Archive for the ‘Silverlight tips and tricks’ Category

Silverlight provides a variety of brushes that can be used to paint just about any area in your app: from text to shapes to borders. The most common brushes are for painting color and images: SolidColorBrush, LinearGradientBrush, RadialGradiantBrush, and ImageBrush.

However, today I paired the less common VideoBrush with an unusual visual element. Click below to see a demonstration of a fun and novel use of the VideoBrush in Silverlight:

Video Jigsaw Puzzle


Note: PuzzleTouch also now allows you to create your own video puzzles using .wmv or .mp4 files. All work is done 100% on the client! To create your own video puzzle, go to the Online Jigsaw Puzzles by PuzzleTouch homepage, choose “Custom Puzzle”, and have fun!

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Here’s a new panel to add to your tool chest. It’s one I expect to use almost daily and save approximately 3.1 hours of typing over the next year. Hopefully you’ll find it useful as useful as I think it is.

What’s wrong with the built-in StackPanel:

You can’t get children to conform to the size of the panel. Imagine you want the following label and list but want the height of the Listbox to stretch or shrink according to the room available:

At first glance, a StackPanel would seem to be the natural choice for which panel to accomplish this. Afterall, you just want a linear list of two objects: a TextBlock and ListBox. However, unless you are willing to hardcode the size of the ListBox or resize it with code, with a StackPanel you’ll end up with:

Yuck! Clipping instead of a scrollbar. So how do you get the desired behavior?

Answer: Grid.

So what’s wrong with a Grid?

  1. Grids take more lines xaml to create. Compare the StackPanel Xaml to the Grid’s above and notice the 4 extra lines of Xaml. Ok, not a huge deal but if you’re doing this every day like me, you start to get sick of creating RowDefinition and ColumnDefinition objects.
  2. With a grid you have to explicitly define the order of the children. Adding the attached property Grid.Row is easy on your first pass but what happens if you want to insert a new row somewhere in the middle. You not only have to add a new RowDefinition, but you also have to remember to go increment the row number on all subsequent siblings. This is a pain and error prone because a sibling would potentially be defined in any order in the grid.

Wouldn’t it be great if you could get the best of both worlds?

What we really want here is a StackPanel that allows you to define the size of the children.

Welcome SuperStackPanel:

Just set the attached property StackPanel.Length to “*” to get a child to stretch.

In fact, SuperStackPanel lets you use all the same GridLength values you can use in a Grid (Auto, *, n*, and x):

Have I sold you yet? The nice part is that SuperStackPanel is completely compatible with a normal StackPanel. Just swap out your StackPanel for SuperStackPanel and everything will look the same because the default value of Length is “Auto”. Frankly, I’d love to see Microsoft expand the role of StackPanel to support this natively. Of course, until then, there’s SuperStackPanel.

SuperStackPanel is lightweight and simple to add to your project, just download the C# source code, add to your project, add the namespace to your xaml and away you’ll go. Enjoy!

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I’m always looking for ways to take advantage of Silverlight to accomplish tasks that traditional web technologies can’t. Here’s one that will save you money, increase scalability, and improve your user’s experience

Allowing users to upload images is becoming common place for many websites and applications today. Equally common is the fact that most cameras and phones today produce very large and high quality images. On the other hand, very rarely do you actually want a high resolution / low compression image sitting on your server; nor does the average user know or care enough to manually reduce the size of their image before uploading it to your site.

Therefore, unless you’re lazy or in “get it done” mode, you are probably going to want to shrink the image and even increase the compression on that image before storing it on your server. Doing so will result in faster downloads of that image which means lower bandwidth costs and a better user experience.

The typical (and only option for standard Javascript+HTML based sites) is to do the work on the server. But wouldn’t it be great if you could do this work on the client BEFORE sending it up to your server!? Doing so would 1) decrease the time it takes to upload the image in the first place, 2) decrease the amount of work required by your server; thereby increasing scalability of your site, and 3) decrease the bandwidth used by both you and your user; thereby saving you money.

Silverlight has your answer! Here’s how:

Step 1) Use the OpenFileDialog to acquire the stream that contains the bytes of the image.

