Win8系统的Loading效果还是很不错的，网上也有人用CSS3等技术实现，研究了一下，并打算用WPF自定义一个Loading控件实现类似的效果，并可以让用户对Loading的颗粒（Particle）背景颜色进行自定义，话不多说，直接上代码：
1、用VS2012新建一个WPF的用户控件库项目WpfControlLibraryDemo，VS自动生成如下结构：
2、删除UserControl1.xaml，并新建一个Loading的CustomControl(不是UserControl),如下图所示：
3、如果报错找不到Loading类型，请编译，下面在Generic.xaml主题文件中对Loading的样式和内容进行定义（注意添加 xmlns:system = "clr-namespace:System;assembly=mscorlib"），代码如下：
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:system = "clr-namespace:System;assembly=mscorlib"
xmlns:local="clr-namespace:WpfControlLibraryDemo"> <Style TargetType="{x:Type local:Loading}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:Loading}">
<Border Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<Grid Width = "50" Height = "50">
<Grid.Resources>
<!-- Value Converters --> <!-- Particle Styling ,must to has RelativeSource -->
<SolidColorBrush x:Key = "ParticleColor" Color = "{Binding Path=FillColor,RelativeSource={RelativeSource TemplatedParent}}" />
<SolidColorBrush x:Key = "ParticleBackgroundColor" Color = "Transparent"/>
<system:Double x:Key = "ParticleOpacity">1</system:Double>
<system:Double x:Key = "ParticleRadius">5</system:Double> <system:Double x:Key = "StartingPointX">0</system:Double>
<system:Double x:Key = "StartingPointY">-20</system:Double> <system:Double x:Key = "RotationPointX">0.5</system:Double>
<system:Double x:Key = "RotationPointY">0.5</system:Double> <!-- StoryBoard -->
<system:TimeSpan x:Key = "StoryBoardBeginTimeP0">00:00:00.000</system:TimeSpan>
<system:TimeSpan x:Key = "StoryBoardBeginTimeP1">00:00:00.100</system:TimeSpan>
<system:TimeSpan x:Key = "StoryBoardBeginTimeP2">00:00:00.200</system:TimeSpan>
<system:TimeSpan x:Key = "StoryBoardBeginTimeP3">00:00:00.300</system:TimeSpan>
<system:TimeSpan x:Key = "StoryBoardBeginTimeP4">00:00:00.400</system:TimeSpan>
<Duration x:Key = "StoryBoardDuration">00:00:01.800</Duration> <!-- Particle Origin Angles -->
<system:Double x:Key = "ParticleOriginAngleP0">0</system:Double>
<system:Double x:Key = "ParticleOriginAngleP1">-10</system:Double>
<system:Double x:Key = "ParticleOriginAngleP2">-20</system:Double>
<system:Double x:Key = "ParticleOriginAngleP3">-30</system:Double>
<system:Double x:Key = "ParticleOriginAngleP4">-40</system:Double> <!-- Particle Position & Timing 1 -->
<system:Double x:Key = "ParticleBeginAngle1">0</system:Double>
<system:Double x:Key = "ParticleEndAngle1">90</system:Double>
<system:TimeSpan x:Key = "ParticleBeginTime1">00:00:00.000</system:TimeSpan>
<Duration x:Key = "ParticleDuration1">00:00:00.750</Duration> <!-- Particle Position & Timing 2 -->
<system:Double x:Key = "ParticleBeginAngle2">90</system:Double>
<system:Double x:Key = "ParticleEndAngle2">270</system:Double>
<system:TimeSpan x:Key = "ParticleBeginTime2">00:00:00.751</system:TimeSpan>
<Duration x:Key = "ParticleDuration2">00:00:00.300</Duration> <!-- Particle Position & Timing 3 -->
<system:Double x:Key = "ParticleBeginAngle3">270</system:Double>
<system:Double x:Key = "ParticleEndAngle3">360</system:Double>
<system:TimeSpan x:Key = "ParticleBeginTime3">00:00:01.052</system:TimeSpan>
<Duration x:Key = "ParticleDuration3">00:00:00.750</Duration> <Style x:Key = "EllipseStyle" TargetType = "Ellipse">
<Setter Property = "Width" Value = "{StaticResource ParticleRadius}"/>
<Setter Property = "Height" Value = "{StaticResource ParticleRadius}"/>
<Setter Property = "Fill" Value = "{StaticResource ParticleColor}"/>
<Setter Property = "RenderTransformOrigin" Value = "0.5, 0.5"/>
<Setter Property = "Opacity" Value = "{StaticResource ParticleOpacity}"/>
