AvaloniaUI(四、自定义控件)

　　Avalonia的自定义控件几乎和wpf的一样，是由axaml 和cs文件来构成的，axaml文件用来写自定义控件的样式。cs文件用来写处理逻辑，今天我们来重写一个textbox文本输入框

首先我们新建一个新建项 选择avalonia中的Templated Control 如图，我将他命名为 IconTextBox

 然后新建完就得到了这么两个文件

 我们直接去cs文件中写逻辑

using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Metadata;
using Avalonia.Controls.Primitives;
using Avalonia.Controls.Templates;
using Avalonia.Input;
using Avalonia.LogicalTree;
using Avalonia.Media;
using Avalonia.VisualTree;
using System;

namespace omc64_aval.Controls.TemplateControls
{
    [TemplatePart(Name = "PART_root", Type = typeof(Border))]
    [TemplatePart(Name = "PART_continer", Type = typeof(Grid))]
    [TemplatePart(Name = "PART_icon", Type = typeof(TextBlock))]
    [TemplatePart(Name = "PART_text", Type = typeof(TextBox))]
    public class IconTextBox : TemplatedControl
    {

        private TextBox? txtbox = null;

        public IconTextBox() 
        {
           
        }

        

        public string Icon
        {
            get => GetValue(IconProperty);
            set => SetValue(IconProperty, value);
        }

        public static readonly StyledProperty<string> IconProperty = AvaloniaProperty.Register<IconTextBox, string>
        (
            nameof(Icon)
        );

        public string Text
        {
            get { return GetValue(TextProperty); }
            set { SetValue(TextProperty, value); }
        }

        public static readonly StyledProperty<string> TextProperty = AvaloniaProperty.Register<IconTextBox, string>
        (
            nameof(Text)
         );

        public IBrush? IconBrush
        {
            get { return GetValue(IconBrushProperty); }
            set { SetValue (IconBrushProperty, value); }
        }

        public static readonly StyledProperty<IBrush?> IconBrushProperty = AvaloniaProperty.Register<IconTextBox, IBrush?>(
            nameof(IconBrush)
            );

        public char PasswordChar
        {
            get { return GetValue(PasswordCharProperty); }
            set { SetValue(PasswordCharProperty, value); }
        }

        public static readonly StyledProperty<char> PasswordCharProperty = AvaloniaProperty.Register<IconTextBox, char>(
            nameof(PasswordChar));
        
        protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
        {
            base.OnApplyTemplate(e);

            TextBox? tb = e.NameScope.Find<TextBox>("PART_text");
            
            if (tb != null)
            {
                txtbox = tb;
            }
           
        }

        protected override void OnGotFocus(GotFocusEventArgs e)
        {
            base.OnGotFocus(e);

            txtbox?.Focus();

        }

    }
}

在这里我新建了 Icon、Text、PasswordChar、IconBrush 这几个依赖项属性，从写法看来与wpf有一些区别

然后在axaxml中写下样式

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:controls="using:omc64_aval.Controls.TemplateControls">
    <Design.PreviewWith>
        <controls:IconTextBox Text="123" />
    </Design.PreviewWith>

    <Style Selector="TextBox">
        <Setter Property="MinWidth" Value="120"></Setter>
        <Setter Property="MinHeight" Value="30"></Setter>
        <Setter Property="BorderThickness" Value="0"/>
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Padding" Value="0"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}"
                            MinWidth="{TemplateBinding MinWidth}"
                            MinHeight="{TemplateBinding MinHeight}"
                            VerticalAlignment="Center" HorizontalAlignment="Left">
                        <TextPresenter Name="PART_TextPresenter"
                                   CaretBrush="{TemplateBinding CaretBrush}"
                                   CaretIndex="{TemplateBinding CaretIndex}"
                                   LineHeight="{TemplateBinding LineHeight}"
                                   LetterSpacing="{TemplateBinding LetterSpacing}"
                                   PasswordChar="{TemplateBinding PasswordChar}"
                                   RevealPassword="{TemplateBinding RevealPassword}"
                                   SelectionBrush="{TemplateBinding SelectionBrush}"
                                   SelectionEnd="{TemplateBinding SelectionEnd}"
                                   SelectionForegroundBrush="{TemplateBinding SelectionForegroundBrush}"
                                   SelectionStart="{TemplateBinding SelectionStart}"
                                   Text="{TemplateBinding Text,Mode=TwoWay}"
                                   TextAlignment="{TemplateBinding TextAlignment}"
                                   TextWrapping="{TemplateBinding TextWrapping}" 
                                       VerticalAlignment="Center"/>
                    </Border>
                
