来瞧瞧， WPF 炫酷走马灯!

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来瞧瞧，WPF 炫酷走马灯!

控件名：SpotLight

作者：WPFDevelopersOrg

原文链接： https://github.com/WPFDevelopersOrg/WPFDevelopers

框架使用大于等于.NET40；
Visual Studio 2022;
项目使用 MIT 开源许可协议；
用Canvas做容器方便针对文本TextBlock做裁剪Clip动画操作；
Canvas内部创建两个TextBlock；
第一个做为背景字体设置字体颜色为浅灰Foreground="#323232"，也可以通过依赖属性设置DefaultForeground；
第二个字体设置会彩虹色当聚光灯走到某个区域后并显示；
Duration可设置动画的从左到右的时长，默认 3 秒；
根据字体的实际宽度ActualWidth做动画展示从左到右并循环Forever播放；

1 ）SpotLight.cs 代码如下；

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;

namespace WPFDevelopers.Controls
{
    [TemplatePart(Name = TextBlockBottomTemplateName, Type = typeof(TextBlock))]
    [TemplatePart(Name = TextBlockTopTemplateName, Type = typeof(TextBlock))]
    [TemplatePart(Name = EllipseGeometryTemplateName, Type = typeof(EllipseGeometry))]
    public class SpotLight : Control
    {
        private const string TextBlockBottomTemplateName = "PART_TextBlockBottom";
        private const string TextBlockTopTemplateName = "PART_TextBlockTop";
        private const string EllipseGeometryTemplateName = "PART_EllipseGeometry";

        public static readonly DependencyProperty TextProperty =
            DependencyProperty.Register("Text", typeof(string), typeof(SpotLight),
                new PropertyMetadata("WPFDevelopers"));

        public static readonly DependencyProperty DefaultForegroundProperty =
            DependencyProperty.Register("DefaultForeground", typeof(Brush), typeof(SpotLight),
                new PropertyMetadata(new SolidColorBrush((Color)ColorConverter.ConvertFromString("#323232"))));


        public static readonly DependencyProperty DurationProperty =
            DependencyProperty.Register("Duration", typeof(TimeSpan), typeof(SpotLight),
                new PropertyMetadata(TimeSpan.FromSeconds(3)));


        private EllipseGeometry _ellipseGeometry;
        private TextBlock _textBlockBottom, _textBlockTop;

        static SpotLight()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(SpotLight),
                new FrameworkPropertyMetadata(typeof(SpotLight)));
        }

       
        public TimeSpan Duration
        {
            get => (TimeSpan)GetValue(DurationProperty);
            set => SetValue(DurationProperty, value);
        }
        public Brush DefaultForeground
        {
            get => (Brush)GetValue(DefaultForegroundProperty);
            set => SetValue(DefaultForegroundProperty, value);
        }

        public string Text
        {
            get => (string)GetValue(TextProperty);
            set => SetValue(TextProperty, value);
        }
        
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            _textBlockBottom = GetTemplateChild(TextBlockBottomTemplateName) as TextBlock;
            _textBlockTop = GetTemplateChild(TextBlockTopTemplateName) as TextBlock;

            _ellipseGeometry = GetTemplateChild(EllipseGeometryTemplateName) as EllipseGeometry;
            var center = new Point(FontSize / 2, FontSize / 2);
            _ellipseGeometry.RadiusX = FontSize;
            _ellipseGeometry.RadiusY = FontSize;
            _ellipseGeometry.Center = center;
            if (_textBlockBottom != null && _textBlockTop != null && _ellipseGeometry != null)
                _textBlockTop.Loaded += _textBlockTop_Loaded;
        }


        private void _textBlockTop_Loaded(object sender, RoutedEventArgs e)
        {
            var doubleAnimation = new DoubleAnimation
            {
                From = 0,
                To = _textBlockTop.ActualWidth,
                Duration = Duration
            };

            Storyboard.SetTarget(doubleAnimation, _textBlockTop);
            Storyboard.SetTargetProperty(doubleAnimation,
                new PropertyPath("(UIElement.Clip).(EllipseGeometry.Transform).(TranslateTransform.X)"));
            var storyboard = new Storyboard
            {
                RepeatBehavior = RepeatBehavior.Forever,
                AutoReverse = true
            };
            storyboard.Children.Add(doubleAnimation);
            storyboard.Begin();
        }
    }
}

2 ）SpotLight.xaml 代码如下；

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:controls="clr-namespace:WPFDevelopers.Controls">
    
    <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="Basic/ControlBasic.xaml"/>
    </ResourceDictionary.MergedDictionaries>
    <LinearGradientBrush x:Key="RainbowBrush" EndPoint="1,1" MappingMode="RelativeToBoundingBox" StartPoint="0,0">
        <GradientStop Color="#FF9C1031" Offset="0.1"/>
        <GradientStop Color="#FFBE0E20" Offset="0.2"/>
        <GradientStop Color="#FF9C12AC" Offset="0.7"/>
        <GradientStop Color="#FF0A8DC3" Offset="0.8"/>
        <GradientStop Color="#FF1AEBCC" Offset="1"/>
    </LinearGradientBrush>
    <Style TargetType="{x:Type controls:SpotLight}" BasedOn="{StaticResource ControlBasicStyle}">
        <Setter Property="Background" Value="#222222"/>
        <Setter Property="FontSize" Value="60"/>
        <Setter Property="FontFamily" Value="Arial Black"/>
        <Setter Property="FontWeight" Value="Bold"/>
        <Setter Property="Foreground" Value="{StaticResource RainbowBrush}"/>
        <Setter Property="VerticalAlignment" Value="Center"/>
        <Setter Property="HorizontalAlignment" Value="Center"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type controls:SpotLight}">
                    <Grid x:Name="PART_Canvas" Background="{TemplateBinding Background}">
                        <TextBlock x:Name="PART_TextBlockBottom" Text="{TemplateBinding Text}"
                                   FontSize="{TemplateBinding FontSize}" 
                                   FontFamily="{TemplateBinding FontFamily}"
                                   FontWeight="{TemplateBinding FontWeight}" 
                                   Foreground="{TemplateBinding DefaultForeground}"/>
                        <TextBlock x:Name="PART_TextBlockTop" Text="{TemplateBinding Text}"
                                   FontSize="{TemplateBinding FontSize}"
                                   FontFamily="{TemplateBinding FontFamily}"
                                   FontWeight="{TemplateBinding FontWeight}"
                                   Foreground="{TemplateBinding Foreground}">
                            <TextBlock.Clip>
                                <EllipseGeometry x:Name="PART_EllipseGeometry">
                                    <EllipseGeometry.Transform>
                                        <TranslateTransform/>
                                    </EllipseGeometry.Transform>
                                </EllipseGeometry>
                            </TextBlock.Clip>
                        </TextBlock>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>

3 ）SpotLightExample.xaml代码如下如何使用；

<UniformGrid Rows="2" Background="#222222">
        <wpfdev:SpotLight FontSize="50" Text="YanJinHua" 
                          DefaultForeground="Crimson" 
                          Foreground="Fuchsia" 
                          Duration="00:00:05" />
        <wpfdev:SpotLight/>
</UniformGrid>