『聚合』 [MAUI]模仿哔哩哔哩的一键三连

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哔哩哔哩(Bilibili)中用户可以通过长按点赞键同时完成点赞、投币、收藏对UP主表示支持，后UP主多用“一键三连”向视频浏览者请求对其作品同时进行点赞、投币、收藏。

“三连按钮”是一组按钮，轻击时当做普通状态按钮使用，当长按 2 秒钟后，转为三连模式，可以控制并显示进度，并在进度完成时弹出一些泡泡

一直想实现这个效果，但由于.NET MAUI对图形填充渲染问题直到.NET 8才修复。想要的效果直到最近才能实现。

两年前Dino老师用UWP实现过“一键三连”:

[UWP]模仿哔哩哔哩的一键三连

今天用MAUI实现。

使用.NET MAU实现跨平台支持，本项目可运行于Android、iOS平台。

创建弧形进度条

新建.NET MAUI项目，命名HoldDownButtonGroup

在项目中添加SkiaSharp绘制功能的引用Microsoft.Maui.Graphics.Skia以及SkiaSharp.Views.Maui.Controls。

<ItemGroup>
    <PackageReference Include="Microsoft.Maui.Graphics.Skia" Version="7.0.59" />
    <PackageReference Include="SkiaSharp.Views.Maui.Controls" Version="2.88.3" />
</ItemGroup>

进度条（ProgressBar）用于展示任务的进度，告知用户当前状态和预期，本项目依赖弧形进度条组件（CircleProgressBar），此组件在本项目中用于展示“三连按钮”长按任务的进度

这里简单介绍弧形进度条组件的原理和实现，更多内容请阅读：[MAUI]弧形进度条与弧形滑块的交互实现。

控件将包含以下可绑定属性：

• Maxiumum：最大值
• Minimum：最小值
• Progress：当前进度
• AnimationLength：动画时长
• BorderWidth：描边宽度
• LabelContent：标签内容
• ContainerColor：容器颜色，即进度条的背景色
• ProgressColor：进度条颜色

创建CircleProgressBar.xaml，代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:forms="clr-namespace:SkiaSharp.Views.Maui.Controls;assembly=SkiaSharp.Views.Maui.Controls"
             x:Class="HoldDownButtonGroup.Controls.CircleProgressBar">
    <ContentView.Content>
        <Grid>
            <forms:SKCanvasView x:Name="canvasView"
                                PaintSurface="OnCanvasViewPaintSurface" />
            <ContentView x:Name="MainContent"></ContentView>
            <Label 
                FontSize="28"
                HorizontalOptions="Center"
                VerticalOptions="Center" 
                x:Name="labelView"></Label>
        </Grid>

    </ContentView.Content>
</ContentView>

SKCanvasView是SkiaSharp.Views.Maui.Controls封装的View控件。

绘制弧

Skia中，通过AddArc方法绘制弧，需要传入一个SKRect对象，其代表一个弧（或椭弧）的外接矩形。startAngle和sweepAngle分别代表顺时针起始角度和扫描角度。

通过startAngle和sweepAngle可以绘制出一个弧，如下图红色部分所示：

在CircleProgressBar.xaml.cs的CodeBehind中，创建OnCanvasViewPaintSurface，通过给定起始角度为正上方，扫描角度为360对于100%进度，通过插值计算出当前进度对应的扫描角度，绘制出进度条。

private void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
{

    var SumValue = Maximum - Minimum;


    SKImageInfo info = args.Info;
    SKSurface surface = args.Surface;
    SKCanvas canvas = surface.Canvas;

    canvas.Clear();