OpenFileDialog openDialog = new OpenFileDialog();

openDialog.Filter = “JPEG Files (*.jpg;*.jpeg)|*.jpg;*.jpeg”;

if (openDialog.ShowDialog().GetValueOrDefault(false))


    using (FileStream stream = openDialog.File.OpenRead())


        // now you have the filestream



Step 2) Create a WriteableBitmap from those bytes using a ScaleTransform to shrink the image.

public static WriteableBitmap GetImageSource(Stream stream, double maxWidth, double maxHeight)


    BitmapImage bmp = new BitmapImage();



    Image img = new Image();

    img.Effect = new DropShadowEffect() { ShadowDepth = 0, BlurRadius = 0 };

    img.Source = bmp;


    double scaleX = 1;

    double scaleY = 1;


    if (bmp.PixelHeight > maxHeight)

        scaleY = maxHeight / bmp.PixelHeight;

    if (bmp.PixelWidth > maxWidth)

        scaleX = maxWidth / bmp.PixelWidth;


    // maintain aspect ratio by picking the most severe scale

    double scale = Math.Min(scaleY, scaleX);


    return new WriteableBitmap(img, new ScaleTransform() { ScaleX = scale, ScaleY = scale });


Note: I’m still investigating the need for setting the Effect property on your image control. While this code does not actually affect the user’s image, it is necessary to get this to work. Maybe a bug in Silverlight 3?

Step 3) Encode the WriteableBitmap object back to a Jpeg using FJCore and set your compression quality.

Stream Source = Encode(wb, 20);

public static Stream Encode(WriteableBitmap bitmap, int quality)


    //Convert the Image to pass into FJCore

    int width = bitmap.PixelWidth;

    int height = bitmap.PixelHeight;

    int bands = 3;


    byte[][,] raster = new byte[bands][,];


    for (int i = 0; i < bands; i++)


        raster[i] = new byte[width, height];



    for (int row = 0; row < height; row++)


        for (int column = 0; column < width; column++)


            int pixel = bitmap.Pixels[width * row + column];

            raster[0][column, row] = (byte)(pixel >> 16);

            raster[1][column, row] = (byte)(pixel >> 8);

            raster[2][column, row] = (byte)pixel;




    ColorModel model = new ColorModel { colorspace = ColorSpace.RGB };


    FluxJpeg.Core.Image img = new FluxJpeg.Core.Image(model, raster);


    //Encode the Image as a JPEG

    MemoryStream stream = new MemoryStream();

    JpegEncoder encoder = new JpegEncoder(img, quality, stream);




    //Move back to the start of the stream


    stream.Seek(0, SeekOrigin.Begin);

    return stream;


Step 4) Send the stream for the new, potentially MUCH smaller Jpeg up to your server!

byte[] buffer;

using (Stream Source = JpgEncoder.Encode(wb, 50))


    int bufferSize = Convert.ToInt32(Source.Length);

    buffer = new byte[bufferSize];

    Source.Read(buffer, 0, bufferSize);



Service1Client service = new Service1Client();


That’s it! Plug this code into your Silverlight app everywhere you upload images and improve your website!

Download the source code here.


Kudos to the folks that made FJCore for sharing all their hard work with those of us that would never consider trying to build it ourselves!

Kudos to nokola for finding a way to build a WriteableBitmap object from an image control without touching the VisualTree.

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UPDATE: The results are in and PuzzleTouch won the grand prize! I had some tough competition so I am extra excited to have won.

The ComponentArt Silverlight Coding Contest results are in for the five finalists and I am super excited to annouce that my creation: PuzzleTouch Online Jigsaw Puzzles made the cut! Thanks to all who voted for me!

If you haven’t see PuzzleTouch yet, check it out. It’s as fun to play as it was to write and is a great testament to what Silverlight is capable of producing.

PuzzleTouch Free Online Jigsaw Puzzles

It’s the only online jigsaw puzzle on the web that supports 360 degree rotation, 100% mathamatically unique shapes, unlimited levels of difficulty, full multi-touch support (my favorite for those that have the hardware!), out of browser mode, the ability to save games, and the ability to run offline (great for planes, trains, and autos).

