This library aims to make implementing Material 2 and Material 3 themes into an Android app as painless as possible.

These use cases are supported:

• Material 2 with custom colors + Material 3 with dynamic colors
• Material 2 with custom colors + Material 3 with dynamic colors + Material 3 with custom colors

Material 2 with fixed colors is not supported, since

• M2 with fixed colors + M3 with dynamic colors is trivial enough to implement that you don't need a library to do that.
• If you offer M3 with custom colors, you also want to offer M2 with custom colors, otherwise it would just be inconsistent.

Material 3 with only custom colors is not supported, since one of its main selling points is the dynamic colors system. It would be strange to offer M3 without that.

Colors

The following custom color schemes are supported:

• Material 2

  • Blue (primary color: #3385ff)
  • Red (primary color: #d8260e)
  • Green (primary color: #00c71e)
  • Purple (primary color: #7700f6)
  • Orange (primary color: #ff8800)
  • Pink (primary color: #e700ef)

• Material 3

  • Blue (primary color: #005bc0)
  • Red (primary color: #bc1400)
  • Green (primary color: #006e0b)
  • Purple (primary color: #7a0df9)
  • Orange (primary color: #924c00)
  • Pink (primary color: #a700ad)

All other colors in a scheme (secondary colors, etc.) are derived from the primary colors mentioned above.

Usage

Create a definition for each theme that inherits the library's:

<style name="MyAppTheme.Material2" parent="AppTheme.Material2">
    <!-- Your attributes here -->
</style>

<style name="MyAppTheme.Material3.DynamicColors" parent="AppTheme.Material3.DynamicColors">
    <!-- Your attributes here -->
</style>

<style name="MyAppTheme.Material3.CustomColors" parent="AppTheme.Material3.CustomColors">
    <!-- Your attributes here -->
</style>

In your Activity subclass, call applyTheming or applyThemingWithoutM3CustomColors in onCreate:

class MyActivity : AppCompatActivity() {
    
    override fun onCreate(savedInstanceState: Bundle?) {
        val preferences: ImmutableThemingPreferencesSupplier
        applyTheming(
            material2ThemeStyleRes = R.style.MyAppTheme_Material2,
            material3CustomColorsThemeStyleRes = R.style.MyAppTheme_Material3_CustomColors,
            material3DynamicColorsThemeStyleRes = R.style.MyAppTheme_Material3_DynamicColors,
            preferencesSupplier = preferences
        )
    }
    
}

public class MyActivity extends AppCompatActivity {
    
    public void onCreate(Bundle savedInstanceState) {
        ImmutableThemingPreferencesSupplier preferences;
        ActivityTheming.applyTheming(
                R.style.MyAppTheme_Material2,
                R.style.MyAppTheme_Material3_CustomColors,
                R.style.MyAppTheme_Material3_DynamicColors,
                preferences
        );
    }
    
}

ImmutableThemingPreferencesSuppliers and ImmutableThemingPreferencesSupplierWithoutM3CustomColors (or specifically their mutable counterparts, ThemingPreferencesSupplier and ThemingPreferencesSupplierWithoutM3CustomColor) can be created from SharedPreferences and PreferenceDataStore using the preference integration library.

Of course, you can create custom implementations of those too.

Extras

• Custom attributes that map to different styles depending on whether the theme currently used is M2 or M3:
  • themeDependantTitleStyle
  • themeDependantFilterChipStyle
  • themeDependantInputChipStyle
  • themeDependantSuggestionChipStyle
  • themeDependantAssistChipStyle
• "Fallback" themes to help with fragment testing in case any of the above attributes are used, as said themes allow to avoid having to redefine them.

For example:

Your theme:

<style name="MyAppTheme.Material2" parent="AppTheme.Material2">
    <item name="yourCustomAttribute">foo</item>
</style>

Your layout references yourCustomAttribute and one or more library attributes, in this case themeDependantTitleStyle.

When it comes to fragment testing, your test theme instead of

<style name="MyAppTheme.Material2.Test" parent="Theme.MaterialComponents.DayNight.NoActionBar">
    <item name="yourCustomAttribute">foo</item>
    <item name="themeDependantTitleStyle">@style/TextAppearance.AppCompat.Title</item>
</style>

can simply be

<style name="MyAppTheme.Material2.Test" parent="AppTheme.Material2.Fallback">
    <item name="yourCustomAttribute">foo</item>
</style>