如何使用 max-height 和 overflow-y 自动滚动 GWT SuggestBox:滚动?

问题描述

如何自动滚动 GWT SuggestBox 并在 PopupPanel 上设置最大高度并持有 SuggestBox?目前，当用户按下键盘向上键和向下键时，建议项目的样式会发生变化，然后按 Enter 将选择列表中当前选定的项目.

How can I auto scroll the GWT SuggestBox with max-height set on the PopupPanel holding the SuggestBox? Currently when the user presses keyboard up keys and down keys styles changes on the suggested items and pressing enter will select the currently selected item on the list.

当项目位于低于最大高度时，滚动条不会滚动.我尝试扩展 SuggestBox 和内部类 DefaultSuggestionDisplay 以覆盖 moveSelectionDown() 和 moveSelectionUp() 以显式调用 popup.setScrollTop().

When the item is located in lower than the max-height scroll bars doesn't scroll.I tried extending the SuggestBox and inner class DefaultSuggestionDisplay to override moveSelectionDown() and moveSelectionUp() to explicitly call popup.setScrollTop().

为了做到这一点，我需要访问当前选择的 MenuItem 的绝对顶部，因此需要访问 SuggestionMenu 这也是 SuggestBox 的内部类，它是私有的并在 DefaultSuggestionDisplay 中声明为私有成员，没有 getter.由于 GWT 是 JavaScript，我们不能使用反射来访问它.... 有人有解决此问题的方法吗?

In order to do this I need access to the absolute top of the currently selected MenuItem therefore need access to SuggestionMenu which is also an inner class of SuggestBox which is private and declared as a private member within DefaultSuggestionDisplay without getter. Since GWT is a JavaScript we can't use reflection to access it.... Does anyone have a workaround for this issue?

谢谢.

推荐答案

我一直在寻找合适的解决方案(除了重新实现 SuggestBox).以下避免了重新实现 SuggestBox:

I've been searching around and couldn't find a proper solution (apart from reimplementing SuggestBox). The following avoids reimplementing SuggestBox:

private static class ScrollableDefaultSuggestionDisplay extends SuggestBox.DefaultSuggestionDisplay {

    private Widget suggestionMenu;

    @Override
    protected Widget decorateSuggestionList(Widget suggestionList) {
        suggestionMenu = suggestionList;

        return suggestionList;
    }

    @Override
    protected void moveSelectionDown() {
         super.moveSelectionDown();
         scrollSelectedItemIntoView();
    }

    @Override
    protected void moveSelectionUp() {
         super.moveSelectionUp();
         scrollSelectedItemIntoView();
    }

    private void scrollSelectedItemIntoView() {
        //                                     DIV          TABLE       TBODY       TR's
        NodeList<Node> trList = suggestionMenu.getElement().getChild(1).getChild(0).getChildNodes();
        for (int trIndex = 0; trIndex < trList.getLength(); ++trIndex) {
            Element trElement = (Element)trList.getItem(trIndex);
            if (((Element)trElement.getChild(0)).getClassName().contains("selected")) {
                trElement.scrollIntoView();

                break;
        }
    }
}

}

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