背水一战 Windows 10 (78) - 自定义控件: 基础知识, 依赖属性, 附加属性

时间:2022-02-01 23:29:38

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背水一战 Windows 10 (78) - 自定义控件: 基础知识, 依赖属性, 附加属性

作者:webabcd

介绍
背水一战 Windows 10 之 控件(自定义控件)

  • 自定义控件的基础知识,依赖属性和附加属性

示例
演示自定义控件的基础知识,依赖属性和附加属性
1、自定义控件的示例
/MyControls/themes/generic.xaml

<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"> <!--
在 themes/generic.xaml 中定义自定义控件的默认样式
-->
<ResourceDictionary.MergedDictionaries>
<!--
注意:
此处在指定 xaml 路径时,要以“项目名”为根路径(因为这个自定控件的项目是要被别的项目引用的)
这个是对的 ms-appx:///MyControls/themes/MyControl1.xaml
这个是错的 ms-appx:///themes/MyControl1.xaml(编译时不会报错,运行时会报错 Failed to assign to property 'Windows.UI.Xaml.ResourceDictionary.Source' because the type 'Windows.Foundation.String' cannot be assigned to the type 'Windows.Foundation.Uri')
-->
<ResourceDictionary Source="ms-appx:///MyControls/themes/MyControl1.xaml"/>
<ResourceDictionary Source="ms-appx:///MyControls/themes/MyControl3.xaml"/>
</ResourceDictionary.MergedDictionaries> </ResourceDictionary>

/MyControls/themes/MyControl1.xaml

<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:MyControls"> <Style TargetType="local:MyControl1">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="local:MyControl1">
<!--
绑定基类中定义的依赖属性
-->
<Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
<StackPanel> <!--
绑定自定义依赖属性
-->
<TextBlock Text="{TemplateBinding Title}" Foreground="White" FontSize="24" /> <!--
绑定自定义附加属性
-->
<TextBlock Text="{TemplateBinding local:MyAttachedProperty.SubTitle}" Foreground="Orange" FontSize="24" /> </StackPanel>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style> </ResourceDictionary>

/MyControls/MyAttachedProperty.cs

/*
* 定义一个附加属性(Attached Property)
*
* 依赖属性:可以用于样式, 模板, 绑定, 动画
* 附加属性:全局可用的依赖属性
*/ using Windows.UI.Xaml; namespace MyControls
{
/// <summary>
/// 定义一个附加属性(Attached Property)
/// </summary>
public sealed class MyAttachedProperty
{
// 获取附加属性
public static string GetSubTitle(DependencyObject obj)
{
return (string)obj.GetValue(SubTitleProperty);
} // 设置附加属性
public static void SetSubTitle(DependencyObject obj, string value)
{
obj.SetValue(SubTitleProperty, value);
} // 注册一个附加属性(winrc 中不支持 public 类型的 field,如果是 dll 项目则无此限制)
private static readonly DependencyProperty SubTitlePropertyField =
DependencyProperty.RegisterAttached(
"SubTitle", // 附加属性的名称
typeof(string), // 附加属性的数据类型
typeof(MyAttachedProperty), // 附加属性所属的类
new PropertyMetadata("", PropertyMetadataCallback)); // 指定附加属性的默认值,以及值发生改变时所调用的方法 // 用属性的方式封装一下 SubTitlePropertyField
public static DependencyProperty SubTitleProperty
{
get
{
return SubTitlePropertyField;
}
} private static void PropertyMetadataCallback(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
object newValue = args.NewValue; // 发生改变之后的值
object oldValue = args.OldValue; // 发生改变之前的值
}
}
}

