UWP保留已激活的可执行组合框选择

Question

这是前面问题的延续。我正在尝试通过绑定combobox Finally来工作，这样我就可以在一些设置中使用它。之后，我想将文本框的内容与要在按钮上执行的组合框选择相结合。如何保持已激活的可执行组合框选择？

private void button_Click(object sender, RoutedEventArgs e)
        {
            String satuan = ComboBox.GetIsSelectionActive(combobox).ToString();
                if (satuan.Equals("0"))
                {
                    awal = Convert.ToDouble(textbox.Text);
                    celcius = awal;
                    textbox1.Text = celcius.ToString();
                    reamur = 0.8 * awal;
                    textbox2.Text = reamur.ToString();
                    fahrenheit = (1.8 * awal) + 32;
                    textbox3.Text = fahrenheit.ToString();
                    kelvin = awal + 273;
                    textbox4.Text = kelvin.ToString();
                }

这是XAML：

<Page
    x:Class="berhasil.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:berhasil"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:converter="using:berhasil.Converter"
    mc:Ignorable="d">
    <Page.Resources>
        <converter:ConverterString x:Key="Converter" />
    </Page.Resources>
    <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>
        <TextBlock Grid.Row="0" Text="Input Value: " VerticalAlignment="Center"/>
        <TextBox x:Name="textbox" 
                 Grid.Row="0" 
                 Grid.Column="1" 
                 Margin="0,10,0.333,0" 
                 Width="154" 
                 VerticalAlignment="Center"
                 InputScope="Number"/>
        <StackPanel Grid.Column="2"
                    Grid.Row="0"
                    VerticalAlignment="Center"
                    Margin="20,10,0,10"
                    Orientation="Horizontal">
            <ComboBox x:Name="combobox" 
                      ItemsSource="{x:Bind ComboBoxOptions}" 
                      SelectedItem="{x:Bind SelectedComboBoxOption, Mode=TwoWay, Converter={StaticResource Converter}}" 
                      SelectedValuePath="ComboBoxOption" 
                      DisplayMemberPath="ComboBoxOption">
            </ComboBox>
        </StackPanel>
        <Button Grid.Row="1" x:Name="button" 
                Content="Conversion" 
                HorizontalAlignment="Center" Margin="78,0,0.333,0" 
                Width="154" Grid.ColumnSpan="2"
                Click="button_Click"/>
        <TextBlock Grid.Row="2" Text="Celcius: " VerticalAlignment="Center"/>
        <TextBox x:Name="textbox1" 
                 Grid.Row="2" 
                 Margin="78,10,-23.333,0" 
                 Grid.ColumnSpan="3" 
                 VerticalAlignment="Center"
                 InputScope="Number" 
                 IsReadOnly="True"/>
        <TextBlock Grid.Row="3" Text="Reamur: " VerticalAlignment="Center"/>
        <TextBox x:Name="textbox2"
                 Grid.Row="3" 
                 Margin="78,10,-23.333,0" 
                 Grid.ColumnSpan="3" 
                 VerticalAlignment="Center"
                 InputScope="Number"
                 IsReadOnly="True"/>
        <TextBlock Grid.Row="4" Text="Fahrenheit: " VerticalAlignment="Center"/>
        <TextBox x:Name="textbox3"
                 Grid.Row="4" 
                 Margin="78,10,-23.333,0" 
                 Grid.ColumnSpan="3" 
                 VerticalAlignment="Center"
                 InputScope="Number"
                 IsReadOnly="True"/>
        <TextBlock Grid.Row="5" Text="Kelvin: " VerticalAlignment="Center"/>
        <TextBox x:Name="textbox4"
                 Grid.Row="5" 
                 Margin="78,10,-23.333,0" 
                 Grid.ColumnSpan="3" 
                 VerticalAlignment="Center"
                 InputScope="Number"
                 IsReadOnly="True"/>
    </Grid>
</Page>

这是背后的代码：

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Xml.Serialization;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Storage;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409
namespace berhasil
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page, INotifyPropertyChanged
    {
        Double awal, celcius, reamur, fahrenheit, kelvin;
        private ObservableCollection<ComboBoxItem> ComboBoxOptions;
        ApplicationDataContainer roamingSettings = null;

