【前端小案例】浪漫动态爱心

浅浅的花香味﹌ 2024-04-01 16:09 81阅读 0赞

#### 爱心 ####

*   *   *  1. 案例简介
         *  2. 爱心实现
         *   *  2.1 盒子模型
             *  2.2 CSS样式
             *  2.3 JS实现动效
         *  3. 完整源码

#### 1. 案例简介 ####

最近网剧《点燃我，温暖你》热映，相信广大男同胞的女朋友都在吵着要李洵的❤，没有女朋友的兄弟也要注意，这机会它不就来了吗，博主在刷短视频时也看了部分剪辑，当时震惊我的是那句台词“这次老师布置的可是求三个数里的最大值，你不会是怕自己做不出来所以不敢交作业吧。”这句多少是有些搞笑了，后来也有刷到更新剧集的，就是C语言考试时，考试题目是打印爱心❤，男主写了个动态爱心❤，给女主看懵了，当时就有不祥的预感，果然下午就有人找我要我给她弄一个，C语言咱真做不到，前端的可以试试，这就来上！完整源码在最后，复制就可用(点击目录直接跳转）！  
效果如图  
![在这里插入图片描述][218b14244e144da4965a01cbf89d6b6f.png]

#### 2. 爱心实现 ####

这个案例其实只是简单的一个盒子模型，关键是使用js让这个爱心实现动效，包括爱心边界要由许多跳动的小心心组成，以及在不断缩小实现跳动效果。

##### 2.1 盒子模型 #####

首先自然是一个盒子模型打底，在其中实现爱心的效果

##### 2.2 CSS样式 #####

CSS也比较简单，只是简单的边界修订，包括背景颜色（黑色），大小，宽高等等有的没的。

![在这里插入图片描述][6154e97c0d404d26b362ffbb25eb427e.png]

html, body {
      height: 100%;
      padding: 0;
      margin: 0;
      background: #000;
    }
    canvas {
      position: absolute;
      width: 100%;
      height: 100%;
    }

##### 2.3 JS实现动效 #####

这个就比较复杂啦，包括动效的方向，动效范围，动效行为类型以及定时等等，利用回调函数实现宽高自适应，因为爱心是要跳动的，大小会改变，这就要求宽高要一起变化，否则会出现特变尴尬的效果，你的爱心可能会比较抽象，，，避免此问题也很简单，直接让宽高产生联系即可，他们一起改变！

**范围指定**

**大致爱心形状**  
简单画出大致形状，后面去进一步改进边框，让边框也实现动效，这里的关键就是爱心的凹下去的部分，可以把爱心看成是一个圆形，只是发生了一些简单的改变，凹下去一块，突出去一块。  
![在这里插入图片描述][eecf5e5df95f428891c13db97db18cfc.png]

**边界小爱心**

这个实现最为麻烦，要设置小爱心的不断更替，以及形状渐变等等，设置定时器，保证每个小爱心的出现时间有规律，这样看起来才会整齐，否则总会有点尴尬的小坚强一直不消散，还有就是要保证小爱心扩散的方向，要结合它所处的位置，如果都是直接朝着一个方向扩散会感觉很奇怪，不符合人类的直观审美，在那个位置的小爱心，就要从那个位置出发去消散，避免诙谐的感受。同时要随着大爱心的大小改变调整自己的出现位置，但是也不能全部出现在内侧，还要有一两个漏网之鱼在外面，有种凌乱美，看起来观感更佳。  
![在这里插入图片描述][5e7082f049a045e6b05dff91d35abafe.png]

**将上述部件组装**  
这里就还是比较简单的啦，只需要把之前写好的部分按照预想该怎么调用就怎么调用，设置好定时器以及出现位置，因为是心形，还要结合一些数学函数，比如cos等，实现变角处理，让整个心形更加圆滑平稳，还要设置页面的显示方式，渐变出现，以及出现的速度等等。

**边界处理以及其他设定**  
这里要设定好小爱心们散落的位置以及出现地址，保证跟随着大爱心一起动，同时圈定大爱心的位置。  
![在这里插入图片描述][d1f2d5cc8fe14e93895f5c8e543c49aa.png]

// render that thing!
      function render() {
        
        // next animation frame
        requestAnimationFrame(render);
        
        // update time
        var newTime   = new Date().getTime() / 1000,
            deltaTime = newTime - (time || newTime);
        time = newTime;
        
        // clear canvas
        context.clearRect(0, 0, canvas.width, canvas.height);
        
        // create new particles
        var amount = particleRate * deltaTime;
        for (var i = 0; i < amount; i++) {
        
          var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());
          var dir = pos.clone().length(settings.particles.velocity);
          particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);
        }
        
