There are three ways to setup an Autosizing TextView in your project: Default, Granularity, and Preset sizes. When using the Default  setting, this allows the TextView to uniformly scale along both the X and Y axis. This can be accomplished by adding the field

android:autoSizeTextType="uniform"

 

to your TextView.

When setting the Granularity property of your TextView, you set a range of minimum and maximum values, along with an incremental value, to determine how your TextView scales. An example of how to set this up in your TextView might look like this:

  android:autoSizeTextType="uniform"
  android:autoSizeMinTextSize="12sp"
  android:autoSizeMaxTextSize="100sp"
  android:autoSizeStepGranularity="2sp"

When using preset sizes with your TextView, you declare an array of sizes in your arrays.xml file and let your TextView know it should  scale according to the values listed in your arrays.xml file. A sample usage might look like:

<resources>
  <array
    name="text_view_sizes">
    <item>8sp</item>
    <item>12sp</item>
    <item>60sp</item>
    <item>100sp</item>
  </array>
</resources>

 

<TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:autoSizeTextType="uniform"
  android:autoSizePresetSizes="@array/text_view_sizes"/>

Conclusion

Android O has a lot of really great API changes coming, including Autosizing Textviews, Font declaration in XML, Unified layout margin and padding, and many other changes. Most of these changes will not be noticeable to the user, but they will certainly make a developer’s life easier.