You probably haven't heard about ViewDragHelper class but if you want to drag things around your screen you will need it. In this lecture we will show you how and why you should use it.

1. ViewDragHelper (VHD)
Ivan Kocijan

2. Overview
•What isVHD?
•How to use it?
•Example

3. What isVHD
• VDH is a class in Android SupportV4 library
• It’s used for writing customViewGroups
• Offers useful operations for allowing user to drag
views around the screen
• Youtube application uses it to maximize video from
a small box in corner to fullscreen

4. How to use it
In order to use VDH you will have to:
• Create customView by extendingViewGroup
• CreateVDH instance
• ImplementVDH callback
• Make sure thatVDH handles touch events
• Add your customView to XML file

5. How to use it
1. Create custom view

6. How to use it
2. CreateViewDragHelper instance

7. How to use it
4. ImplementVHD callbacks

8. How to use it
3.ViewDragHelper will now handle touch events

9. How to use it
4. XML layout

10. Resources
•https://developer.android.com/reference/android/
support/v4/widget/ViewDragHelper.Callback.html
!
•http://blog.denevell.org/android-viewdraghelper-
example-tutorial.html