Question

我有一个自定义控件，它由Label和Custom Picker组成。我需要将值绑定到Xaml中的ItemSource属性。这是我到目前为止所尝试过的，但是选择器中没有显示任何值。编辑04/10/2017：我已将示例项目上传到github，该项目具有自定义控件：https://github.com/libin85/BindablePicker
这是CustomControl Xaml文件

<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms" 
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
xmlns:controls="clr-namespace:WoolQ.Core.Controls;assembly=WoolQ.Core" 
x:Class="WoolQ.Core.Controls.CustomLabelWithPicker">
<Grid x:Name="grid" VerticalOptions="Start">
    <Grid.RowDefinitions>
        <RowDefinition Height="35" />
        <RowDefinition Height="45" />
    </Grid.RowDefinitions>
    <controls:RoundedFrame OutlineColor="Red" Grid.Row="0" Grid.Column="0" Grid.RowSpan="2" />
    <Label x:Name="title" Text="" Grid.Row="0" Margin="5,5,5,0" Style="{StaticResource CustomConrtolLabelStyle}" />
    <controls:BorderlessPicker x:Name="pickerValue" Title="_" Grid.Row="1" Style="{StaticResource CustomConrtolPickerStyle}" ItemsSource="{Binding ItemSource}">
    </controls:BorderlessPicker>
</Grid>

在我背后的代码中：

public static readonly BindableProperty ItemSourceProperty = 
        BindableProperty.Create(nameof(ItemSource), typeof(List<string>), typeof(CustomLabelWithPicker), null);

    public List<string> ItemSource
    {
        get
        {
            return (List<string>)GetValue(ItemSourceProperty);
        }
        set
        {
            SetValue(ItemSourceProperty, value);
        }
    }

    protected override void OnPropertyChanged(string propertyName = null)
    {
        base.OnPropertyChanged(propertyName);
        if (propertyName == nameof(ItemSource))
        {
            this.pickerValue.Items.Clear();
            if (ItemSource != null)
            {
                foreach (var item in ItemSource)
                {
                    this.pickerValue.Items.Add(item);
                }
            }
        }
    }

最后在我的View中，我将Itemsource与这样的List绑定。

<controls:CustomLabelWithPicker Grid.Row="1" Grid.Column="2" 
LabelText="Bin Codes" ItemSource="{Binding BinCodes}"/>

但我没有看到任何绑定的值。感谢您的帮助

Answer 1

在自定义选择器中尝试以下代码：

public static readonly BindableProperty ItemsSourceProperty =
            BindableProperty.Create("ItemsSource", typeof(IEnumerable), typeof(CustomPicker), null, BindingMode.TwoWay, null, OnItemsSourceChanged);

        public IList ItemsSource
        {
            get { return (IList)GetValue(ItemsSourceProperty); }
            set { SetValue(ItemsSourceProperty, value); }
        }

private static void OnItemsSourceChanged(BindableObject bindable, object oldValue, object newValue)
        {
            var picker = (CustomPicker)bindable;
            picker.ItemsSource = (IList)newValue;
        }

在Xamarin表单中的自定义选择器上的ItemSource绑定

1 个答案: