WriteableBitmap Constructor (BitmapSource)
December 03, 2013System.Windows.Media.Imaging
Assembly: System.Windows (in System.Windows.dll)
If source does not use a natively supported bitmap format, format conversions are applied for each frame update, which reduces performance.
If you use a BitmapImage as the source, remember that a BitmapImage constructed by a URL is initialized asynchronously. The default mode is DelayCreation, and in this case the image is possibly not being added to the visual tree and is thus not immediately requested for download. As such the image may be null and throws an exception in the constructor. It may be necessary to construct the image separately (using IgnoreImageCache), attach a handler for ImageOpened for the source, and only construct the WriteableBitmap once the ImageOpened event is handled.