本文经原作者授权以原创方式二次分享，欢迎转载、分享。
原文作者：普通的地球人
原文地址：https://www.cnblogs.com/tsliwei/p/6282183.html
Github地址：https://github.com/WPFDevelopersOrg/WPFDevelopers
效果
前阵子看到ay的蜘蛛网效果和知乎的登录页背景,觉得效果很酷.自己也想写一个.于是写着写着就变成这样了.少女梦幻的赶脚有木有.我这有着一颗少女心的抠脚大汉；
实现思路分为两个部分:
1）星星无休止的漫游；
2）星星之间的连线；
星星和连线非别放到两个容器里,以便分开操作；
星星
把星星的运动分解为
X轴和Y轴两个不相干的运动,分别操作.操作就是随机生成一个速度,随机生成一个时间.运动完之后再随机生成一个速度,随机生成一个时间......无限循环；星星的旋转也是同样的道理；
连线
首先解释下连线的规则.两个星星之间连线,每个星星都有一个连线的势力范围,就是宽度乘以连线倍率,这个连线倍率可以在窗体设置.当两个势力范围有交集的时候,就连线;
例:
星1宽度5,星2宽度10,连线倍率是3,那么这两个星星的距离小于5*3+10*3=45时就连线,大于45时断开.如果连线倍率设置为4,则两个星星减的距离小于5*4+10*4=60时连线,大于60时断开;
实现与资源占有率
星星运动的实现有两种:
1）基于Grid和TranslateTransform用DoubleAnimation动画控制星星的位移.
2）基于Canvas通过帧动画控制Canvas的X,Y.
连线的实现也有两种:
1）简单粗暴.在每一帧都清空连线容器.然后双层循环星星,重新连接所有星星(符合连线规则的).
2）在每一帧循环连线,判断连线规则.符合就改变此连线的X1,Y1,X2,Y2而不去重新new连线.不符合规则的就移除.然后依然是双层循环星星,看符合规则的两个星星间有没有连线,没有的就new一个.
众所周知,WPF做这种动画资源占有率还是比较高的,写了这么多实现,也是因为这个.
大体上还是基于Canvas的实现占用资源稍低.但也有个问题,如果给星星再加一个模糊效果的话,基于Canvas实现的资源占有率不会飙升,而是帧数明显降低.(也可能是我电脑环境的原因)
并不能说那种实现好与坏,可能具体运行环境不一样,参数设置不一样,每种实现都有不同的表现.
然后关于资源占有率问题,以我目前的水平,就只能到这了.博友们自己取舍吧.
源码如下
1）StarrySky.cs代码如下；
using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;namespace WPFDevelopers.Controls
{[TemplatePart(Name = GridTemplateName, Type = typeof(Grid))][TemplatePart(Name = CanvasTemplateName, Type = typeof(Canvas))]public class StarrySky : Control{private const string GridTemplateName = "PART_GridLineContainer";private const string CanvasTemplateName = "PART_CanvasStarContainer";private Grid _grid;private Canvas _canvas;public static readonly DependencyProperty StarCountProperty =DependencyProperty.Register("StarCount", typeof(int), typeof(StarrySky), new UIPropertyMetadata(10));public static readonly DependencyProperty StarSizeMinProperty =DependencyProperty.Register("StarSizeMin", typeof(int), typeof(StarrySky), new UIPropertyMetadata(5));public static readonly DependencyProperty StarSizeMaxProperty =DependencyProperty.Register("StarSizeMax", typeof(int), typeof(StarrySky), new UIPropertyMetadata(20));public static readonly DependencyProperty StarVMinProperty =DependencyProperty.Register("StarVMin", typeof(int), typeof(StarrySky), new UIPropertyMetadata(10));public static readonly DependencyProperty StarVMaxProperty =DependencyProperty.Register("StarVMax", typeof(int), typeof(StarrySky), new UIPropertyMetadata(20));public static readonly DependencyProperty StarRVMinProperty =DependencyProperty.Register("StarRVMin", typeof(int), typeof(StarrySky), new UIPropertyMetadata(90));public static readonly DependencyProperty StarRVMaxProperty =DependencyProperty.Register("StarRVMax", typeof(int), typeof(StarrySky), new UIPropertyMetadata(360));public static readonly DependencyProperty LineRateProperty =DependencyProperty.Register("LineRate", typeof(int), typeof(StarrySky), new UIPropertyMetadata(3));private readonly Random _random = new Random();private StarInfo[] _stars;static StarrySky(){DefaultStyleKeyProperty.OverrideMetadata(typeof(StarrySky),new FrameworkPropertyMetadata(typeof(StarrySky)));}public StarrySky(){Loaded += delegate{CompositionTarget.Rendering += delegate{StarRoamAnimation();AddOrRemoveStarLine();MoveStarLine();};};}public override void OnApplyTemplate(){base.OnApplyTemplate();_grid = GetTemplateChild(GridTemplateName) as Grid;_canvas = GetTemplateChild(CanvasTemplateName) as Canvas;}public int StarCount{get => (int)GetValue(StarCountProperty);set => SetValue(StarCountProperty, value);}public int StarSizeMin{get => (int)GetValue(StarSizeMinProperty);set => SetValue(StarSizeMinProperty, value);}public int StarSizeMax{get => (int)GetValue(StarSizeMaxProperty);set => SetValue(StarSizeMaxProperty, value);}public int StarVMin{get => (int)GetValue(StarVMinProperty);set => SetValue(StarVMinProperty, value);}public int StarVMax{get => (int)GetValue(StarVMaxProperty);set => SetValue(StarVMaxProperty, value);}public int StarRVMin{get => (int)GetValue(StarRVMinProperty);set => SetValue(StarRVMinProperty, value);}public int StarRVMax{get => (int)GetValue(StarRVMaxProperty);set => SetValue(StarRVMaxProperty, value);}public int LineRate{get => (int)GetValue(LineRateProperty);set => SetValue(LineRateProperty, value);}public void InitStar(){//清空星星容器_stars = new StarInfo[StarCount];_canvas.Children.Clear();_grid.Children.Clear();//生成星星for (var i = 0; i < StarCount; i++){double size = _random.Next(StarSizeMin, StarSizeMax + 1); //星星尺寸var starInfo = new StarInfo{X = _random.Next(0, (int)_canvas.ActualWidth),XV = (double)_random.Next(-StarVMax, StarVMax) / 60,XT = _random.Next(6, 301), //帧Y = _random.Next(0, (int)_canvas.ActualHeight),YV = (double)_random.Next(-StarVMax, StarVMax) / 60,YT = _random.Next(6, 301), //帧StarLines = new Dictionary<StarInfo, Line>()};var star = new Path{Data = Application.Current.Resources["PathStarrySky"] as Geometry,Width = size,Height = size,Stretch = Stretch.Fill,Fill = GetRandomColorBursh(),RenderTransformOrigin = new Point(0.5, 0.5),RenderTransform = new RotateTransform { Angle = 0 }};Canvas.SetLeft(star, starInfo.X);Canvas.SetTop(star, starInfo.Y);starInfo.StarRef = star;//设置星星旋转动画SetStarRotateAnimation(star);//添加到容器_stars[i] = starInfo;_canvas.Children.Add(star);}}private void SetStarRotateAnimation(Path star){double v = _random.Next(StarRVMin, StarRVMax + 1); //速度double a = _random.Next(0, 360 * 5); //角度var t = a / v; //时间var dur = new Duration(new TimeSpan(0, 0, 0, 0, (int)(t * 1000)));var sb = new Storyboard{Duration = dur};//动画完成事件 再次设置此动画sb.Completed += (S, E) => { SetStarRotateAnimation(star); };var da = new DoubleAnimation{To = a,Duration = dur};Storyboard.SetTarget(da, star);Storyboard.SetTargetProperty(da, new PropertyPath("(UIElement.RenderTransform).(RotateTransform.Angle)"));sb.Children.Add(da);sb.Begin(this);}private SolidColorBrush GetRandomColorBursh(){var r = (byte)_random.Next(128, 256);var g = (byte)_random.Next(128, 256);var b = (byte)_random.Next(128, 256);return new SolidColorBrush(Color.FromRgb(r, g, b));}/// <summary>/// 星星漫游动画/// </summary>private void StarRoamAnimation(){if (_stars == null)return;foreach (var starInfo in _stars){//X轴运动if (starInfo.XT > 0){//运动时间大于0,继续运动if (starInfo.X >= _canvas.ActualWidth || starInfo.X <= 0)//碰到边缘,速度取反向starInfo.XV = -starInfo.XV;//位移加,时间减starInfo.X += starInfo.XV;starInfo.XT--;Canvas.SetLeft(starInfo.StarRef, starInfo.X);}else{//运动时间小于0,重新设置速度和时间starInfo.XV = (double)_random.Next(-StarVMax, StarVMax) / 60;starInfo.XT = _random.Next(100, 1001);}//Y轴运动if (starInfo.YT > 0){//运动时间大于0,继续运动if (starInfo.Y >= _canvas.ActualHeight || starInfo.Y <= 0)//碰到边缘,速度取反向starInfo.YV = -starInfo.YV;//位移加,时间减starInfo.Y += starInfo.YV;starInfo.YT--;Canvas.SetTop(starInfo.StarRef, starInfo.Y);}else{//运动时间小于0,重新设置速度和时间starInfo.YV = (double)_random.Next(-StarVMax, StarVMax) / 60;starInfo.YT = _random.Next(100, 1001);}}}/// <summary>/// 添加或者移除星星之间的连线/// </summary>private void AddOrRemoveStarLine(){//没有星星 直接返回if (_stars == null || StarCount != _stars.Length)return;//生成星星间的连线for (var i = 0; i < StarCount - 1; i++)for (var j = i + 1; j < StarCount; j++){var star1 = _stars[i];var x1 = star1.X + star1.StarRef.Width / 2;var y1 = star1.Y + star1.StarRef.Height / 2;var star2 = _stars[j];var x2 = star2.X + star2.StarRef.Width / 2;var y2 = star2.Y + star2.StarRef.Height / 2;var s = Math.Sqrt((y2 - y1) * (y2 - y1) + (x2 - x1) * (x2 - x1)); //两个星星间的距离var threshold = star1.StarRef.Width * LineRate + star2.StarRef.Width * LineRate;if (s <= threshold){if (!star1.StarLines.ContainsKey(star2)){var line = new Line{X1 = x1,Y1 = y1,X2 = x2,Y2 = y2,Stroke = GetStarLineBrush(star1.StarRef, star2.StarRef)};star1.StarLines.Add(star2, line);_grid.Children.Add(line);}}else{if (star1.StarLines.ContainsKey(star2)){_grid.Children.Remove(star1.StarLines[star2]);star1.StarLines.Remove(star2);}}}}/// <summary>/// 移动星星之间的连线/// </summary>private void MoveStarLine(){//没有星星 直接返回if (_stars == null)return;foreach (var star in _stars)foreach (var starLine in star.StarLines){var line = starLine.Value;line.X1 = star.X + star.StarRef.Width / 2;line.Y1 = star.Y + star.StarRef.Height / 2;line.X2 = starLine.Key.X + starLine.Key.StarRef.Width / 2;line.Y2 = starLine.Key.Y + starLine.Key.StarRef.Height / 2;}}/// <summary>/// 获取星星连线颜色画刷/// </summary>/// <param name="star0">起始星星</param>/// <param name="star1">终点星星</param>/// <returns>LinearGradientBrush</returns>private LinearGradientBrush GetStarLineBrush(Path star0, Path star1){return new LinearGradientBrush{GradientStops = new GradientStopCollection{new GradientStop { Offset = 0, Color = (star0.Fill as SolidColorBrush).Color },new GradientStop { Offset = 1, Color = (star1.Fill as SolidColorBrush).Color }}};}}/// <summary>/// 星星/// </summary>internal class StarInfo{/// <summary>/// X坐标/// </summary>public double X { get; set; }/// <summary>/// X轴速度(单位距离/帧)/// </summary>public double XV { get; set; }/// <summary>/// X坐标以X轴速度运行的时间(帧)/// </summary>public int XT { get; set; }/// <summary>/// Y坐标/// </summary>public double Y { get; set; }/// <summary>/// Y轴速度(单位距离/帧)/// </summary>public double YV { get; set; }/// <summary>/// Y坐标以Y轴速度运行的时间(帧)/// </summary>public int YT { get; set; }/// <summary>/// 对星星的引用/// </summary>public Path StarRef { get; set; }public Dictionary<StarInfo, Line> StarLines { get; set; }}
}2）StarrySky.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><RadialGradientBrush x:Key="StarrySkyRadialGradientBrush" GradientOrigin="0.5,0" Center="0.5,0.3" RadiusX="0.7"><GradientStop Color="#FF04040E" Offset="0"/><GradientStop Color="#FF24315D" Offset="1"/></RadialGradientBrush><Style TargetType="{x:Type controls:StarrySky}" BasedOn="{StaticResource ControlBasicStyle}"><Setter Property="Background" Value="{StaticResource StarrySkyRadialGradientBrush}"></Setter><Setter Property="Template"><Setter.Value><ControlTemplate TargetType="{x:Type controls:StarrySky}"><Grid Background="{TemplateBinding Background}"><Grid x:Name="PART_GridLineContainer"/><Canvas x:Name="PART_CanvasStarContainer"/></Grid></ControlTemplate></Setter.Value></Setter></Style>
</ResourceDictionary>3）StarrySkyExample.xaml代码如下；
