Xamarin中有一种对滑块进行分组的方法 在Xmal 在后面的代码中 ContentPage

如何解决Xamarin中有一种对滑块进行分组的方法 在Xmal 在后面的代码中 ContentPage

我正在尝试将各种滑块元素组合在一起。例如，如果我有两个元素，两个元素都设置为50（值从0到100），则值的总和必须始终为100，因此，如果将其中一个滑块设置为值70，则另一个必须动态减小到30的值。

<ListView x:Name="listView"
          ItemSource="myList">
   <ListView.ItemTemplate>
       <DataTemplate>
           <ViewCell>
               <Slider x:Name="slider"
                       Maximum="100"
                       Minimum="0"
                       Value="{Binding MyValue}"
                       HorizontalOptions="FillAndExpand"
                       MinimumTrackColor="Black"
                       MaximumTrackColor="Black"
                       ThumbColor="{StaticResource myColor}"
                       ValueChanged="OnValueChanged"
                       PropertyChanging="ChangingSliderValue"/>
               <Label Text="{Binding Source={x:Reference slider},Path=Value,StringFormat='{0:0}'}"
                      FontSize="Medium"
                      FontAttributes="Bold"
                      HorizontalOptions="End"
                      WidhtRequest="40"/>
           </ViewCell>
       </DataTemplate>
   </ListView.ItemTemplate>
</ListView>

我对象的C＃类是

public class MyClass : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private int _value;
    private string _name;
    private bool _someBool;

    public int MyValue { get {return _value;} set {_value = value;} }
    public string Name { get {return _name;} set {_name = value;} }
    public bool SomeBool { get {return _someBool;} set {_someBool = value; OnPropertyChanged();} }

    void OnPropertyChanged ([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null)
        {
            handler(this,new PropertyChangedEventArgs(propertyName));
        }
    }
}

Xaml页面的部分类是：

namespace MyApp
{
[XamlCompilation(XamlCompilationoptions.Compile)]
public partial class SliderPage: ContentPage
{
    private ObservableCollection<MyClass> list = new ObservableCollection<MyClass>();
    ...

    public SliderPage ()
    {
        InitializeComponent();
        InitList();
        listView.ItemsSource = list;
        ...
    }

    private void InitList () ...

    private void ChangingSliderValue (object sender,PropertyChangedEventArgs e)
    {
        //Code to stick together the slider...
    }
}

关于如何实现我的目标的任何建议？

解决方法

工作，但没有动态显示

您需要在属性 MyValue 上实现接口 INotifyPropertyChanged ，以便该元素在运行时更新。

顺便说一句，因为您在项目中使用了数据绑定。最好在ViewModel中处理逻辑。因此，您可以像下面这样修改代码

在Xmal

 <ListView 
          ItemsSource="{Binding MySource}">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <StackLayout Orientation="Horizontal" HeightRequest="300" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
                            <Slider x:Name="slider"
                       Maximum="100"
                       Minimum="0"
                       Value="{Binding MyValue,Mode=TwoWay}"
                       HorizontalOptions="FillAndExpand"
                       MinimumTrackColor="Black"
                       MaximumTrackColor="Black"/>
                            
                      <Label Text="{Binding Source={x:Reference slider},Path=Value,StringFormat='{0:0}'}"
                      FontSize="20"
                      FontAttributes="Bold"             
                      WidthRequest="40"/>
                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

在后面的代码中

型号

public class MyClass : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public int Id { get; set; }  // add this property to index the slider

    private int _value;
    private string _name;
    private bool _someBool;

    public int MyValue {
     
         get
        {
            return _value;
        }

        set
        {
            if(_value!=value)
            {
                _value = value;
                OnPropertyChanged("MyValue");
            }
        }
    
    }
    public string Name { get { return _name; } set { _name = value; } }
    public bool SomeBool { get { return _someBool; } set { _someBool = value; OnPropertyChanged("SomeBool"); } }

    void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        var handler = PropertyChanged;
        if (handler != null)
        {
            handler(this,new PropertyChangedEventArgs(propertyName));
        }
    }
}

ViewModel

public class MyViewModel
{
    public ObservableCollection<MyClass> MySource { get; set; }


    bool isFirstLoad = true;

    public MyViewModel()
    {
        MySource = new ObservableCollection<MyClass>() { 
        
            new MyClass(){MyValue = 50,Id=0 },new MyClass(){MyValue = 50,Id=1 },};

        

        foreach (MyClass model in MySource)
        {
            model.PropertyChanged += Model_PropertyChanged;
        }

       
    }

    private void Model_PropertyChanged(object sender,PropertyChangedEventArgs e)
    {
        
        if (e.PropertyName== "MyValue")
        {
            //handle your logic here as you need 
            MyClass model = sender as MyClass;

                foreach (MyClass item in MySource)
                {
                    if (model.Id != item.Id)
                    {
                        item.MyValue = 100 - model.MyValue;  
                    }
                }
           

        }
    }
}

ContentPage

public xxxPage()
{
   InitializeComponent();

   BindingContext = new MyViewModel();
}