菜单弹出在页面的中心

本文关键字：菜单 | 更新日期: 2023-09-27 18:09:43

在我的UWP中，我试图在框架中心打开一个菜单窗口。

我怎样才能把它放在中间?

我试过这段代码，但是它在框架顶部设置了飞出。

private void ListView_ItemClick(object sender,ItemClickEventArgs e) {
    var m = new MenuFlyout();
    var t = new MenuFlyoutItem() { Text = "SomeTxt"};
    m.Items.Add(t);
    m.ShowAt((FrameworkElement)Frame);
}

甚至试图添加m.Placement = Windows.UI.Xaml.Controls.Primitives.FlyoutPlacementMode.Center;，但FlyoutPlacementMode enum不包含Center。

菜单弹出在页面的中心

不幸的是，在FlyoutPlacementMode中没有Center值，所以您需要编写更多的代码来解决这个问题。

我们的想法是首先将FlyoutPlacementMode设置为Full，然后我们改变MenuFlyoutPresenter的Style，使其内容在水平和垂直方向上居中，而不是让内容伸展以填充整个页面。

所以我所做的是使用Blend生成以下默认样式，并将其放置在Page.Resources中，然后我在根Grid上指定HorizontalAlignment="Center" VerticalAlignment="Center"，以便将内容居中。

<Page.Resources>
    <Style x:Key="CenteredMenuFlyoutPresenterStyle" TargetType="MenuFlyoutPresenter">
        <Setter Property="Background" Value="{ThemeResource SystemControlBackgroundChromeMediumLowBrush}" />
        <Setter Property="BorderBrush" Value="{ThemeResource SystemControlForegroundChromeHighBrush}" />
        <Setter Property="BorderThickness" Value="{ThemeResource FlyoutBorderThemeThickness}" />
        <Setter Property="Padding" Value="{ThemeResource MenuFlyoutPresenterThemePadding}" />
        <Setter Property="ScrollViewer.HorizontalScrollMode" Value="Disabled" />
        <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled" />
        <Setter Property="ScrollViewer.VerticalScrollMode" Value="Auto" />
        <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto" />
        <Setter Property="ScrollViewer.IsHorizontalRailEnabled" Value="False" />
        <Setter Property="ScrollViewer.IsVerticalRailEnabled" Value="False" />
        <Setter Property="ScrollViewer.ZoomMode" Value="Disabled" />
        <Setter Property="MinWidth" Value="{ThemeResource FlyoutThemeMinWidth}" />
        <Setter Property="MaxWidth" Value="{ThemeResource FlyoutThemeMaxWidth}" />
        <Setter Property="MinHeight" Value="{ThemeResource MenuFlyoutThemeMinHeight}" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="MenuFlyoutPresenter">
                    <Grid Background="{TemplateBinding Background}" HorizontalAlignment="Center" VerticalAlignment="Center">
                        <ScrollViewer x:Name="MenuFlyoutPresenterScrollViewer" AutomationProperties.AccessibilityView="Raw" HorizontalScrollMode="{TemplateBinding ScrollViewer.HorizontalScrollMode}" HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}" IsHorizontalRailEnabled="{TemplateBinding ScrollViewer.IsHorizontalRailEnabled}" IsVerticalRailEnabled="{TemplateBinding ScrollViewer.IsVerticalRailEnabled}" Margin="{TemplateBinding BorderThickness}" Padding="{TemplateBinding Padding}" VerticalScrollBarVisibility="{TemplateBinding ScrollViewer.VerticalScrollBarVisibility}" VerticalScrollMode="{TemplateBinding ScrollViewer.VerticalScrollMode}" ZoomMode="{TemplateBinding ScrollViewer.ZoomMode}">
                            <ItemsPresenter />
                        </ScrollViewer>
                        <Border x:Name="MenuFlyoutPresenterBorder" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" />
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

然后简单地应用样式到MenuFlyout像这样-

var m = new MenuFlyout
{
    Placement = FlyoutPlacementMode.Full,
    MenuFlyoutPresenterStyle = (Style)this.Resources["CenteredMenuFlyoutPresenterStyle"]
};
var t = new MenuFlyoutItem() { Text = "SomeTxt" };
m.Items.Add(t);
m.ShowAt((FrameworkElement)sender);
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