Question

我目前正在尝试开发基于Xamarin Forms选项卡页面的应用程序。首先，应用程序只有一个用C＃编写的内容页面。我现在要做的是将现有的内容页面实现到选项卡页面的一个选项卡中。

我正在XAML中编写标签页，我不知道如何用这种语言执行“SetBinding”或“BindingContext”。

以下是我想从C＃转到XAML的内容：

    public MyPage()
    {

        this.BindingContext = new MyPageViewModel();

        Picker pickerBluetoothDevices = new Picker() { Title = "Select a bth device" };
        pickerBluetoothDevices.SetBinding(Picker.ItemsSourceProperty, "ListOfDevices");
        pickerBluetoothDevices.SetBinding(Picker.SelectedItemProperty, "SelectedBthDevice");
        pickerBluetoothDevices.SetBinding(VisualElement.IsEnabledProperty, "IsPickerEnabled");

        Entry entrySleepTime = new Entry() {Keyboard = Keyboard.Numeric, Placeholder = "Sleep time" };
        entrySleepTime.SetBinding(Entry.TextProperty, "SleepTime");

        Button buttonConnect = new Button() { Text = "Connect" };
        buttonConnect.SetBinding(Button.CommandProperty, "ConnectCommand");
        buttonConnect.SetBinding(VisualElement.IsEnabledProperty, "IsConnectEnabled");

        Button buttonDisconnect = new Button() { Text = "Disconnect" };
        buttonDisconnect.SetBinding(Button.CommandProperty, "DisconnectCommand");
        buttonDisconnect.SetBinding(VisualElement.IsEnabledProperty, "IsDisconnectEnabled");

        Button buttonSend = new Button() { Text = "Send" };
        buttonSend.SetBinding(Button.CommandProperty, "SendCommand");
        buttonSend.SetBinding(VisualElement.IsEnabledProperty, "IsSendEnabled");

        StackLayout slButtons = new StackLayout() {Orientation = StackOrientation.Horizontal, Children = {buttonDisconnect, buttonConnect, buttonSend } };

        ListView lv = new ListView();
        lv.SetBinding(ListView.ItemsSourceProperty, "ListOfBarcodes");
        lv.ItemTemplate = new DataTemplate(typeof(TextCell));
        lv.ItemTemplate.SetBinding(TextCell.TextProperty, ".");

        int topPadding = 0;
        if (Device.RuntimePlatform == Device.iOS)
            topPadding = 20;

        StackLayout sl = new StackLayout { Children = { pickerBluetoothDevices, entrySleepTime, slButtons, lv }, Padding = new Thickness(0,topPadding,0,0) };
        Content = sl;
    }

XAML中这个C＃代码的等价物是什么？

我从这样的事情开始：

<?xml version="1.0" encoding="utf-8" ?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="TestBth.MyTabbedPage">
  <!--Pages can be added as references or inline-->
  <ContentPage Title="Connect">



        <ContentPage.Content>
            <StackLayout VerticalOptions="Center" HorizontalOptions="Center">

                <Picker x:Name="pickerBluetoothDevices" Title="Select a bth device"/>

                <Button x:Name="buttonConnect" Text="Connect"/>
                <Button x:Name="buttonDisconnect" Text="Disconnect"/>
                <Button x:Name="buttonSend" Text="Send"/>

                <ListView x:Name="lv"/>

            </StackLayout>

        </ContentPage.Content>

  </ContentPage>

Answer 1

您只需将c＃绑定属性更改为Xaml属性即可。

与c＃中的ItemSourceProperty一样，xaml绑定为ItemSource

<StackLayout VerticalOptions="Center" HorizontalOptions="Center">

            <Picker x:Name="pickerBluetoothDevices" ItemsSource="{Binding ListOfDevices}" Title="Select a bth device" SelectedItem="{Binding SelectedBthDevice}" IsEnable="{Binding IsPickerEnabled}"/>

            <Button x:Name="buttonConnect" Text="Connect" Command="{Binding ConnectCommand}"/>
            <Button x:Name="buttonDisconnect" Text="Disconnect" Command="{Binding DisconnectCommand}"/>
            <Button x:Name="buttonSend" Text="Send" Command="{Binding SendCommand}"/>

            <ListView x:Name="lv" ItemSource="{Binding ListOfBarcodes}"/>

        </StackLayout>

Answer 2

您想在代码中创建绑定的任何原因？您也可以在代码中进行绑定，例如将命令绑定到按钮，您可以使用：

<Button Command="{Binding ButtonCommand}"/>

在视图的构造函数中，您需要设置上下文：

 public View()
  {
        InitializeComponent();
        this.BindingContext = this; // or instance of your ViewModel
  }

并且您还需要在BindingContext实例中定义您的命令：

public ICommand ButtonCommand { get; set; }

如何在XAML页面中执行SetBinding和BindingContext？

2 个答案: