Using an "on integer changed" listener, GLSurfaceView - cannot use thread error

Question

Situation:

I have implemented the code suggested in Android execute code on variable change

brief summary of above answer: A class (IntStoreValue) that stores an int and a listener, and proposes an interface for listening to changes in this int && A custom UI item (in this case a TextView) that implements the above interface and applies setText() when this int is changed.

I implemented this solution by setting this custom textview to listen to a public IntStoreValue constantly modified in my GLSurfaceView renderer class.

This causes a view.ViewRootImpl$CalledFromWrongThreadException. (trying to access UI from outside UI thread)...

This I can live with / understand...

What I don't understand, is why I am able to make this solution work with a custom SeekBar / ProgressBar using setProgress(int newValue) in the onIntChanged interface method...?

I used this "loophole" to make a normal TextView setText() onProgressChanged of my custom seekBar...

Why does this work with these widget.Bar items and not with TextViews?

I don't mind using this "SeekBar pass-through" loophole, but I would like to know why I cannot directly use the TV solution...

Thanks!

neo · Accepted Answer · 2014-01-02 14:31:50Z

0

GLSurfaceView creates a separate rendering thread. You try to change the value of a variable you created on main thread from GLSurfaceView rendering thread.

edited Jan 2, 2014 at 14:31

answered Jan 2, 2014 at 14:23

neo

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3 Comments

Werner Over a year ago

So I'm guessing setProgress() in SeekBar and ProgressBar indirectly make their changes to the UI, whereas TextView's setText() applies the transformation directly? I was just wondering why some changes to UI (setProgress) work from outside the main thread, and others (SetText) do not... But thanks for info anyhow :D!

neo Over a year ago

The problem is you changing state which you created on main thread from GLSurfaceView rendering thread. There are ways to update UIThread state from another thread.

Werner Over a year ago

I still don't know why it works for SeekBar/ProgressBar.setProgress() and not for TextView/Button.setText()... This has been my question all along. As I have stated, I made it work.

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