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>



    <Style Selector="controls|IconTextBox">
        <Setter Property="Icon" Value="&#xe656;"></Setter>
        <Setter Property="BorderThickness" Value="0,0,0,1"></Setter>
        <Setter Property="BorderBrush" Value="Black"></Setter>
        <Setter Property="IconBrush" Value="Black"></Setter>
        <Setter Property="Width" Value="100"></Setter>
        <Setter Property="Height" Value="30"></Setter>
        <Setter Property="FontSize" Value="20"></Setter>
        <Setter Property="Background" Value="Transparent"></Setter>
        <!-- Set Defaults -->
        <Setter Property="Template">
            <ControlTemplate>
                <Border x:Name="PART_root"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        Width="{TemplateBinding Width}"
                        Background="{TemplateBinding Background}"
                        Margin="1">
                    <Grid x:Name="PART_continer"
                          Width="{Binding ElementName=PART_root,Path=Width}"
                          Height="{Binding ElementName=PART_root,Path=Height}">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="auto"></ColumnDefinition>
                            <ColumnDefinition></ColumnDefinition>
                        </Grid.ColumnDefinitions>
                        <TextBlock Classes="" x:Name="PART_icon" VerticalAlignment="Center"
                                   FontFamily="/Assets/Fonts/fonteditor.ttf#fonteditor"
                                   Text="{TemplateBinding Icon}"
                                   Foreground="{TemplateBinding IconBrush}"
                                   FontSize="{TemplateBinding FontSize}"></TextBlock>
                        <TextBox  x:Name="PART_text" Grid.Column="1" Margin="3,0,0,0" 
                                  BorderBrush="Red"
                                 BorderThickness="0"
                                 Background="{TemplateBinding Background}"
                                 Text="{TemplateBinding Text}"
                                  FontSize="{TemplateBinding FontSize}"
                                  PasswordChar="{TemplateBinding PasswordChar}"
                                 Focusable="{Binding Focusable,RelativeSource={RelativeSource TemplatedParent},Mode=OneWayToSource}"
                                 ></TextBox>

                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter>
    </Style>

    <Style Selector="controls|IconTextBox:focus">
        <Setter Property="BorderBrush" Value="Orange"></Setter>
        <Setter Property="IconBrush" Value="Orange"></Setter>
    </Style>

    <!--<Style Selector="controls|IconTextBox:pointerover">
        <Setter Property="BorderBrush" Value="Orange"></Setter>
        <Setter Property="IconBrush" Value="Orange"></Setter>
    </Style>-->
    
</Styles>

这样我们就写好了 一个自定义的控件，那么该如何使用呢？

与wpf一样，首先使用的时候需要引入命名空间

xmlns:tc="clr-namespace:omc64_aval.Controls.TemplateControls"，这里命名空间需要与你写的控件的一致，然后在你使用的地方直接使用

<tc:IconTextBox BorderBrush="Gray" IconBrush="Gray"  Classes="IconTextBox" Width="200" Height="30"  Text=""></tc:IconTextBox>

这个时候控件还显示不出来，是因为没有引入刚才的样式文件，我这里要全局使用于是在app.axaml中引入样式就可以了

<!--自定义控件-->
<StyleInclude Source="avares://omc64_aval/Controls/ControlsStylesSummary.axaml"></StyleInclude>

注意 我写的这个ControlsStylesSummary.axaml 里面包含了 IconTextbox的样式，也可以直接引用 IconTextBox.axaml文件

这样我们就得到了这样的自定义控件

 其中需要注意的是，小人和小锁的图标使用的是IconFont