我有一个带有两个选择器的xamarin控制模板，并添加到app.xml中，我在两个页面的“首页和详细信息”中使用该模板，我想：
PS：我的选择器项源将在运行时根据我的模型进行设置。并根据第一选择器的选择项，第二选择器的源将发生变化。
app.xaml
<?xml version="1.0" encoding="UTF-8"?>
<Application xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="SimpleTheme.App">
<Application.Resources>
<ResourceDictionary>
<ControlTemplate x:Key="ActiveProfileTemplate">
<Grid Padding="5,0,0,0" BackgroundColor="#f7f6fb">
<Grid.RowDefinitions>
<RowDefinition Height="0.1*" />
<RowDefinition Height="0.8*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<BoxView Grid.ColumnSpan="2"/>
<Picker x:Name="FirstPicker" Title="FirstPicker" SelectedIndex="{TemplateBinding Parent.FirstPickerSelectedIndex}" Grid.Column="0" HorizontalOptions="Center" VerticalOptions="Center" WidthRequest="180" FontSize="Small" TextColor="#214189">
<Picker.Items>
<x:String>FirstPicker_1</x:String>
<x:String>FirstPicker_2</x:String>
<x:String>FirstPicker_3</x:String>
<x:String>FirstPicker_4</x:String>
<x:String>FirstPicker_5</x:String>
</Picker.Items>
</Picker>
<Picker x:Name="SecondPicker" Title="SecondPicker" SelectedIndex="{TemplateBinding Parent.SecondPickerSelectedIndex}" Grid.Column="1" HorizontalOptions="Center" VerticalOptions="Center" WidthRequest="210" FontSize="Small" TextColor="#214189" >
<Picker.Items>
<x:String>SecondPicker_1</x:String>
<x:String>SecondPicker_2</x:String>
<x:String>SecondPicker_3</x:String>
<x:String>SecondPicker_4</x:String>
<x:String>SecondPicker_5</x:String>
</Picker.Items>
</Picker>
<ContentPresenter Grid.Row="1" Grid.ColumnSpan="2"/>
</Grid>
</ControlTemplate>
</ResourceDictionary>
</Application.Resources>
</Application>
HomePage.xaml
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="SimpleTheme.HomePage">
<ContentView x:Name="contentView" Padding="0,20,0,0" ControlTemplate="{StaticResource ActiveProfileTemplate}">
<StackLayout VerticalOptions="CenterAndExpand">
<Label Text="Welcome to the HomePage!" HorizontalOptions="Center" />
<Label x:Name="lbl_firstpicker" Text="First Picker Selected Item" HorizontalOptions="Center" TextColor="DarkRed"/>
<Label x:Name="lbl_secondpicker" Text="Second Picker Selected Item" HorizontalOptions="Center" TextColor="DarkRed"/>
</StackLayout>
</ContentView>
</ContentPage>
HomePage.cs
public partial class HomePage : ContentPage
{
public static readonly BindableProperty FirstPickerSelectedIndexProperty = BindableProperty.Create(
"FirstPickerSelectedIndex",
typeof(int),
typeof(HomePage),
2);
public static readonly BindableProperty SecondPickerSelectedIndexProperty = BindableProperty.Create(
"SecondPickerSelectedIndex",
typeof(int),
typeof(HomePage),
3);
public int FirstPickerSelectedIndex => (int)GetValue(FirstPickerSelectedIndexProperty);
public int SecondPickerSelectedIndex => (int)GetValue(SecondPickerSelectedIndexProperty);
public HomePage()
{
InitializeComponent();
}
}
DetailPage.xaml
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="SimpleTheme.DetailPage">
<ContentView x:Name="contentView" Padding="0,20,0,0" ControlTemplate="{StaticResource ActiveProfileTemplate}">
<StackLayout VerticalOptions="CenterAndExpand">
<Label Text="Welcome to the DetailPage!" HorizontalOptions="Center" />
<Label x:Name="lbl_firstpicker" Text="First Picker Selected Item" HorizontalOptions="Center" TextColor="Teal" />
<Label x:Name="lbl_secondpicker" Text="Second Picker Selected Item" HorizontalOptions="Center" TextColor="Teal" />
</StackLayout>
</ContentView>
</ContentPage>
答案 0 :(得分：1)
由于我找不到设置侦听器的好方法，因此我使用自定义ContentView来包含ControlTemplate的布局，如下所示：
MyView.xaml ：
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="App5.MyView">
<ContentView.Content>
<Grid Padding="5,0,0,0" BackgroundColor="#f7f6fb">
<Grid.RowDefinitions>
<RowDefinition Height="0.1*" />
<RowDefinition Height="0.8*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<BoxView Grid.ColumnSpan="2"/>
<Picker x:Name="FirstPicker" Title="FirstPicker" Grid.Column="0" HorizontalOptions="Center" VerticalOptions="Center" WidthRequest="180" FontSize="Small" TextColor="#214189" >
</Picker>
<Picker x:Name="SecondPicker" Title="SecondPicker" Grid.Column="1" HorizontalOptions="Center" VerticalOptions="Center" WidthRequest="210" FontSize="Small" TextColor="#214189" >
</Picker>
<ContentPresenter Grid.Row="1" Grid.ColumnSpan="2"/>
</Grid>
</ContentView.Content>
</ContentView>
MyView.xaml.cs ：
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MyView : ContentView
{
public MyView()
{
InitializeComponent();
List<FirstModel> listFirstModel = new List<FirstModel>();