    SKRect rect = new SKRect(_mainRectPadding, _mainRectPadding, info.Width - _mainRectPadding, info.Height - _mainRectPadding);
    float startAngle = -90;
    float sweepAngle = (float)((_realtimeProgress / SumValue) * 360);

    canvas.DrawOval(rect, OutlinePaint);

    using (SKPath path = new SKPath())
    {
        path.AddArc(rect, startAngle, sweepAngle);
        
        canvas.DrawPath(path, ArcPaint);
    }
}

其中SumValue表明进度条的总进度，通过Maximum和Minimum计算得出。

public double SumValue => Maximum - Minimum;

创建进度条轨道背景画刷和进度条画刷，其中进度条画刷的StrokeCap属性设置为SKStrokeCap.Round，使得进度条两端为圆形。

protected SKPaint _outlinePaint;

public SKPaint OutlinePaint
{
    get
    {
        if (_outlinePaint == null)
        {
            RefreshMainRectPadding();
            SKPaint outlinePaint = new SKPaint
            {
                Color = this.ContainerColor.ToSKColor(),
                Style = SKPaintStyle.Stroke,
                StrokeWidth = (float)BorderWidth,
            };
            _outlinePaint = outlinePaint;
        }
        return _outlinePaint;
    }
}

protected SKPaint _arcPaint;

public SKPaint ArcPaint
{
    get
    {
        if (_arcPaint == null)
        {
            RefreshMainRectPadding();
            SKPaint arcPaint = new SKPaint
            {
                Color = this.ProgressColor.ToSKColor(),
                Style = SKPaintStyle.Stroke,
                StrokeWidth = (float)BorderWidth,
                StrokeCap = SKStrokeCap.Round,
            };
            _arcPaint = arcPaint;
        }

        return _arcPaint;
    }
}

在Progress值变更时，重新渲染进度条，并触发ValueChanged事件。

private void UpdateProgress()
{
    this._realtimeProgress = this.Progress;
    this.labelView.Text = this.Progress.ToString(LABEL_FORMATE);
    this.canvasView?.InvalidateSurface();
}

效果如下

准备物料

点赞、投币、收藏三个按钮的图片来自于哔哩哔哩（Bilibili）网站。这些按钮用svg格式在html中。

我们只需前往哔哩哔哩主站，要打开浏览器的开发者工具，用元素检查器，在找到按钮位置后查看其样式，拷贝path中的svg代码，即可得到这些矢量图片。

拷贝右侧红色区域选中的部分，我们只需要这些svg代码。

在Xaml中我们创建Path元素，并设置Data属性为svg代码。即可得到一个图形

<Path HeightRequest="65"
        WidthRequest="65"
        x:Name="Icon1"
        Fill="Transparent"
        Aspect="Uniform"
        Data="M 9.77234 30.8573 V 11.7471 H 7.54573 C 5.50932 11.7471 3.85742 13.3931 3.85742 15.425 V 27.1794 C 3.85742 29.2112 5.50932 30.8573 7.54573 30.8573 H 9.77234 Z M 11.9902 30.8573 V 11.7054 C 14.9897 10.627 16.6942 7.8853 17.1055 3.33591 C 17.2666 1.55463 18.9633 0.814421 20.5803 1.59505 C 22.1847 2.36964 23.243 4.32583 23.243 6.93947 C 23.243 8.50265 23.0478 10.1054 22.6582 11.7471 H 29.7324 C 31.7739 11.7471 33.4289 13.402 33.4289 15.4435 C 33.4289 15.7416 33.3928 16.0386 33.3215 16.328 L 30.9883 25.7957 C 30.2558 28.7683 27.5894 30.8573 24.528 30.8573 H 11.9911 H 11.9902 Z"
        VerticalOptions="Center"
        HorizontalOptions="Center" />

