How do I scale my text size for multi-device compatibility on Android Studio?

Question

I am having trouble scaling my text size based on the user's device. I use constraint layout to constrain the TextViews. I found that autoTextSize could be used to automatically fit my text in the TextViews. However, when I run my code on an Emulator like BlueStacks, some texts are not scaled properly. Weirdly, some work but some do not, even though I am implementing it the same way.

This is an example of what it looks like: The register button is in a big font but other texts aren't This is what it looks like on my layout Editor:

My code for the register button:

<TextView
        android:id="@+id/register"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:text="REGISTER"
        app:autoSizeTextType="uniform"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="5:1"
        app:layout_constraintEnd_toEndOf="@id/guideline3"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="@id/guideline2"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.541" />

my code for the "up to 8 characters" text.

    <TextView
        android:id="@+id/req"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:autoSizeTextType="uniform"
        android:text="*up to 8 characters"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="7:1"
        app:layout_constraintEnd_toEndOf="@+id/guideline5"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="@+id/guideline4"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.538" />

Am I misusing autoSizeTextType somehow?

Also, my "Enter Username" text is very small. I use EditText and implement it the same way I did for the other two texts. If there is anyway I can make the font size bigger to fit the layout size, please let me know.

Answer 1

your <TextView android:id="@+id/register" is using app:autoSizeTextType="uniform" attr, <TextView android:id="@+id/req" have android:autoSizeTextType="uniform" - note the difference app/android. try to consolidate this param, you should probably use app in both/all TextViews

note that setAutoSizeTextTypeWithDefaults was introduced in API 26, so when you use android: prefix then this attr will be respected only on 26+. using custom app: makes this attr usable for TextView (in fact TextViewCompat) on any OS version

in Android Studio above layout preview you have an option to switch "Device to preview" and also API version - try to change to some older (in this sample 25 at most, preferably lowest supported minSdkVersion) or newest OS version, IDE should catch and show differences in look