listFirstModel.Add(new FirstModel { Key = "Pl", Description = "DescPl" });
listFirstModel.Add(new FirstModel { Key = "Ps", Description = "DescPs" });
listFirstModel.Add(new FirstModel { Key = "En", Description = "DescEn" });
listFirstModel.Add(new FirstModel { Key = "H", Description = "DescH" });
List<SecondModel> listSecondModel = new List<SecondModel>();
listSecondModel.Add(new SecondModel { FirstModelKey = "Pl", Key = "Pl1", Description = "SecondModelPl1" });
listSecondModel.Add(new SecondModel { FirstModelKey = "Pl", Key = "Pl2", Description = "SecondModelPl2" });
listSecondModel.Add(new SecondModel { FirstModelKey = "Pl", Key = "Pl3", Description = "SecondModelPl3" });
listSecondModel.Add(new SecondModel { FirstModelKey = "Ps", Key = "Ps1", Description = "SecondModelPs1" });
listSecondModel.Add(new SecondModel { FirstModelKey = "Ps", Key = "Ps2", Description = "SecondModelPs2" });
listSecondModel.Add(new SecondModel { FirstModelKey = "Ps", Key = "Ps3", Description = "SecondModelPs3" });
listSecondModel.Add(new SecondModel { FirstModelKey = "En", Key = "En1", Description = "SecondModelEn1" });
listSecondModel.Add(new SecondModel { FirstModelKey = "En", Key = "En2", Description = "SecondModelEn2" });
listSecondModel.Add(new SecondModel { FirstModelKey = "En", Key = "En3", Description = "SecondModelEn3" });
listSecondModel.Add(new SecondModel { FirstModelKey = "H", Key = "H1", Description = "SecondModelH1" });
listSecondModel.Add(new SecondModel { FirstModelKey = "H", Key = "H2", Description = "SecondModelH2" });
listSecondModel.Add(new SecondModel { FirstModelKey = "H", Key = "H3", Description = "SecondModelH3" });
foreach (FirstModel fm in listFirstModel)
{
FirstPicker.Items.Add(fm.Description);
}
FirstPicker.SelectedIndexChanged += (sender, e) => {
SecondPicker.Items.Clear();
string key = listFirstModel[FirstPicker.SelectedIndex].Key;
foreach (SecondModel sm in listSecondModel.FindAll(o => o.FirstModelKey == key))
SecondPicker.Items.Add(sm.Description);
};
// use MessagingCenter to get the SelectedIndex and set it
MessagingCenter.Subscribe<string, int>("firstpicker", "indext", (sender, args) => {
FirstPicker.SelectedIndex = args;
});
MessagingCenter.Subscribe<string, int>("secondpicker", "indext", (sender, args) => {
SecondPicker.SelectedIndex = args;
});
}
}
HomePage.xaml ：
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:App5"
x:Class="App5.HomePage">
<StackLayout x:Name="ss" VerticalOptions="CenterAndExpand">
//use the custom contentView
<local:MyView x:Name="mv"></local:MyView>
<Label Text="Welcome to the HomePage!" HorizontalOptions="Center" />
<Label x:Name="lbl_firstpicker" Text="First Picker Selected Item" HorizontalOptions="Center" TextColor="DarkRed"/>
<Label x:Name="lbl_secondpicker" Text="Second Picker Selected Item" HorizontalOptions="Center" TextColor="DarkRed"/>
<Button Text="todetail" Clicked="Button_Clicked"/>
</StackLayout>
HomePage.xaml.cs ：
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class HomePage : ContentPage
{
private int firstSelectedIndex;
private int secondSelectedIndex;
public HomePage()
{
InitializeComponent();
//find the picker control and set listener
Picker p = mv.FindByName<Picker>("FirstPicker");
Picker s = mv.FindByName<Picker>("SecondPicker");
p.SelectedIndexChanged += FirstPicker_SelectedIndexChanged;
s.SelectedIndexChanged += SecondPicker_SelectedIndexChanged;
}
void FirstPicker_SelectedIndexChanged(object sender, EventArgs e)
{
var picker = (Picker)sender;
firstSelectedIndex = picker.SelectedIndex;
if (firstSelectedIndex != -1)
{
lbl_firstpicker.Text = picker.Items[firstSelectedIndex];
}
}
void SecondPicker_SelectedIndexChanged(object sender, EventArgs e)
{
var picker = (Picker)sender;
secondSelectedIndex = picker.SelectedIndex;
if (secondSelectedIndex != -1)
{
lbl_secondpicker.Text = picker.Items[secondSelectedIndex];
}
}
// navigation to detailpage and notice Picker to set the selected indext
async void Button_Clicked(object sender, EventArgs e)
{
await Navigation.PushAsync(new DetailPage());
MessagingCenter.Send<string, int>("firstpicker", "indext", firstSelectedIndex);
MessagingCenter.Send<string, int>("secondpicker", "indext", secondSelectedIndex);
}
}
模型：通过按键实现链接
class FirstModel
{
public string Key { get; set; }
public string Description { get; set; }
public FirstModel()
{
}
}
class SecondModel
{
public string FirstModelKey { get; set; }
public string Key { get; set; }
public string Description { get; set; }
public SecondModel()
{
}
}
DetailsPage 与主页
相似