如何将占位符颜色属性添加到 xamarin 表单中的自动完成字段？

Question

我想将占位符颜色属性添加到我的自动完成字段。我使用以下代码在我的表单中显示自动完成功能。我的 Xmal 代码如下，我使用了 xmlns:auto="clr-namespace:XLabs.Forms.Controls;assembly=XLabs.Forms"。 我无法将 placeholderColor 属性绑定到我的 xmal 页面。但 AutoCompleteViewModel 包含 placeholderColor 属性的定义。如何解决此问题。

<StackLayout Orientation="Horizontal" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"  Margin="20,10,20,0"  BackgroundColor="#91BC47">     
    <auto:AutoCompleteView x:Name="Auto_Area" Text="Select Area"  TextColor="White" IsVisible="True" Placeholder="select Area" PlaceholderColor="{Binding PlaceholderColor}"
        HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"
        SearchCommand="{Binding SearchCommand}"
        SearchTextColor="Yellow" 
        SelectedCommand="{Binding CellSelectedCommand}"
        SelectedItem="{Binding SelectedItem}"
        ShowSearchButton="False"
        SuggestionBackgroundColor="#91BC47"
        Margin="5,0,0,0"
        SuggestionItemDataTemplate="{StaticResource SugestionItemTemplate}"
        Suggestions="{Binding Items,
        Mode=TwoWay}" />                  
</StackLayout>   


public class AutoCompleteViewModel : XLabs.Forms.Mvvm.ViewModel
{
    private ObservableCollection<AutoComplete> _items;
    private Command<string> _searchCommand;
    private Command<AutoComplete> _cellSelectedCommand;
    private AutoComplete _selectedItem;
    private Color _placeholderColor;

    public AutoCompleteViewModel()
    {
        Items = new ObservableCollection<AutoComplete>();

        Items = App._areas1.OrderBy(p => p).Select(p => new AutoComplete
        {
            Name = p,
            ID = 1
        }).ToObservableCollection();
    }

    public static BindableProperty PlaceholderColorProperty
        = BindableProperty.Create(nameof(PlaceholderColor), typeof(Color), typeof(EditorControl), Color.White);

    public Color PlaceholderColor
    {
        get
        {
            return  _placeholderColor;
        }
        set
        {
            SetProperty(ref _placeholderColor, value);
        }
    }

    public ObservableCollection<AutoComplete> Items
    {
        get
        {
            return _items;
        }
        set
        {
            SetProperty(ref _items, value);
        }
    }

    public Command<AutoComplete> CellSelectedCommand
    {
        get
        {
            return _cellSelectedCommand ?? (_cellSelectedCommand = new Command<AutoComplete>(parameter => Debug.WriteLine(parameter.ID + parameter.Name)));
        }
    }

    public Command<string> SearchCommand
    {
        get
        {
            return _searchCommand ?? (_searchCommand = new Command<string>(
                obj => { },
                obj => !string.IsNullOrEmpty(obj.ToString())));
        }
    }

    public AutoComplete SelectedItem
    {
        get
        {
            return _selectedItem;
        }
        set
        {
            SetProperty(ref _selectedItem, value);
        }
    }
}

Answer 1

您的BindableProperty 需要添加到您的AutoCompleteView 而不是您的AutoCompleteViewModel

public class AutoCompleteView
{
    public static BindableProperty PlaceholderColorProperty = BindableProperty.Create(nameof(PlaceholderColor), typeof(Color), typeof(AutoCompleteView), Color.White);

    public Color PlaceholderColor
    {
        get
        {
            return (Color)GetValue(PlaceholderColorProperty);
        }
        set
        {
            SetValue(PlaceholderColorProperty, value);
        }
    }
}

然后它只需要绑定到 ViewModel 中的 PlaceholderColor。

public class AutoCompleteViewModel : XLabs.Forms.Mvvm.ViewModel
{
    private Color _placeholderColor = Color.White;

    public Color PlaceholderColor
    {
        get
        {
           return  _placeholderColor;
        }
        set
        {
            SetProperty(ref _placeholderColor, value);
        }
    }
}