Android Programming: The Big Nerd Ranch Guide, 2nd Edition
by Bill Phillips, Chris Stewart, Brian Hardy, Kristin Marsicano
Challenge: Rotating Boxes
For a harder challenge, make it so that you can use a second finger to rotate your rectangles. To do this, you will need to handle multiple pointers in your MotionEvent handling code. You will also need to rotate your canvas.
When dealing with multiple touches, you need these extra ideas:
|
pointer index |
tells you which pointer in the current set of pointers the event is for |
|
pointer ID |
gives you a unique ID for a specific finger in a gesture |
The pointer index may change, but the pointer ID will not.
For more details, check out the documentation for the following MotionEvent methods:
public final int getActionMasked() public final int getActionIndex() public final int getPointerId(int ...
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