How to load an image from a base64 encoded png in UWP app C++/CX

Question

Hello!

I have a base64 encoded PNG file (a QR code), and I would like to show the picture on a Page.

I have this XAML element:

<Image Grid.Row="3" Name="QRCode" Height="200" Width="200"/>  

I converted the base64 string to an IBuffer:

Windows::Storage::Streams::IBuffer^ buf = Windows::Security::Cryptography::CryptographicBuffer::DecodeFromBase64String(base64string);  

Now I would like to create a BitmapImage, to set it as the source of the Image on the page:

BitmapImage^ Image = ref new BitmapImage();  
QRCode->Source = Image;  

The question is, that how can I set the IBuffer as the source of the Image? What is the missing step?

Thanks if you help me!

Answer 1

You can use the GetPointerToPixelData function from Obtaining pointers to data buffers (C++/CX)
with a WriteableBitmap that you can set as source of an Image

Answer 2

Meanwhile I found a working solution, so I paste it here, to help others who are facing with the same problem:

Windows::Storage::Streams::IBuffer^ buf = Windows::Security::Cryptography::CryptographicBuffer::DecodeFromBase64String(base64string);  
auto bitmapImage = ref new BitmapImage();  
QRCode->Source = bitmapImage;  
auto stream = ref new InMemoryRandomAccessStream();  
auto writer = ref new DataWriter(stream->GetOutputStreamAt(0));  
writer->WriteBuffer(buf);  
create_task(writer->StoreAsync()).then([=](unsigned bytesStored)  
{  
return bitmapImage->SetSourceAsync(stream);  
});