silverlight - 我如何获得 startX 和 startY 位置？

Question

如何获取 rectToGetXAndY 的 startX 和 startY 位置。这条功能对我的应用程序非常重要，但它让我发疯。我想到的唯一方法是要求用户手动单击网格的左上边框，然后处理 mouseleftbuttondown 事件。显然这不是我想要的解决方案。这是我的代码:-

<UserControl xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"  x:Class="DelSilverlightApp.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="600" d:DesignWidth="800">

    <Grid x:Name="LayoutRoot" Background="DarkSlateGray">
        <Grid x:Name="rectToGetXAndY" Background="HotPink" Width="300" Height="300" HorizontalAlignment="Center" VerticalAlignment="Center">

        </Grid>
    </Grid>
</UserControl>

编辑:-

这是背后的代码:-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace DelSilverlightApp
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
            this.Loaded += new RoutedEventHandler(MainPage_Loaded);
        }

        void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            GeneralTransform gt = rectToGetXAndY.TransformToVisual(null);
            Point p = gt.Transform(new Point(0, 0));
            MessageBox.Show(p.X + " " + p.Y);
        }
    }
}

提前致谢:)

Answer 1

我使用@AnthonyWJones 的代码使用以下代码使其工作:

XAML

        <UserControl x:Class="GetPositionUi.MainPage"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
            xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
            mc:Ignorable="d"
            DataContext="{Binding RelativeSource={RelativeSource Self}}"
            d:DesignHeight="300" d:DesignWidth="400">

            <Grid x:Name="LayoutRoot" Background="DarkSlateGray">
                <Grid x:Name="rectToGetXAndY" 
                        Background="HotPink" 
                        Width="300" 
                        Height="300" 
                        HorizontalAlignment="Center" 
                        VerticalAlignment="Center">
                    <TextBlock x:Name="PositionTextBlock" Text="{Binding Path=ReferencePosition}"/>
                </Grid>
            </Grid>
        </UserControl>

代码隐藏:

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Net;
    using System.Windows;
    using System.Windows.Controls;
    using System.Windows.Documents;
    using System.Windows.Input;
    using System.Windows.Media;
    using System.Windows.Media.Animation;
    using System.Windows.Shapes;

    namespace GetPositionUi
    {
        public partial class MainPage : UserControl
        {

            #region ReferencePosition

            /// <summary>
            /// ReferencePosition Dependency Property
            /// </summary>
            public static readonly DependencyProperty ReferencePositionProperty =
                DependencyProperty.Register("ReferencePosition", typeof(Point), typeof(MainPage),
                    new PropertyMetadata((Point)(new Point(0, 0)),
                        new PropertyChangedCallback(OnReferencePositionChanged)));

            /// <summary>
            /// Gets or sets the ReferencePosition property.  This dependency property 
            /// indicates the reference position of the child element.
            /// </summary>
            public Point ReferencePosition
            {
                get { return (Point)GetValue(ReferencePositionProperty); }
                set { SetValue(ReferencePositionProperty, value); }
            }

            /// <summary>
            /// Handles changes to the ReferencePosition property.
            /// </summary>
            private static void OnReferencePositionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
            {
                ((MainPage)d).OnReferencePositionChanged(e);
            }

            /// <summary>
            /// Provides derived classes an opportunity to handle changes to the ReferencePosition property.
            /// </summary>
            protected virtual void OnReferencePositionChanged(DependencyPropertyChangedEventArgs e)
            {
            }

            #endregion

            public MainPage()
            {
                InitializeComponent();
            }

            protected override Size ArrangeOverride(Size finalSize)
            {
                var arrangedSize = base.ArrangeOverride(finalSize);
                GeneralTransform gt = rectToGetXAndY.TransformToVisual(LayoutRoot);
                Point p = gt.Transform(new Point(0, 0));
                ReferencePosition = p;
                return arrangedSize;
            }
        }
    }

这里的关键是让base先排列控件，然后使用transform找到位置，最后返回新的arrangedSize。

此时我不建议显示消息框，但您可以使用依赖属性更改回调对更新后的位置执行任何您想做的事情。