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c# - Xamarin 表单 ListView : Deselecting selected item by checking with OnTapped Event

转载 作者:行者123 更新时间:2023-11-30 21:46:22 25 4
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当我第二次点击它时,我将能够取消选择我的项目。当我点击一个项目时,背景颜色变为蓝色。当我第二次点击列表中的同一项目时,我希望背景获得默认颜色。您可以在这里找到我的代码,但它不起作用。

XAML

<StackLayout Margin="5,0,5,0" HorizontalOptions="FillAndExpand" VerticalOptions="CenterAndExpand">
<Frame Style="{StaticResource StandardFrameStyle}" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<ListView x:Name="lst_pickList" ItemSelected="OnItemSelected" ItemTapped="OnItemTapped" ItemsSource="{Binding PickList}" HasUnevenRows="True" Style="{StaticResource StandardListViewStyle}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<Grid x:Name="grd_pickList" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" >
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>

<Label x:Name="lbl_comment" Text="Comment:" FontAttributes="Bold" Grid.Row="0" Grid.Column="0" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
<Label x:Name="lbl_itemNo" Text="ItemNo:" FontAttributes="Bold" Grid.Row="0" Grid.Column="2" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
<Label x:Name="lbl_description" Text="Description:" FontAttributes="Bold" Grid.Row="1" Grid.Column="0" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
<Label x:Name="lbl_restant" Text="Restant:" FontAttributes="Bold" Grid.Row="1" Grid.Column="2" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />

<Label x:Name="lbl_comment_binding" Text="{Binding Comment}" Grid.Row="0" Grid.Column="1" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
<Label x:Name="lbl_itemNo_binding" Text="{Binding ItemNo}" Grid.Row="0" Grid.Column="3" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
<Label x:Name="lbl_description_binding" Text="{Binding Description}" Grid.Row="1" Grid.Column="1" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
<Label x:Name="lbl_restant_binding" Text="{Binding Restant}" Grid.Row="1" Grid.Column="3" VerticalTextAlignment="Center" Style="{StaticResource StandardLabelStyle}" />
</Grid>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Frame>
</StackLayout>

代码隐藏

public void OnItemTapped(object sender, ItemTappedEventArgs args)
{
var newSelectedPick = args.Item as Pick;

if(selectedPick != null && selectedPick.Id == newSelectedPick.Id)
{
lst_pickList.SelectedItem = null;
}
else
{
selectedPick = newSelectedPick;
}
}

最佳答案

在名为 IsSelectedPick 对象上创建一个 boolean 属性,然后将其Bind 到您的 grd_pickList BackgroundColor 带有转换器。

即:

//Xaml

<ListView.Resources>
<ResourceDictionary>
<local:BgConverter x:Key="BgConverter"/>
</ResourceDictionary>
</ListView.Resources>

<Grid x:Name="grd_pickList" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" BackgroundColor="{Binding IsSelected,Converter={StaticResource BgConverter}}" >

//转换器

class BgConverter : IValueConverter
{

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is bool &&(bool)value)
return Color.Blue;
else
return Color.White;
}

public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotSupportedException();
}
}

//Xaml.cs

public void OnItemTapped(object sender, ItemTappedEventArgs args)
{
var itm = args.Item as Pick;
itm.IsSelected = !itm.IsSelected;
}

重要:确保 IsSelected 属性触发 OnPropertyChanged 事件。

关于c# - Xamarin 表单 ListView : Deselecting selected item by checking with OnTapped Event,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39265968/

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