如何自动滚动带有最大高度和溢出y的GWT建议框:滚动? [英] How to auto scroll GWT SuggestBox with max-height and overflow-y: scroll?

问题描述

如何在按住SuggestBox的PopupPanel上设置最大高度的情况下自动滚动GWT SuggestBox?当前，当用户按下键盘上键和下键时，样式会更改建议项，然后按Enter键将在列表中选择当前选定的项.

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.

当项目位于最大高度以下时，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().

为此，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，并且在DefaultSuggestionDisplay中声明为私有成员没有吸气剂.由于GWT是JavaScript，因此我们不能使用反射来访问它....有人对此问题有解决方法吗?

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

我一直在搜索，找不到合适的解决方案(除了重新实现RecommendationBox之外).以下内容避免了重新实现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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