Avalonia踩坑

1.ResourceDictionary文件报错“Unable to cast object of type ‘Avalonia.Controls.ResourceDictionary’ to type ‘Avalonia.Controls.Control’”

解决方法：因为这些文件不能被转换成控件，所以不能被预览，这时候按下功能键F7，切换到“XAML View”，就能消除这个报错。

2.应用阿里巴巴IconFont

2.1. 应用

2.1.1 首先下载iconfont文件，并添加到项目

2.1.2在App.axaml文件中引入字体

  <Application.Resources>
        <ResourceDictionary>
            <FontFamily x:Key="IconFont">/Assets/Fonts/#iconfontFontFamily>
        ResourceDictionary>
    Application.Resources>
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2.1.3应用

<TextBlock
                FontFamily="{StaticResource IconFont}"
                FontSize="30"
                Foreground="white"
                Text="" />
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2.2 坑

如果在样式文件中定义了Textblock的样式，像这样

<Style Selector="TextBlock.Manual">
        "Text" Value="" />
Style>
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并在App.axaml文件中引入

<Application.Styles>
        <StyleInclude Source="/Styles/WpTextBlock.axaml" />
        <FluentTheme Mode="Dark" />
Application.Styles>
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像下面这样应用是没问题的

<TextBlock
                Classes="Manual"
                FontFamily="{StaticResource IconFont}"
                FontSize="30"
                Foreground="white" />
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**但是，未使用样式文件中样式的其他TextBlock将不会显示。就算像下面这样写也不会显示不是不会显示，是会被覆盖掉！！！ **

<TextBlock
                FontFamily="{StaticResource IconFont}"
                FontSize="30"
                Foreground="white"
                Text="" />
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不过，Label可以显示

3.深入浅出Avalonia.Xaml.Behaviors

avalonia ui控件事件转命令包
项目地址
Nuget包地址
安装指令：

dotnet add package Avalonia.Xaml.Behaviors --version 11.0.0-preview4
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3.1应用实例：

一、前端：

首先引入命名空间

xmlns:i="clr-namespace:Avalonia.Xaml.Interactivity;assembly=Avalonia.Xaml.Interactivity"
xmlns:ia="clr-namespace:Avalonia.Xaml.Interactions.Core;assembly=Avalonia.Xaml.Interactions"
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将事件转为命令

            <TreeView x:Name="Navigation"
                      Classes="navigation">
                <TreeViewItem Classes="navigation"
                              Header="选项1">
                    <TreeViewItem Classes="navigation"
                                  Header="选项12" />
                    <TreeViewItem Classes="navigation"
                                  Header="选项13" />
                TreeViewItem>
                <TreeViewItem Classes="navigation"
                              Header="选项2" />
                <TreeViewItem Classes="navigation"
                              Header="选项3" />
                <i:Interaction.Behaviors>
                    <ia:EventTriggerBehavior EventName="PointerReleased">
                        <ia:InvokeCommandAction Command="{Binding NavigationItemClickCmd}"
                                                CommandParameter="{Binding RelativeSource={RelativeSource Mode=Self}, Path=SelectedItem}" />

                        
                    ia:EventTriggerBehavior>
                i:Interaction.Behaviors>
            TreeView>
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二、后端

 private ICommand _navigationItemClickCmd;

        public ICommand NavigationItemClickCmd
        {
            get
            {
                _navigationItemClickCmd = ReactiveCommand.Create<TreeViewItem>(tvi =>
                {
                    if (tvi is not null)
                    {
                        tvi.IsExpanded = !tvi.IsExpanded;
                    }
                });
                return _navigationItemClickCmd;
            }
        }
    }
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