Eclipsed4utoo's Blog

This is a short code snippet on creating an animation in WPF through code.

In my Twitter app that I have been working on, I was recently doing some optimizations.  When I first did the app, I was new to WPF and knew nothing about animations.  After spending time in Silverlight, I used that knowledge to do some animations in WPF.

I wanted to do simple “fade-in” and “fade-out” animations when removing tweets from view and adding new tweets to the view.   And being the person that I am, I like doing this stuff in code.  While I like XAML a lot, I still like writing the code.  So here is how to do an animation that changes the Opacity property programmatically.

// because I am doing these as extension methods, they
//   will be available to all UIElement objects, which are
//   basically all controls that can be added to the GUI
public static class ControlAnimationExtensionMethods
{
    public static void FadeIn(this UIElement targetControl)
    {
        DoubleAnimation fadeInAnimation = new DoubleAnimation(0, 1, new Duration(TimeSpan.FromSeconds(1.5)));
        Storyboard.SetTarget(fadeInAnimation, targetControl);
        Storyboard.SetTargetProperty(fadeInAnimation, new PropertyPath(UIElement.OpacityProperty));
        Storyboard sb = new Storyboard();
        sb.Children.Add(fadeInAnimation);
        sb.Begin();
    }

    public static void FadeOut(this UIElement targetControl)
    {
        DoubleAnimation fadeInAnimation = new DoubleAnimation(1, 0, new Duration(TimeSpan.FromSeconds(1.5)));
        Storyboard.SetTarget(fadeInAnimation, targetControl);
        Storyboard.SetTargetProperty(fadeInAnimation, new PropertyPath(UIElement.OpacityProperty));
        Storyboard sb = new Storyboard();
        sb.Children.Add(fadeInAnimation);
        sb.Begin();
    }
}

This code is useful when dynamically creating controls that you want to do animations on.

TextBlock tb = new TextBlock();
tb.Name = "textBlock1";
// set more property values

tb.FadeIn();

This is going to be a real short post about an issue that I ran into recently with WPF.

I was wanting to use an app config file with my WPF application.  I was running into an issue with the ConfigurationManager calls not getting the information from the app config file.

I added the app config just like I would in a Windows Form..

My app config file looked something like this…

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
     <add key="myKey" value="SomeValue" />
  </appSettings>
</configuration>

I was using the standard code that works fine in Windows Forms(needed to add a reference to the System.Configuration):

using System.Configuration

private void Window_Loaded(object sender, RoutedEventArgs e)
{
     var myKey = ConfigurationManager.AppSettings["myKey"];
}

However, the app settings were not being found.  After scratching my head for a while and searching numerous places online, I found a small response on a forum.  None of the “MVP”s picked up on it.  It was because of the name of the app config file.  By default, VS2008 added the file as “App1.config”.  For some reason, the ConfigurationManager class looks for a file named exactly “App.config”.

So simply changing the name of the config file to “App.config” fixed the issue and the code started working.

I have released a BETA version of my Twitter Desktop Client called TwitEclipse.  I have been writing a Twitter API library in .Net for a while now, and figured I might as well write a desktop client also.

The client uses .Net 3.5 SP1 and WPF.  It was a great learning experience to learn WPF since I had almost no previous experience with it.

If you want to download it and test it out, you can download it from here.  Remember that it is a BETA.  You could run into issues.  If you do, be sure to let me know so I can fix them.  I will also be adding additional features to the app once I get a chance.

I will be releasing my Twitter API library soon also.