Pinch-to-zoom with multi-touch gestures

The previous recipe used the SimpleOnGestureListener to provide detection of simple, one-finger, gestures. In this recipe, we will demonstrate multi-touch with the common pinch-to-zoom gesture using the SimpleOnScaleGestureListener class.

The following screenshot shows the icon zoomed out using the application created in the following recipe:

The following screenshot shows the icon zoomed in:

Getting ready

Create a new project in Android Studio and call it: MultiTouchZoom. Use the default Phone & Tablet options and select Empty Activity when prompted for the Activity Type.

How to do it...

To provide a visual indication of the pinch-to-zoom, we'll use an ImageView with the application icon. Open activity_main.xml and follow these steps:

1. Replace the existing TextView with the following ImageView:

   <ImageView
       android:id="@+id/imageView"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:src="@mipmap/ic_launcher...