如何在窗口中居中弹出窗口（Windows 商店应用程序）

Question

我有一个以编程方式加载的自定义弹出窗口（作为用户控件）。我无法将它集中在 x 轴上，只能在垂直方向上。弹出窗口不会添加到 xaml 文件中，而是添加到根窗口中。

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using System.Windows;
using Windows.UI.Core;

// The User Control item template is documented at http://go.microsoft.com/fwlink/?LinkId=234236

namespace QSTLibrary.WIN8.Tools
{
    public sealed partial class CustomProgressRingPopup : UserControl
    {

        public CustomProgressRingPopup()
        {
            this.InitializeComponent();
        }

        public string Text
        {
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); }
        }

        // Using a DependencyProperty as the backing store for Text.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty TextProperty = DependencyProperty.Register(
                        "Text", 
                        typeof(string), 
                        typeof(CustomProgressRingPopup),
                        new PropertyMetadata("", OnTextChanged));


        public void OpenPopup()
        {
            this.ParentPopup.IsOpen = true;
        }

        public void ClosePopup()
        {
            this.ParentPopup.IsOpen = false;
        }

        private static void OnTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            var instance = d as CustomProgressRingPopup;
            var newValue = e.NewValue as string;
            if (instance != null && newValue != null)
            {
                instance.CustomTextBlock.Text = newValue;
            }
        }

        private void OnPopupLoaded(object sender, RoutedEventArgs e)
        {
            this.ParentPopup.HorizontalOffset = (Window.Current.Bounds.Width - gdChild.ActualWidth) / 2;
            this.ParentPopup.VerticalOffset = (Window.Current.Bounds.Height - gdChild.ActualHeight) / 2;
        }
    }
}

userControl xaml：

<UserControl
    x:Class="QSTLibrary.WIN8.Tools.CustomProgressRingPopup"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:QSTLibrary.WIN8.Tools"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400">

    <Popup x:Name="ParentPopup" HorizontalAlignment="Center" VerticalAlignment="Center" Loaded="OnPopupLoaded">
        <Grid x:Name="gdChild" Height="auto" Width="auto" Background="Blue" Margin="20">
            <Grid.RowDefinitions>
                <RowDefinition/>
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition/>
                <ColumnDefinition/>
            </Grid.ColumnDefinitions>
            <ProgressRing x:Name="CustomProgressRing" Height="40" Width="40" IsActive="true" Grid.Column="0" Margin="20"/>
            <TextBlock x:Name="CustomTextBlock" Height="auto" Width="auto" FontSize="25" Grid.Column="1" Margin="20"/>
        </Grid>
    </Popup>    
</UserControl>

这是我在外部使用它的方式：

_loginProgressRingPopup.Text = "Logging in";
_loginProgressRingPopup.OpenPopup();

Answer 1

我在cs文件中添加了弹窗的LayoutUpdate回调，现在可以使用了。

private void OnLayoutUpdated(object sender, object e)
        {
            if(gdChild.ActualWidth == 0 && gdChild.ActualHeight == 0)
            {
                return;
            }

            var coordinates = ParentPopup.TransformToVisual(Window.Current.Content).TransformPoint(new Point(0, 0));            

            double ActualHorizontalOffset = ParentPopup.HorizontalOffset;
            double ActualVerticalOffset = ParentPopup.VerticalOffset;

            double NewHorizontalOffset = ((Window.Current.Bounds.Width - gdChild.ActualWidth) / 2) - coordinates.X;
            double NewVerticalOffset = ((Window.Current.Bounds.Height - gdChild.ActualHeight) / 2) - coordinates.Y;

            if (ActualHorizontalOffset != NewHorizontalOffset || ActualVerticalOffset != NewVerticalOffset)
            {
                this.ParentPopup.HorizontalOffset = NewHorizontalOffset;
                this.ParentPopup.VerticalOffset = NewVerticalOffset;
            }
        }

以及来自 XAML 的弹出窗口：

<Popup x:Name="ParentPopup" LayoutUpdated="OnLayoutUpdated">

Answer 2

在 UWP Windows 应用商店应用中定位 Popup 并不像想象的那么简单。这就是我最终解决它的方法。与其观察 LayoutUpdated 事件（这可能导致布局循环），不如观察视图顶层元素的 SizeChanged 事件，并使用它来重新定位它包含的弹出窗口。

在我的例子中，我将对话框定位在窗口的中心，因此使用Window.Current。您还需要转换坐标，因为弹出窗口将根据您的布局中实际定义的 Popup 元素的位置使用自己的相对坐标系：

private void MyDialog_SizeChanged(object sender, SizeChangedEventArgs e) {
    var transform = Window.Current.Content.TransformToVisual(_popup);
    Point point = transform.TransformPoint(new Point(0, 0)); // gets the window's (0,0) coordinate relative to the popup

    double hOffset = (Window.Current.Bounds.Width - this.ActualWidth) / 2;
    double vOffset = (Window.Current.Bounds.Height - this.ActualHeight) / 2;

    _popup.HorizontalOffset = point.X + hOffset;
    _popup.VerticalOffset = point.Y + vOffset;
}

Answer 3

您可以在 XAML 文件中居中：

<Popup x:Name="ParentPopup" PlacementTarget="{Binding ElementName=MainPanel}" Placement="Center" />

Answer 4

我修改了 Butzke 的答案，使其更具普遍性：

<Popup PlacementTarget="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}}" Placement="Center" />