</Style>
</Grid.Resources>
<Canvas Width = "1" Height = "1" Margin="0,0,0,0">
<Canvas.Triggers>
<EventTrigger RoutedEvent = "Canvas.Loaded">
<EventTrigger.Actions>
<BeginStoryboard>
<Storyboard BeginTime = "{StaticResource StoryBoardBeginTimeP0}"
Duration = "{StaticResource StoryBoardDuration}"
RepeatBehavior = "Forever">
<DoubleAnimation
Storyboard.TargetName = "p0"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle1}"
To = "{StaticResource ParticleEndAngle1}"
BeginTime = "{StaticResource ParticleBeginTime1}"
Duration = "{StaticResource ParticleDuration1}"/>
<DoubleAnimation
Storyboard.TargetName = "p0"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle2}"
To = "{StaticResource ParticleEndAngle2}"
BeginTime = "{StaticResource ParticleBeginTime2}"
Duration = "{StaticResource ParticleDuration2}"/>
<DoubleAnimation
Storyboard.TargetName = "p0"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle3}"
To = "{StaticResource ParticleEndAngle3}"
BeginTime = "{StaticResource ParticleBeginTime3}"
Duration = "{StaticResource ParticleDuration3}"/>
</Storyboard>
</BeginStoryboard>
<BeginStoryboard>
<Storyboard BeginTime = "{StaticResource StoryBoardBeginTimeP1}"
Duration = "{StaticResource StoryBoardDuration}"
RepeatBehavior = "Forever"> <DoubleAnimation
Storyboard.TargetName = "p1"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle1}"
To = "{StaticResource ParticleEndAngle1}"
BeginTime = "{StaticResource ParticleBeginTime1}"
Duration = "{StaticResource ParticleDuration1}"/>
<DoubleAnimation
Storyboard.TargetName = "p1"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle2}"
To = "{StaticResource ParticleEndAngle2}"
BeginTime = "{StaticResource ParticleBeginTime2}"
Duration = "{StaticResource ParticleDuration2}"/>
<DoubleAnimation
Storyboard.TargetName = "p1"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle3}"
To = "{StaticResource ParticleEndAngle3}"
BeginTime = "{StaticResource ParticleBeginTime3}"
Duration = "{StaticResource ParticleDuration3}"/>
</Storyboard>
</BeginStoryboard>
<BeginStoryboard>
<Storyboard BeginTime = "{StaticResource StoryBoardBeginTimeP2}"
Duration = "{StaticResource StoryBoardDuration}"
RepeatBehavior = "Forever"> <DoubleAnimation
Storyboard.TargetName = "p2"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle1}"
To = "{StaticResource ParticleEndAngle1}"
BeginTime = "{StaticResource ParticleBeginTime1}"
Duration = "{StaticResource ParticleDuration1}"/>
<DoubleAnimation
Storyboard.TargetName = "p2"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle2}"
To = "{StaticResource ParticleEndAngle2}"
BeginTime = "{StaticResource ParticleBeginTime2}"
Duration = "{StaticResource ParticleDuration2}"/>
<DoubleAnimation
Storyboard.TargetName = "p2"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle3}"
To = "{StaticResource ParticleEndAngle3}"
BeginTime = "{StaticResource ParticleBeginTime3}"
Duration = "{StaticResource ParticleDuration3}"/>
</Storyboard>
</BeginStoryboard> <BeginStoryboard>
<Storyboard BeginTime = "{StaticResource StoryBoardBeginTimeP3}"
Duration = "{StaticResource StoryBoardDuration}"
RepeatBehavior = "Forever"> <DoubleAnimation
Storyboard.TargetName = "p3"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle1}"
To = "{StaticResource ParticleEndAngle1}"
BeginTime = "{StaticResource ParticleBeginTime1}"
Duration = "{StaticResource ParticleDuration1}"/>
<DoubleAnimation
Storyboard.TargetName = "p3"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle2}"
To = "{StaticResource ParticleEndAngle2}"
