Question

我有一个WCF RIA POCO对象 - ＆gt;交通信号灯具有描述其状态的枚举类型。

[DataContract]
public class TrafficLight
{
    [Key]
    [DataMember]
    public long Id { get; set; }    

    [DataMember]
    public Longitude Longitude { get; set; }

    [DataMember]
    public Latitude Latitude { get; set; }

    [DataMember]
    public TrafficLightState SelectedLight { get; set; }
}

[DataMember]
public enum TrafficLightState
{
    [EnumMember]
    Red = 0,

    [EnumMember]
    Yellow = 1,

    [EnumMember]
    Green = 2
}

因此，鉴于WCF RIA服务，我需要将此交通灯对象提供给Silverlight客户端应用程序：

public IEnumerable<TrafficLight> GetTrafficLightsForCity(int cityId)
{
    return Data.GetTrafficLightsForCity(cityId).AsEnumerable();
}

这样可行。我得到了我的清单，一切都很好，直到我决定将列表绑定到一个将显示我的交通信号灯的网格...（PS。这是一个类似sim城市的游戏）：

交通信号灯在网格中的显示方式是通过一个显示灯光状态的小控件 - ＆gt;红色，黄色，绿色，加上其他一些东西。现在我将向您展示Light状态和ID：

<UserControl x:Name="MiniTrafficLightControl" x:Class="UI.MiniTrafficLight"
    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="15" 
    d:DesignWidth="15"
    Width="15" Height="15">
    <StackPanel Orientation="Horizontal">
        <Border x:Name="BrdGreen" Visibility="Visible" CornerRadius="10" Width="15" Height="15" Margin="0" ToolTipService.ToolTip="Runing" d:IsLocked="True">
        <Border.Background>
            <RadialGradientBrush  GradientOrigin="0.4,0.3" Center="0.4,0.3" RadiusX="0.5" RadiusY="0.5">
            <RadialGradientBrush.GradientStops>
                <GradientStop Color="LightGreen" Offset="0" />
            <GradientStop Color="Green" Offset="0.95" />
            </RadialGradientBrush.GradientStops>
        </RadialGradientBrush>
        </Border.Background>
    </Border>
    <Border x:Name="BrdYellow" Visibility="Collapsed" CornerRadius="10" Width="15" Height="15" Margin="0" ToolTipService.ToolTip="Action Pending" d:IsHidden="True" d:IsLocked="True">
        <Border.Background>
            <RadialGradientBrush  GradientOrigin="0.4,0.3" Center="0.4,0.3" RadiusX="0.5" RadiusY="0.5">
            <RadialGradientBrush.GradientStops>
                <GradientStop Color="Yellow" Offset="0" />
            <GradientStop Color="Orange" Offset="0.95" />
            </RadialGradientBrush.GradientStops>
        </RadialGradientBrush>
        </Border.Background>
    </Border>
    <Border x:Name="BrdRed" Visibility="Collapsed" CornerRadius="10" Width="15" Height="15" Margin="0" ToolTipService.ToolTip="Stopped" d:IsHidden="True" d:IsLocked="True">
        <Border.Background>
            <RadialGradientBrush  GradientOrigin="0.4,0.3" Center="0.4,0.3" RadiusX="0.5" RadiusY="0.5">
            <RadialGradientBrush.GradientStops>
                <GradientStop Color="Orange" Offset="0" />
            <GradientStop Color="Red" Offset="0.95" />
            </RadialGradientBrush.GradientStops>
        </RadialGradientBrush>
        </Border.Background>
    </Border>
    </StackPanel>
</UserControl>

