This document provides an overview of touch support and gestures in Android. It discusses how to handle touch events via the MotionEvent class and onTouchEvent method. It also covers using the GestureDetector class to detect gestures like taps, swipes, pinches. Specific tasks demonstrated include drawing lines as the user touches, connecting drawn dots, and implementing swipe to delete in a ListView.

1. Android
Touch
Android Training
By Khaled Anaqwa

2. Android touch basics
 The Android standard View class support
touch events.
 You can react to touch events in your
custom views and your activities.
 Android supports multiple pointers, e.g.
fingers which are interacting with the
screen.

3.  The base class for touch support is the
MotionEvent class which is passed to
Views via the onTouchEvent() method.
 To react to touch events you override the
onTouchEvent() method.

4. Single touch
 If single input is used you can use the
getX() and getY() methods to get the
current position of the first finger.
 Via the getAction() method you receive
the action which was performed

5. The MotionEvent class provides the following
constants to determine the action which was
performed.

6. Demo
 Using One Touch
 Create custom View
 Draw in it
 Track touches points
 Draw lines while move

7. Task
 Draw dot’s and connects these dot’s on
screen

8. Gestures
 Android provides special types of touch
screen events such as pinch , double tap,
scrolls , long presses and flinch. These are
all known as gestures.
 Android provides GestureDetector class
to receive motion events and tell us that
these events correspond to gestures or
not.

9. Using
 you need to create an object of
GestureDetector and then extend
another class with
GestureDetector.SimpleOnGestureListener
to act as a listener.

10. Gestures Type
 Touch
 Long press
 Swipe or drag
 Long press drag
 Double touch (Tap)
 Pinch open / close

11. Where I can use onTouch
Listener
 onTouchEvent (Activity Override)
 onTouchEvent (CustomView Override)
 onTouch(view.setOnTouchListener)

12. Demo
 Use GestureDetector.
SimpleOnGestureListener

13. Task
 Create Listview and implement Swipe to
delete