GestureImageView
· This is a simple Android View class which provides basic pinch and zoom capability for images. Can be used as a replacement for a standard ImageView when you want to include pinch and zoom.
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window gestureimageview-1.0.0.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.