BeginTime = "{StaticResource ParticleBeginTime2}"
Duration = "{StaticResource ParticleDuration2}"/>
<DoubleAnimation
Storyboard.TargetName = "p3"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle3}"
To = "{StaticResource ParticleEndAngle3}"
BeginTime = "{StaticResource ParticleBeginTime3}"
Duration = "{StaticResource ParticleDuration3}"/>
</Storyboard>
</BeginStoryboard> <BeginStoryboard>
<Storyboard BeginTime = "{StaticResource StoryBoardBeginTimeP4}"
Duration = "{StaticResource StoryBoardDuration}"
RepeatBehavior = "Forever"> <DoubleAnimation
Storyboard.TargetName = "p4"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle1}"
To = "{StaticResource ParticleEndAngle1}"
BeginTime = "{StaticResource ParticleBeginTime1}"
Duration = "{StaticResource ParticleDuration1}"/>
<DoubleAnimation
Storyboard.TargetName = "p4"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle2}"
To = "{StaticResource ParticleEndAngle2}"
BeginTime = "{StaticResource ParticleBeginTime2}"
Duration = "{StaticResource ParticleDuration2}"/>
<DoubleAnimation
Storyboard.TargetName = "p4"
Storyboard.TargetProperty = "(UIElement.RenderTransform).(RotateTransform.Angle)"
From = "{StaticResource ParticleBeginAngle3}"
To = "{StaticResource ParticleEndAngle3}"
BeginTime = "{StaticResource ParticleBeginTime3}"
Duration = "{StaticResource ParticleDuration3}"/>
</Storyboard>
</BeginStoryboard>
</EventTrigger.Actions>
</EventTrigger>
</Canvas.Triggers>
<Border
x:Name = "p0"
Background = "{StaticResource ParticleBackgroundColor}"
Opacity = "{StaticResource ParticleOpacity}">
<Border.RenderTransform>
<RotateTransform/>
</Border.RenderTransform>
<Border.RenderTransformOrigin>
<Point X = "{StaticResource RotationPointX}" Y = "{StaticResource RotationPointY}"/>
</Border.RenderTransformOrigin>
<Ellipse Style = "{StaticResource EllipseStyle}">
<Ellipse.RenderTransform>
<TransformGroup>
<TranslateTransform X = "{StaticResource StartingPointX}" Y = "{StaticResource StartingPointY}"/>
<RotateTransform Angle = "{StaticResource ParticleOriginAngleP0}"/>
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
</Border>
<Border
x:Name = "p1"
Background = "{StaticResource ParticleBackgroundColor}"
Opacity = "{StaticResource ParticleOpacity}">
<Border.RenderTransform>
<RotateTransform/>
</Border.RenderTransform>
<Border.RenderTransformOrigin>
<Point X = "{StaticResource RotationPointX}" Y = "{StaticResource RotationPointY}"/>
</Border.RenderTransformOrigin>
<Ellipse Style = "{StaticResource EllipseStyle}">
<Ellipse.RenderTransform>
<TransformGroup>
<TranslateTransform X = "{StaticResource StartingPointX}" Y = "{StaticResource StartingPointY}"/>
<RotateTransform Angle = "{StaticResource ParticleOriginAngleP1}"/>
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
</Border>
<Border
x:Name = "p2"
Background = "{StaticResource ParticleBackgroundColor}"
Opacity = "{StaticResource ParticleOpacity}">
<Border.RenderTransform>
<RotateTransform/>
</Border.RenderTransform>
<Border.RenderTransformOrigin>
<Point X = "{StaticResource RotationPointX}" Y = "{StaticResource RotationPointY}"/>
</Border.RenderTransformOrigin>
<Ellipse Style = "{StaticResource EllipseStyle}">
<Ellipse.RenderTransform>
<TransformGroup>
<TranslateTransform X = "{StaticResource StartingPointX}" Y = "{StaticResource StartingPointY}"/>
<RotateTransform Angle = "{StaticResource ParticleOriginAngleP2}"/>
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
</Border>
<Border
x:Name = "p3"
Background = "{StaticResource ParticleBackgroundColor}"
