iOS 上的动画 stroke-dashoffset

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【中文标题】iOS 上的动画 stroke-dashoffset【英文标题】：Animated stroke-dashoffset on iOS 【发布时间】：2020-01-17 18:23:38 【问题描述】：

所以，我通过增加 stroke-dashoffset 值来动画化这个 SVG 标志

svg 
  position: absolute; top: 50%; left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 150px;


.cls-1,
.cls-2 
  fill:none;
  stroke:#a9a9a9;
  stroke-linecap:round;
  stroke-linejoin:round;
  stroke-width:10px;


.cls-1 
  stroke-dasharray: 496;
  stroke-dashoffset: -496;
  animation: firstLine 2s ease-out 0s infinite normal;


.cls-2 
  stroke-dasharray: 458;
  stroke-dashoffset: -458;
  animation: secondLine 2s ease-out 0s infinite normal;


@keyframes firstLine 
  0%  stroke-dashoffset: -496; 
  40%  stroke-dashoffset: 0; 
  60%  stroke-dashoffset: 0; 
  85%  stroke-dashoffset: 496; 
  100%  stroke-dashoffset: 496; 


@keyframes secondLine 
  0%  stroke-dashoffset: -458; 
  45%  stroke-dashoffset: 0; 
  60%  stroke-dashoffset: 0; 
  90%  stroke-dashoffset: 458; 
  100%  stroke-dashoffset: 458; 

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200.17 135"><path class="cls-1" d="M132.67,28.44a39.06,39.06,0,0,1,0,78.12H113.22V59.11A54.11,54.11,0,0,0,5,59.11v57.35a13.54,13.54,0,0,0,27.08,0v-9.9h27"/><path class="cls-2" d="M113.63,5h19a62.5,62.5,0,0,1,0,125H102.44a16.29,16.29,0,0,1-16.3-16.29V59.11a27,27,0,0,0-54.06,0V79.89h27"/></svg>

在桌面浏览器上打开时，一切正常。安卓也一样。但是在 ios 上，动画就大错特错了。是否有一些我不知道的特定于 iOS 的错误 stroke-dashoffset？

【问题讨论】：

Safari 不支持将负数作为 stroke-dashoffset 值。这是一个长期存在的错误，其他 UA 对负数没有问题。 @RobertLongson 哦，我期待一个错误，但不是那样的。谢谢:) 【参考方案1】：

长期以来，我一直在寻找一种解决方案，如何用正值替换负的 stroke-dashoffset 值，以规避 safari 施加的限制。

给出了动画一行的解释。对于第二行，计算类似。

行总长度为496 px；因此， stroke-dashoffset = "496"的值完全隐藏了该行。 用双精度值stroke-dashoffset ="992"画线 使用三重值stroke-dashoffset =" 1488 "，该行被擦除 再次

CSS 解决方案

svg 
  position: absolute; top: 50%; left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 150px;


.cls-1,
.cls-2 
  fill:none;
  stroke:#a9a9a9;
  stroke-linecap:round;
  stroke-linejoin:round;
  stroke-width:10px;

.cls-1 
  stroke-dasharray: 496;
  stroke-dashoffset: 0;
  animation: firstLine 2s ease-out 0s infinite normal;


.cls-2 
  stroke-dasharray: 458;
  stroke-dashoffset: 0;
  animation: secondLine 2s ease-out 0s infinite normal;


@keyframes firstLine 
  0%  stroke-dashoffset: 496; 
  40%  stroke-dashoffset: 992; 
  60%  stroke-dashoffset: 992; 
  85%  stroke-dashoffset: 1488; 
  100%  stroke-dashoffset: 1488; 


@keyframes secondLine 
  0%  stroke-dashoffset: 458; 
  45%  stroke-dashoffset: 916; 
  60%  stroke-dashoffset: 916; 
  90%  stroke-dashoffset: 1374; 
  100%  stroke-dashoffset: 1374; 
 
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200.17 135">
<path class="cls-1 " d="M132.67,28.44a39.06,39.06,0,0,1,0,78.12H113.22V59.11A54.11,54.11,0,0,0,5,59.11v57.35a13.54,13.54,0,0,0,27.08,0v-9.9h27" >
</path>
  <path class="cls-2" d="M113.63,5h19a62.5,62.5,0,0,1,0,125H102.44a16.29,16.29,0,0,1-16.3-16.29V59.11a27,27,0,0,0-54.06,0V79.89h27" > 
</path>
 
</svg>

标志周围有阴影的选项

添加阴影

<defs>
        <filter id="shadow" x="-20%" y="-20%"  >
            <feDropShadow dx="4" dy="8" stdDeviation="4"/>
        </filter>
    </defs> 


body 
background: rgb(144,210,152);
background: linear-gradient(286deg, rgba(144,210,152,1) 29%, rgba(236,234,154,1) 69%);

svg 
  position: absolute; top: 50%; left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 150px;


.cls-1,
.cls-2 
  fill:none;
  stroke:#a9a9a9;
  stroke-linecap:round;
  stroke-linejoin:round;
  stroke-width:10px;
  filter:url(#shadow);

