Adding new accent colors and brushes (MahApps) - xaml

Question

I'm in the process of converting an application to use the MahApps colour and brush resources, to allow us to programmatically change the application theme/accent.
I need a very pale accented background colour (which will be used in dozens of places, and by different types of control), but the palest MahApps colour ("AccentColor4") isn't light enough. Short of modifying the MahApps library, is there any way to create additional Color and Brush resources in my application that would somehow be able to alter their colour based on the current MahApps accent?

Answer 1

In your case, I think I'd add a new key to my Accent (maybe AccentColor5?) based on the AccentColor4 value.
Here you can find a ThemeManagerHelper class made by punker76, which might help you calculating AccentColor5 from AccentColor4 (see CreateAppStyleBy method).
I also made this, which should make your life easier:
private void AddKeyForCurrentAccent(object key, object value, bool changeAccentImmediately = false)
{
Tuple<MahApps.Metro.AppTheme, MahApps.Metro.Accent> currentAppStyle = MahApps.Metro.ThemeManager.DetectAppStyle(Application.Current);
if(currentAppStyle.Item2.Resources.Contains(key))
{
currentAppStyle.Item2.Resources.Remove(key);
}
currentAppStyle.Item2.Resources.Add(key, value);
if(changeAccentImmediately)
{
var accentName = string.Format("CustomTheme.xaml");
CreateAccentFrom(accentName, currentAppStyle.Item2.Resources);
MahApps.Metro.ThemeManager.ChangeAppStyle(Application.Current, MahApps.Metro.ThemeManager.GetAccent(accentName), currentAppStyle.Item1);
}
}
private void CreateAccentFrom(string accentName, ResourceDictionary resourceDictionary)
{
var fileName = System.IO.Path.Combine(System.IO.Path.GetTempPath(), accentName);
using (var writer = System.Xml.XmlWriter.Create(fileName, new System.Xml.XmlWriterSettings { Indent = true }))
{
System.Windows.Markup.XamlWriter.Save(resourceDictionary, writer);
writer.Close();
}
resourceDictionary = new ResourceDictionary() { Source = new Uri(fileName, UriKind.Absolute) };
var newAccent = new MahApps.Metro.Accent { Name = accentName, Resources = resourceDictionary };
MahApps.Metro.ThemeManager.AddAccent(accentName, newAccent.Resources.Source);
}
AddKeyForCurrentAccent will add (or replace - if it already exists) a key in the current Accent for the application.
If changeAccentImmediately is set to true, it will create a new file and save the new Accent (with the inserted/replaced keys) and set it as the Accent for the application
TIP: You can add/replace all the keys you want and set changeAccentImmediately to true only on the last one (this should improve performance).
Use it like this:
AddKeyForCurrentAccent("AccentColor5", Brushes.Pink); // Does not replace the accent immediately (so changes are not visible) - works faster
// AND/OR
AddKeyForCurrentAccent("AccentColor5", Brushes.HotPink, true); // Will update the UI
IMPORTANT: Please note that if you use your custom keys, and you forget to add it to your Accent, it'll use the default value for that type.
Good luck!