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javascript - 将时间转换为关键帧动画百分比

问题描述

我正在制作动画，并试图了解关键帧如何融入其中。

我想显示一个元素 3 秒，淡出 1 秒，等待 3 秒，淡入 1 秒，可见 3 秒。所以总共 8 秒 (3 + 1 + 3 + 1)。

我不知道如何将其写为关键帧。我的动画中有备用设置，因为它使用百分比。这是我到目前为止所拥有的：

time = 0;
window.addEventListener("load", function() {
   setInterval(function() {
    var label = document.getElementById("label");
    
    if (time==0) {
      label.innerHTML = ++time;
    }
    else {
      label.innerHTML = ++time;
    }
    if (time>=8) time = 0;
    
   }, 1000);
})
* {
		margin: 0;
		padding: 0;
    font-family:sans-serif;
	}
	#Icons_A0 {
		position: absolute;
		box-sizing: border-box;
		transform: translateX(-50%) translateY(-50%);
		left: 50%;
		top: 50%;
		border: 1px solid #A1A1A1;
		background: #E5E5E5;
		width: 234px;
		height: 238px;
		background-color: rgba(255,255,255,1);
		overflow: hidden;
		opacity: 1;
	}
	#Rectangle_175 {
		opacity: 1;
		fill: rgba(75,134,193,1);
		stroke: rgb(84, 75, 193);
		stroke-width: 4px;
		stroke-linejoin: miter;
		stroke-linecap: butt;
		stroke-miterlimit: 4;
		shape-rendering: auto;
	}
	.Rectangle_175 {
		position: absolute;
		overflow: visible;
		width: 134.35028076171875px;
		height: 134.3502655029297px;
		left: 49.825px;
		top: 76.825px;
		transform: rotate(45deg);
		transform-origin: left;
	}
	#Ellipse_49 {
		opacity: 1;
		fill: rgba(180,180,180,1);
		stroke: rgb(112, 112, 112);
		stroke-width: 1px;
		stroke-linejoin: miter;
		stroke-linecap: butt;
		stroke-miterlimit: 4;
		shape-rendering: auto;
	}
	.Ellipse_49 {
		position: absolute;
		overflow: visible;
		width: 56px;
		height: 56px;
		left: 72px;
		top: 51px;
    animation: fadein 8s linear 0s infinite alternate;
	}
	@keyframes fadein {
	
		0% {
			opacity: 1;
		}
		20% {
			opacity: 1;
		}
		30% {
			opacity: 0;
		}
		60% {
			opacity: 0;
		}
		70% {
			opacity: 1;
		}
		100% {
			opacity: 1;
		}
	
	}
<div id="Icons_A0">
	<svg data-name="Rectangle 175" data-type="Rectangle" class="Rectangle_175">
		<rect id="Rectangle_175" rx="0" ry="0" x="0" y="0" width="120" height="70">
		</rect>
	</svg>
	<svg class="Ellipse_49">
		<ellipse id="Ellipse_49" rx="28" ry="28" cx="28" cy="28">
		</ellipse>
	</svg>
  <span id="label"></span>
</div>

标签： javascripthtmlcsscss-animations

解决方案

如果我正确理解了您的问题，则可以通过以下关键帧集来实现：

@keyframes fadein {
  0% {
    opacity: 1;

  }
  37.5% {
    /* 3 / 8 */
    opacity: 1; 
  }
  50% {
    /* (3 + 1) / 8 */
    opacity: 0.0; 
  }
  87.5% {
    /* (3 + 1 + 3) / 8 */
    opacity: 0.0; 
  }
  100% {
    opacity: 1; 
  }
}

注释显示了如何根据您的要求计算不同关键帧的百分比。要进行的另一个关键更改是alternate从动画规则中删除行为，以确保动画循环按照需要以一致的方式重复：

/* remove alternate */
animation: fadein 8s linear 0s infinite;

这是您的代码的精简副本，用于隔离动画圈：

function animationListener(event) {
  var type = event.type;
  var label = type;
  
  if (type=="animationiteration") {
    if (app.interval!=null) {
      clearInterval(app.interval);
    }
    app.time = 0;
    app.startTime = new Date().getTime();
    app.interval = setInterval(intervalFunction, 1000);
    intervalFunction();
    label = "iteration";
  }
  else if (type=="animationstart") {
    label = "start";
  }
  else if (type=="animationend") {
    label = "end";
  }
  
  app.stateLabel.innerHTML = label;
}

function intervalFunction() {
  var time = new Date().getTime();
  app.timeLabel.innerHTML = Math.round((time - app.startTime)/1000);
  app.keyframeLabel.innerHTML = window.getComputedStyle(app.ellipse).content;
}

function loadHandler() {
  app.ellipse = document.getElementById("Ellipse_49").parentNode;
  app.stateLabel = document.getElementById("stateLabel");
  app.timeLabel = document.getElementById("timeLabel");
  app.keyframeLabel = document.getElementById("keyframeLabel");
  
  app.ellipse.addEventListener("animationiteration", animationListener);
  app.ellipse.addEventListener("animationend", animationListener);
  app.ellipse.addEventListener("animationstart", animationListener);
}

document.addEventListener("DOMContentLoaded", loadHandler);
var app = {};
* {
  font-family: sans-serif;
  font-size: 11px;
  letter-spacing: .6px;
}

#Ellipse_49 {
  opacity: 1;
  fill: rgba(180, 180, 180, 1);
  stroke: rgb(112, 112, 112);
  stroke-width: 1px;
  stroke-linejoin: miter;
  stroke-linecap: butt;
  stroke-miterlimit: 4;
  shape-rendering: auto;
}

.Ellipse_49 {
  position: absolute;
  overflow: visible;
  width: 56px;
  height: 56px;
  left: 72px;
  top: 51px;
  
  /* remove alternate */
  animation: fadein 8s linear 0s infinite;
}

#container {
   top: 130px;
   left: 10px;
   position: relative;
   display: block;
   align-items: center;
   
}

label {
  width: 80px;
  display: inline-block;
}

@keyframes fadein {
  0% {
    opacity: 1;
    content: "show";
  }
  37.5% {
    /* 3 / 8 */
    opacity: 1;
    content: "fade out";
  }
  50% {
    /* (3 + 1) / 8 */
    opacity: 0.0;
    content: "wait";
  }
  87.5% {
    /* (3 + 1 + 3) / 8 */
    opacity: 0.0;
    content: "fade in";
  }
  100% {
    opacity: 1;
    content: "show";
  }
}
<svg class="Ellipse_49">
		<ellipse id="Ellipse_49" rx="28" ry="28" cx="28" cy="28">
		</ellipse>
</svg>


<div id="container">
  <label>time: </label>
  <span id="timeLabel"></span>
  <br>
  <label>state: </label>
  <span id="stateLabel"></span>
  <br>
  <label>key frame: </label>
  <span id="keyframeLabel"></span>
</div>

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