How does the theme system of the App work?

[xfqwdsj]

The theme of LSPosed App is very beautiful, and I plan to use this theme system in my application. But when I work to night mode, I found that it will not automatically switch to night mode anyway, manual switching is effective.

Example Activity:

package com.xfq.easytest.activity

import com.xfq.easytest.activity.base.BaseActivity

class MainActivity : BaseActivity() {
    //My codes.
}

BaseActivity:

package com.xfq.easytest.activity.base

import android.content.res.Resources
import android.content.res.Resources.Theme
import android.graphics.Color
import android.os.Build
import com.xfq.easytest.util.ThemeUtil
import rikka.core.util.ResourceUtils.resolveColor
import rikka.material.app.MaterialActivity


open class BaseActivity : MaterialActivity() {
    override fun onApplyUserThemeResource(theme: Theme, isDecorView: Boolean) {
        theme.applyStyle(ThemeUtil.getNightThemeStyleRes(this), true)
        theme.applyStyle(ThemeUtil.getColorThemeStyleRes(), true)
    }

    override fun computeUserThemeKey(): String? {
        return ThemeUtil.getColorTheme() + ThemeUtil.getNightTheme(this)
    }

    override fun onApplyTranslucentSystemBars() {
        super.onApplyTranslucentSystemBars()
        window.statusBarColor = Color.TRANSPARENT
        window.decorView.post {
            if (window.decorView.rootWindowInsets.systemWindowInsetBottom >= Resources.getSystem().displayMetrics.density * 40) {
                window.navigationBarColor = resolveColor(theme, android.R.attr.navigationBarColor) and 0x00ffffff or -0x20000000
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                    window.isNavigationBarContrastEnforced = false
                }
            } else {
                window.navigationBarColor = Color.TRANSPARENT
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                    window.isNavigationBarContrastEnforced = true
                }
            }
        }
    }
}

(ThemeUtil.java has not been changed)
Strictly speaking, this is the only change:

//Some codes.
public class ThemeUtil {
    //Some codes.
    private static final String THEME_BLACK = "BLACK";

    static {
        //The following line is the change.
        preferences = MyClass.INSTANCE.getPreferences();

        colorThemeMap.put("COLOR_PRIMARY", R.style.ThemeOverlay_color_primary);
        colorThemeMap.put("MATERIAL_RED", R.style.ThemeOverlay_material_red);
        colorThemeMap.put("MATERIAL_PINK", R.style.ThemeOverlay_material_pink);
        //Some codes.
    }
    //Some codes.
}

MyClass:

package com.xfq.easytest.util

import android.annotation.SuppressLint
import android.content.Context
import android.content.SharedPreferences
import androidx.preference.PreferenceManager

@SuppressLint("StaticFieldLeak")
object MyClass {
    private var context: Context? = null

    fun getPreferences(): SharedPreferences {
        return PreferenceManager.getDefaultSharedPreferences(context)
    }

    fun init(context: Context) {  //Will be called in Application.
        MyClass.context = context
    }
}

prefs:

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    <com.takisoft.preferencex.PreferenceCategory android:title="@string/theme">
        <com.xfq.easytest.util.ThemeColorPreference
            android:defaultValue=""
            android:dialogTitle="@string/theme_color"
            android:key="theme_color"
            android:summary="@string/theme_color_summary"
            android:title="@string/theme_color" />
        <rikka.preference.SimpleMenuPreference
            android:defaultValue="MODE_NIGHT_FOLLOW_SYSTEM"
            android:entries="@array/theme_texts"
            android:entryValues="@array/theme_values"
            android:key="dark_theme"
            android:summary="%s"
            android:title="@string/dark_theme" />
        <SwitchPreference
            android:key="black_dark_theme"
            android:summary="@string/black_dark_theme_summary"
            android:title="@string/black_dark_theme" />
    </com.takisoft.preferencex.PreferenceCategory>
</PreferenceScreen>

Settings Activity:

package com.xfq.easytest.activity

import android.content.Context
import android.content.Intent
import android.os.Bundle
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.preference.SwitchPreference
import androidx.recyclerview.widget.RecyclerView
import com.takisoft.preferencex.PreferenceFragmentCompat
import com.xfq.easytest.R
import com.xfq.easytest.activity.base.BaseActivity
import com.xfq.easytest.databinding.ActivitySettingsBinding
import com.xfq.easytest.util.MyClass
import com.xfq.easytest.util.ThemeColorPreference
import com.xfq.easytest.util.ThemeUtil
import rikka.core.util.ResourceUtils
import rikka.material.app.DayNightDelegate
import rikka.preference.SimpleMenuPreference
import rikka.recyclerview.fixEdgeEffect
import rikka.widget.borderview.BorderRecyclerView


class SettingsActivity : BaseActivity() {
    private val prefixKey = SettingsActivity::class.java.name + '.'
    private val savedInstanceStateExtra = prefixKey + "SAVED_INSTANCE_STATE"

    //My codes.

    class SettingsFragment(val binding: ActivitySettingsBinding) : PreferenceFragmentCompat() {
        override fun onCreatePreferencesFix(savedInstanceState: Bundle?, rootKey: String?) {
            setPreferencesFromResource(R.xml.root_preferences, rootKey)

            findPreference<SimpleMenuPreference>("dark_theme")?.setOnPreferenceChangeListener { _, newValue ->
                if (!MyClass.getPreferences().getString("dark_theme", ThemeUtil.MODE_NIGHT_FOLLOW_SYSTEM)?.equals(newValue)!!) {
                    DayNightDelegate.setDefaultNightMode(ThemeUtil.getDarkTheme(newValue as String))
                    val activity = activity as SettingsActivity
                    activity.restart()
                }
                true
            }

            findPreference<SwitchPreference>("black_dark_theme")?.setOnPreferenceChangeListener { _, _ ->
                val activity = activity as SettingsActivity
                if (ResourceUtils.isNightMode(resources.configuration)) {
                    activity.restart()
                }
                true
            }

            findPreference<ThemeColorPreference>("theme_color")?.setOnPreferenceChangeListener { _, _ ->
                val activity = activity as SettingsActivity
                activity.restart()
                true
            }
        }

        override fun onCreateRecyclerView(inflater: LayoutInflater?, parent: ViewGroup?, savedInstanceState: Bundle?): RecyclerView {
            val recyclerView: BorderRecyclerView = super.onCreateRecyclerView(inflater, parent, savedInstanceState) as BorderRecyclerView
            recyclerView.fixEdgeEffect(false)
            recyclerView.borderViewDelegate.setBorderVisibilityChangedListener { top, _, _, _ ->
                binding.appbar.isRaised = !top
            }
            return recyclerView
        }
    }

    private fun newIntent(context: Context): Intent {
        return Intent(context, SettingsActivity::class.java)
    }

    private fun newIntent(savedInstanceState: Bundle, context: Context): Intent {
        return newIntent(context).putExtra(savedInstanceStateExtra, savedInstanceState)
    }

    private fun restart() {
        val savedInstanceState = Bundle()
        onSaveInstanceState(savedInstanceState)
        finish()
        startActivity(newIntent(savedInstanceState, this))
        overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out)
    }
}

If you don’t mind, you can check my project: https://github.com/xfqwdsj/EasyTest-Android

[xfqwdsj]

Add

DayNightDelegate.setApplicationContext(this)
DayNightDelegate.setDefaultNightMode(ThemeUtil.getDarkTheme())

to Application.java