java 购物车 - 增加减少商品数量 - 控件

Posted 2021-05-08

/**
 * 加和减数量的控件
 * Created by 洪少鹏 on 2017/10/16.
 */
 public class AddAndSunTextView extends android.support.v7.widget.AppCompatTextView {

    Drawable mADD, mSUB, mSUB_UNABLE;

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

    public AddAndSunTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();//初始化
    }

    /**
     * 初始化，设置初始值
     */
    private void init() {


//getCompoundDrawables获取到的是textview的 android:drawableLeft="@drawable/cart_minus"
//android:drawableRight="@drawable/cart_add" 这里面的图标。
        mSUB = getCompoundDrawables()[0];
        mADD = getCompoundDrawables()[2];
        mSUB_UNABLE = getResources().getDrawable(R.drawable.cart_minus);
        this.setText(1 + "");//设置初始值为0
    }

    /**
     * 获取点击时X值，判断其所在位置来虚拟点击事件
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {

        int num;
        float X, add_left, add_right, sub_left, sub_right;
        X = event.getX();
        add_right = getTotalPaddingLeft();
        add_left = getPaddingLeft();
        sub_right = getWidth() - getPaddingRight();
        sub_left = getWidth() - getTotalPaddingRight();
        if (TextUtils.isEmpty(this.getText().toString())) {
            num = 1;
        } else {
            num = Integer.parseInt(getText().toString());
        }
        if (X > add_left && X < add_right) {
            //如果为1，模拟不响应点击事件
            if (num == 1) {
                this.setText(1 + "");
            } else {
                num--;
                // num = setCheckadle(num);//检验当前输入框数字,若为1则设置减号按钮不可见;
                this.setText(num + "");

            }
        } else if (X > sub_left && X < sub_right) {
            num++;
            num = setCheckadle(num);//检验当前输入框数字,若不为1则设置减号按钮可见
            this.setText(num + "");
        }
        return super.onTouchEvent(event);
    }

    /**
     * 判断num值，对加减号进行设置：若num = 1，减号不可用；若num = 99，加号不可用（限制num在0~99区间）
     *
     * @param num
     * @return
     */
    private int setCheckadle(int num) {
        if (num == 1) {
            setCompoundDrawables(mSUB_UNABLE, getCompoundDrawables()[1], getCompoundDrawables()[2], getCompoundDrawables()[3]);
        } else {
            setCompoundDrawables(mSUB, getCompoundDrawables()[1], getCompoundDrawables()[2], getCompoundDrawables()[3]);
        }
        if (num == 99) {
            setCompoundDrawables(getCompoundDrawables()[0], getCompoundDrawables()[1], null, getCompoundDrawables()[3]);
        } else {
            setCompoundDrawables(getCompoundDrawables()[0], getCompoundDrawables()[1], mADD, getCompoundDrawables()[3]);
        }
        return num;
    }

    /**
     * 获取此时计数器的值
     *
     * @return
     */
    public String getNum() {
        return this.getText().toString();
    }

}