使用WIC将QImage编码为png？

Question

我正在尝试测试WIC和QT中的编码函数之间的性能。但是我找不到一种使用WIC从QImage (QT对象)编码到PNG的方法。

需要从IStream中初始化来自WIC的编码器，它应该提供与图像文件相同的数据。但我有的是位图。

有人能帮我吗？如有任何意见，将不胜感激。

Answer 1

这是很容易做到的。我不知道如何使用编码器。IWICBitmapFrameEncode.WritePixels是我应该放置原始像素的地方：

factory = CreateComObject(CLSID_WICImagingFactory);

IWICBitmapEncoder pngEncoder = factory.CreateEncoder(GUID_ContainerFormatPng, null);
pngEncoder.Initialize(targetStream, WICBitmapEncoderNoCache);

IPropertyBag2 propertyBag;
IWICBitmapFrameEncode frame = pngEncoder.CreateNewFrame(ref propertyBag);

frame.Initialize(propertyBag);

//Set the size of the image
frame.SetSize(640, 480);

//Request the encoder use this format.
Guid format = GUID_WICPixelFormat32bppPBGRA;

//If the encoder doesn't support that format, it will set format to the closest it does support
frame.SetPixelFormat(ref format);

//if the frame encoder doesn't support the pixel format we want to give it
//then we just cannot proceed
Assert(format == GUID_WICPixelFormat32bppPBGRA); 

frame.WritePixels(
     lineCount, 
     stride, 
     bufferSize, 
     pointerToPixelData);

frame.Commit();
pngEncoder.Commit();