Html 使用 css3 的 SVG 投影

SVG drop shadow using css3

提问by bsr

Is it possible to set drop shadow for an svg element using css3 , something like

是否可以使用 css3 为 svg 元素设置投影，例如

box-shadow: -5px -5px 5px #888;
-webkit-box-shadow: -5px -5px 5px #888;

I saw some remarks on creating shadow using filter effects. Is there an example of using css alone. Below is a working code where the cusor style is correctly applied, but no shadow effect. Please help me to get the shadow effect with least bit of code.

我看到了一些关于使用滤镜效果创建阴影的评论。有没有单独使用css的例子。下面是一个工作代码，其中正确应用了 cusor 样式，但没有阴影效果。请帮我用最少的代码获得阴影效果。

svg .shadow { 
  cursor:crosshair; 
  -moz-box-shadow: -5px -5px 5px #888;
  -webkit-box-shadow: -5px -5px 5px #888;
  box-shadow: -5px -5px 5px #888; 
} 

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" baseProfile="full"  viewBox="0 0 120 70"> 
    <rect class="shadow" x="10" y="10" width="100" height="50" fill="#c66" />
</svg>

采纳答案by Erik Dahlstr?m

Here's an exampleof applying dropshadow to some svg using the 'filter' property. If you want to control the opacity of the dropshadow have a look at this example. The slopeattribute controls how much opacity to give to the dropshadow.

这是使用“过滤器”属性将投影应用于某些 svg的示例。如果您想控制阴影的不透明度，请查看此示例。该slope属性控制赋予阴影的不透明度。

Relevant bits from the example:

示例中的相关位：

<filter id="dropshadow" height="130%">
  <feGaussianBlur in="SourceAlpha" stdDeviation="3"/> <!-- stdDeviation is how much to blur -->
  <feOffset dx="2" dy="2" result="offsetblur"/> <!-- how much to offset -->
  <feComponentTransfer>
    <feFuncA type="linear" slope="0.5"/> <!-- slope is the opacity of the shadow -->
  </feComponentTransfer>
  <feMerge> 
    <feMergeNode/> <!-- this contains the offset blurred image -->
    <feMergeNode in="SourceGraphic"/> <!-- this contains the element that the filter is applied to -->
  </feMerge>
</filter>
<circle r="10" style="filter:url(#dropshadow)"/>

Box-shadow is defined to work on CSS boxes (read: rectangles), while svg is a bit more expressive than just rectangles. Read the SVG Primerto learn a bit more about what you can do with SVG filters.

Box-shadow 被定义为处理 CSS 框（阅读：矩形），而 svg 比矩形更具表现力。阅读SVG Primer以了解更多关于您可以使用 SVG 过滤器做什么的信息。

回答by hitautodestruct

Use the newCSS filterproperty.

使用新的CSSfilter属性。

Supported by webkit browsers, Firefox 34+ and Edge.

受 webkit 浏览器、Firefox 34+ 和Edge 支持。

You can use this polyfillthat will support FF < 34, IE6+.

您可以使用此填充工具，将支持FF <34，IE6 +。

You would use it like so:

你会像这样使用它：

/* Use -webkit- only if supporting: Chrome < 54, iOS < 9.3, Android < 4.4.4 */

.shadow {
  -webkit-filter: drop-shadow( 3px 3px 2px rgba(0, 0, 0, .7));
  filter: drop-shadow( 3px 3px 2px rgba(0, 0, 0, .7));
  /* Similar syntax to box-shadow */
}

<img src="https://upload.wikimedia.org/wikipedia/commons/c/ce/Star_wars2.svg" alt="" class="shadow" width="200">

<!-- Or -->

<svg class="shadow" ...>
    <rect x="10" y="10" width="200" height="100" fill="#bada55" />
</svg>

This approach differs from the box-shadoweffect in that it accounts for opacity and does not apply the drop shadow effect to the box but rather to the corners of the svg element itself.

