Windows Store

Windows Store Apps: Application Tile Colour Within an App

When you define your package manifest for a Windows Store app you can specify the background colour used for your tile. Chances are this is a brand colour which you want to use throughout your app. You could specify it twice – once in the manifest and once in a XAML resource. However imagine the scenario where you are creating a custom control and need to use this colour without actually having access to the executing app code. The solution is quite simple and involves reading the compiled manifest from within your executing app package. The file in question is called AppxManifest.xml. We can use an XmlReader to locate the specific attribute we need. I wouldn’t poke around for too many things in this file as most of this information is accessible through the Windows.ApplicationModel.Package class. The code below (error checking removed for clarity) shows the steps to open the file for reading, locating the required Element and reading the “BackgroundColor” attribute. This string contains an RGB value in HEX notation so we can extract the Red, Green and Blue values and save to a Color. I’ve saved this to the apps Resources dictionary with the name “AppAccentBrush”.

Stream s = await Windows.ApplicationModel.Package.Current.InstalledLocation.OpenStreamForReadAsync("AppxManifest.xml");
System.Xml.XmlReader reader = System.Xml.XmlReader.Create(s);
reader.ReadToDescendant(<"VisualElements", "");
string attr = reader.GetAttribute("BackgroundColor");
byte r, g, b;
r = byte.Parse(attr.Substring(1, 2), System.Globalization.NumberStyles.HexNumber);
g = byte.Parse(attr.Substring(3, 2), System.Globalization.NumberStyles.HexNumber);
b = byte.Parse(attr.Substring(5, 2), System.Globalization.NumberStyles.HexNumber);
accentColor = Windows.UI.Color.FromArgb(0xff, r, g, b);
this.Resources.Add("AppAccentBrush", new SolidColorBrush(accentColor));

What else might you want to use this for? Well one feature we found annoying was that regardless of your colour scheme the indeterminate progress bar uses a default colour. As it turns out this is defined in the ProgressBarIndeterminateForegroundThemeBrush resource. You can access this Brush and modify its colour to match your tile colour.

 var brush = this.Resources["ProgressBarIndeterminateForegroundThemeBrush"] as SolidColorBrush;
 brush.Color = accentColor;

By Peter Foot

Microsoft Windows Development MVP