c# - 如何更改 SelectedItem(在 ListBox 中)的颜色？

Question

有如下的ListBox

<ListBox x: Name = "ListBoxQuestionAnswers" ItemsSource = "{x: Bind Question.Answers}" SelectionMode = "Single" SelectionChanged = "ListBoxQuestionAnswers_OnSelectionChanged">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <TextBlock x: Name = "TextBlockInListBox" TextWrapping = "Wrap" Text = "{Binding}" />
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

哪里有问题。答案 - List<string> .有必要在 ListBox 单击处理程序中更改所选项目的颜色。现在处理程序代码如下所示:

private void ListBoxQuestionAnswers_OnSelectionChanged (object sender, SelectionChangedEventArgs e)
{
    if (ListBoxQuestionAnswers.SelectedIndex == Question.CorrectAnswerIndex)
    {
        Application.Current.Resources ["SystemControlHighlightListAccentLowBrush"] = new SolidColorBrush (Colors.Green);
        Application.Current.Resources ["SystemControlHighlightListAccentMediumBrush"] = new SolidColorBrush (Colors.Green);
    }
    else
    {
        Application.Current.Resources ["SystemControlHighlightListAccentLowBrush"] = new SolidColorBrush (Colors.Red);
        Application.Current.Resources ["SystemControlHighlightListAccentMediumBrush"] = new SolidColorBrush (Colors.Red);
    }

}

此方法的问题在于应用程序中各处的颜色都会发生变化。为什么 SelectedItem 的颜色只在这个 ListBox 中发生了变化？

Answer 1

您正在修改 Application.Current.Resources，这将影响所有 ListView 。而是更改控件实例上的资源:

private void ListBoxQuestionAnswers_OnSelectionChanged (object sender, SelectionChangedEventArgs e)
{
    if (ListBoxQuestionAnswers.SelectedIndex == Question.CorrectAnswerIndex)
    {
        ListBoxQuestionAnswers.Resources ["SystemControlHighlightListAccentLowBrush"] = new SolidColorBrush (Colors.Green);
        ListBoxQuestionAnswers.Resources ["SystemControlHighlightListAccentMediumBrush"] = new SolidColorBrush (Colors.Green);
    }
    else
    {
        ListBoxQuestionAnswers.Resources ["SystemControlHighlightListAccentLowBrush"] = new SolidColorBrush (Colors.Red);
        ListBoxQuestionAnswers.Resources ["SystemControlHighlightListAccentMediumBrush"] = new SolidColorBrush (Colors.Red);
    }

}

每个 FrameworkElement 都可以有自己的资源，在找到父元素(如页面或应用程序)以寻找合适的来源之前，将首先查看这些资源。