这种方法与box-shadow效果的不同之处在于它考虑了不透明度，并且不会将阴影效果应用于框，而是应用于 svg 元素本身的角落。

Please Note: This approach only works when the class is placed on the <svg>element alone. You can NOTuse this on an inline svg element such as <rect>.

请注意：这种方法仅在类<svg>单独放置在元素上时才有效。你可以不是一个内联SVG元素上使用这个功能，比如<rect>。

<!-- This will NOT work! -->
<svg><rect class="shadow" ... /></svg>

Read more about css filters on html5rocks.

在html5rocks上阅读有关 css 过滤器的更多信息。

回答by Jonny Ekholm

You can easily add a drop-shadow effect to an svg-element using the drop-shadow() CSS function and rgba color values. By using rgba color values you can change the opacity of your shadow.

您可以使用 drop-shadow() CSS 函数和 rgba 颜色值轻松地为 svg 元素添加阴影效果。通过使用 rgba 颜色值，您可以更改阴影的不透明度。

img.light-shadow{
  filter: drop-shadow(0px 3px 3px rgba(0, 0, 0, 0.4));
}

img.dark-shadow{
  filter: drop-shadow(0px 3px 3px rgba(0, 0, 0, 1));
}

<img class="light-shadow" src="https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-logo.svg" />
<img class="dark-shadow" src="https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-logo.svg" />

回答by nikk wong

Easiest way I've found is with feDropShadow. I will never go back to using those incredibly esoteric filter tag names that I don't understand.

我发现的最简单的方法是使用feDropShadow. 我永远不会再使用那些我不理解的令人难以置信的深奥过滤器标签名称。

<filter id="shadow" x="0" y="0" width="200%" height="200%">
  <feDropShadow dx="40" dy="40" stdDeviation="35" flood-color="#ff0000" flood-opacity="1" />
</filter>

回答by F. Hauri

Black text with white shadow

带有白色阴影的黑色文本

Another way, I used for white shadow (on text): create a clone for shadow:

另一种方式，我用于白色阴影（在文本上）：为阴影创建一个克隆：

Note: This require xmlns:xlink="http://www.w3.org/1999/xlink"at SVG declaration.

注意：这需要xmlns:xlink="http://www.w3.org/1999/xlink"在 SVG 声明中。

Real text value is located in <defs>section, with position and style, but without a filldefinition.

真正的文本值位于<defs>节中，有位置和样式，但没有fill定义。

The text is cloned two times: first for shadow and second for the text itself.

文本被克隆两次：第一次用于阴影，第二次用于文本本身。

<svg xmlns="http://www.w3.org/2000/svg" width="640" height="70"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
  <filter id="Blur"><feGaussianBlur stdDeviation="0.8" /></filter>
  <text style="font-family:sans,helvetica;font-weight:bold;font-size:12pt"
      id="Text"><tspan x="12" y="19">
        Black text with white shadow
    </tspan></text>
  </defs>
  <rect style="fill:#8AB" width="640" height="70" />
  <use style="fill:white;" filter="url(#Blur)" xlink:href="#Text"
      transform="translate(1.8,.9)"/>
  <use style="fill:black;" xlink:href="#Text"/>
</svg>

More distantshadow with biggest value as blur deviation:

更远处的阴影与最大价值模糊偏差：

<svg xmlns="http://www.w3.org/2000/svg" width="640" height="70"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
  <filter id="Blur"><feGaussianBlur stdDeviation="3" /></filter>
  <text style="font-family:sans,helvetica;font-weight:bold;font-size:12pt"
      id="Text"><tspan x="12" y="19">
        Black text with white shadow
    </tspan></text>
  </defs>
  <rect style="fill:#8AB" width="640" height="70" />
  <use style="fill:white;" filter="url(#Blur)" xlink:href="#Text"
      transform="translate(7,5)"/>
  <use style="fill:black;" xlink:href="#Text"/>
</svg>

You can use this same approach with regular SVG objects.

