Android, Multiple Views on screen but only one will respond to touch

Question

I have a main FrameLayout and a collection of balls 5 by 7 (each a View) under it. I added onTouchEvent() to switch colors. But regardless which ball I click, only the bottom right ball responds to my touch event (it was the last one to be drawn). Is there a way to get each ball recognize its own touch event?

A thought: I think this might be happening because I'm inserting each Ball (a View) into the main FrameLayout which is supposed to show only one thing at a time. I think it's like a stack of Views and only the top one is responding. Any ideas?

in the Ball class

public class Ball extends View {
    private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    ...
}

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawCircle(x, y, r, mPaint);
}

public boolean onTouchEvent(MotionEvent event) {
    int eventAction = event.getAction();

    if(eventAction == MotionEvent.ACTION_DOWN) {
        switchcolor();
        this.postInvalidate();
        return true;
    } else {
        return false;
    }
}

private void switchcolor() {
    mPaint.setColor(touched ? 0xFFFFFFFF : 0xFFA606E2);
    touched = !touched;
}

in main Activity

FrameLayout main = (FrameLayout) findViewById(R.id.main_view);
...

some loop {
    main.addView(new Ball(this, x, y, radius - margin));
}

That's all well and good, but where's your touch listener code? — dmon, Jun 02 '11 at 00:06
Errrr... and `switchcolor()`? Basically everything we need to follow the flow through and through. — dmon, Jun 02 '11 at 00:27
Hmmm I believe (disclaimer: I might be wrong since there's quite a bit of code missing still, and I have yet to build a completely custom `View`), that you need to check if the touch event lies within your ball's bounds. I bet that if you return false in `onTouchEvent()` ALL of your balls would switch colors. — dmon, Jun 02 '11 at 00:37
@dmon you're absolutely right. returning false from `onTouchEvent()` surely toggles all the balls. Any tips for boundary checking? I've never done it b4 — chizzle, Jun 02 '11 at 03:44
Use trigonometry to find if the distance between the center of the circle and your point is less than the radius (see [this answer](http://stackoverflow.com/questions/481144/how-do-you-test-if-a-point-is-inside-a-circle)). — dmon, Jun 02 '11 at 12:22

score 0 · Answer 1 · answered Jun 01 '11 at 23:37

0

As you are creating custom builds, just create a field called last one or something like that... and change the color of the ball just if that is the last one:

some loop {
    Ball ball = new Ball(this, x, y, radius - margin);
    if(this is the last one)
        ball.setLast(true);
    else
        ball.setLast(false);
    main.addView(ball);
}

Then, inside the Ball class in its onTouchEvent:

if(isLast()){
    // do it
}

answered Jun 01 '11 at 23:37

Cristian

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Thank you for your reply. I'm not sure if I described my problem clearly. I want the each 35 balls to recognize its own touch. Currently, regardless of which ball I click only the last one will change color even if I clicked on some other ball LOL! – chizzle Jun 01 '11 at 23:46

score 0 · Accepted Answer · edited May 23 '17 at 11:55

0

solved with 2 LinearLayout(s).

see here for a good answer. I tried both answers one using LinearLayout(s) and the other, TableLayout. The one using LinearLayout(s) will keep the cells the same size regardless of the text length

edited May 23 '17 at 11:55

Community

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answered Jun 04 '11 at 03:40

chizzle

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Android, Multiple Views on screen but only one will respond to touch

2 Answers2