c# - WPF - 将 TextBox 的 FontFamily 绑定(bind)到 ComboBox

Question

我知道这篇文章:TextBox FontFamily Binding ，看起来和我的问题类似，但我的情况更简单，我想将 TextBox 控件的 FontFamily 属性绑定(bind)到 ComboBox，当 ComboBox 的值更改时，TextBox 的内容也会相应更改。我没有使用虚拟机或依赖属性，我遵循了本教程:https://dotnetstories.wordpress.com/2011/07/31/using-type-converters-in-wpf/

并想出了:

<Window x:Class="NumericControlTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:NumericControlTest"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">

<Window.Resources>
    <local:FontFamilyConversions x:Key="FontFamilyConversions" />
</Window.Resources>

<DockPanel>

    <ComboBox  DockPanel.Dock="Top" x:Name="Fonttype" >
        <ComboBoxItem IsSelected="True">Arial</ComboBoxItem>
        <ComboBoxItem>Batang</ComboBoxItem>
        <ComboBoxItem>BatangChe</ComboBoxItem>
        <ComboBoxItem>Gungsuh</ComboBoxItem>
        <ComboBoxItem>GungsuhChe</ComboBoxItem>
        <ComboBoxItem>Courier New</ComboBoxItem>
    </ComboBox>
    <TextBox x:Name="editor" FontSize="16" FontFamily="{Binding Path=SelectedValue, ElementName=Fonttype, Mode=OneWay, Converter={StaticResource FontFamilyConversions}}" >

    </TextBox>
</DockPanel>

using System.Windows.Data;
using System.Windows.Media;

namespace NumericControlTest
{
    class FontFamilyConversions : IValueConverter
    {
        public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            FontFamily fontfamily = new FontFamily("Verdana");
            if (value != null)
            {
                fontfamily = new FontFamily(value.ToString());
            }
            return fontfamily;
        }

        public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return null;
        }
    }
}

但是它不起作用，在我更改 ComboBox 的值后，什么也没有发生。

感谢您的宝贵时间。

Answer 1

return fontfamily; 上的断点会表明您没有从 value.ToString() 得到您所期望的结果。您需要获取Content来自ComboBoxItem :

public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
    FontFamily fontfamily = new FontFamily("Verdana");
    ComboBoxItem selectedFont = value as ComboBoxItem;
    if (selectedFont != null)
    {
        fontfamily = new FontFamily(selectedFont.Content.ToString());
    }
    return fontfamily;
}

您可以通过添加 <FontFamily> 来完全避免使用转换器。对象直接到 ComboBox :

<ComboBox  DockPanel.Dock="Top" x:Name="Fonttype" SelectedIndex="0">
    <FontFamily>Arial</FontFamily>
    <FontFamily>Segoe UI</FontFamily>            
</ComboBox>

然后绑定(bind)到SelectedValue无需转换器。

FontFamily="{Binding Path=SelectedValue, ElementName=Fonttype, Mode=OneWay}"

或者您可能想自动获取已安装字体的列表:

<ComboBox  DockPanel.Dock="Top" x:Name="Fonttype" ItemsSource="{x:Static Fonts.SystemFontFamilies}" SelectedIndex="0" />

虽然不太可能SystemFontFamilies将被排序，所以你需要 use a CollectionViewSource to sort .