Tools namespace attribute for showing layout in ViewPager in design time

Nope, there is no such attribute. Currently (Mar 2021) there is: tools:context Intended for: Any root View tools:itemCount Intended for: RecyclerView tools:layout Intended for: fragment tools:listitem / tools:listheader / tools:listfooter Intended for: AdapterView (and subclasses like ListView) tools:showIn Intended for: Any root View in a layout that’s referred to by an include tools:menu Intended for: … Read more

What is the ‘app’ Android XML namespace?

The app namespace is not specific to a library, but it is used for all attributes defined in your app, whether by your code or by libraries you import, effectively making a single global namespace for custom attributes – i.e., attributes not defined by the android system. In this case, the appcompat-v7 library uses custom … Read more

Preview layout with merge root tag in Intellij IDEA/Android Studio

There is a new parentTag tools attribute (added in Android Studio 2.2) that you can use to specify the layout type for a merge tag, which will make the layout render correctly in the layout editor preview. So using your example: <merge xmlns:android=”http://schemas.android.com/apk/res/android” xmlns:tools=”http://schemas.android.com/tools” android:layout_width=”match_parent” android:layout_height=”match_parent” tools:parentTag=”LinearLayout” tools:orientation=”horizontal”> <TextView android:layout_width=”wrap_content” android:layout_height=”wrap_content” android:text=”Some text” android:textSize=”20sp”/> <TextView … Read more

What’s “tools:context” in Android layout files?

This is the activity the tools UI editor uses to render your layout preview. It is documented here: This attribute declares which activity this layout is associated with by default. This enables features in the editor or layout preview that require knowledge of the activity, such as what the layout theme should be in the … Read more