带有 UWP MapItemsControl 的多个数据模板 [英] Multiple DataTemplates with UWP MapItemsControl

问题描述

我在 UWP 中有一个 MapControl:

I have a MapControl in UWP:

<maps:MapControl x:Name="BikeMap" ZoomLevel="17" Center="{Binding CenterPoint, Mode=TwoWay}">
    <maps:MapItemsControl x:Name="MapItems" ItemsSource="{Binding BikePoints}"
                        ItemTemplate="{StaticResource BikePointTemplate}"/>
</maps:MapControl>

并且正在使用 XAML 数据模板添加 MapElements，我的 ItemsSource 是一个简单对象列表.

and am adding MapElements using XAML data templates, my ItemsSource is a list of simple objects.

但是，UWP 似乎没有提供一种方法来指定 DataTemplate 的 DataType 并且 MapItemsControl 没有用于设置 DataTemplateSelector 的属性.

But, UWP doesn't seem to provide a way to specify the DataType of a DataTemplate and the MapItemsControl doesn't have a property for setting a DataTemplateSelector.

有谁知道我如何将多个数据模板与 MapItemsControl 一起使用，并根据 ItemsSource 中的对象类型选择相关数据模板?

Does anyone know how I can use multiple data templates with the MapItemsControl and have the relevent data template selected based on the object type within the ItemsSource?

推荐答案

MapItemsControl Class 没有用于设置 DataTemplateSelector.为了实现您想要的，我们可以利用 ContentControl 通过将其设置为 DataTemplate 然后使用 ContentControl.ContentTemplateSelector 属性设置 DataTemplateSelector.

MapItemsControl Class does not have a property for setting DataTemplateSelector. To achieve what you want, we can take advantage of ContentControl by setting it as the template content in DataTemplate and then using ContentControl.ContentTemplateSelector property to set DataTemplateSelector.

以下是一个简单的示例:

Following is a simple sample:

XAML:

<Page x:Class="UWPApp.MainPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:Maps="using:Windows.UI.Xaml.Controls.Maps"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:local="using:UWPApp"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      mc:Ignorable="d">
    <Page.Resources>
        <DataTemplate x:Key="GreenDataTemplate">
            <StackPanel Background="Green">
                <TextBlock Margin="5"
                           Maps:MapControl.Location="{Binding Location}"
                           Maps:MapControl.NormalizedAnchorPoint="0.5,0.5"
                           FontSize="20"
                           Text="{Binding Name}" />
            </StackPanel>
        </DataTemplate>
        <DataTemplate x:Key="RedDataTemplate">
            <StackPanel Background="Red">
                <TextBlock Margin="5"
                           Maps:MapControl.Location="{Binding Location}"
                           Maps:MapControl.NormalizedAnchorPoint="0.5,0.5"
                           FontSize="20"
                           Text="{Binding Name}" />
            </StackPanel>
        </DataTemplate>

        <local:MyTemplateSelector x:Key="MyTemplateSelector" GreenTemplate="{StaticResource GreenDataTemplate}" RedTemplate="{StaticResource RedDataTemplate}" />
    </Page.Resources>
    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <Maps:MapControl x:Name="MyMap" MapServiceToken="MapServiceToken">
            <Maps:MapItemsControl x:Name="MyMapItemsControl" ItemsSource="{Binding}">
                <Maps:MapItemsControl.ItemTemplate>
                    <DataTemplate>
                        <ContentControl Content="{Binding}" ContentTemplateSelector="{StaticResource MyTemplateSelector}" />
                    </DataTemplate>
                </Maps:MapItemsControl.ItemTemplate>
            </Maps:MapItemsControl>
        </Maps:MapControl>
    </Grid>
</Page>

代码隐藏:

public class MyTemplateSelector : DataTemplateSelector
{
    public DataTemplate GreenTemplate { get; set; }
    public DataTemplate RedTemplate { get; set; }

    protected override DataTemplate SelectTemplateCore(object item, DependencyObject container)
    {
        if (item != null)
        {
            if (item is GreenPOI)
            {
                return GreenTemplate;
            }

            return RedTemplate;
        }

        return null;
    }
}

public class POI
{
    public string Name { get; set; }

    public Geopoint Location { get; set; }
}

public class GreenPOI : POI { }

public class RedPOI : POI { }

这只是举例.在示例中，我使用了两个不同背景的数据模板，并创建了一个自定义的DataTemplateSelector，它可以根据对象类型选择DataTemplate.而且如果你有多个对象类型，你也可以参考这个答案:如何将视图与视图模型或多个数据模板关联给视图模型?

This is just for example. In the sample, I used two data template with different background and I create a custom DataTemplateSelector which can choose DataTemplate based on the object type. And if you have several object types, you can also refer to this answer: How to associate view with viewmodel or multiple DataTemplates for ViewModel?

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