2D1Bitmap对象**:
现在你可以将`d2dBitmap`传递给D2D绘图上下文，进行后续的渲染或操作。

注意，上述代码示例并未完全涵盖错误处理，实际开发中应加入适当的异常处理。此外，你需要确保已包含所需的WIC和D2D库。