Themes in Android Studio

 This post continues from the previous post at

https://varanasisoftwarejunction.blogspot.com/2021/01/a-very-simple-calculator-using-android.html 

In this post we will make some changes to the Android Theme.

Here is the relevant information.

The themes are stored in res/values/themes

There are 2 files 

themes.xml

<resources xmlns:tools="http://schemas.android.com/tools">

    <!-- Base application theme. -->

    <style name="Theme.MyKotlinProject" parent="Theme.MaterialComponents.DayNight.DarkActionBar">

        <!-- Primary brand color. -->

        <item name="colorPrimary">@drawable/layoutbackround</item>

        <item name="colorPrimaryVariant">@color/purple_700</item>

        <item name="colorOnPrimary">@color/teal_700</item>

        <item name="android:background">@color/teal_700</item>

        <!-- Secondary brand color. -->

        <item name="colorSecondary">@color/teal_200</item>

        <item name="colorSecondaryVariant">@color/teal_700</item>

        <item name="colorOnSecondary">@color/black</item>

        <!-- Status bar color. -->

        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>

        <!-- Customize your theme here. -->

    </style>

    <style name="Theme.MyKotlinProject.NoActionBar">

        <item name="windowActionBar">false</item>

        <item name="windowNoTitle">true</item>

    </style>

    <style name="Theme.MyKotlinProject.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

    <style name="Theme.MyKotlinProject.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

</resources>

and the night version

<resources xmlns:tools="http://schemas.android.com/tools">

    <!-- Base application theme. -->

    <style name="Theme.MyKotlinProject" parent="Theme.MaterialComponents.DayNight.DarkActionBar">

        <!-- Primary brand color. -->

        <item name="colorPrimary">@color/purple_200</item>

        <item name="colorPrimaryVariant">@color/purple_700</item>

        <item name="colorOnPrimary">@color/black</item>

        <!-- Secondary brand color. -->

        <item name="colorSecondary">@color/teal_200</item>

        <item name="colorSecondaryVariant">@color/teal_200</item>

        <item name="colorOnSecondary">@color/black</item>

        <!-- Status bar color. -->

        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>

        <!-- Customize your theme here. -->

    </style>

</resources>

And the theme is referenced in AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.varanasisoftwarejunction.mykotlinproject">

    <application

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:roundIcon="@mipmap/ic_launcher_round"

        android:supportsRtl="true"

        android:theme="@style/Theme.MyKotlinProject">

        <activity

            android:name=".MainActivity"

            android:label="@string/app_name"

            android:theme="@style/Theme.MyKotlinProject.NoActionBar">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>

A list of Android terms is available at

https://developer.android.com/reference/android/R.attr

Let us define the background

<resources xmlns:tools="http://schemas.android.com/tools">

    <!-- Base application theme. -->

    <style name="Theme.MyKotlinProject" parent="Theme.MaterialComponents.DayNight.DarkActionBar">

        <!-- Primary brand color. -->

        <item name="colorPrimary">@drawable/layoutbackround</item>

        <item name="colorPrimaryVariant">@color/purple_700</item>

        <item name="colorOnPrimary">@color/teal_700</item>

        <item name="android:background">@color/teal_700</item>

        <!-- Secondary brand color. -->

        <item name="colorSecondary">@color/teal_200</item>

        <item name="colorSecondaryVariant">@color/teal_700</item>

        <item name="colorOnSecondary">@color/black</item>

        <!-- Status bar color. -->

        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>

        <!-- Customize your theme here. -->

    </style>

    <style name="Theme.MyKotlinProject.NoActionBar">

        <item name="windowActionBar">false</item>

        <item name="windowNoTitle">true</item>

    </style>

    <style name="Theme.MyKotlinProject.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

    <style name="Theme.MyKotlinProject.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

</resources>

Here is the teal color in colors.xml

<?xml version="1.0" encoding="utf-8"?>

<resources>

    <color name="purple_200">#FFBB86FC</color>

    <color name="purple_500">#FF0000</color>

    <color name="purple_700">#FF3700B3</color>

    <color name="teal_200">#FF03DAC5</color>

    <color name="teal_700">#FF018786</color>

    <color name="black">#FF000000</color>

    <color name="white">#FFFFFFFF</color>

    <color name="textbgcolor">0AFF00</color>

</resources>

Look up the fragment_first.xml in design view now.

You can change the parent theme here.

in themes.xml

And the fragment looks

Try this theme design tool

https://material.io/resources/color/#!/?view.left=0&view.right=0&primary.color=6002ee

More design tools.

https://material.io/design/color/the-color-system.html#tools-for-picking-colors