Android - 콜백 메소드

 

 

실습1

package com.example.touchevent;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;

class MyView extends View {
    int key;
    String str;

    int x, y;


    public MyView(Context context){
        super(context);
        setBackgroundColor(Color.YELLOW);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event){
        x = (int) event.getX(0);
        y = (int) event.getY(0);
        invalidate();
        return super.onTouchEvent(event);
    }

    @Override
    protected void onDraw(Canvas canvas){
        Paint paint = new Paint();
        paint.setTextSize(50);
        canvas.drawCircle(x, y, 30, paint);
        canvas.drawText("(" + x + ", " + y + ") 에서 터치 이벤트 발생", x, y + 100, paint);
    }
}

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        MyView w = new MyView(this);
        setContentView(w);
    }
}