.NET Rocker

Silverlight 4 supports printing scenarios. It’s quite easy. Just create a PrintDocument instance, handle the PrintPage-Event and call the Print-Method. In the PrintPage-Event set the PageVisual-Property of the PrintPageEventArgs to a UIElement of your choice. If there are more pages, set the HasMorePages-Property of the PrintPageEventArgs to true and the PrintPage-Eventhandler would be called again for the next page.

Below a simple example using a lambda expression. When the Print-Method is called a PrintDialog is displayed to the User, where he can select the printer of his choice. When the PrintDialog was accepted, the PrintPage-Event gets fired and the lambda expression below get’s called. The PageVisual-Property is set to a TextBlock. So that TextBlock with the text “Thoams says…” is printed out.

var pd = new PrintDocument();
pd.PrintPage += (s, e) =>
  {
    e.PageVisual = new TextBlock {Text="Thomas says Hello"};
  };
pd.Print();

Ok, so far so good. As I was working on an example for my upcoming Silverlight 4 book I needed to create an Image-Element on the fly and print this out. And then I noticed that the Image doesn’t appear on the output.

While searching for a solution I found somebody having the same problem in this thread in Microsoft’s Silverlight forums:

http://forums.silverlight.net/forums/t/145680.aspx

So, it seemed it was not my cause, it was a Beta-cause. So let’s look at a workaround. But first look at the bug.

I made a smaller example to reproduce it. View the following code. What do you think is printed on the page?

void PrintButton_Click(object sender, RoutedEventArgs e)
{
  var streamResourceInfo =
    Application.GetResourceStream(
      new Uri("thomas.png", UriKind.Relative));

  var bitmapImage = new BitmapImage();
  bitmapImage.SetSource(streamResourceInfo.Stream);

  var image = new Image
  {
    Width = bitmapImage.PixelWidth,
    Height = bitmapImage.PixelHeight,
    Source = bitmapImage
  };

  var pd = new PrintDocument();
  pd.PrintPage += (s, args) =>
    {
      args.PageVisual = image;
    };
  pd.Print();
}

Right, an Image should be printed on the page. But it isn’t. The page is empty. Well, the next thing I tried was to call Measure, Arrange and UpdateLayout on the Image to force a layout-pass. But anyway, it didn’t work, the printed page is always empty.

When the Image isn’t created on the fly, it works. Define the Image in XAML like this

<Image Source="thomas.png" x:Name="image"/>

and a Print-Method in the Codebehind-File would work like that:

void PrintButton_Click(object sender, RoutedEventArgs e)
{
  var pd = new PrintDocument();
  pd.PrintPage += (s, args) =>
    {
      args.PageVisual = image;
    };
  pd.Print();
}

But we want to print an Image on the fly. So how to do that? One way I found out was to create an ImageBrush and set its ImageSource-Property to the BitmapImage. Use the ImageBrush for a Rectangle’s Fill-Property and print out that Rectangle. So here is some code to dynamically print an image by using an ImageBrush in combination with a Rectangle:

void PrintButton_Click(object sender, RoutedEventArgs e)
{
  var streamResourceInfo =
    Application.GetResourceStream(
      new Uri("thomas.png", UriKind.Relative));

  var bitmapImage = new BitmapImage();
  bitmapImage.SetSource(streamResourceInfo.Stream);

  var imageBrush = new ImageBrush();
  imageBrush.ImageSource = bitmapImage;

  var rectangle = new Rectangle
  {
    Width = bitmapImage.PixelWidth,
    Height = bitmapImage.PixelHeight,
    Fill = imageBrush
  };

  var pd = new PrintDocument();
  pd.PrintPage += (s, args) =>
    {
      args.PageVisual = rectangle;
    };
  pd.Print();
}

And voilà, the output looks like this when printed to my PDFCreator-Printer:

[Download the Source]

Cheers Thomas

I’ll give you just a short information of what is coming up next and what I did the last months. Let’s start with the things coming up…

… what’s coming up next:

• WebTech-Conference – 16th November, Karlsruhe/Germany
  Another talk about datadriven Silverlight-Applications. Meet me at this conference for discussions about WPF, Silverlight, .NET in general, my books and other topics. Find more about the WebTech-conference on webtech
• Update of the WPF-book to .NET 4.0 and Visual Studio 2010
  The WPF-book was written about .NET 3.5. Next year .NET 4.0 will be released. There are many new things introduced in WPF. The DataGrid- and DatePicker-Control, VisualStateManager, Animation Easing Functions, Layout Rounding and so on. I’m working on an update of the book that will be released next year shortly after the German Visual Studio Release.
• Writing a german book about Silverlight 4
  Currently I’m working hard on my book about Silverlight 4. I’ve already written about 300 pages. The book will be released next year shortly after the Silverlight 4 release. There are no comments on the Silverlight 4 release, but at PDC in mid-November there’s a session about the Silverlight-Roadmap. Then we’ll know more. So stay tuned. Find more about the upcoming Silverlight-Book on the new silverlight-category on my homepage

… what I did the last months:

• Silverlight-Articles
  I’ve written six articles about Silverlight for the German dotnet-magazine. Download the articles beside others on www.thomasclaudiushuber.com/articles.php.
• PrioConference – 28th October, Munich/Germany
  I had a session about datadriven Silverlight-Applications. Find the Details on the new talks-category on my homepage.

So stay tuned. If you’ve any questions, leave a comment or write me an email via the contact-form on my homepage.

Thomas