Advanced Silverlight bitmaps

Bitmap handling - using WriteableBitmap in particular differs greatly from WPF. In this article we look as the problems of loading bitmaps and generating them dynamically.

Bitmaps from streams

  Although a bitmap source seems only to be creatable from other bitmaps or UIElements you can in fact create a bitmap from any suitably formatted stream using the SetSource method.
The only real problem here is that the stream of bytes that you provided have to take the form of a valid jpeg, png or gif and this makes it difficult to convert a raw bit stream into a finished bitmap.
As a simple example, let’s use the OpenFileDialog to read in an image stored on the local machine. This has to be called from a button handler or some user initiated code otherwise you generate a security error. So add a button to and an image control to a new Silverlight project and:

using System.Windows.Media.Imaging;
using System.IO;

To create a stream we first use the OpenFileDialog:

private void button1_Click(object sender, RoutedEventArgs e)
{

OpenFileDialog ofd = new OpenFileDialog();
ofd.Filter = "JPEG Files (*.jpg;*.jpeg)|*.jpg;*.jpeg | All Files (*.*)|*.*";
ofd.FilterIndex = 1;
bool?  result=ofd.ShowDialog();

Notice that we can’t use DialogResult as we would in WPF because Silverlight does things differently.

Read more: I Programmer

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