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Silverlight apps are nothing more than big zip files and Amazon S3 is dirt cheap and hyper-scalable. Why would you ever host your Silverlight .xap files on your own server or ISP? … especially with Silverlight Streaming being dropped soon.

Here’s a quick guide to putting your Silverlight apps on Amazon S3 and depending on your app, never worry about scalability or bandwidth costs again…

1) Create your Amazon S3 account.

2) Install S3 Organizer FireFox plugin (this is the equivelent of an FTP client for Amazon S3).

3) Run S3 Organizer, log into your account and create your bucket.

Create a bucket in S3 Organizer via the toolbar

4) Upload your xap file to your bucket. BUT… you must add custom headers unless you are also going to host your .html file there too. Silverlight xaps need a MIME type specified when they are loaded from another domain. The good news is, this is easy with S3 as long as you do it at the time that you upload the file. There is probably a way to set it after the fact but not with S3 Organizer.

Upload your .xap file to Amazon S3 but don't forget to add custom headers

Set the content type for your xap file

Simply set the content type to ‘application/x-silverlight-app’ and send up your xap. Don’t forget to do this EVERY time you upload an update.

5) After uploading your .xap file, set permissions so everyone can read your xap file. Right click on your newly uploaded xap file and choose “Edit ACL…”. Then check Read access for Everyone and Authenticated Users. You do NOT need to do this every time as S3 remembers your ACL settings.

Edit ACL settings in S3 Organizer for your xap file

6) Add the enableHtmlAccess param to your object tag within your html file to enable access to the DOM bridge (assuming your Silverlight app needs access to the DOM bridge).

For example:

Set EnableHtmlAccess param in the object tag

7) Change your html page to load your xap file from S3 directly by setting the source param in your object tag.

For example:

Change the source of your xap file to load from S3

Note: ‘mybucket’ is the name of your bucket on S3.

8 ) Upload your html (or aspx) page to your web server. GoDaddy.com offers cheap hosting for only $5 per month.

That’s it! At this point, the only scalability concerns you should have are those of your web services (assuming you call web services from your Silverlight app).

And with S3, the costs depend on the usage — which will literally cost you just pennies per month until you have some descent traffic. Do the math and you’ll see that it would only cost 17 cents to have a  300K .xap get hit 3500 times. At that rate you’d pay ~$48 to have 1 million new users per month. (I say “new” users because unless you update your xap, users should be caching your xap file and won’t need to re-download it).

Happy cheap hosting and Silverlight coding!

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Thanks to all who attended my presentation tonight at the Eugene .NET users group (EADNUG)! There were many great questions I had a fantastic time showing off all the cool things Silverlight can do.

Click here to get all the fun little projects covered (and a few we didn’t have time for).

See you again at the next meeting.

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In case you haven’t heard, Google just debuted Google Chrome Frame; allowing developers to run the Google Chrome rendering engine inside IE as a plugin and thereby trumping IE.

Reading blogs like this one, I distinctly get the feeling that most of the tech journalists out there don’t understand what this is really all about. This is not about Google being annoyed with old versions of IE, it’s about HTML5 vs. Silverlight vs. Flash. Right now HTML5 has 3 big disadvantages over their plugin counterparts…

  1. Different browsers will implement HTML5 differently. Even if it is standards based. 
  2. Most browsers don’t support HTML5 and getting a user to switch browsers is a lot harder than getting them to install a plugin.
  3. Standards based innovation is slow. HTML5 in its entirety should be ready for browsers to implement in 2012; just in time to be as far behind Flash and Silverlight as HTML4 is today.

In the end, there are only 2 ways around all of these disadvantages:

  1. Either get everyone to use your browser or
  2. Run everything thru a plugin.

Google Chrome (the browser) and Google Chrome Frame together make it possible for developers to write and test code in an IE-less world, thereby getting more developers to care about Chrome, less to care about IE, and more to choose HTML5 as a framework to develop apps on.

Right now the plugin is an ActiveX plugin and therefore only works on IE, but give Google some time and I’m sure they’ll have a Netscape plugin too that will work in Safari and Firefox. It’s only a matter of time before you Google will be nearly in complete control over how HTML5 will be rendered (if the developer chooses so) and thereby won’t need to wait on a standards committe to approve further innovation to HTML.