Opacity = "{StaticResource ParticleOpacity}">
<Border.RenderTransform>
<RotateTransform/>
</Border.RenderTransform>
<Border.RenderTransformOrigin>
<Point X = "{StaticResource RotationPointX}" Y = "{StaticResource RotationPointY}"/>
</Border.RenderTransformOrigin>
<Ellipse Style = "{StaticResource EllipseStyle}">
<Ellipse.RenderTransform>
<TransformGroup>
<TranslateTransform X = "{StaticResource StartingPointX}" Y = "{StaticResource StartingPointY}"/>
<RotateTransform Angle = "{StaticResource ParticleOriginAngleP3}"/>
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
</Border>
<Border
x:Name = "p4"
Background = "{StaticResource ParticleBackgroundColor}"
Opacity = "{StaticResource ParticleOpacity}">
<Border.RenderTransform>
<RotateTransform/>
</Border.RenderTransform>
<Border.RenderTransformOrigin>
<Point X = "{StaticResource RotationPointX}" Y = "{StaticResource RotationPointY}"/>
</Border.RenderTransformOrigin>
<Ellipse Style = "{StaticResource EllipseStyle}">
<Ellipse.RenderTransform>
<TransformGroup>
<TranslateTransform X = "{StaticResource StartingPointX}" Y = "{StaticResource StartingPointY}"/>
<RotateTransform Angle = "{StaticResource ParticleOriginAngleP4}"/>
</TransformGroup>
</Ellipse.RenderTransform>
</Ellipse>
</Border>
</Canvas>
</Grid> </Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style> </ResourceDictionary>
在构建中发现，一开始在设定绑定时，写成<SolidColorBrush x:Key = "ParticleColor" Color = "{Binding Path=FillColor}" />一直都无法绑定成功，后来查了资料，改成<SolidColorBrush x:Key = "ParticleColor" Color = "{Binding Path=FillColor,RelativeSource={RelativeSource TemplatedParent}}" /> 后成功。
4、编辑Loading.cs文件，对自定义属性FillColor和逻辑进行编码：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes; namespace WpfControlLibraryDemo
{
using System.ComponentModel;
/// <summary>
/// 按照步骤 1a 或 1b 操作，然后执行步骤 2 以在 XAML 文件中使用此自定义控件。
///
/// 步骤 1a) 在当前项目中存在的 XAML 文件中使用该自定义控件。
/// 将此 XmlNamespace 特性添加到要使用该特性的标记文件的根
/// 元素中:
///
/// xmlns:MyNamespace="clr-namespace:WpfControlLibraryDemo"
///
///
/// 步骤 1b) 在其他项目中存在的 XAML 文件中使用该自定义控件。
/// 将此 XmlNamespace 特性添加到要使用该特性的标记文件的根
/// 元素中:
///
/// xmlns:MyNamespace="clr-namespace:WpfControlLibraryDemo;assembly=WpfControlLibraryDemo"
///
/// 您还需要添加一个从 XAML 文件所在的项目到此项目的项目引用，
/// 并重新生成以避免编译错误:
///
/// 在解决方案资源管理器中右击目标项目，然后依次单击
/// “添加引用”->“项目”->[浏览查找并选择此项目]
///
///
/// 步骤 2)
/// 继续操作并在 XAML 文件中使用控件。
///
/// <MyNamespace:Loading/>
///
/// </summary>
public class Loading : Control
{
static Loading()
{
//重载默认样式
DefaultStyleKeyProperty.OverrideMetadata(typeof(Loading), new FrameworkPropertyMetadata(typeof(Loading)));
//DependencyProperty 注册 FillColor
FillColorProperty = DependencyProperty.Register("FillColor",
typeof(Color),
typeof(Loading),
new UIPropertyMetadata(Colors.DarkBlue,
new PropertyChangedCallback(OnUriChanged))
);
//Colors.DarkBlue为控件初始化默认值 }
//属性变更回调函数
private static void OnUriChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
//Border b = (Border)d;
//MessageBox.Show(e.NewValue.ToString()); }
#region 自定义Fields
// DependencyProperty属性定义 FillColorProperty=FillColor+Property组成
public static readonly DependencyProperty FillColorProperty;
#endregion
//VS设计器属性支持
[Description("背景色"), Category("个性配置"), DefaultValue("#FF668899")]
public Color FillColor
{
//GetValue,SetValue为固定写法，此处一般不建议处理其他逻辑
get { return (Color)GetValue(FillColorProperty); }
set { SetValue(FillColorProperty, value); }
}
}
}
5、编译，如果无误后，可以添加WPF应用程序WpfAppLoadingTest进行测试（添加项目引用）。
打开MainWindow.xaml，将Loading控件拖放到设计界面上，如下图所示：
6、控件颜色修改，选中控件，在属性栏中进行配置即可：
7.总结
可以看到WPF自定义控件还是比较容易的，但是难点在于UI的设计，如果需要做的美观，需要美工的参与，而且需要转换成XAML。