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I have been having issues with the DownloadCompleted and DownloadFailed events failing to fire correctly from the BitmapImage object. This is a huge issue as the asynchronous processing of images is central to many types of WPF apps. Having events failing to fire correctly will likely have a rather large negative impact on these apps.

The problem is easily recreated. Iterate through any number of BitmapImage creations, subscribe to the DownloadCompleted and DownloadFailed events, and track the number of DownloadCompleted + DownloadFailed events which fire vs the number of events subscribed to. Those numbers should always add up.

In my testing the events only fire correctly on the first full iteration. After the first iteration they will never fire again. Ever. The event subscriptions are simply going into a black hole. Verify for yourself. You can create your own app or just use my test app.

I’d be interested to hear the results of everyones testing.

-MGE

Here is the updated source code for the PostItBoard WPF example app so that it compiles and runs on the latest NET 3.0 / WPF RC1. Or if you are only inerested in the binaries you can grab those too. In addition, apologies to everyone who asked me about the source code for the flickr assemblies that were missing from the previous release. This release has all the source code and projects.

Please drop me a line if you have any problems running this WPF example application.

Note: I get quite a few emails asking me if the image above is an actual screenshot of the application or if it was photoshopped. The image was in no way photoshopped. It is the application as it appears at runtime.

Cheers!

Michael G. Emmons

Click the image to run the WPF ScrollingCanvas example xbap or you can get the source code for it. This example creates a custom user control based on the Canvas container. This ScrollingCanvas allows you to scroll any FrameworkElement: text, video, shapes, or even whole scenes. Moreover, you can scroll multiple FrameworkElement objects at the same time in a single scroll container.Both speed and direction of the scroll is controllable via dependency properties. Simply drop the ScrollingCanvas control on the design surface or add it in XAML, add any FrameworkElements you want to scroll to the ScrollingCanvas container and call the ScrollBegin() method. All object scrolling is handled through local animations in the C# codebehind.

Greetings from Italy! I’m still on vacation enjoying Rome, so no new examples from me. However, Kevin Moore left a note indicating that the KevinButton source code, which my SmileyButton was based on, is now available from Kevin’s  Bag-o-Tricks RC1. It has a lot of cool stuff besides the KevinButton, so check it out! Head on over to Kevin’s Blog and peruse some screen shots of it.

 -MGE

Here are the project files for the SmileyButton WPF example. Enjoy!

 If you have any problems with this or any of my other WPF examples, drop me a line.

-Michael G. Emmons

Here is the XAML source code for the SmileyButton control templating xbap example which I showed in my previous post.

I still see lots of questions on how to make a main application window transparent or semi-transparent. This was a bit involved in versions of WPF previous to the June CTP and was not very practical because it could not be rendered in hardware. But functionality added to WPF since has made it easy to accomplish and it supports hardware rendering when available. All you need to do is to base your main scene on the Window class and add the following code to the constructor:

this.WindowStyle = WindowStyle.None;
this.AllowsTransparency = true;
this.Background = new SolidColorBrush(System.Windows.Media.Color.FromArgb(0, 34, 34, 34));

Note that the amount of transparency, or more correctly, opaqueness, is set by the alpha channel which is the first number in the FromArgb method. Setting the alpha channel to 1.0 would be 100% opaque. 0 is 0% opaque and .5 is 50% opaque.

-MGE

Here is the source code for the PostIt Board WPF Example. This was compiled under the July CTP of WPF. The Visual Studio 2005 solution file was built with the June CTP of Orcas. Feel free to drop me a line if you have any questions or comments.