Of course, the picture is even bigger than that… whoever owns the developers will own the dominant OS. In my opinion, this is all a tactic in the Android/Chrome OS vs. iApple vs. Windows war and the reason Google built Chrome in the first place.

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Silverlight 3 introduces the WriteableBitmap class and with it, the ability to crop an image programmatically on the client!

All you need to do is create a new instance of the WritableBitmap class as your destination (supplying the dimensions in the constructor). Then create or acquire another instance of the WriteableBitmap class fully loaded with an image (among other ways, you can do this by creating a BitmapSource object from a stream via .SetSource and passing that BitmapSource instance into the constructor of a new WriteableBitmap)

Once you have your source and destination WriteableBitmap classes, just retrieve one pixel at a time from the source instance and set that pixel on a destination instance. The pixels are stored in a property on the object call Pixels which is a 1 dimensional array. Geting the index of a given pixel in an array is simple: index = x + y * width.

In my first pass, I just looped thru pixel by pixel. This was fast but not as fast as using Array.Copy (almost twice as fast)…

private static WriteableBitmap CropImage(WriteableBitmap Source, int XOffset, int YOffset, int Width, int Height)


    int SourceWidth = Source.PixelWidth;

    WriteableBitmap Result = new WriteableBitmap(Width, Height);

    for (int y = 0; y <= Height – 1; y++)


        int SourceIndex = XOffset + (YOffset + y) * SourceWidth;

        int DestIndex = y * Width;


        Array.Copy(Source.Pixels, SourceIndex, Result.Pixels, DestIndex, Width);


    return Result;


The result (a WriteableBitmap) can then simply be used as the source of an Image control to display your cropped image.

Note: WriteableBitmap.PixelWidth is expensive. Be sure to call it only once if possible.

Possible Improvement: Had the source width and destination width been the same I could have done it in a single call to Array.Copy and presumably made it even faster.

It’s high time that web developers are able to do complicated tasks on the client and not forced to use the server just because the client-side platform doesn’t support it. We’re still not all the way there yet but Silverlight gets us a lot closer than anything before it.

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How many people have Silverlight installed? According to Rich Internet Application Statistics, Silverlight is installed on 30.27% of the machines out there. However, I’ve been tracking stats on my own site: MyPadlock.com (a free password manager for Windows) and have seen a much different number. Here are my results from the previous month:


Find out more about tracking Silverlight usage over Google Analytics.

Caveats: There are a number of differences that could account for why I’m seeing a larger percentage than the Rich Internet Application Site. First of all, I doubt I have the same volume of traffic being tracked. However, I do have a fairly healthy volume, most of my visitors are not repeat, and the numbers have shown relative consistency from month to month, so think what you like, but I’m going to rule this out as a relevant factor.

Also note that my site does not use Silverlight in anyway nor does it receive any real traffic from a source that uses Silverlight. Oh, and my own visits are not counted either.

Most likely, the difference is due to differences in audiences. Certainly, a password manager is the kind of software that power users would use for more than novice users. Also, power users are probably more apt to explore new corners of the web are therefore more likely to have encountered Silverlight at some point. And lastly, my site gives away a Windows only app and perhaps Windows users are more likely to have Silverlight installed (might be a reach but worth speculating).

Nevertheless, whatever the reason is, I still belive the statistic is valuable and at the very least, tells me what to loosely expect for anyone thinking of porting a Windows app to Silverlight.

What kind of numbers are you seeing? I’d love to hear from anyone with access to similar stats for their own site(s).

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I just finished one of the coolest and most exciting apps I’ve ever written and the client-side was done in 100% native Silverlight 2. Fortunately, I was able to get it done just in time to debut for the NewCloudApp Windows Azure contest.

It’s an online jigsaw puzzle and it was as fun to write as it is to play. You can choose from over a hundred images or use your own photo, select practically any number of pieces (I recommend 12 to start), and even send puzzles to your friends.

Click the link below to check it out and tell your friends if you like it!

PuzzleTouch Online Jigsaw Puzzles

I can’t wait to write more about why I chose Silverlight for this project (really, why Silverlight was the only platform up for the job) and all the new things I learned along the way. But for now, go forth and play puzzles.

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