Question

我正在创建一个Windows 8应用程序，过去几天我在使用自定义用户控件时遇到了困难。我无法弄清楚什么是错的。

奇怪的是，当我在代码中更改Source时，dependencyproperty会调用propertychanged事件，但是绑定不会更新。

所以这是我的代码：

GamePage.xaml.cs

public sealed partial class GamePage
    {
        GamePageViewModel viewModel;

        public GamePage()
        {
            this.InitializeComponent();
            viewModel = new GamePageViewModel();
        }
    }

GamePage.xaml

<common:LayoutAwarePage x:Class="WordSearcher.GamePage"
                        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"
                        xmlns:common="using:WordSearcher.Common"
                        xmlns:controls="using:WordSearcher.Controls"
                        xmlns:ignore="http://www.ignore.com"
                        mc:Ignorable="d ignore"
                        d:DesignHeight="768"
                        d:DesignWidth="1366"
                        DataContext="{Binding GamePageViewModel, Source={StaticResource Locator}}">
<StackPanel Orientation="Horizontal">
        <StackPanel.Background>
            <ImageBrush ImageSource="Assets/Wood.jpg" Stretch="UniformToFill"/>
        </StackPanel.Background>
<controls:PuzzleControl Source="{Binding Path=PuzzleData}"/>

    </StackPanel>
</common:LayoutAwarePage>

GamePageViewModel.cs

public class GamePageViewModel : ViewModelBase
    {
        private List<string> _puzzleData;

        public List<string> PuzzleData
        {
            get
            {
                return _puzzleData;
            }
            set
            {
                this._puzzleData = value;
                RaisePropertyChanged("PuzzleData");
            }
        }

        public GamePageViewModel()
        {
            SetNewData();
        }

        private async void SetNewData()
        {
            await SomeManager.Prepare();
            PuzzleData = SomeManager.Create(20);
        }
    }

PuzzleControl.xaml.cs

<UserControl
    x:Class="WordSearcher.Controls.PuzzleControl"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:WordSearcher.Controls"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="500"
    d:DesignWidth="500">

    <Grid x:Name="puzzleGrid" 
          Width="500" 
          Height="500"
          >

    </Grid>
</UserControl>

PuzzleControl.xaml.cs

public sealed partial class PuzzleControl : UserControl
    {

        public static readonly DependencyProperty SourceProperty =
            DependencyProperty.Register("Source", typeof(ObservableCollection<string>), typeof(PuzzleControl), new PropertyMetadata(null, PropertyChanged));

        private static void PropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            //
            // not called from binding
            //
            ((PuzzleControl)d).OnItemsSourcePropertyChanged(e);
        }

        private void OnItemsSourcePropertyChanged(DependencyPropertyChangedEventArgs e)
        {
            Source = (ObservableCollection<string>)e.NewValue;
            SetGridData();
        }

        public ObservableCollection<string> Source
        {
            get
            {
                return (ObservableCollection<string>)GetValue(SourceProperty);
            }
            set
            {
                SetValue(SourceProperty, value);
            }
        }

        public PuzzleControl()
        {
            this.InitializeComponent();
            CreateRowsAndColumns();
        }

        private void CreateRowsAndColumns()
        {
            //create rows and columns in puzzleGrid
            //works fine
        }

        private void SetGridData()
        {
            //fill puzzleGrid with data
            //works fine
        }
    }

有人知道我的代码有错吗？因为当我把Source = new ObservableCollection（）;在PuzzleData的构造函数中，PropertyChanged事件将引发。是DataContext的任何内容吗？

Thnx提前！

Answer 1

我不确定，

但您设置了<controls:PuzzleControl Source="{Binding Path=PuzzleData}"/>

PuzzleData = List<string>

和

Source = ObservableCollection<string>

如果绑定甚至第一次工作（它显然是什么），那么可能是源以某种方式设置为List <string>而不是ObservableCollection<string>。这可能就是为什么没有调用dependencyproperty方法（PropertyChanged）因为它已注册到ObservableCollection<string>的原因。

但这都是纯粹的猜测，没有经过测试。

在我对他的代码进行审核之后，我发现PuzzleData从未真正设置过，那就是错误...错误报警......

Answer 2

您确定绑定上下文吗？以及如何绑定对象？如果您在gridview中使用用户控件，则会更改DataContext，并对根页的差异Datacontext进行更改。

<controls:PuzzleControl Source="{Binding Path=DataContext.PuzzleData}"/>

如果您使用子控件，您的用户控件;绑定ElementName属性，如下所示：

<controls:PuzzleControl Source="{Binding Path=DataContext.PuzzleData, ElementName=pageRoot}"/>

如果您不确定，请通过断点跟踪调试DataContext绑定值。

UserControl Dependencyproperty不通过绑定更新

2 个答案: