In WinRT, how do I load an image and then wait only as long as is needed for it to load before writing to it?

Question

I\'m using WriteableBitmapEx in a WinRT project. I load an image into a WriteableBitmap from the users Picture library. However, I cannot then immediately write to that im

Answer 1

This method loads an image from the app's content, decodes it and passes back an ready-to-use WriteableBitmap. Taken from the WriteableBitmapEx library:

/// 

/// Loads an image from the applications content and fills this WriteableBitmap with it.
/// 
/// The WriteableBitmap.
/// The URI to the content file.
/// The WriteableBitmap that was passed as parameter.
public static async Task FromContent(this WriteableBitmap bmp, Uri uri)
{
   // Decode pixel data
   var file = await StorageFile.GetFileFromApplicationUriAsync(uri);
   var decoder = await BitmapDecoder.CreateAsync(await file.OpenAsync(FileAccessMode.Read));
   var transform = new global::Windows.Graphics.Imaging.BitmapTransform();
   var pixelData = await decoder.GetPixelDataAsync(decoder.BitmapPixelFormat, decoder.BitmapAlphaMode, transform, ExifOrientationMode.RespectExifOrientation, ColorManagementMode.ColorManageToSRgb);
   var pixels = pixelData.DetachPixelData();

   // Copy to WriteableBitmap
   bmp = new WriteableBitmap((int)decoder.PixelWidth, (int)decoder.PixelHeight);
   using (var bmpStream = bmp.PixelBuffer.AsStream())
   {
      bmpStream.Seek(0, SeekOrigin.Begin);
      bmpStream.Write(pixels, 0, (int)bmpStream.Length);
      return bmp;
   }
}

BTW, WinRT is now officially supported by WriteableBitmapEx. ;) http://kodierer.blogspot.de/2012/05/one-bitmap-to-rule-them-all.html