Month: June 2011

Global ProgressBar in WP7

I quite like to have a global Performance Progress Bar in my Windows Phone 7 apps so the user has a consistent frame of reference when I’m interacting with web services. The requirements are simple, a progress bar that appears on all pages without any special requirements (ie. no custom controls, special code snippets, etc.). It should be managed in one place, and be easy to extend. Fortunately the extreme flexibility Silverlight offers makes this a doddle:

First add the following style to your App.xaml file:

<Style x:Key="mainFrameStyle" TargetType="phone:PhoneApplicationFrame">
    <Setter Property="Template">
            <ControlTemplate TargetType="phone:PhoneApplicationFrame">
                <Border x:Name="ClientArea"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        Background="{TemplateBinding Background}"
                        HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
                        VerticalAlignment="{TemplateBinding VerticalAlignment}">
                            Foreground="{StaticResource PhoneAccentBrush}"
                                ContentTemplate="{TemplateBinding ContentTemplate}"
                                Content="{TemplateBinding Content}"
                                HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
                                HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                                VerticalAlignment="{TemplateBinding VerticalAlignment}"
                                VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
                                Margin="{TemplateBinding Padding}">

Next go into the code behind, and add the following variable to the top of the class:

private PerformanceProgressBar _globalProgressBar = null;

Next add the following methods to the bottom the App class:

private void globalProgressBar_Loaded(object sender, RoutedEventArgs e)
    _globalProgressBar = sender as PerformanceProgressBar;

public void ShowProgressBar()
    if (_globalProgressBar != null)
        _globalProgressBar.Visibility = Visibility.Visible;

public void HideProgressBar()
    if (_globalProgressBar != null)
        _globalProgressBar.Visibility = Visibility.Collapsed;

Now find the InitializePhoneApplication() method, and amend the RootFrame instantiation code to the following:

RootFrame = new PhoneApplicationFrame()
    Style = (Style)Resources["mainFrameStyle"]

And you’re done! You can call the progress bar like so:


You can download the sample project here for your reference.

Update: This method for displaying a global ProgressBar doesn’t always play well with the WP7 Toolkit Transitions. However, I would highly recommend using the WP7Contrib Transitions anyway (they work well with the global ProgressBar too). I’ve created a 3-part guide on the transitions here.

Posted by Dan in C#, Guides, Windows Phone, 3 comments

LongListSelector ListFooterTemplate {Binding} Resolves to NULL

It’s quite common to have a ‘More’ button at the end of long lists within a LongListSelector. The problem is the template inexplicably doesn’t cascade the DataContext, so you have no access to the collection to trigger a more command. Fortunately the workaround is simple, albeit you can’t use pre-defined DataTemplates.

<toolkit:LongListSelector x:Name="SimilarList" ItemTemplate="{StaticResource GeneralCatalogListItemTemplate}" SelectionChanged="SimilarList_SelectionChanged" DataContext="{StaticResource dummyCatalogTitlesList}" ItemsSource="{Binding}" IsFlatList="True">
            <bindings:CommandButton Content="More..." Command="{StaticResource moreCommand}" DataContext="{Binding ElementName=SimilarList, Path=DataContext}" CommandParameter="{Binding}" />

You need to give your list a name, then when setting the DataContext for your controls make sure to provide the ElementName as seen above.

I’m not sure why the other templates cascade correctly and this one doesn’t, but I’m hopeful it’ll be fixed in a future release of the toolkit. As an aside there is a fairly clean workaround if/when MS add the Freezable class to WP7.

Posted by Dan in C#, Windows Phone, 2 comments