Is android's motion event handling accurate??
- by Peterdk
Bug
I have a weird bug in my piano app. Sometimes keys (and thus notes) hang. I did a lot of debugging and narrowed it down to what looks like androids inaccuracy of motion event handling:
DEBUG/(2091): ACTION_DOWN A4
DEBUG/(2091): KeyDown: A4
DEBUG/(2091): ACTION_MOVE A4 => A4
DEBUG/(2091): ACTION_MOVE ignoring
DEBUG/(2091): ACTION_MOVE A4 => A4
DEBUG/(2091): ACTION_MOVE ignoring
DEBUG/(2091): ACTION_MOVE A4 => A4
DEBUG/(2091): ACTION_MOVE ignoring
DEBUG/(2091): ACTION_UP B4 //HOW CAN THIS BE????
DEBUG/(2091): KeyUp: B4
DEBUG/(2091): Stream is null, can't stop
DEBUG/(2091): Hanging Note: A4 X=240-287 EventX=292 Y=117-200 EventY=164
DEBUG/(2091): KeyUp Note: B4 X=288-335 EventX=292 Y=117-200 EventY=164
Clearly it can be seen here that out of nowhere I suddenly have an ACTION_UP for another note. Shouldn't I definitely get a ACTION_MOVE first?
As shown in the end of the log, it's definitely not an error in region detection, since the ACTION_UP event is clearly in the B4 region.
Logging Implementation details
Every onTouchEvent() call is logged, so the log is accurate.
The relevant pseudo-code for the ACTION_MOVE logging is:
Key oldKey = Key.get(event.getHistoricalX(), event.getHistoricalY());
Key newKey = Key.get(event.getX(), event.getY());
Question
Is this normal behaviour for Android (the jumping in coordinates)? Am I missing something?
