🐛 [bug]fix the current date is not between the maximum and the minimum date.(#17)

Author: lanjingling0510

lib/DatePickerItem.js

@@ -65,6 +65,7 @@ class DatePickerItem extends Component<void, Props, State> {
         this.touchY = 0;                        // 保存touchstart的pageY
         this.translateY = 0;                    // 容器偏移的距离
         this.currentIndex = MIDDLE_INDEX;       // 滑动中当前日期的索引
+        this.moveDateCount = 0;                 // 一次滑动移动了多少个时间
 
         this.state = {
             translateY: MIDDLE_Y,
@@ -180,9 +181,9 @@ class DatePickerItem extends Component<void, Props, State> {
     _moveToNext(direction) {
         const date = this.state.dates[MIDDLE_INDEX];
         const { max, min } = this.props;
-        if (direction === -1 && date.getTime() < min.getTime()) {
+        if (direction === -1 && date.getTime() < min.getTime() && this.moveDateCount) {
             this._updateDates(1);
-        } else if (direction === 1 && date.getTime() > max.getTime()) {
+        } else if (direction === 1 && date.getTime() > max.getTime() && this.moveDateCount) {
             this._updateDates(-1);
         }
 
@@ -220,6 +221,7 @@ class DatePickerItem extends Component<void, Props, State> {
             event.pageY;
 
         this.translateY = this.state.translateY;
+        this.moveDateCount = 0;
     }
 
 
@@ -244,6 +246,7 @@ class DatePickerItem extends Component<void, Props, State> {
 
         // 检测是否更新日期列表
         if (this._checkIsUpdateDates(direction, translateY)) {
+            this.moveDateCount = direction > 0 ? this.moveDateCount + 1 : this.moveDateCount - 1;
             this._updateDates(direction);
         }