/MyControls/MyControl1.cs

/*
* 开发一个自定义控件,并定义一个依赖属性(Dependency Property)
*
* 依赖属性:可以用于样式, 模板, 绑定, 动画
* 附加属性:全局可用的依赖属性
*/ using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml; namespace MyControls
{
/// <summary>
/// 开发一个自定义控件,并定义一个依赖属性(Dependency Property)
/// </summary>
// 注意:
// 在 winrc 中用 c# 写的类必须是 sealed 的(否则编译时会报错 Exporting unsealed types is not supported.Please mark type 'MyControls.MyControl1' as sealed)
// 如果是 dll 项目则无此限制
public sealed class MyControl1 : Control
{
public MyControl1()
{
// 指定默认样式为 typeof(MyControl1),即使用 TargetType 为 MyControl1 的样式,即 <Style xmlns:local="using:MyControls" TargetType="local:MyControl1" />
// 如果不指 DefaultStyleKey 的话,则默认使用基类即 Control 的样式
this.DefaultStyleKey = typeof(MyControl1);
} // 通过 DependencyObject.GetValue() 和 DependencyObject.SetValue() 访问依赖属性,这里由 Title 属性封装一下,以方便对依赖属性的访问
public string Title
{
get { return (string)GetValue(TitleProperty); }
set { SetValue(TitleProperty, value); }
} // 注册一个依赖属性
// 注意:
// 在 winrc 中不支持 public 类型的 field(在 dll 项目无此限制),所以这里改为 private 的,之后再用 public 属性的方式封装一下即可
// 如果使用了 public 类型的 field 的话,编译时会报错 Type 'MyControls.MyControl1' contains externally visible field 'Windows.UI.Xaml.DependencyProperty MyControls.MyControl1.TitlePropertyField'. Fields can be exposed only by structures
private static readonly DependencyProperty TitlePropertyField =
DependencyProperty.Register(
"Title", // 依赖属性的名称
typeof(string), // 依赖属性的数据类型
typeof(MyControl1), // 依赖属性所属的类
new PropertyMetadata("", PropertyMetadataCallback)); // 指定依赖属性的默认值,以及值发生改变时所调用的方法 // 用属性的方式封装一下 TitlePropertyField
public static DependencyProperty TitleProperty
{
get
{
return TitlePropertyField;
}
} private static void PropertyMetadataCallback(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
object newValue = args.NewValue; // 发生改变之后的值
object oldValue = args.OldValue; // 发生改变之前的值
}
}
}

2、调用自定义控件的示例
Controls/CustomControl/Demo1.xaml

<Page
x:Class="Windows10.Controls.CustomControl.Demo1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:Windows10.Controls.CustomControl"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" xmlns:myControls="using:MyControls"> <Grid Background="Transparent">
<StackPanel Margin="10 0 10 10"> <!--
演示自定义控件的基础知识,依赖属性和附加属性
本例所用到的自定义控件请参看:MyControls/MyControl1.cs
--> <!--
依赖属性和附加属性可以用于绑定
-->
<myControls:MyControl1 x:Name="control1" Background="Blue" BorderBrush="Yellow" BorderThickness="1" Width="200" HorizontalAlignment="Left" Margin="5"
Title="{Binding Value, ElementName=slider}"
myControls:MyAttachedProperty.SubTitle="{Binding Value, ElementName=slider}">
</myControls:MyControl1>
<Slider Name="slider" Width="200" Minimum="0" Maximum="200" IsThumbToolTipEnabled="False" HorizontalAlignment="Left" Margin="5" Foreground="Orange" Background="White" Style="{StaticResource MySliderStyle}" /> <!--
依赖属性和附加属性可以用于 Storyboard 动画
但是无法通过 Storyboard 对自定义附加属性做动画,在文档中找到了这样一句话“However, an existing limitation of the Windows Runtime XAML implementation is that you cannot animate a custom attached property.”
-->
<myControls:MyControl1 x:Name="control2" Background="Blue" BorderBrush="Yellow" BorderThickness="1" Width="200" HorizontalAlignment="Left" Margin="5">
<myControls:MyControl1.Resources>
<BeginStoryboard x:Name="storyboard1">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="control2" Storyboard.TargetProperty="Title" Duration="0:0:10" RepeatBehavior="Forever">
<DiscreteObjectKeyFrame KeyTime="0:0:1" Value="w" />
<DiscreteObjectKeyFrame KeyTime="0:0:2" Value="we" />
<DiscreteObjectKeyFrame KeyTime="0:0:3" Value="web" />
<DiscreteObjectKeyFrame KeyTime="0:0:4" Value="weba" />
<DiscreteObjectKeyFrame KeyTime="0:0:5" Value="webab" />
<DiscreteObjectKeyFrame KeyTime="0:0:6" Value="webabc" />
<DiscreteObjectKeyFrame KeyTime="0:0:7" Value="webabcd" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</myControls:MyControl1.Resources>
</myControls:MyControl1> <!--
在 code-behind 中设置依赖属性和附加属性
-->
<myControls:MyControl1 x:Name="control3" Background="Blue" BorderBrush="Yellow" BorderThickness="1" Width="200" HorizontalAlignment="Left" Margin="5" /> </StackPanel>
</Grid>
</Page>

Controls/CustomControl/Demo1.xaml.cs

/*
* 本例用于演示自定义控件的基础知识,依赖属性和附加属性
*/ using MyControls;
using Windows.UI.Xaml.Controls; namespace Windows10.Controls.CustomControl
{
public sealed partial class Demo1 : Page
{
public Demo1()
{
this.InitializeComponent(); this.Loaded += Demo1_Loaded;
} private void Demo1_Loaded(object sender, Windows.UI.Xaml.RoutedEventArgs e)
{
// 设置依赖属性
control3.Title = "我是依赖属性"; // 设置附加属性
control3.SetValue(MyAttachedProperty.SubTitleProperty, "我是附加属性");
}
}
}

OK
[源码下载]