Android Training (Touch)

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