控制背后的代码：

namespace UI
{
    public partial class MiniTrafficLight : UserControl
    {
        public static readonly DependencyProperty TrafficLightStateProperty = DependencyProperty.Register("TrafficLightState", typeof(TrafficLightState), typeof(MiniTrafficLight), null);

        public TrafficLightState TrafficLightState
    {
        get
        {
            return (TrafficLightState)this.GetValue(TrafficLightStateProperty);
        }
        set
        {
            if (value == TrafficLightState.Red)
        {
            this.BrdRed.Visibility = System.Windows.Visibility.Visible;
            this.BrdGreen.Visibility = System.Windows.Visibility.Collapsed;
            this.BrdYellow.Visibility = System.Windows.Visibility.Collapsed;
        }
        else if (value == TrafficLightState.Yellow)
        {
            this.BrdRed.Visibility = System.Windows.Visibility.Collapsed;
            this.BrdGreen.Visibility = System.Windows.Visibility.Collapsed;
            this.BrdYellow.Visibility = System.Windows.Visibility.Visible;
        }
        else
        {
             this.BrdRed.Visibility = System.Windows.Visibility.Collapsed;
                     this.BrdGreen.Visibility = System.Windows.Visibility.Visible;
             this.BrdYellow.Visibility = System.Windows.Visibility.Collapsed;
        }

                this.SetValue(TrafficLightStateProperty, value);
        }
        }
    }
}

所以现在问题是，如果页面上的任何地方我有一个网格，使用网格内的MiniTraficLight控件显示所有红绿灯对象 - MiniTrafficLight控件永远不会工作......或者它永远不会显示绿色的红色或黄色的灯光。我调试了该服务，并验证了从每个红绿灯对象的数据库中读取TrafficLightState属性时的设置。我还可以在客户端silverlight应用程序上验证每个TrafficLight对象的TrafficLightState是否正确到达（也就是......它已设置）。

但是，如果我手动设置MiniTrafficLight的控件TrafficLightState而不进行绑定则可以正常工作。如果我使用绑定它永远不会出现。有或没有转换器，MiniTrafficLight控件上的属性永远不会被调用。我知道的原因是我在属性的set访问器上添加了MessageBox.Show(...)，我没有看到任何消息框。如果我提出破发点 - 他们永远不会达成。 Bellow是显示网格内交通灯对象的示例代码：

<datagrid:DataGrid x:Name="ReceiverNodesDataGrid" Grid.Row="1" AutoGenerateColumns="False" IsReadOnly="True" HorizontalAlignment="Stretch" SelectionMode="Single">
    <datagrid:DataGrid.Columns>
        <datagrid:DataGridTemplateColumn Header="Status">
            <datagrid:DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <local:MiniTraficLight TrafficLightState="{Binding TrafficLightState}"/>
        </DataTemplate>
            </datagrid:DataGridTemplateColumn.CellTemplate>
    </datagrid:DataGridTemplateColumn>
        <datagrid:DataGridTextColumn Header="Id" Binding="{Binding Id}" />
    </datagrid:DataGrid.Columns>
</datagrid:DataGrid>

知道为什么这种绑定不起作用？

全部谢谢，马丁

Answer 1

显然，这样做的诀窍是正确实现依赖属性。 UGHHHHH！

namespace UI
{
    public partial class MiniTrafficLight : UserControl
    {
        private static PropertyMetaData trafficLightStateMetaData = new PropertyMetaData(new PropertyChangedCallBack(TrafficLightState_Changed));
        public static readonly DependencyProperty TrafficLightStateProperty = DependencyProperty.Register("TrafficLightState", typeof(TrafficLightState), typeof(MiniTrafficLight), trafficLightStateMetaData);

        public TrafficLightState TrafficLightState
        {
            get { return (TrafficLightState)this.GetValue(TrafficLightStateProperty); }
            set { this.SetValue(TrafficLightStateProperty, value); }
        }

        private static void TrafficLightState_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            MiniTrafficLight sender = d as MiniTrafficLight;
            TrafficLightState state = (TrafficLightState)e.NewState;

            if( state == TrafficLightState.Red )
            {
                //...
            }
            else if ( state == TrafficLightState.Yellow )
            {
                //...
            }
            else
            {
                //...
            }
        }
    }
}

Silverlight 4 - Binding对枚举类型的POCO对象不起作用？

1 个答案: