无法使用 UpdateLayout() [UWP] 刷新 CalendarView [英] Unable to refresh a CalendarView with UpdateLayout() [UWP]

问题描述

在我的 UWP 应用程序中，如果用户单击按钮，我会尝试刷新 calendarview 上的密度条，但问题是，尽管 calendarView.UpdateLayout(); 应该重新运行 CalendarViewDayItemChanging 事件，它仅在第一次加载 CalendarView 时运行.难道我做错了什么?

In my UWP app, I'm trying to refresh the density bars on a calendarview if the user clicks a button, the problem is that, although calendarView.UpdateLayout(); should re-run the CalendarViewDayItemChanging event, it runs only when the CalendarView is loaded the first time. Am I doing something wrong?

 public MainPage()
        {
            this.InitializeComponent();
            densityColors.Add(Colors.Green); 
        }

      private void CalendarView_CalendarViewDayItemChanging(CalendarView sender, CalendarViewDayItemChangingEventArgs args)
            {
                item = args.Item;
                if (item < DateTimeOffset.Now)
                {
                    item.SetDensityColors(densityColors);
                }

            }

            private void Button_Click(object sender, RoutedEventArgs e)
            {
                densityColors[0]=Colors.Blue;
                calendarView.UpdateLayout();
            }

推荐答案

UpdateLayout 不会在这里做任何事情，因为没有 layout 更新和 CalendarViewDayItemChanging 仅在您移动到另一个日历视图时触发.

UpdateLayout won't do anything here since there's no layout update and CalendarViewDayItemChanging is only triggered when you move to another calendar view.

在您的情况下，您只需要手动定位所有 CalendarViewDayItems 并在现有视图上更新它们的颜色.

In your case, you just need to manually locate all the CalendarViewDayItems and update their colors on the existing view.

首先，创建一些Children 扩展方法来帮助检索所有相同类型的子项.

First, create a little Children extension methods to help retrieve all the children of the same type.

public static class Helper
{
    public static List<FrameworkElement> Children(this DependencyObject parent)
    {
        var list = new List<FrameworkElement>();

        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);

            if (child is FrameworkElement)
            {
                list.Add(child as FrameworkElement);
            }

            list.AddRange(Children(child));
        }

        return list;
    }
}

然后，只需在按钮单击处理程序中调用它即可获取所有 CalendarViewDayItem，循环它们并相应地设置每个颜色.

Then, simply call it in your button click handler to get all CalendarViewDayItems, loop them through and set each's color accordingly.

var dayItems = calendarView.Children().OfType<CalendarViewDayItem>();
foreach (var dayItem in dayItems)
{
    dayItem.SetDensityColors(densityColors);
}

请注意，您无需担心新的 CalendarViewDayItem 进入视图，因为它们将由您的 CalendarView_CalendarViewDayItemChanging 回调处理.

Note you don't need to worry about new CalendarViewDayItems coming into view as they will be handled by your CalendarView_CalendarViewDayItemChanging callback.

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