使用View繪製可以移動的座標軸

public class view extends View {
    private Paint paint;
    //中心點座標
    private float pointX = 500;
    private float pointY =800;

    //控制是否可以移動的變量 true的時候可以移動
    private boolean xmovetrue;
    private boolean ymovetrue;

    public view(Context context) {
        super(context);
    }
    public view(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        paint = new Paint();
        paint.setStrokeWidth(5);
        paint.setColor(Color.RED);
        paint.setAntiAlias(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawLine(pointX+20000,pointY,pointX-20000,pointY,paint);
        canvas.drawLine(pointX,pointY+20000,pointX,pointY-20000,paint);

    }

    public boolean onTouchEvent(MotionEvent event) {

//        event.getAction()判斷事件的類型
        switch (event.getAction()) {

            //按下的事件
            case MotionEvent.ACTION_DOWN:
                float touchX = event.getX();
                float touchY= event.getY();
                if (touchX > pointX-2000 && touchX < pointX+2000 && touchY<pointY+20 && touchY>pointY-20) {
                    xmovetrue = true;
                    Toast.makeText(getContext(), "我按下了x軸", Toast.LENGTH_LONG).show();
                }
                
                if (touchY >pointY-2000 && touchY < pointY+2000 && touchX<pointX+20 && touchX>pointX-20 ) {
                    ymovetrue = true;
                    Toast.makeText(getContext(), "我按下了y軸", Toast.LENGTH_LONG).show();
                }
                
                if (touchY<pointY+20 && touchY>pointY-20 && touchX<pointX+20 && touchX>pointX-20) {
                    xmovetrue = true;
                    ymovetrue = true;
                    Toast.makeText(getContext(), "我按下了x軸和Y軸", Toast.LENGTH_LONG).show();
                }
                break;
            //移動的事件
            case MotionEvent.ACTION_MOVE:
                float x = event.getX();
                float y = event.getY();

                if (xmovetrue==true) {
                    pointY =y;
                    invalidate();
                }
                
                if(ymovetrue==true){
                    pointX =x;
                    invalidate();
                }
                
                if (xmovetrue==true&&ymovetrue==true){
                    pointX =x;
                    pointY =y;
                    invalidate();
                }
                break;
            //擡起的事件
            case MotionEvent.ACTION_UP:
                Toast.makeText(getContext(), "擡起",Toast.LENGTH_SHORT).show();
                xmovetrue = false;
                ymovetrue = false;
                break;
        }
        return true;
    }
}