android: align system bars with app theme

The colors of both the status and the navigation bars and their icons
were not always matching the app background.

Also, forcing the app theme in the settings and then switching the OS
theme was sometime causing the bar icons to change and blend with the
bars.

This commit does the following:
- Drives the colors of both bars and icons in the setDarkTheme method
to avoid misalignemnts with the app theme
- Removes the onConfigurationChanged overriding, which was conficting
with the implemented theme handling, which is delegated to the frontend
DarkmodeProvider. Listening of OS theme changes in the activity must be
avoided as it could fire unwanted changes in the app theme.
- Improve the app static styles, to reduce the color flickering before
setDarkTheme() is called for the first time.
- Apply matching backgrounds to the root layout and WebView so the bars
blend with the app in both light and dark modes.

Author: beero's agent

frontends/android/BitBoxApp/app/src/main/java/ch/shiftcrypto/bitboxapp/MainActivity.java

@@ -4,11 +4,12 @@
 import android.content.Context;
 import android.content.Intent;
 import android.content.ServiceConnection;
-import android.content.res.Configuration;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.IBinder;
 import android.view.View;
+import android.view.Window;
 import android.view.WindowManager;
 import android.webkit.WebView;
 
@@ -50,37 +51,46 @@ public void onServiceDisconnected(ComponentName arg0) {
         }
     };
 
-    @Override
-    public void onConfigurationChanged(Configuration newConfig) {
-        int currentNightMode = newConfig.uiMode & Configuration.UI_MODE_NIGHT_MASK;
-        switch (currentNightMode) {
-            case Configuration.UI_MODE_NIGHT_NO:
-                // Night mode is not active, we're using the light theme
-                setDarkTheme(false);
-                break;
-            case Configuration.UI_MODE_NIGHT_YES:
-                // Night mode is active, we're using dark theme
-                setDarkTheme(true);
-                break;
-        }
-        super.onConfigurationChanged(newConfig);
-    }
-
     public void setDarkTheme(boolean isDark) {
-        int flags = getWindow().getDecorView().getSystemUiVisibility(); // get current flag
+        int statusBarColor = ContextCompat.getColor(
+                getApplicationContext(),
+                isDark ? R.color.colorPrimaryDark : R.color.colorPrimary
+        );
+        // Pre-Oreo devices cannot render light nav bar icons, so fall back to dark bar to keep icons visible.
+        boolean supportsLightNavIcons = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O;
+        int navBarColor = supportsLightNavIcons
+                ? statusBarColor
+                : ContextCompat.getColor(getApplicationContext(), R.color.colorPrimaryDark);
+
+        Window window = getWindow();
+        window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
+        window.setStatusBarColor(statusBarColor);
+        window.setNavigationBarColor(navBarColor);
+
+        View decorView = window.getDecorView();
+        int flags = decorView.getSystemUiVisibility(); // get current flag
         if (isDark) {
             Util.log("Dark theme");
-            getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
-            getWindow().setStatusBarColor(ContextCompat.getColor(getApplicationContext(), R.color.colorPrimaryDark));
-            getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
-            flags &= ~View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;   // remove LIGHT_STATUS_BAR to flag
-            getWindow().getDecorView().setSystemUiVisibility(flags);
+            flags &= ~View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;   // remove LIGHT_STATUS_BAR flag
+            if (supportsLightNavIcons) {
+                flags &= ~View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR;
+            }
         } else {
             Util.log("Light theme");
-            getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
-            getWindow().setStatusBarColor(ContextCompat.getColor(getApplicationContext(), R.color.colorPrimary));
-            flags |= View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;   // add LIGHT_STATUS_BAR to flag
-            getWindow().getDecorView().setSystemUiVisibility(flags);
+            flags |= View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR;   // add LIGHT_STATUS_BAR flag
+            if (supportsLightNavIcons) {
+                flags |= View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR;
+            }
+        }
+        decorView.setSystemUiVisibility(flags);
+
+        View root = findViewById(R.id.root_layout);
+        WebView vw = findViewById(R.id.vw);
+        if (root != null) {
+            root.setBackgroundColor(statusBarColor);
+        }
+        if (vw != null) {
+            vw.setBackgroundColor(statusBarColor);
         }
     }
 
@@ -93,7 +103,6 @@ protected void onCreate(Bundle savedInstanceState) {
         if (actionBar != null) {
             actionBar.hide(); // hide title bar with app name.
         }
-        onConfigurationChanged(getResources().getConfiguration());
         setContentView(R.layout.activity_main);
         final WebView vw = findViewById(R.id.vw);
 

frontends/android/BitBoxApp/app/src/main/res/layout/activity_main.xml

@@ -4,6 +4,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:id="@+id/root_layout"
     android:keepScreenOn="true"
     android:fitsSystemWindows="true"
     tools:context="ch.shiftcrypto.bitboxapp.MainActivity">

frontends/android/BitBoxApp/app/src/main/res/values-night-v23/styles.xml

@@ -0,0 +1,8 @@
+<resources>
+    <style name="AppTheme" parent="BaseAppTheme">
+        <item name="android:statusBarColor">@color/colorPrimaryDark</item>
+        <item name="android:navigationBarColor">@color/colorPrimaryDark</item>
+        <item name="android:windowLightStatusBar">false</item>
+        <item name="android:windowLightNavigationBar">false</item>
+    </style>
+</resources>

frontends/android/BitBoxApp/app/src/main/res/values-v23/styles.xml

@@ -2,6 +2,8 @@
     <!-- extend the base theme to add styles available only with API level 23+ -->
     <style name="AppTheme" parent="BaseAppTheme">
         <item name="android:statusBarColor">@color/colorPrimary</item>
+        <item name="android:navigationBarColor">@color/colorPrimary</item>
         <item name="android:windowLightStatusBar">true</item>
+        <item name="android:windowLightNavigationBar">true</item>
     </style>
 </resources>