MvvmCross：在MonoDroid上更改绑定的更新源触发器属性 [英] MvvmCross: change update source trigger property of binding on MonoDroid

问题描述

我想在Droid EditText视图中将PropertyChanged的默认绑定触发器更改为LostFocus：

 < EditText 
 android：layout_width =fill_parent
 android：layout_gravity =center
 android：textSize =16dp
 android：minWidth =168dp
 local：MvxBind =Text SelectedCode，UpdateSourceTrigger = LostFocus/> 
  

但是，我找不到正确的语法从维基

我知道这是可能在框架内，但找不到参考。 / p>

想法？

TIA。

解决方案

绑定语法不提供 UpdateSourceTrigger

触发机制是：

• 提供自定义绑定


• 或提供自定义控件li>
  

我会去自定义绑定，如：

  public class MvxEditTextFocusChangeTextSpecialTargetBinding 
：MvxAndroidTargetBinding 
 {
 protected EditText EditText 
 {
 get {return（EditText） } 
} 
 
 private bool _subscribed; 
 
 public MvxEditTextFocusChangeTextSpecialTargetBinding（EditText view）
：base（view）
 {
} 
 
 protected override void SetValueImpl（object target，object值）
 {
 var editText = EditText; 
 if（editText == null）
 return; 
 
 value = value？ string.Empty; 
 editText.Text = value.ToString（）; 
} 
 
 public override MvxBindingMode DefaultMode 
 {
 get {return MvxBindingMode.TwoWay; } 
} 
 
 public override void SubscribeToEvents（）
 {
 var editText = EditText; 
 if（editText == null）
 return; 
 
 editText.FocusChange + = HandleFocusChange; 
 _subscribed = true; 
} 
 
 private void HandleFocusChange（object sender，View.FocusChangeEventArgs e）
 {
 var editText = EditText; 
 if（editText == null）
 return; 
 
 if（！e.HasFocus）
 FireValueChanged（editText.Text）; 
} 
 
 public override类型TargetType 
 {
 get {return typeof（string）; 
 
 
 protected override void Dispose（bool isDisposing）
 {
 if（isDisposing）
 {
 var editText = EditText; 
 if（editText！= null&& _subscribed）
 {
 editText.FocusChange  -  = HandleFocusChange; 
 _subscribed = false; 
} 
} 
 base.Dispose（isDisposing）; 
} 
} 
  

注册使用：

  registry.RegisterCustomBindingFactory< EditText>（FocusText，
 textView => new MvxEditTextFocusChangeTextSpecialTargetBinding（textView））; 
  

然后用作：

 本地：MvxBind =FocusText VMProperty
  

有关自定义绑定的更多信息，请参阅N = 28教程 - http://slodge.blogspot.co.uk/2013/06/n28-custom-bindings-n1-days-of-mvvmcross.html

I will like to change the default binding trigger from PropertyChanged to LostFocus on a Droid EditText view:

 <EditText
                android:layout_width="fill_parent"
                android:layout_gravity="center"
                android:textSize="16dp"
                android:minWidth="168dp"
                local:MvxBind="Text SelectedCode, UpdateSourceTrigger=LostFocus" />

But I cannot find the correct syntax from the Wiki

I know this is possible within the framework but cannot find the reference.

Ideas?

TIA.

解决方案

The binding syntax doesn't provide UpdateSourceTrigger

The only ways to change the triggering mechanism are:

• to provide a custom binding
• or to provide a custom control

I'd go for custom binding - something like:

public class MvxEditTextFocusChangeTextSpecialTargetBinding
    : MvxAndroidTargetBinding
{
    protected EditText EditText
    {
        get { return (EditText)Target; }
    }

    private bool _subscribed;

    public MvxEditTextFocusChangeTextSpecialTargetBinding(EditText view)
        : base(view)
    {
    }

    protected override void SetValueImpl(object target, object value)
    {
        var editText = EditText;
        if (editText == null)
            return;

        value = value ?? string.Empty;
        editText.Text = value.ToString();
    }

    public override MvxBindingMode DefaultMode
    {
        get { return MvxBindingMode.TwoWay; }
    }

    public override void SubscribeToEvents()
    {
        var editText = EditText;
        if (editText == null)
            return;

        editText.FocusChange += HandleFocusChange;
        _subscribed = true;
    }

    private void HandleFocusChange(object sender, View.FocusChangeEventArgs e)
    {
        var editText = EditText;
        if (editText == null)
            return;

        if (!e.HasFocus)
            FireValueChanged(editText.Text);
    }

    public override Type TargetType
    {
        get { return typeof(string); }
    }

    protected override void Dispose(bool isDisposing)
    {
        if (isDisposing)
        {
            var editText = EditText;
            if (editText != null && _subscribed)
            {
                editText.FocusChange -= HandleFocusChange;
                _subscribed = false;
            }
        }
        base.Dispose(isDisposing);
    }
}

registered using:

registry.RegisterCustomBindingFactory<EditText>("FocusText",
                                                        textView => new MvxEditTextFocusChangeTextSpecialTargetBinding(textView));

then used as:

 local:MvxBind="FocusText VMProperty"

For more on custom bindings, see the N=28 tutorial - http://slodge.blogspot.co.uk/2013/06/n28-custom-bindings-n1-days-of-mvvmcross.html

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