Autosizing TextViews

Introduction#

A TextView that automatically resizes text to fit perfectly within its bounds.

Android O allows you to instruct a TextView to let the size of the text expand or contract automatically to fill its layout based on the TextView’s characteristics and boundaries.

You can set up the TextView autosizing in either code or XML.

There are two ways to set autosizing TextView: Granularity and Preset Sizes

Granularity

In Java:

Call the setAutoSizeTextTypeUniformWithConfiguration() method:

setAutoSizeTextTypeUniformWithConfiguration(int autoSizeMinTextSize, int autoSizeMaxTextSize, int autoSizeStepGranularity, int unit)

In XML:

Use the autoSizeMinTextSize, autoSizeMaxTextSize, and autoSizeStepGranularity attributes to set the auto-sizing dimensions in the layout XML file:

<TextView android:id=”@+id/autosizing_textview_presetsize” 
        android:layout_width=”wrap_content” 
        android:layout_height=”250dp” 
        android:layout_marginLeft=”0dp” 
        android:layout_marginTop=”0dp” 
        android:autoSizeMaxTextSize=”100sp” 
        android:autoSizeMinTextSize=”12sp” 
        android:autoSizeStepGranularity=”2sp” 
        android:autoSizeText=”uniform” 
        android:text=”Hello World!” 
        android:textSize=”100sp” 
        app:layout_constraintLeft_toLeftOf=”parent” 
        app:layout_constraintTop_toTopOf=”parent” />

Check out the AutosizingTextViews-Demo at GitHub for more details.

Preset Sizes

In Java:

Call the setAutoSizeTextTypeUniformWithPresetSizes() method:

setAutoSizeTextTypeUniformWithPresetSizes(int[] presetSizes, int unit)

In XML:

Use the autoSizePresetSizes attribute in the layout XML file:

<TextView android:id=”@+id/autosizing_textview_presetsize” 
        android:layout_width=”wrap_content” 
        android:layout_height=”250dp” 
        android:layout_marginLeft=”0dp” 
        android:layout_marginTop=”0dp” 
        android:autoSizeText=”uniform” 
        android:autoSizePresetSizes=”@array/autosize_text_sizes” 
        android:text=”Hello World!” 
        android:textSize=”100sp” 
        app:layout_constraintLeft_toLeftOf=”parent” 
        app:layout_constraintTop_toTopOf=”parent” />

To access the array as a resource, define the array in the res/values/arrays.xml file:

<array name=”autosize_text_sizes”>
    <item>10sp</item>
    <item>12sp</item>
    <item>20sp</item>
    <item>40sp</item>
    <item>100sp</item>
</array>

Check out the AutosizingTextViews-Demo at GitHub for more details.