创建气泡

气泡实现分为两个步骤：

Bubble.xaml 创建单一气泡动画
Bubbles.xaml 包含气泡集群。随机生成气泡动画路径，创建气泡集群的动画

Bubbles控件将包含以下可绑定属性：

• Brush：气泡颜色
• BubbleCnt：气泡数量
• BubbleSize：气泡大小

气泡动画算法参考于火火的 BubbleButton，这里只帖关键代码

单一气泡的动画：先变大后消失

public Animation GetAnimation()
{

    var scaleAnimation = new Animation();

    var scaleUpAnimation0 = new Animation(v => MainBox.Scale = v, 0, 1);
    var scaleUpAnimation1 = new Animation(v => MainBox.Scale = v, 1, 0);


    scaleAnimation.Add(0, 0.2, scaleUpAnimation0);
    scaleAnimation.Add(0.8, 1, scaleUpAnimation1);

    scaleAnimation.Finished = () =>
    {
        this.MainBox.Scale = 0;
    };

    return scaleAnimation;

}

生成气泡

public void SpawnBubbles()
{
    this.PitContentLayout.Clear();
    for (int i = 0; i < BubbleCnt; i++)
    {
        var currentBox = new Bubble();
        currentBox.FillColor = i % 2 == 0 ? this.Brush : SolidColorBrush.Transparent;
        currentBox.BorderColor = this.Brush;
        currentBox.HeightRequest = BubbleSize;
        currentBox.WidthRequest = BubbleSize;
        currentBox.HorizontalOptions = LayoutOptions.Start;
        currentBox.VerticalOptions = LayoutOptions.Start;
        this.PitContentLayout.Add(currentBox);
    }
}

计算单个气泡的动画路径：随机产生动画运动的随机坐标

private Animation InitAnimation(Bubble element, Size targetSize, bool isOnTop = true)
{


    var offsetAnimation = new Animation();

    if (targetSize == default)
    {
        targetSize = element.DesiredSize;

    }
    var easing = Easing.Linear;

    var originX = PitContentLayout.Width / 2;
    var originY = PitContentLayout.Height / 2;

    var targetX = rnd.Next(-(int)targetSize.Width, (int)targetSize.Width) + (int)targetSize.Width / 2 + originX;
    var targetY = isOnTop ? rnd.Next(-(int)(targetSize.Height * 1.5), 0) + (int)targetSize.Height / 2 + originY :
            rnd.Next(0, (int)(targetSize.Height * 1.5)) + (int)targetSize.Height / 2 + originY
        ;


    var offsetX = targetX - originX;
    var offsetY = targetY - originY;


    var offsetAnimation1 = new Animation(v => element.TranslationX = v, originX - targetSize.Width / 2, targetX - targetSize.Width / 2, easing);
    var offsetAnimation2 = new Animation(v => element.TranslationY = v, originY - targetSize.Height / 2, targetY - targetSize.Height / 2, easing);

    offsetAnimation.Add(0.2, 0.8, offsetAnimation1);
    offsetAnimation.Add(0.2, 0.8, offsetAnimation2);
    offsetAnimation.Add(0, 1, element.BoxAnimation);

    offsetAnimation.Finished = () =>
    {

        element.TranslationX = originX;
        element.TranslationY = originY;
        element.Rotation = 0;
    };

    return offsetAnimation;
}

开始气泡动画

public void StartAnimation()
{

    Content.AbortAnimation("ReshapeAnimations");
    var offsetAnimationGroup = new Animation();

    foreach (var item in this.PitContentLayout.Children)
    {
        if (item is Bubble)
        {
            var isOntop = this.PitContentLayout.Children.IndexOf(item) > this.PitContentLayout.Children.Count / 2;
            var currentAnimation = InitAnimation(item as Bubble, targetSize, isOntop);
            offsetAnimationGroup.Add(0, 1, currentAnimation);


        }
    }
    offsetAnimationGroup.Commit(this, "ReshapeAnimations", 16, 400);

}

创建手势

可喜可贺，在新发布的.NET 8 中， .NET MAUI 引入了指针手势识别器(PointerGestureRecognizer)，使用方式如下，终于不用自己实现手势监听控件了。

Xaml:

