CODEWITHSUNDEEP
javaandroidmotionevent
Nicolas Tyler
Nicolas Tyler

Reputation: 10552

MotionEvents not firing

Im trying to draw a square on a canvas but only the MotionEvent.ACTION_DOWN is run, and then the listener stops.

The idea is when the user touches the screen it get the x1 and y1 locations and every time the onTouch is fired it must draw the rect frim x1 y1 to the current location, and lastly save the last location in x2 y2 once the user lets go of the screen.

My code looks like this:

surfaceView.setOnTouchListener(new View.OnTouchListener()
{
    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
        holder = surfaceView.getHolder();
        canvas = holder.lockCanvas();
        if(event.getAction() == MotionEvent.ACTION_DOWN)
        {
            x1=event.getX();
            y1=event.getY();
        }
        else if(event.getAction() == MotionEvent.ACTION_UP)
        {
            x2=event.getX();
            y2=event.getY();
        }
        canvas.drawRect(x1, y1, event.getX(), event.getY(), paint);
        holder.unlockCanvasAndPost(canvas);
        return true;
    }
});

Can anyone give me an example.

Upvotes: 0

Views: 178

Answers (2)

akaya
akaya

Reputation: 1140

ACTION_UP triggers from above code. Try the code below and you will see the log.

I think your problem may be related with the points you get. I don't know how you defined x1, y1, x2, y2 but when declared out of scope they must be final. Try this instead.

final SurfaceView s = (SurfaceView) findViewById(R.id.surface);

final RectF rect = new RectF();

s.setOnTouchListener(new OnTouchListener() {

    @Override
    public boolean onTouch(View v, MotionEvent event) {
        SurfaceHolder holder = s.getHolder();
        Canvas canvas = holder.lockCanvas();

        if(event.getAction() == MotionEvent.ACTION_DOWN) {
            Log.d("action", "down");
            rect.left = event.getX();
            rect.top = event.getY();
        }
        if(event.getAction() == MotionEvent.ACTION_UP){
            Log.d("action", "up");
            rect.right = event.getX();
            rect.bottom = event.getY();

            Paint paint = new Paint();
            paint.setColor(Color.RED);
            canvas.drawRect(rect, paint);
        }

        holder.unlockCanvasAndPost(canvas);
        return true;
    }
});

Upvotes: 1

NaviRamyle
NaviRamyle

Reputation: 4007

Try using this.

surfaceView.setOnTouchListener(new View.OnTouchListener()
{
    @Override
    public boolean onTouch(View v, MotionEvent event)
    {

        if(event.getAction() == MotionEvent.ACTION_DOWN)
        {
            x1=event.getX();
            y1=event.getY();
        }
        else if(event.getAction() == MotionEvent.ACTION_UP)
        {
            x2=event.getX();
            y2=event.getY();

            holder = surfaceView.getHolder();
            canvas = holder.lockCanvas();
            canvas.drawRect(x1, y1, x2, y2, paint);
            holder.unlockCanvasAndPost(canvas);
        }

        return true;
    }
});

If you move your finger it calls the listener every move you do. So this code

holder = surfaceView.getHolder();
canvas = holder.lockCanvas();

and this code

canvas.drawRect(x1, y1, event.getX(), event.getY(), paint);
holder.unlockCanvasAndPost(canvas);

Will be executed, maybe that's why it's stopping.

So I put the drawRect inside the MotionEvent.ACTION_UP condition, so the drawRect will be executed once.

Upvotes: 0

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