        public MainPage()
        {
            this.InitializeComponent();
            ComboBoxOptions = new ObservableCollection<ComboBoxItem>();
            ComboBoxOptionsManager.GetComboBoxList(ComboBoxOptions);
            roamingSettings = ApplicationData.Current.RoamingSettings;
            var value = (string)roamingSettings.Values["ComboBoxSelection"];
            if (value != null)
            {
                var deserialized = Deserialize<ComboBoxItem>(value);
                // using ComboBoxOption as the primary key field of your object
                SelectedComboBoxOption = ComboBoxOptions.SingleOrDefault(c =>
                            c.ComboBoxOption == deserialized.ComboBoxOption);
            }
            else
            {
                SelectedComboBoxOption = ComboBoxOptions[0];
            }
        }
        public class ComboBoxItem
        {
            public int ComboBoxId { get; set; }
            public string ComboBoxOption { get; set; }
        }
        public class ComboBoxOptionsManager
        {
            public static void GetComboBoxList(ObservableCollection<ComboBoxItem> ComboBoxItems)
            {
                var allItems = getComboBoxItems();
                ComboBoxItems.Clear();
                allItems.ForEach(p => ComboBoxItems.Add(p));
            }
            private static List<ComboBoxItem> getComboBoxItems()
            {
                var items = new List<ComboBoxItem>();
                items.Add(new ComboBoxItem() { ComboBoxId = 1, ComboBoxOption = "Celcius"});
                items.Add(new ComboBoxItem() { ComboBoxId = 2, ComboBoxOption = "Reamur" });
                items.Add(new ComboBoxItem() { ComboBoxId = 3, ComboBoxOption = "Fahrenheit" });
                items.Add(new ComboBoxItem() { ComboBoxId = 4, ComboBoxOption = "Kelvin" });
                return items;
            }
        }
        private ComboBoxItem _SelectedComboBoxOption;
        public ComboBoxItem SelectedComboBoxOption
        {
            get
            {
                return _SelectedComboBoxOption;
            }
            set
            {
                if (_SelectedComboBoxOption != value)
                {
                    _SelectedComboBoxOption = value;
                    roamingSettings.Values["ComboBoxSelection"] = Serialize(value);
                    RaisePropertyChanged("SelectedComboBoxOption");
                }
            }
        }
        public static string Serialize(object obj)
        {
            using (var sw = new StringWriter())
            {
                var serializer = new XmlSerializer(obj.GetType());
                serializer.Serialize(sw, obj);
                return sw.ToString();
            }
        }
        public static T Deserialize<T>(string xml)
        {
            using (var sw = new StringReader(xml))
            {
                var serializer = new XmlSerializer(typeof(T));
                return (T)serializer.Deserialize(sw);
            }
        }
        void RaisePropertyChanged(string prop)
        {
            if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(prop)); }
        }
        public event PropertyChangedEventHandler PropertyChanged;

        private void button_Click(object sender, RoutedEventArgs e)
        {
            String satuan = ComboBox.GetIsSelectionActive(combobox).ToString();
                if (satuan.Equals("0"))
                {
                    awal = Convert.ToDouble(textbox.Text);
                    celcius = awal;
                    textbox1.Text = celcius.ToString();
                    reamur = 0.8 * awal;
                    textbox2.Text = reamur.ToString();
                    fahrenheit = (1.8 * awal) + 32;
                    textbox3.Text = fahrenheit.ToString();
                    kelvin = awal + 273;
                    textbox4.Text = kelvin.ToString();
                }
                else if (satuan.Equals("1"))
                {
                    awal = Convert.ToDouble(textbox.Text);
                    celcius = 1.25 * awal;
                    textbox1.Text = celcius.ToString();
                    reamur = awal;
                    textbox2.Text = reamur.ToString();
                    fahrenheit = (2.25 * awal) + 32;
                    textbox3.Text = fahrenheit.ToString();
                    kelvin = celcius + 273;
                    textbox4.Text = kelvin.ToString();
                }
                else if (satuan.Equals("2"))
                {
                    awal = Convert.ToDouble(textbox.Text);
                    celcius = 0.55555 * (awal - 32);
                    textbox1.Text = celcius.ToString();
                    reamur = 0.44444 * (awal - 32);
                    textbox2.Text = reamur.ToString();
                    fahrenheit = awal;
                    textbox3.Text = fahrenheit.ToString();
                    kelvin = celcius + 273;
                    textbox4.Text = kelvin.ToString();
                }
                else if (satuan.Equals("3"))
                {
                    awal = Convert.ToDouble(textbox.Text);
                    celcius = awal - 273;
                    textbox1.Text = celcius.ToString();
                    reamur = 0.8 * (awal - 273);
                    textbox2.Text = reamur.ToString();
                    fahrenheit = (1.8 * (awal - 273)) + 32;
                    textbox3.Text = fahrenheit.ToString();
                    kelvin = awal;
                    textbox4.Text = kelvin.ToString();
                }
        }
    }
}

Answer 1

似乎有问题

String satuan=组合框.GetIsSelectionActive（组合框）.ToString（）；

Selector.GetIsSelectionActive方法获取一个值，该值指示指定的Selector是否具有焦点。它返回的值为bool类型。Selector.GetIsSelectionActive总是返回false。因为当你点击按钮时，它失去了焦点。因此satuan.Equals("0")也总是返回false。

您可以使用Selector.SelectedIndex获取所选项目的索引。然后你可以使用索引来区分数字的大小写。

例如：

private void button_Click(object sender, RoutedEventArgs e)
{
    string satuan=combobox.SelectedIndex.ToString();
    switch (satuan)
    {
        case "0":
            //To do
            break;
        case "1":
            //To do
            break;
        case "2":
            //To do
            break;
        case "3":
            //To do
            break;  
    }
}