How to save a Canvas like an Image

I have a Silverlight application that allows you to write with the mouse like a paint开发者_StackOverflow中文版. I am using a canvas inside a grid, and now I want to save that you draw on the canvas in a kind of file that you can open again in any time. Finally I use FileDialogs to do it.

I don´t know the way to save the canvas and neither how to open the file saved. I have a clue, maybe writeable bitmap will be a good solution, but I didn´t find a good tutorial about it.

Thanks in advance.

Best regards.

---

Please look at the following: How save canvas as image?