Import from MahApps: Accent color when Windows determines the accent color itself

https://github.com/MahApps/MahApps.Metro/issues/4156

Describe the bug

Windows 10 has an option:

“Automatically select an accent color from my background”.

This will select an accent color based on the background. But the color that MahApps / ControlzEx then sets is unfortunately not the same one that Windows then uses 😕

Maybe the error is also in “ControlzEx”. But since I only used MahApps I post it here 😃

Steps to reproduce

• create a project (.net 5 for example)
• include MahApps.Metro
• Overwrite “OnStartup” in the App.xaml.cs" and add the following:

ControlzEx.Theming.ThemeManager.Current.ThemeSyncMode = ControlzEx.Theming.ThemeSyncMode.SyncAll;
ControlzEx.Theming.ThemeManager.Current.SyncTheme();

• In Windows, set the “Automatically select an accent color from my background” setting.

• Compare accent colors

Expected behavior

That the accent color MahApps.Metro uses is the same as in Windows.

Actual behavior

The accent color MahApps.Metro uses is not the same as in Windows. (Usually a little darker than the current color)

Environment

MahApps.Metro version: v2.4.7
Windows build number: Win10 21H1 [Version 119043.1151]
Visual Studio: 2019 16.10.4
Target Framework: .Net Core 5.0 (but also happens in other versions)

Screenshots

Example project

MahAccent.zip

Not really useful, but here it is when needed 😃

[batzen]

@Rerago @punker76 I was able to find out what’s wrong. As we implemented the WindowsThemeHelper and as we designed everything else around accent colors we were under the assumption, at least i was, that there is only one accent color. That’s not the case. Windows stores different accent colors for different things. The accent color we want/have to use is stored under HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent\AccentPalette which is a byte array and stores the value of interest at index 0x0C, 0x0D and 0x0E.

Simplified this means: There is one accent color for the titlebar, which is also the only one we currently use, and one accent color for content inside windows. More complex: There are various accent colors, or variations of it, available for various things.

Simple solution: We switch from using the titlebar accent color to using the content accent color and everything works as currently expected.

More complex solution: We do the simple solution and in addition to that introduce the concept of different accent colors for content and the titlebar. This is what i will do in ControlzEx as that’s the basic building block for theming in MahApps.Metro and Fluent.Ribbon. We then would need to make changes to MahApps.Metro and Fluent.Ribbon to make use of the provided values. The newly provided values would at least be the titlebar color and an ideal foreground color for that. Maybe we can provide even more accent colors from ControlzEx, but that’s a thing i will have to figure out while implementing and visualizing the available colors.

Plan: Implement the simple solution as it’s a, from my point of view, non breaking change (we just use the expected value) and is easy to implement. After that i will start the more complex solution as that also requires breaking API changes, as we now need to transport more than one color. To make that possible i will most likely introduce a new type as a replacement for Color accentColor. I think i will introduce a new class similar to UISettings from Windows.UI.ViewManagement which could then have properties like Accent, AccentLight1, AccentLight2, AccentDark1, IdealForeground, TitleBar, TitleBarForeground etc.

[Rerago]

First of all, thank you for the detailed investigation of the problem.

I think the plan sounds very good for now. With this we would have solved the accent problem for the time being. But also the more complex solution sounds very good for later use. I’m very curious what possibilities this brings with it.