您可以对常规 SVG 对象使用相同的方法。

With same requirement: No fill definition at <defs>section!

具有相同的要求：在<defs>部分没有填充定义！

<svg xmlns="http://www.w3.org/2000/svg" width="364" height="172"
    xmlns:xlink="http://www.w3.org/1999/xlink">
  <defs>
    <filter id="Blur"><feGaussianBlur stdDeviation="0.8" /></filter>
    <g transform="matrix(.7,0,0,.7,-117.450795,-335.320895)" id="Img">
        <g transform="matrix(12.997776,0,0,-12.997776,389.30313,662.04015)">
            <path d="m 0,0 -1.107,0 c -0.039,0 -0.067,0.044 -0.067,0.086 0,0.015 0.589,1.914 0.589,1.914 0.021,0.071 0.023,0.073 0.031,0.073 l 0.001,0 c 0.009,0 0.01,-0.002 0.031,-0.073 0,0 0.589,-1.899 0.589,-1.914 C 0.067,0.044 0.037,0 0,0 M 1.493,4.345 C 1.482,4.383 1.448,4.411 1.408,4.414 l -4.065,0 C -2.698,4.41 -2.731,4.383 -2.742,4.346 c 0,0 -2.247,-7.418 -2.247,-7.432 0,-0.037 0.029,-0.067 0.067,-0.067 l 2.687,0 c 0.021,0.008 0.037,0.028 0.042,0.051 l 0.313,1 c 0.01,0.025 0.033,0.042 0.061,0.043 l 2.479,0.002 c 0.027,-0.002 0.051,-0.021 0.061,-0.045 l 0.32,-1 c 0.005,-0.023 0.021,-0.044 0.042,-0.052 0,0 2.642,10e-4 2.644,10e-4 0.037,0 0.068,0.028 0.068,0.065 0,0.013 -2.302,7.433 -2.302,7.433" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,508.27177,644.93113)">
            <path d="m 0,0 -1.651,-0.001 c 0,0 -0.044,0.013 -0.044,0.063 l -10e-4,0.833 c 0,0.05 0.044,0.063 0.044,0.063 l 1.514,0 C 0.038,0.958 0.394,0.87 0.394,0.463 0.394,0.056 0,0 0,0 m 7.916,0.645 3.741,0 0,2.453 -4.81,0 C 6.397,3.098 5.764,2.866 5.401,2.597 5.038,2.328 4.513,1.715 4.513,0.87 c 0,-0.845 0.513,-1.502 0.513,-1.502 0.263,-0.326 0.925,-1.005 0.925,-1.005 0.015,-0.016 0.024,-0.037 0.024,-0.061 0,-0.051 -0.041,-0.092 -0.092,-0.092 l -3.705,0 c -0.451,0.002 -0.482,0.181 -0.482,0.207 0,0.046 0.056,0.075 0.056,0.075 0.169,0.081 0.514,0.35 0.514,0.35 0.732,0.57 0.82,1.352 0.82,1.771 0,0.42 -0.063,1.163 -0.814,1.814 C 1.521,3.078 0.57,3.096 0.57,3.096 l -5.287,0 c 0,0 0,-7.52 0,-7.522 0,-0.024 0.022,-0.043 0.046,-0.043 l 2.943,0 0,2.11 c 0,0.037 0.057,0 0.057,0 l 1.533,-1.54 c 0.545,-0.551 1.446,-0.57 1.446,-0.57 l 5.796,0.001 c 0.989,0 1.539,0.538 1.69,0.688 0.15,0.151 0.651,0.714 0.651,1.647 0,0.932 -0.426,1.409 -0.608,1.628 C 8.675,-0.309 8.029,0.375 7.894,0.517 7.878,0.53 7.868,0.55 7.868,0.572 c 0,0.033 0.019,0.064 0.048,0.073" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,306.99861,703.01559)">
            <path d="m 0,0 c 0.02,0 0.034,0.014 0.04,0.036 0,0 2.277,7.479 2.277,7.486 0,0.02 -0.012,0.042 -0.031,0.044 0,0 -2.805,0 -2.807,0 -0.014,0 -0.023,-0.011 -0.026,-0.026 0,-0.001 -0.581,-1.945 -0.581,-1.946 -0.004,-0.016 -0.012,-0.026 -0.026,-0.026 -0.014,0 -0.026,0.014 -0.028,0.026 L -1.79,7.541 c -0.002,0.013 -0.012,0.025 -0.026,0.025 -10e-4,0 -3.1,0.001 -3.1,0.001 -0.009,-0.002 -0.017,-0.01 -0.02,-0.018 0,0 -0.545,-1.954 -0.545,-1.954 -0.003,-0.017 -0.012,-0.027 -0.027,-0.027 -0.013,0 -0.024,0.01 -0.026,0.023 l -0.578,1.952 c -0.001,0.012 -0.011,0.022 -0.023,0.024 l -2.992,0 c -0.024,0 -0.044,-0.02 -0.044,-0.045 0,-0.004 10e-4,-0.012 10e-4,-0.012 0,0 2.31,-7.471 2.311,-7.474 C -6.853,0.014 -6.839,0 -6.819,0 c 0.003,0 2.485,-0.001 2.485,-0.001 0.015,0.002 0.03,0.019 0.034,0.037 10e-4,0 0.865,2.781 0.865,2.781 0.005,0.017 0.012,0.027 0.026,0.027 0.015,0 0.023,-0.012 0.027,-0.026 L -2.539,0.024 C -2.534,0.01 -2.521,0 -2.505,0 -2.503,0 0,0 0,0" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,278.90126,499.03369)">
            <path d="m 0,0 c -0.451,0 -1.083,-0.232 -1.446,-0.501 -0.363,-0.269 -0.888,-0.882 -0.888,-1.727 0,-0.845 0.513,-1.502 0.513,-1.502 0.263,-0.326 0.925,-1.01 0.925,-1.01 0.015,-0.016 0.024,-0.037 0.024,-0.06 0,-0.051 -0.041,-0.093 -0.092,-0.093 -0.008,0 -6.046,0 -6.046,0 l 0,-2.674 7.267,0 c 0.988,0 1.539,0.538 1.69,0.689 0.15,0.15 0.65,0.713 0.65,1.646 0,0.932 -0.425,1.414 -0.607,1.633 -0.162,0.196 -0.808,0.876 -0.943,1.017 -0.016,0.014 -0.026,0.034 -0.026,0.056 0,0.033 0.019,0.063 0.048,0.073 l 3.5,0 0,-5.114 2.691,0 0,5.101 3.267,0 0,2.466 L 0,0 Z" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,583.96822,539.30215)">
            <path d="m 0,0 -1.651,-0.001 c 0,0 -0.044,0.013 -0.044,0.063 l -10e-4,0.833 c 0,0.05 0.044,0.063 0.044,0.063 l 1.514,0 C 0.038,0.958 0.394,0.87 0.394,0.463 0.394,0.056 0,0 0,0 m 2.178,-1.79 c -0.45,0.002 -0.482,0.181 -0.482,0.207 0,0.046 0.056,0.075 0.056,0.075 0.169,0.081 0.514,0.35 0.514,0.35 0.732,0.57 0.82,1.352 0.82,1.771 0,0.42 -0.063,1.163 -0.814,1.814 C 1.521,3.078 0.57,3.098 0.57,3.098 l -5.287,0 c 0,0 0,-7.522 0,-7.524 0,-0.024 0.022,-0.043 0.046,-0.043 0.005,0 2.943,0 2.943,0 l 0,2.109 c 0,0.038 0.057,0 0.057,0 l 1.533,-1.539 c 0.545,-0.551 1.446,-0.57 1.446,-0.57 l 4.525,0 0,2.679 -3.655,0 z" />
        </g>
        <g transform="matrix(12.997776,0,0,-12.997776,466.86346,556.40203)">
            <path d="m 0,0 -1.107,0 c -0.041,0 -0.067,0.044 -0.067,0.086 0,0.016 0.589,1.914 0.589,1.914 0.021,0.071 0.027,0.073 0.031,0.073 l 0.001,0 c 0.004,0 0.01,-0.002 0.031,-0.073 0,0 0.589,-1.898 0.589,-1.914 C 0.067,0.044 0.04,0 0,0 M 1.49,4.347 C 1.479,4.385 1.446,4.412 1.405,4.414 l -4.065,0 C -2.7,4.412 -2.734,4.385 -2.745,4.348 c 0,0 -2.245,-7.42 -2.245,-7.434 0,-0.037 0.03,-0.067 0.067,-0.067 l 2.687,0 c 0.022,0.007 0.038,0.028 0.043,0.051 l 0.313,1.001 c 0.01,0.024 0.033,0.041 0.061,0.042 l 2.478,0 C 0.687,-2.061 0.71,-2.078 0.721,-2.102 l 0.32,-1 c 0.005,-0.023 0.021,-0.044 0.042,-0.052 0,0 2.642,10e-4 2.644,10e-4 0.037,0 0.067,0.028 0.067,0.066 0,0.012 -2.304,7.434 -2.304,7.434" />
        </g>
    </g>
  </defs>
  <rect style="fill:#8AB" width="364" height="172" />
  <use style="fill:white;" filter="url(#Blur)" xlink:href="#Img"
    transform="translate(1.8,.9)"/>
  <use style="fill:black;" xlink:href="#Img"/>
</svg>

