CODEWITHSUNDEEP
javaandroidcoordinatesandroid-canvasrect
Ahmad Dwaik 'Warlock'
Ahmad Dwaik 'Warlock'

Reputation: 5971

Android Are RectF coordinates differ from touch coordinates?

I was playing around drawing some ovals in response to touch, I've got confused by the coordinates given by touch and translating it into some oval, I dont know why I got offset in Y, here an image that illustrate my problem, piece of code and some ouptut.

enter image description here

public class TestView extends View implements OnTouchListener
{
    RectF rectf;
    Paint paint;

    public TestView(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        paint = new Paint();
        rectf = new RectF();
        rectf.set(30, 80, 80, 30);
        this.setOnTouchListener(this);
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);
        canvas.save();
        canvas.drawOval(rectf, paint);
        canvas.restore();
    }
    @Override
    public boolean onTouch(View v, MotionEvent event)
    {
    float x=event.getRawX();
    float y=event.getRawY();
        rectf.set(x-2, y+2, x+2, y-2);
        Log.v("", "****************");
        Log.v("x "+x, "y "+y);
        Log.v("rect", rectf.left +" " + rectf.right +" " +rectf.top +" " +rectf.bottom);
        Log.v("center", rectf.centerX()+" "+rectf.centerY());
        invalidate();//
    return true;
    }
}

output

 "****************
x 211.0: y 560.0
rect: 209.0 213.0 562.0 558.0
center: 211.0 560.0
 :****************
x 220.0: y 547.0
rect: 218.0 222.0 549.0 545.0
center: 220.0 547.0

Any help would be appreciated

Upvotes: 1

Views: 1748

Answers (2)

Deemoe
Deemoe

Reputation: 961

If for some reason you want to show a title bar again then you'll need to get the X and Y coordinates for the view canvas area not the entire screen.

You should use event.getX() and .getY() rather than .getRawX() and .getRawY().

Upvotes: 3

Ahmad Dwaik 'Warlock'
Ahmad Dwaik 'Warlock'

Reputation: 5971

Solved!!
It was the title bar offset :) I've added setTheme(android.R.style.Theme_Light_NoTitleBar_Fullscreen); to MainActivity and it worked perfectly

Upvotes: 0

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