自定义画圆及拖拽

1：自定义一个类继承view

public class CustomClicle extends View {
    private float currentX = 100;
    private float currentY = 100;

    public CustomClicle(Context context) {
        super(context);
    }

    public CustomClicle(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomClicle(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.GREEN);
        Paint paint = new Paint();
        //颜色
        paint.setColor(Color.BLUE);
        //抗锯齿
        paint.setAntiAlias(true);
        //宽度
        paint.setStrokeWidth(10);
        //同心圆
        paint.setStyle(Paint.Style.STROKE);
        canvas.drawCircle(currentX, currentY, 50, paint);

    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        ;
        currentX = event.getX();
        currentY = event.getY();
        invalidate();
        return true;
    }
}

接下来就是布局了

<com.bawei.CustomViewStudy.view.CustomClicle
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"></com.bawei.CustomViewStudy.view.CustomClicle>