Android: how to set app wide default font, with out overriding textAppearance

Question

Im using custom font in my android app. I want to set this custom font to app default font (as fallback) but I still want to use the TextView textAppearance property to set font and text style.

It looks like setting textViewStyle or fontFamily in my app base theme, allays overrides TextView textAppearance style?

<style name="MyApp.Base" parent="Theme.AppCompat.Light.NoActionBar">

    <!-- Overriding fontFamily also overrides textView textAppearance -->
    <item name="android:fontFamily">@font/open_sans</item>

    <!-- Overriding textViewStyle also overrides textView textAppearance -->
    <item name="android:textViewStyle">@style/DefaultTextAppearance</item>

</style>

 <style name="DefaultTextAppearance" parent="TextAppearance.AppCompat">
    <item name="android:textStyle">normal</item>
    <item name="fontFamily">@font/open_sans_regular</item>
</style>

<style name="BoldTextAppearance" parent="TextAppearance.AppCompat">
    <item name="android:textStyle">normal</item>
    <item name="fontFamily">@font/open_sans_extra_bold</item>
</style>


<!-- This textView does not get bold style -->
<TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="Me happy"
  android:textAppearance="@style/BoldTextAppearance" />

Answer 1

View's style attributes has more priority to textAppearance.

In both cases you have fontFamily inside style instead of textAppearance. When you put fontFamily directly inside base theme, view obtains that style from its activity.

So, instead of setting base fontFamily value in style, you need to set base TextView's textAppearance:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="android:textViewStyle">@style/TextViewStyle</item>
</style>

<style name="TextViewStyle" parent="@android:style/TextAppearance.Widget.TextView">
    <item name="android:textAppearance">@style/DefaultTextAppearance</item>
</style>

<style name="DefaultTextAppearance" parent="TextAppearance.AppCompat">
    <item name="android:textStyle">normal</item>
    <item name="fontFamily">@font/roboto_regular</item>
</style>

<style name="LobsterTextAppearance" parent="TextAppearance.AppCompat">
    <item name="android:textStyle">normal</item>
    <item name="fontFamily">@font/lobster</item>
</style>

So, here I have 2 textAppearances: DefaultTextAppearance, that is used as default for all TextViews and LobsterTextAppearance, that I use in specific case.

Layout looks like:

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Default roboto text" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Lobster text"
    android:textAppearance="@style/LobsterTextAppearance" />

So, first TextView uses fontFamily from base textAppearance, second one uses overridden @style/LobsterTextAppearance