        // update and draw particles
        particles.update(deltaTime);
        particles.draw(context, image);
      }
      
      // handle (re-)sizing of the canvas
      function onResize() {
        
        canvas.width  = canvas.clientWidth;
        canvas.height = canvas.clientHeight;
      }
      window.onresize = onResize;
      
      // delay rendering bootstrap
      setTimeout(function() {
        
        onResize();
        render();
      }, 10);
    })(document.getElementById('pinkboard'));

#### 3. 完整源码 ####

相信也有同志可能不是程序员，但被迫找到这里，这个源码只需要复制到一个空的`txt`文件里，然后把`txt`的后缀改成`html`打开就可以啦。

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
    <HTML>
     <HEAD>
      <TITLE> New Document </TITLE>
      <META NAME="Generator" CONTENT="EditPlus">
      <META NAME="Author" CONTENT="">
      <META NAME="Keywords" CONTENT="">
      <META NAME="Description" CONTENT="">
      <style>
      html, body {
        
      height: 100%;
      padding: 0;
      margin: 0;
      background: #000;
    }
    canvas {
        
      position: absolute;
      width: 100%;
      height: 100%;
    }
      </style>
     </HEAD>
    
     <BODY>
      <canvas id="pinkboard"></canvas>
      <script>
      /*
     * Settings
     */
    var settings = {
        
      particles: {
        
        length:   500, // maximum amount of particles
        duration:   2, // particle duration in sec
        velocity: 100, // particle velocity in pixels/sec
        effect: -0.75, // play with this for a nice effect
        size:      30, // particle size in pixels
      },
    };
    
    /*
     * RequestAnimationFrame polyfill by Erik Möller
     */
    (function(){
        var b=0;var c=["ms","moz","webkit","o"];for(var a=0;a<c.length&&!window.requestAnimationFrame;++a){
        window.requestAnimationFrame=window[c[a]+"RequestAnimationFrame"];window.cancelAnimationFrame=window[c[a]+"CancelAnimationFrame"]||window[c[a]+"CancelRequestAnimationFrame"]}if(!window.requestAnimationFrame){
        window.requestAnimationFrame=function(h,e){
        var d=new Date().getTime();var f=Math.max(0,16-(d-b));var g=window.setTimeout(function(){
        h(d+f)},f);b=d+f;return g}}if(!window.cancelAnimationFrame){
        window.cancelAnimationFrame=function(d){
        clearTimeout(d)}}}());
    
    /*
     * Point class
     */
    var Point = (function() {
        
      function Point(x, y) {
        
        this.x = (typeof x !== 'undefined') ? x : 0;
        this.y = (typeof y !== 'undefined') ? y : 0;
      }
      Point.prototype.clone = function() {
        
        return new Point(this.x, this.y);
      };
      Point.prototype.length = function(length) {
        
        if (typeof length == 'undefined')
          return Math.sqrt(this.x * this.x + this.y * this.y);
        this.normalize();
        this.x *= length;
        this.y *= length;
        return this;
      };
      Point.prototype.normalize = function() {
        
        var length = this.length();
        this.x /= length;
        this.y /= length;
        return this;
      };
      return Point;
    })();
    
    /*
     * Particle class
     */
    var Particle = (function() {
        
      function Particle() {
        
        this.position = new Point();
        this.velocity = new Point();
        this.acceleration = new Point();
        this.age = 0;
      }
      Particle.prototype.initialize = function(x, y, dx, dy) {
        
        this.position.x = x;
        this.position.y = y;
        this.velocity.x = dx;
        this.velocity.y = dy;
        this.acceleration.x = dx * settings.particles.effect;
        this.acceleration.y = dy * settings.particles.effect;
        this.age = 0;
      };
      Particle.prototype.update = function(deltaTime) {
        
        this.position.x += this.velocity.x * deltaTime;
        this.position.y += this.velocity.y * deltaTime;
        this.velocity.x += this.acceleration.x * deltaTime;
        this.velocity.y += this.acceleration.y * deltaTime;
        this.age += deltaTime;
      };
      Particle.prototype.draw = function(context, image) {
        
        function ease(t) {
        
          return (--t) * t * t + 1;
        }
        var size = image.width * ease(this.age / settings.particles.duration);
        context.globalAlpha = 1 - this.age / settings.particles.duration;
        context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);
      };
      return Particle;
    })();
    