<Image Source="dotnet_bot.png">
    <Image.GestureRecognizers>
        <PointerGestureRecognizer PointerEntered="OnPointerEntered"
                                  PointerExited="OnPointerExited"
                                  PointerMoved="OnPointerMoved" />
  </Image.GestureRecognizers>
</Image>

C#:

void OnPointerEntered(object sender, PointerEventArgs e)
{
    // Handle the pointer entered event
}

void OnPointerExited(object sender, PointerEventArgs e)
{
    // Handle the pointer exited event
}

void OnPointerMoved(object sender, PointerEventArgs e)
{
    // Handle the pointer moved event
}

具体请阅读官方文档：
.NET 8 中 .NET MAUI 的新增功能以及
识别指针手势

在本项目中，需要监听长按动作，当“三连按钮”长按2秒后，转为三连模式，此时需要监听手指释放情况，当时长不足时取消三连。

由于在之前的文章中实现过监听手势，这里仅简单介绍定义，其余内容不再重复，如需了解请阅读： [MAUI程序设计] 用Handler实现自定义跨平台控件

定义可以监听的手势类别，分别是按下、移动、抬起、取消、进入、退出

 public enum TouchActionType
    {
        Entered,
        Pressed,
        Moved,
        Released,
        Exited,
        Cancelled
    }

添加手势监听器TouchRecognizer，它将提供一个事件OnTouchActionInvoked，用触发手势动作。

public partial class TouchRecognizer: IDisposable
{
    public event EventHandler<TouchActionEventArgs> OnTouchActionInvoked;
    public partial void Dispose();
}

EventArg类TouchActionEventArgs，用于传递手势动作的参数

创建交互与动效

在页面创建完三个按钮后，在CodeBehind中编写交互逻辑

添加更新圆环进度的方法UpdateProgressWithAnimate，此方法根据圆环进度的百分比，计算圆环进度的动画时间，并开始动画

private void UpdateProgressWithAnimate(CircleProgressBar progressElement, double progressTarget = 100, double totalLenght = 5*1000, Action<double, bool> finished = null)
{
    Content.AbortAnimation("ReshapeAnimations");
    var scaleAnimation = new Animation();

    double progressOrigin = progressElement.Progress;

    var animateAction = (double r) =>
    {
        progressElement.Progress = r;
    };

    var scaleUpAnimation0 = new Animation(animateAction, progressOrigin, progressTarget);

    scaleAnimation.Add(0, 1, scaleUpAnimation0);
    var calcLenght = (double)(Math.Abs((progressOrigin - progressTarget) / 100)) * totalLenght;

    scaleAnimation.Commit(progressElement, "ReshapeAnimations", 16, (uint)calcLenght, finished: finished);

}

创建“三连成功”的动画方法StartCelebrationAnimate，在这里通过改变按钮的Scale和Fill属性，实现三连成功时“点亮”图标的动画效果。

private void StartCelebrationAnimate(Path progressElement, Action<double, bool> finished = null)
{
    var toColor = (Color)this.Resources["BrandColor"];
    var fromColor = (Color)this.Resources["DisabledColor"];

    var scaleAnimation = new Animation();

    var scaleUpAnimation0 = new Animation(v => progressElement.Scale=v, 0, 1.5);
    var scaleUpAnimation1 = new Animation(v => progressElement.Fill=GetColor(v, fromColor, toColor), 0, 1);
    var scaleUpAnimation2 = new Animation(v => progressElement.Scale=v, 1.5, 1);

    scaleAnimation.Add(0, 0.5, scaleUpAnimation0);
    scaleAnimation.Add(0, 1, scaleUpAnimation1);
    scaleAnimation.Add(0.5, 1, scaleUpAnimation2);

    scaleAnimation.Commit(progressElement, "CelebrationAnimate", 16, 400, finished: finished);