回答by jbeard4

I'm not aware of a CSS-only solution.

我不知道只有 CSS 的解决方案。

As you mentioned, filters are the canonical approach to creating drop shadow effects in SVG. The SVG specification includes an example of this.

正如您所提到的，过滤器是在 SVG 中创建阴影效果的规范方法。SVG 规范包括一个这样的例子。

回答by NVRM

Probably an evolution, it appears that inline css filters works nicely on elements, in a certain way.

可能是一种演变，内联 css 过滤器似乎以某种方式很好地处理元素。

Declaring a drop-shadow css filter, in an svg element, in both a class or inline does NOTworks, as specified earlier.

声明一个下拉阴影CSS滤镜，在SVG元素，在这两个类或内联确实不工作，如前面规定。

But, at least in Firefox, with the following wizardry:

但是，至少在 Firefox 中，具有以下魔法：

Appending the filter declaration inline, with javascript, after DOM load.

在 DOM load 之后使用 javascript附加过滤器声明inline。

// Does not works, with regular dynamic css styling:

shadow0.onchange = () => {
  rect1.style.filter = "filter:drop-shadow(0 0 " + shadow0.value + "rem black);"
}

// Okay! Inline styling, appending.

shadow1.onchange = () => {
  rect1.style += " ;filter:drop-shadow(0 0 " + shadow1.value + "rem black);"
  rect2.style += " ;filter:drop-shadow(0 0 " + shadow1.value + "rem black);"
}

<h4>
Does not works! 
<input id="shadow0" type="number" min="0" max="100" step="0.1">

 | Okay!
<input id="shadow1" type="number" min="0" max="100" step="0.1">

<svg viewBox="0 0 120 70">  
    <rect id="rect1" x="10" y="10" width="100" height="50" fill="#c66" />
    
    <!-- Inline style declaration does NOT works at svg level, no shadow at loading: -->
    <rect id="rect2" x="40" y="30" width="10" height="10" fill="#aaa" style="filter:drop-shadow(0 0 20rem black)" />
    
</svg>