[안드로이드 스튜디오] paint 사용

(1) MainActivity.java

package com.example.mutitouch;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MultiTouchView(this, null));
    }
}

(2) MultTouchView.java

package com.example.mutitouch;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.Nullable;

import java.util.jar.Attributes;

public class MultiTouchView extends View {
    private static final int SIZE = 60;
    final int MAX_POINTS = 10;
    float[] x = new float[MAX_POINTS];
    float[] y = new float[MAX_POINTS];
    boolean[] touching = new boolean[MAX_POINTS];

    private Paint mPaint;

    public MultiTouchView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mPaint = new Paint((Paint.ANTI_ALIAS_FLAG));
        mPaint.setColor(Color.BLUE);
        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int index = event.getActionIndex();
        int id = event.getPointerId(index);
        int action = event.getActionMasked();
        switch (action){
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_POINTER_DOWN:
                x[id] = (int) event.getX(index);
                y[id] = (int) event.getY(index);
                touching[id] = true;
            case MotionEvent.ACTION_MOVE:
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_POINTER_UP:
            case MotionEvent.ACTION_CANCEL:
                    touching[id] = false;
                break;
        }
        invalidate();
        return true;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for(int i = 0; i < MAX_POINTS; i++){
            if(touching[i]){
                canvas.drawCircle(x[i], y[i], SIZE, mPaint);
            }
        }
    }
}