    /*
     * ParticlePool class
     */
    var ParticlePool = (function() {
        
      var particles,
          firstActive = 0,
          firstFree   = 0,
          duration    = settings.particles.duration;
      
      function ParticlePool(length) {
        
        // create and populate particle pool
        particles = new Array(length);
        for (var i = 0; i < particles.length; i++)
          particles[i] = new Particle();
      }
      ParticlePool.prototype.add = function(x, y, dx, dy) {
        
        particles[firstFree].initialize(x, y, dx, dy);
        
        // handle circular queue
        firstFree++;
        if (firstFree   == particles.length) firstFree   = 0;
        if (firstActive == firstFree       ) firstActive++;
        if (firstActive == particles.length) firstActive = 0;
      };
      ParticlePool.prototype.update = function(deltaTime) {
        
        var i;
        
        // update active particles
        if (firstActive < firstFree) {
        
          for (i = firstActive; i < firstFree; i++)
            particles[i].update(deltaTime);
        }
        if (firstFree < firstActive) {
        
          for (i = firstActive; i < particles.length; i++)
            particles[i].update(deltaTime);
          for (i = 0; i < firstFree; i++)
            particles[i].update(deltaTime);
        }
        
        // remove inactive particles
        while (particles[firstActive].age >= duration && firstActive != firstFree) {
        
          firstActive++;
          if (firstActive == particles.length) firstActive = 0;
        }
        
        
      };
      ParticlePool.prototype.draw = function(context, image) {
        
        // draw active particles
        if (firstActive < firstFree) {
        
          for (i = firstActive; i < firstFree; i++)
            particles[i].draw(context, image);
        }
        if (firstFree < firstActive) {
        
          for (i = firstActive; i < particles.length; i++)
            particles[i].draw(context, image);
          for (i = 0; i < firstFree; i++)
            particles[i].draw(context, image);
        }
      };
      return ParticlePool;
    })();
    
    /*
     * Putting it all together
     */
    (function(canvas) {
        
      var context = canvas.getContext('2d'),
          particles = new ParticlePool(settings.particles.length),
          particleRate = settings.particles.length / settings.particles.duration, // particles/sec
          time;
      
      // get point on heart with -PI <= t <= PI
      function pointOnHeart(t) {
        
        return new Point(
          160 * Math.pow(Math.sin(t), 3),
          130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25
        );
      }
      
      // creating the particle image using a dummy canvas
      var image = (function() {
        
        var canvas  = document.createElement('canvas'),
            context = canvas.getContext('2d');
        canvas.width  = settings.particles.size;
        canvas.height = settings.particles.size;
        // helper function to create the path
        function to(t) {
        
          var point = pointOnHeart(t);
          point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;
          point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;
          return point;
        }
        // create the path
        context.beginPath();
        var t = -Math.PI;
        var point = to(t);
        context.moveTo(point.x, point.y);
        while (t < Math.PI) {
        
          t += 0.01; // baby steps!
          point = to(t);
          context.lineTo(point.x, point.y);
        }
        context.closePath();
        // create the fill
        context.fillStyle = '#ea80b0';
        context.fill();
        // create the image
        var image = new Image();
        image.src = canvas.toDataURL();
        return image;
      })();
      
      // render that thing!
      function render() {
        
        // next animation frame
        requestAnimationFrame(render);
        
        // update time
        var newTime   = new Date().getTime() / 1000,
            deltaTime = newTime - (time || newTime);
        time = newTime;
        
        // clear canvas
        context.clearRect(0, 0, canvas.width, canvas.height);
        
        // create new particles
        var amount = particleRate * deltaTime;
        for (var i = 0; i < amount; i++) {
        
          var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());
          var dir = pos.clone().length(settings.particles.velocity);
          particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);
        }
        
        // update and draw particles
        particles.update(deltaTime);
        particles.draw(context, image);
      }
      
      // handle (re-)sizing of the canvas
      function onResize() {
        
        canvas.width  = canvas.clientWidth;
        canvas.height = canvas.clientHeight;
      }
      window.onresize = onResize;
      
      // delay rendering bootstrap
      setTimeout(function() {
        
        onResize();
        render();
      }, 10);
    })(document.getElementById('pinkboard'));
      </script>
     </BODY>
    </HTML>

[218b14244e144da4965a01cbf89d6b6f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/63933be9e32e4cf9ba8bc9402067edbc.png
[6154e97c0d404d26b362ffbb25eb427e.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/e0440759ac3349c4ab163e8897c51d6f.png
[eecf5e5df95f428891c13db97db18cfc.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/ff6ba26839174c36a5c3ca3c7531245a.png
[5e7082f049a045e6b05dff91d35abafe.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/5e66e22de48d4b0b94e2292e77a995be.png
[d1f2d5cc8fe14e93895f5c8e543c49aa.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/01/b2396453672d4a82836016c7fd6678a7.png