<UserControl x:Class="WPFDevelopers.Samples.ExampleViews.StarrySkyExample"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:wpfdev="https://github.com/WPFDevelopersOrg/WPFDevelopers"xmlns:ws="https://github.com/WPFDevelopersOrg.WPFDevelopers.Minimal"xmlns:local="clr-namespace:WPFDevelopers.Samples.ExampleViews"mc:Ignorable="d" d:DesignHeight="450" d:DesignWidth="800"><UserControl.Resources><Style TargetType="{x:Type TextBlock}"><Setter Property="Foreground" Value="White"></Setter><Setter Property="FontSize" Value="14"></Setter><Setter Property="VerticalAlignment" Value="Center"></Setter><Setter Property="Margin" Value="2"></Setter></Style><Style TargetType="{x:Type StackPanel}"><Setter Property="Margin" Value="2"></Setter></Style><Style TargetType="{x:Type TextBox}" BasedOn="{StaticResource {x:Type TextBox}}"><Setter Property="ws:ElementHelper.Watermark" Value="输入内容"></Setter><Setter Property="Margin" Value="-30,0"></Setter><Setter Property="Width" Value="100"></Setter></Style></UserControl.Resources><Grid><!--<wpfdev:StarrySky StarCount="{Binding ElementName=tbx_starCount,Path=Text}"StarSizeMin="{Binding ElementName=tbx_starSizeMin,Path=Text}"StarSizeMax="{Binding ElementName=tbx_starSizeMax,Path=Text}"StarVMin="{Binding ElementName=tbx_starVMin,Path=Text}"StarVMax="{Binding ElementName=tbx_starVMax,Path=Text}"StarRVMin="{Binding ElementName=tbx_starRVMin,Path=Text}"StarRVMax="{Binding ElementName=tbx_starRVMax,Path=Text}"LineRate="{Binding ElementName=tbx_lineRate,Path=Text}"Name="myStarrySky"></wpfdev:StarrySky>--><wpfdev:StarrySky Name="myStarrySky"></wpfdev:StarrySky><StackPanel HorizontalAlignment="Left" VerticalAlignment="Top"><StackPanel Orientation="Horizontal"><TextBlock Text="星星个数:"></TextBlock><TextBox x:Name="tbx_starCount" Text="{Binding ElementName=myStarrySky,Path=StarCount}"/></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="最小尺寸:"></TextBlock><TextBox Name="tbx_starSizeMin" Text="{Binding ElementName=myStarrySky,Path=StarSizeMin}"></TextBox></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="最大尺寸:"></TextBlock><TextBox Name="tbx_starSizeMax" Text="{Binding ElementName=myStarrySky,Path=StarSizeMax}"></TextBox></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="最小速度:"></TextBlock><TextBox Name="tbx_starVMin" Text="{Binding ElementName=myStarrySky,Path=StarVMin}"></TextBox></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="最大速度:"></TextBlock><TextBox Name="tbx_starVMax" Text="{Binding ElementName=myStarrySky,Path=StarVMax}"></TextBox></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="最小转速:"></TextBlock><TextBox Name="tbx_starRVMin" Text="{Binding ElementName=myStarrySky,Path=StarRVMin}"></TextBox></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="最大转速:"></TextBlock><TextBox Name="tbx_starRVMax" Text="{Binding ElementName=myStarrySky,Path=StarRVMax}"></TextBox></StackPanel><StackPanel Orientation="Horizontal"><TextBlock Text="连线倍率:"></TextBlock><TextBox Name="tbx_lineRate" Text="{Binding ElementName=myStarrySky,Path=LineRate}"></TextBox></StackPanel><Button Name="btn_render" Content="生成" Click="btn_render_Click"/></StackPanel></Grid>
</UserControl>4）StarrySkyExample.xaml.cs代码如下；
using System.Windows.Controls;namespace WPFDevelopers.Samples.ExampleViews
{/// <summary>/// StarrySkyExample.xaml 的交互逻辑/// </summary>public partial class StarrySkyExample : UserControl{public StarrySkyExample(){InitializeComponent();}private void btn_render_Click(object sender, System.Windows.RoutedEventArgs e){myStarrySky.InitStar();}}
}源码1[1]Gtihub[2]Gitee[3]
参考资料
[1]
源码: https://files.cnblogs.com/files/tsliwei/StarrySkyBasedOnCanvasYOUHUA.zip
[2]Gtihub: https://github.com/WPFDevelopersOrg/WPFDevelopers
[3]gitee: https://gitee.com/WPFDevelopersOrg/WPFDevelopers
