Question

我有一个带有自定义视单元的ListView，我在其中放置了Label和GestureRecognizers。如何使用带有TapGestureRecognizer的Label处理不同的项目。所以这是我的代码。

<ViewCell>
  <StackLayout>
    <StackLayout Orientation="Horizontal" Padding="5">
      <Label Text="{Binding Title, Converter={StaticResource LettersConverter}}" FontSize="30" TextColor="#edfff1"/>
      <Label Text="&#xf017;" FontSize="40">
        <Label.GestureRecognizers>
          <TapGestureRecognizer Tapped="TapGestureRecognizer_Tapped" />
        </Label.GestureRecognizers>
      </Label>                                    
    </StackLayout>                                
    <StackLayout Orientation="Horizontal" Padding="1">
      <Label Text="Alarm" TextColor="#edfff1" FontSize="Micro"/>
      <Label Text="{Binding AlarmTime, StringFormat='{0:dddd, d MMMM, yyyy, HH:mm}'}"/>                                    
    </StackLayout>
  </StackLayout>
</ViewCell>

谢谢。

更新代码：

的Xaml：

<Label Text="&#xf017;">
                                                <Label.GestureRecognizers>
                                                    <TapGestureRecognizer                                                         
                                                        Command="{Binding TapCommand}"
                                                        CommandParameter="{Binding .}" />
                                                </Label.GestureRecognizers>
                                            </Label>

代码：

ICommand tapCommand;
        public MainPage()
        {
            tapCommand = new Command(OnTapped);
        }
        public ICommand TapCommand
        {
            get { return tapCommand; }
        }
        void OnTapped(object s)
        {
            test.Text = "Works";            
        }

最终工作守则。

的Xaml：

<Label Text="Test">
                                                <Label.GestureRecognizers>
                                                    <TapGestureRecognizer
                                                        Command="{Binding Path = TapCommand, Source={x:Reference MainPage}}" CommandParameter="{Binding .}"
                                                     />
                                                </Label.GestureRecognizers>
                                            </Label>

代码背后。

ICommand tapCommand;

//constructor
    public MainPage()
    {
        tapCommand = new Command(OnClick);
    }

    public ICommand TapCommand
    {
        get { return tapCommand; }
    }

    void OnClick(object i)
    {
        var model = (Note)i;
        st.Text = model.Title;

    }

Answer 1

这真的很容易。 3个特殊步骤

1像这样CommandObject =“ {Binding。}”
将该对象绑定到标签。
2 create函数来调用Tapped =“ TapGestureRecognizer_Tapped”

<StackLayout Orientation="Horizontal" Padding="5">
  <Label Text="{Binding Title, Converter={StaticResource LettersConverter}}" FontSize="30" TextColor="#edfff1"/>
  <Label Text="&#xf017;" FontSize="40">
    <Label.GestureRecognizers>
      <TapGestureRecognizer Tapped="TapGestureRecognizer_Tapped" CommandParameter="{Binding .}" />
    </Label.GestureRecognizers>
  </Label>                                    
</StackLayout>

在您的代码后面的
3处获得所选标签var lbl = sender作为Label；将绑定模型作为选定对象获取var selectedItem = lbl.BindingContext作为YourModel;

 private void TapGestureRecognizer_Tapped(object sender, EventArgs e)
    {


        var lbl = sender as Label;

        var selectedItem = lbl.BindingContext as YourModel;
        if (selectedItem == null) return;
        // now you can access any property of your model
        // for example  var id = YourModel.id

        // or you can pass your model to a function like
        //HideorShowDetail(selectedItem);
    }

请注意，您可以对任何对象使用此方法。例如，如果您在listView中创建可点击的图像。

var lbl = sender as Label; will be var img = sender as Image;

button would be var btn = sender as Button; 等等

Answer 2

如果我理解正确，您想知道点击了哪个标签。如果我是你，我会使用ICommand而不是事件处理程序和CommandParameter，它会为你提供项目ID。

MusicPlayManager.sharedInstance.player

在您的ViewModel或后面的代码中（取决于您的<TapGestureRecognizer Command="{Binding OnClickCommand}" CommandParameter="{Binding ItemId}" />是什么，您需要像这样实现ICommand：

BindingContext

Xamarin在官方文档here上有一个很好的教程如何做这样的事情。

编辑：所以，这似乎是您正在寻找的。

ICommand _onClickCommand;

public ICommand OnClickCommand 
{
    get { return _onClickCommand; }
}

public YourViewModel() {
    OnClickCommand = new Command (OnClick);
}

void OnClick(object i) {
    var labelId = Convert.ToString(i);

    // Now you know which label was clicked and you can do something with it
}

然后

<TapGestureRecognizer Command="{Binding OnClickCommand}"
                      CommandParameter="{Binding .}" />

编辑2：这里的问题是TapGestureRecognizer没有指向页面的BindingContext。你要做的是以下几点：

void OnClick(object i) {
    var model = (YourViewModel)i;

    // Now you can access model.AlarmTime, model.Title etc.
}

另外，将x：Name添加到您的页面，如下所示：

<TapGestureRecognizer Command="{Binding Path = BindingContext.OnClickCommand, Source={x:Reference MainPage}}" CommandParameter="{Binding .}" />

现在，当您点击标签时，OnClickCommand位于主BindingContext中，而不是ListView的ItemsSource中。

如何通过viewcell TapGestureRecognizer处理ListView的项目

2 个答案: