如何从硬盘上的Internet保存BitmapImage？ （C＃UniversalApp）

Question

This might sound simple but I'v noticed that it's not to me! I want to save a simple jpg or other format image from internet to hard drive. I use the following code to get an image from the net. How do I save it to HDD ?

BitmapImage posterBitmap = new BitmapImage(new Uri(imageLocationOnNet, UriKind.Absolute));

I'd appreciate lot if someone could give me a simple code example and explain how it works.
Preferably in C# and Windows Universal App compatible, thank you.

EDIT. I'm also interested to know if it is possible to convert BitmapImage to JSON and read it back from there?

Answer 1

I'm guessing the reason it doesn't seem simple to you is that you are looking in the wrong place

Bitmap source and Bitmap image are only for loading images, the saving functionality is in the encoder classed such as PngEncoder

once you have selected the correct encoder then you just need to add the image to it as a frame and then save it to a stream

encoder.Frames.Add(BitmapFrame.Create(image));
encoder.Save(stream);

Answer 2

Found here . When you create that image it takes some time to download it. You can check if it's downloading with

posterBitmap.IsDownloading

after it's done, add the handler

posterBitmap.DownloadCompleted += posterBitmap_DownloadCompleted;

and then write the function to save the image

private void objImage_DownloadCompleted(object sender, EventArgs e)
{
  JpegBitmapEncoder encoder = new JpegBitmapEncoder();
  Guid photoID = System.Guid.NewGuid();
  String photolocation = photoID.ToString() + ".jpg";  //file name 

  encoder.Frames.Add(BitmapFrame.Create((BitmapImage)sender));

  using (var filestream = new FileStream(photolocation, FileMode.Create))
    encoder.Save(filestream);
}