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Xamarin形成行为-与外部类的交互

xamarin.forms xamarin

0

Journeyman1234 · 技术社区 · 7 年前

我已经创建了一个与自定义Xamarin表单映射相关的ViewModel

在这个地图上,我在触发器上显示一个输入字段,根据条件显示为可见或不可见

我已经成功地将条目IsVisible参数绑定到行为,并且可以在按钮上进行切换

然而,我真正想要的是实现这一点,以回应点击一个引脚

尝试此操作时,无法启动OnPropertyChange

我不知道如何克服这个问题-pin在一个单独的类中,所以我无法将它绑定到包含文本条目的网格视图

我在自定义pin上附加了一个click事件,并使用它与视图模型进行交互

        pin.Clicked += (object sender, EventArgs e) =>
        {
            var p = sender as CustomPin;

            var callingMethod = new HandleEditor();

            callingMethod.Pin_Clicked(p);

        };

这是XAML

    <Grid x:Name="LayoutGrid">

    <Grid.BindingContext>
        <local:HandleEditor />
    </Grid.BindingContext>

<Grid.RowDefinitions>
    <RowDefinition Height="*" />
    <RowDefinition Height="150" />
    <RowDefinition Height="*" />     
</Grid.RowDefinitions>

    <local:CustomMap Grid.RowSpan="3"  Grid.Row="0"  MapType="Street" WidthRequest="300" HeightRequest="300" />                        

    <Editor x:Name="TextEntry" Grid.Row="1" VerticalOptions="FillAndExpand" IsVisible="{Binding SwitchVisible, Mode=TwoWay}"/>

    <Button Grid.Row="2" Text="Switch Bool Test" Command="{Binding ChangeBoolValue}"/>

    </Grid>

这是ViewModel

    public event PropertyChangedEventHandler PropertyChanged;

    bool isEditorVisible = false;

    public ICommand ChangeBoolValue { protected set; get; }
    public ICommand Debug { protected set; get; }


    public bool SwitchVisible

    {



        get

        {

            System.Diagnostics.Debug.WriteLine("Debug: SwitchVisible has been fired " + isEditorVisible);
            return isEditorVisible;

        }



    }




    public HandleEditor()


    {


        ChangeBoolValue = new Command(() =>
        {


            if (isEditorVisible == true)

            {

                isEditorVisible = false;
                OnPropertyChanged("SwitchVisible");
            }

            else
            {

                isEditorVisible = true;
                OnPropertyChanged("SwitchVisible");

            }


        });


    }


    protected virtual void OnPropertyChanged(string propertyName)
    {
        System.Diagnostics.Debug.WriteLine("Debug: OnPropertyChanged has been fired " + propertyName + " : " + isEditorVisible);

        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public void Pin_Clicked(CustomPin pin)

    {


        isEditorVisible = true;
        OnPropertyChanged("SwitchVisible");


    }

0 回复 | 直到 7 年前

1

0

Umar3x 7 年前

isEditorVisible 财产。

我已成功地将条目IsVisible参数绑定到

您正在使用 Editor Entry . 另外,你正在绑定 Command 命令 在你的 ViewModel ChangeBoolValue . 您没有使用 Behavior<T>

<Editor x:Name="TextEntry" Grid.Row="1" VerticalOptions="FillAndExpand" IsVisible="{Binding SwitchVisible, Mode=TwoWay}"/>

所以你想要达到的是 编辑 IsVisibleProperty将根据 SwitchIsVisible 属性,你绑定到哪一个,对吗?

我将在ViewModel中执行类似的操作,而不是实际实现:

public event PropertyChangedEventHandler PropertyChanged;

public ICommand ChangeBoolValue { protected set; get; }
public ICommand Debug { protected set; get; }

private bool _switchVisible;
public bool SwitchVisible
{

    get => _switchVisible;
    set
    {            
      if(_switchVisible == value) return;
      _switchVisible = value;
      OnPropertyChanged("SwitchVisible");
    }
}


public HandleEditor()
{
    ChangeBoolValue = new Command(() =>
    {
       SwitchVisible = !SwitchVisible;

    });
}


protected virtual void OnPropertyChanged(string propertyName)
{
    System.Diagnostics.Debug.WriteLine("Debug: OnPropertyChanged has been fired " + propertyName + " : " + isEditorVisible);

    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

public void Pin_Clicked(CustomPin pin)
{
   SwitchVisible = true;
}