GetPixelAddress()函数Alpha通道会丢失

void CGBImage::Load(){
	CImage sourceImage;
	sourceImage.Load(L"C:\\Users\\Ju'k\\Desktop\\CGaussBlur\\1.png");
	int bpp = sourceImage.GetBPP();
	int width = sourceImage.GetWidth();
	int height = sourceImage.GetHeight();

	CImage newImage;
	newImage.Create(width,height,32);
	for(int w = 0; w < width;w++){
		for(int h = 0; h < height;h++){
			if(w == 20 && h == 20){
				int xx = 0;
			}
			BYTE* buffer = (BYTE*)sourceImage.GetPixelAddress(w,h);
			BYTE b = buffer[0];
			BYTE g = buffer[1];
			BYTE r = buffer[2];
			BYTE a = buffer[3];


			BYTE* newBuffer = (BYTE*)newImage.GetPixelAddress(w,h);

			newBuffer[0] = b;
			newBuffer[1] = g;
			newBuffer[2] = r;
			newBuffer[3] = a;

		}
	}

	CLSID pngClsid;
	GetEncoderClsid(_T("image/png"), &pngClsid);
	newImage.Save(L"C:\\Users\\Ju'k\\Desktop\\CGaussBlur\\1_1.png");


}