如何解决嵌套网格 TapGestureRecognizer 不起作用？
我是 Xamarin 的新手。我一直试图点击我网格的每一行，但不幸的是没有工作。我有一个带有 A 网格的 CollectionView，在 row=1 的网格内我有另一个带有新网格的 CollectionView。
我的问题是当我点击行时 onlu row=0 和 row=2 正在触发，而不是 row=1 那里我有另一个 COllectionView。我在下面附上了我的代码。
<RefreshView Command="{Binding LoadAlertsCommand}" IsRefreshing="{Binding IsBusy,Mode=TwoWay}" IsVisible="{Binding RefreshViewVisible}">
<CollectionView x:Name="AlertsListView"
ItemsSource="{Binding Alerts}"
SelectionMode="None" >
<CollectionView.ItemTemplate>
<DataTemplate>
<SwipeView x:DataType="model:AlertsTable" Threshold="250">
<SwipeView.RightItems>
<SwipeItems Mode="Execute">
<SwipeItem Text="Delete"
BackgroundColor="#ff453a"
Command="{Binding Source={RelativeSource AncestorType={x:Type local:AlertViewModel}},Path=DeleteCommand}"
CommandParameter="{Binding .}"/>
</SwipeItems>
</SwipeView.RightItems>
<Grid Padding="15,5,15,0" x:DataType="model:AlertsTable" x:Name="Grid1" BackgroundColor="Black">
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<BoxView Color="#292929" Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="4"/>
<Label x:Name="TextLabel" Grid.Row="0" Grid.Column="0" Text="{Binding title}" TextColor="White" FontSize="20" FontAttributes="Bold"/>
<Label x:Name="RightTextLabel" Grid.Row="0" Grid.Column="1" FontSize="15" Text="{Binding date}" HorizontalOptions="Center" VerticalOptions="CenterAndExpand" TextColor="White"/>
<Label Text="{x:Static fontAwesome:FontAwesomeIcons.Circle}"
IsVisible="{Binding wasRead}"
Grid.Row="0" Grid.Column="3"
HorizontalOptions="Center"
VerticalOptions="CenterAndExpand"
FontSize="Medium"
TextColor="White"
FontFamily="fa5r"/>
<!--<Frame >-->
<CollectionView x:Name="ConditionsListView"
ItemsSource="{Binding alertmetadata.Conditions}"
SelectionMode="None" Grid.Row="1" Grid.ColumnSpan="4" Grid.Column="0" HeightRequest="120">
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid x:DataType="model:AlertConditionEx">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Label Text="{Binding LeftItem.NS}" Grid.Row="0" Grid.Column="0" HorizontalOptions="Center" VerticalOptions="CenterAndExpand" TextColor="White"/>
<Image Source="{x:Binding OS,Converter={StaticResource ImageConverter}}" Grid.Row="0" Grid.Column="1" HorizontalOptions="Center" VerticalOptions="CenterAndExpand"
HeightRequest="40"></Image>
<Label Text="{Binding RightItem.NS}" Grid.Row="0" Grid.Column="2" HorizontalOptions="Center" VerticalOptions="CenterAndExpand" TextColor="White"/>
<Image Source="{x:Binding OS,Converter={StaticResource ChartImageConverter}}" Grid.Row="0" Grid.Column="3"
HeightRequest="40"></Image>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
<Label Text="..." TextColor="White" FontAttributes="Bold" FontSize="Large" Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="4" IsVisible="{Binding alertmetadata.ThreeDots}" HorizontalTextAlignment="Center" HorizontalOptions="CenterAndExpand"/>
<BoxView VerticalOptions="FillAndExpand" HeightRequest="1" Color="#59595b"
Grid.Row="3" Grid.Column="0" Grid.ColumnSpan="4"/>
<!--</Frame>-->
<Grid.GestureRecognizers>
<TapGestureRecognizer
NumberOfTapsRequired="1"
Command="{Binding Source={RelativeSource AncestorType={x:Type local:AlertViewModel}},Path=AlertsTapped}"
CommandParameter="{Binding .}">
</TapGestureRecognizer>
</Grid.GestureRecognizers>
</Grid>
</SwipeView>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
</RefreshView>
解决方法
Tap 手势不起作用，因为 CollectionView 与 BoxView 或 Label 不同，CollectionView 本身能够接收动作（点击项目），因此会发生冲突用外部手势出来。
为了解决这个问题，我们可以在内部 collectionview 上设置额外的点击手势。
<CollectionView x:Name="ConditionsListView"
ItemsSource="{Binding alertmetadata.Conditions}"
SelectionMode="None" Grid.Row="1" Grid.ColumnSpan="4" Grid.Column="0" HeightRequest="120">
<CollectionView.ItemTemplate>
<DataTemplate>
<Grid x:DataType="model:AlertConditionEx">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Label Text="{Binding LeftItem.NS}" Grid.Row="0" Grid.Column="0" HorizontalOptions="Center" VerticalOptions="CenterAndExpand" TextColor="White"/>
<Image Source="{x:Binding OS,Converter={StaticResource ImageConverter}}" Grid.Row="0" Grid.Column="1" HorizontalOptions="Center" VerticalOptions="CenterAndExpand" HeightRequest="40"></Image>
<Label Text="{Binding RightItem.NS}" Grid.Row="0" Grid.Column="2" HorizontalOptions="Center" VerticalOptions="CenterAndExpand" TextColor="White"/>
<Image Source="{x:Binding OS,Converter={StaticResource ChartImageConverter}}" Grid.Row="0" Grid.Column="3" HeightRequest="40"></Image>
//add this code
<Grid.GestureRecognizers>
<TapGestureRecognizer
NumberOfTapsRequired="1"
Command="{Binding Source={RelativeSource AncestorType={x:Type local:AlertViewModel}},Path=AlertsTapped}" CommandParameter="{Binding .}">
</TapGestureRecognizer>
</Grid.GestureRecognizers>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
参考
https://forums.xamarin.com/discussion/57539/listview-with-mvvm-tapgesturerecognizer-not-working。
,你必须像这样使用它：
Command="{Binding Source={x:Reference AlertsListView},Path=BindingContext.YourCommandName}"
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