}

按钮触发TouchContentView_OnTouchActionInvoked事件：

_dispatcherTimer作用是延时1秒，如果按钮被点击，则开始执行后续操作。当按钮被点击时此Timer会开。

一秒后，开始进入“三连模式”，此时更新圆环进度，当进度完成后开始气泡动画和“三连成功”的动画。

若中途按钮被释放，则取消此Timer，并重置圆环进度。

若按钮未进入“三连模式”，则直接播放按钮的点击动画。

private void TouchContentView_OnTouchActionInvoked(object sender, TouchActionEventArgs e)
{
    var layout = ((Microsoft.Maui.Controls.Layout)(sender as TouchContentView).Content).Children;
    var bubbles = layout[0] as Bubbles;
    var circleProgressBar = layout[1] as CircleProgressBar;


    switch (e.Type)
    {
        case TouchActionType.Entered:
            break;
        case TouchActionType.Pressed:
            _dispatcherTimer =Dispatcher.CreateTimer();
            _dispatcherTimer.Interval=new TimeSpan(0, 0, 1);

            _dispatcherTimer.Tick+=   async (o, e) =>
            {
                _isInProgress=true;
                this.UpdateProgressWithAnimate(ProgressBar1, 100, 2*1000, (d, b) =>
                {
                    if (circleProgressBar.Progress==100)
                    {
                        this.bubbles1.StartAnimation();
                        StartCelebrationAnimate(this.Icon1);
                    }
                });
                this.UpdateProgressWithAnimate(ProgressBar2, 100, 2*1000, (d, b) =>
                {
                    if (circleProgressBar.Progress==100)
                    {
                        this.bubbles2.StartAnimation();
                        StartCelebrationAnimate(this.Icon2);
                    }
                });
                this.UpdateProgressWithAnimate(ProgressBar3, 100, 2*1000, (d, b) =>
                {
                    if (circleProgressBar.Progress==100)
                    {
                        this.bubbles3.StartAnimation();
                        StartCelebrationAnimate(this.Icon3);
                    }
                });

            };

            _dispatcherTimer.Start();


            break;
        case TouchActionType.Moved:
            break;
        case TouchActionType.Released:

            if (!_isInProgress)
            {
                var brandColor = (Color)this.Resources["BrandColor"];
                var disabledColor = (Color)this.Resources["DisabledColor"];

                if (circleProgressBar.Progress==100)
                {
                    this.UpdateProgressWithAnimate(ProgressBar1, 0, 1000);
                    this.UpdateProgressWithAnimate(ProgressBar2, 0, 1000);
                    this.UpdateProgressWithAnimate(ProgressBar3, 0, 1000);
                    (ProgressBar1.LabelContent as Path).Fill=disabledColor;
                    (ProgressBar2.LabelContent as Path).Fill=disabledColor;
                    (ProgressBar3.LabelContent as Path).Fill=disabledColor;


                }
                else
                {
                    if (((circleProgressBar.LabelContent as Path).Fill  as SolidColorBrush).Color==disabledColor)
                    {
                        StartCelebrationAnimate(circleProgressBar.LabelContent as Path);

                    }
                    else
                    {
                        (circleProgressBar.LabelContent as Path).Fill=disabledColor;
                    }
                }


            }
            if (_dispatcherTimer!=null)
            {
                if (_dispatcherTimer.IsRunning)
                {
                    _dispatcherTimer.Stop();
                    _isInProgress=false;

                }
                _dispatcherTimer=null;

                if (circleProgressBar.Progress==100)
                {
                    return;
                }

                this.UpdateProgressWithAnimate(ProgressBar1, 0, 1000);
                this.UpdateProgressWithAnimate(ProgressBar2, 0, 1000);
                this.UpdateProgressWithAnimate(ProgressBar3, 0, 1000);
            }



            break;
        case TouchActionType.Exited:
            break;
        case TouchActionType.Cancelled:
            break;
        default:
            break;
    }
}

进入三联模式动画效果如下：

未进入三联模式动画效果如下：

最终效果如下：

项目地址

Github:maui-samples