Use the D2D drawing pictures-CodePudding

Use the following code to open a PNG image with alpha channel, but you can't draw transparent effect, why?
 
Retrieves the hr; 

IWICBitmapDecoder * pDecoder=NULL; 
PSource IWICBitmapFrameDecode *=NULL; 
PStream IWICStream *=NULL; 
IWICFormatConverter * pConverter=NULL; 
IWICBitmapScaler * pScaler=NULL; 

Hr=pIWICFactory - & gt; CreateDecoderFromFilename (
Uri, 
NULL, 
GENERIC_READ, 
WICDecodeMetadataCacheOnLoad, 
& PDecoder 
); 
If (SUCCEEDED (hr)) 
{

//Create the initial frame. 
Hr=pDecoder - & gt; GetFrame (0, & amp; PSource); 
} 

If (SUCCEEDED (hr)) 
{
Hr=pIWICFactory - & gt; CreateFormatConverter (& amp; PConverter); 
} 
UINT originalWidth originalHeight; 
Hr=pSource - & gt; GetSize (& amp; OriginalWidth, & amp; OriginalHeight); 
If (SUCCEEDED (hr)) 
{

Hr=pIWICFactory - & gt; CreateBitmapScaler (& amp; PScaler); 
If (SUCCEEDED (hr)) 
{
Hr=pScaler - & gt; The Initialize (
PSource, 
OriginalWidth. 
OriginalHeight, 
WICBitmapInterpolationModeCubic 
); 
} 
If (SUCCEEDED (hr)) 
{
Hr=pConverter - & gt; The Initialize (
PScaler, 
GUID_WICPixelFormat32bppPRGBA, 
WICBitmapDitherTypeNone, 
NULL, 
0 f, 
WICBitmapPaletteTypeMedianCut 
); 
} 
} 
If (SUCCEEDED (hr)) 
{
//Create a Direct2D bitmap from the WIC bitmap. 
Hr=pRenderTarget - & gt; CreateBitmapFromWicBitmap (pConverter, NULL, ppBitmap); 
} 

D2D1: : Matrix3x2F a=D2D1: : Matrix3x2F: : Scale (2, 2, D2D1: : Point2F (250, 250)); 
G_pRenderTarget - & gt; SetTransform (a); 

G_pRenderTarget - & gt; DrawBitmap (pBitmap, 
D2D1: : RectF (200 f, 200. F, 300 f, 300 f), 1.0 f, 
D2D1_BITMAP_INTERPOLATION_MODE_LINEAR, 
D2D1: : RectF (00 00, 200 f, 200. F) 
);