setScrollPosition method

void setScrollPosition(int currentIndex)

Implementation

void setScrollPosition(int currentIndex) {
  WidgetsBinding.instance.addPostFrameCallback((timeStamp) async {
    await animationForward();
    if (currentIndex != -1) {
      double totalHeight = widget.dropdownList.length *
              (widget.dropdownItemHeight + widget.dropdownItemGap) +
          widget.dropdownItemTopGap +
          widget.dropdownItemBottomGap;
      double scrollPosition = currentIndex *
              (widget.dropdownItemHeight + widget.dropdownItemGap) +
          widget.dropdownItemTopGap -
          widget.dropdownItemGap;
      double overScrollPosition = ((widget.dropdownItemHeight *
                  widget.dropdownList.length) +
              (widget.dropdownItemGap * (widget.dropdownList.length - 1)) +
              widget.dropdownItemTopGap) -
          widget.dropdownHeight +
          widget.dropdownItemBottomGap;
      if (currentIndex == 0) {
        scrollPosition = 0;
      }
      if (overScrollPosition < scrollPosition) {
        scrollPosition = overScrollPosition;
      }
      if (totalHeight < widget.dropdownHeight) {
        scrollPosition = 0;
      }
      _scrollController.animateTo(scrollPosition,
          duration: au.isAnimation(
              status: widget.isAnimation,
              duration: Duration(milliseconds: 300)),
          curve: Curves.easeInOut);

      setState(() {
        widget.dropdownIsSelected[currentIndex] = true;
      });

      _DCController[currentIndex].forward();
      _paddingController[currentIndex].forward();
    }
  });
}