.cls-1 
  stroke-dasharray: 496;
  stroke-dashoffset: 0;
  animation: firstLine 4s ease-out 0s infinite normal;


.cls-2 
  stroke-dasharray: 458;
  stroke-dashoffset: 0;
  animation: secondLine 4s ease-out 0s infinite normal;


@keyframes firstLine 
  0%  stroke-dashoffset: 496; 
  40%  stroke-dashoffset: 992; 
  60%  stroke-dashoffset: 992; 
  85%  stroke-dashoffset: 1488; 
  100%  stroke-dashoffset: 1488; 


@keyframes secondLine 
  0%  stroke-dashoffset: 458; 
  45%  stroke-dashoffset: 916; 
  60%  stroke-dashoffset: 916; 
  90%  stroke-dashoffset: 1374; 
  100%  stroke-dashoffset: 1374; 
 
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 220.17 150">
<defs>
        <filter id="shadow" x="-20%" y="-20%"  >
            <feDropShadow dx="4" dy="8" stdDeviation="4"/>
        </filter>
    </defs> 
 	
<path class="cls-1 " d="M132.67,28.44a39.06,39.06,0,0,1,0,78.12H113.22V59.11A54.11,54.11,0,0,0,5,59.11v57.35a13.54,13.54,0,0,0,27.08,0v-9.9h27" >
</path>
  <path class="cls-2" d="M113.63,5h19a62.5,62.5,0,0,1,0,125H102.44a16.29,16.29,0,0,1-16.3-16.29V59.11a27,27,0,0,0-54.06,0V79.89h27" > 
</path> 

</svg>

SVG 解决方案

svg 
  position: absolute; top: 50%; left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 150px;


.cls-1,
.cls-2 
  fill:none;
  stroke:#a9a9a9;
  stroke-linecap:round;
  stroke-linejoin:round;
  stroke-width:10px;

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200.17 135">
<path class="cls-1 " d="M132.67,28.44a39.06,39.06,0,0,1,0,78.12H113.22V59.11A54.11,54.11,0,0,0,5,59.11v57.35a13.54,13.54,0,0,0,27.08,0v-9.9h27" stroke-dasharray="496,496" stroke-dashoffset="496">
  <animate id="an_offset"
    attributeName="stroke-dashoffset"
	begin="0s"
	dur="3s"
	values="496;992;992;1488"
	fill="freeze"
	repeatCount="indefinite"  />
</path>
  <path class="cls-2" d="M113.63,5h19a62.5,62.5,0,0,1,0,125H102.44a16.29,16.29,0,0,1-16.3-16.29V59.11a27,27,0,0,0-54.06,0V79.89h27" stroke-dasharray="458,458" stroke-dashoffset="458"> 
    <animate id="an_offset2"
	 attributeName="stroke-dashoffset"
	 begin="0s"
	 dur="3s"
	 values="458;916;916;1374"
	 fill="freeze"
	 repeatCount="indefinite" />
</path>
 
</svg>

其他示例 从每条线的中点开始绘制

要实现动画，改变stroke-dasharray属性的参数

总行长为496px，一半是`248px

由于参数值按顺序表示：0 - line,248 - space0 - line,248 - space. 因此，写stroke-dasharray = "0,248 0,248" 将完全隐藏这一行 使用stroke-dasharray = "0,0 496,0"，该行将完全可见。 

svg 
  position: absolute; top: 50%; left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 150px;


.cls-1,
.cls-2 
  fill:none;
  stroke:#a9a9a9;
  stroke-linejoin:round;
  stroke-width:10px;

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200.17 135">
<path class="cls-1 " d="M132.67,28.44a39.06,39.06,0,0,1,0,78.12H113.22V59.11A54.11,54.11,0,0,0,5,59.11v57.35a13.54,13.54,0,0,0,27.08,0v-9.9h27" stroke-dasharray="496,496" stroke-dashoffset="496">
  <animate id="an_array"
    attributeName="stroke-dasharray"
	begin="0s"
	dur="4s"
	values="0,248 0,248;0,0 496,0;0,0 496,0;0,248 0,248"
	fill="freeze"
	repeatCount="indefinite"  />
</path>
  <path class="cls-2" d="M113.63,5h19a62.5,62.5,0,0,1,0,125H102.44a16.29,16.29,0,0,1-16.3-16.29V59.11a27,27,0,0,0-54.06,0V79.89h27" stroke-dasharray="458,458" stroke-dashoffset="458"> 
    <animate id="an_array2"
	  attributeName="stroke-dasharray"
	  begin="0s"
	  dur="4s"
	  values="0,229 0,229;0,0 458,0;0,0 458,0;0,229 0,229"
	  fill="freeze"
	  repeatCount="indefinite" />
</path>

【讨论】：

嗨，对不起，由于我已经用我的回答结束了这个问题，我没有注意通知。我的错，解决这个问题，谢谢:) @Axiol 感谢您提出有趣的问题。解决它很有趣。【参考方案2】：

正如@RobertLongson 所述，这是一个 Safari 错误，不支持 stroke-dashiffset 的负值

【讨论】：

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