在最新的 Material Design 文档 ( https://www.google.com/design/spec/what-is-material/elevation-shadows.html#elevation-shadows-elevation-android- ) 中引用了一组详尽的 UI 元素以及它们各自的高度（dp 中的 z-index）。例如，开关提升1dp，而对话框提升24dp。目前，Google 的 UI 元素列表使用 10 种不同的海拔高度。由于高程决定了元素的阴影，我们需要 10 个不同的阴影。这就是我迷路的地方。
您如何计算/推断每个高程级别的正确阴影值（颜色、x 偏移、y 偏移、模糊、散布）？
我发现不同的来源计算了 5 个不同高度的阴影值（https://news.layervault.com/stories/42319-calculating-shadow-values-for-material-design）。然而，5 个海拔台阶是不够的，它们也没有解释它们是如何达到这些各自的值的。
有一个好消息！我得到了从深度 1 到深度 24 的所有阴影深度。我从Angular Material得到这个。希望这会对你有所帮助。
.md-whiteframe-1dp {
box-shadow: 0px 1px 3px 0px rgba(0, 0, 0, 0.2),
0px 1px 1px 0px rgba(0, 0, 0, 0.14),
0px 2px 1px -1px rgba(0, 0, 0, 0.12); }
.md-whiteframe-2dp {
box-shadow: 0px 1px 5px 0px rgba(0, 0, 0, 0.2),
0px 2px 2px 0px rgba(0, 0, 0, 0.14),
0px 3px 1px -2px rgba(0, 0, 0, 0.12); }
.md-whiteframe-3dp {
box-shadow:0px 1px 8px 0px rgba(0, 0, 0, 0.2),
0px 3px 4px 0px rgba(0, 0, 0, 0.14),
0px 3px 3px -2px rgba(0, 0, 0, 0.12); }
.md-whiteframe-4dp {
box-shadow: 0px 2px 4px -1px rgba(0, 0, 0, 0.2),
0px 4px 5px 0px rgba(0, 0, 0, 0.14),
0px 1px 10px 0px rgba(0, 0, 0, 0.12); }
.md-whiteframe-5dp {
box-shadow: 0px 3px 5px -1px rgba(0, 0, 0, 0.2),
0px 5px 8px 0px rgba(0, 0, 0, 0.14),
0px 1px 14px 0px rgba(0, 0, 0, 0.12); }
.md-whiteframe-6dp {
box-shadow: 0px 3px 5px -1px rgba(0, 0, 0, 0.2),
0px 6px 10px 0px rgba(0, 0, 0, 0.14),
0px 1px 18px 0px rgba(0, 0, 0, 0.12); }
.md-whiteframe-7dp {
box-shadow: 0px 4px 5px -2px rgba(0, 0, 0, 0.2),
0px 7px 10px 1px rgba(0, 0, 0, 0.14),
0px 2px 16px 1px rgba(0, 0, 0, 0.12); }
.md-whiteframe-8dp {
box-shadow: 0px 5px 5px -3px rgba(0, 0, 0, 0.2),
0px 8px 10px 1px rgba(0, 0, 0, 0.14),
0px 3px 14px 2px rgba(0, 0, 0, 0.12); }
.md-whiteframe-9dp {
box-shadow: 0px 5px 6px -3px rgba(0, 0, 0, 0.2),
0px 9px 12px 1px rgba(0, 0, 0, 0.14),
0px 3px 16px 2px rgba(0, 0, 0, 0.12); }
.md-whiteframe-10dp {
box-shadow: 0px 6px 6px -3px rgba(0, 0, 0, 0.2),
0px 10px 14px 1px rgba(0, 0, 0, 0.14),
0px 4px 18px 3px rgba(0, 0, 0, 0.12); }
.md-whiteframe-11dp {
box-shadow: 0px 6px 7px -4px rgba(0, 0, 0, 0.2),
0px 11px 15px 1px rgba(0, 0, 0, 0.14),
0px 4px 20px 3px rgba(0, 0, 0, 0.12); }
.md-whiteframe-12dp {
box-shadow: 0px 7px 8px -4px rgba(0, 0, 0, 0.2),
0px 12px 17px 2px rgba(0, 0, 0, 0.14),
0px 5px 22px 4px rgba(0, 0, 0, 0.12); }
.md-whiteframe-13dp {
box-shadow: 0px 7px 8px -4px rgba(0, 0, 0, 0.2),
0px 13px 19px 2px rgba(0, 0, 0, 0.14),
0px 5px 24px 4px rgba(0, 0, 0, 0.12); }
.md-whiteframe-14dp {
box-shadow: 0px 7px 9px -4px rgba(0, 0, 0, 0.2),
0px 14px 21px 2px rgba(0, 0, 0, 0.14),
0px 5px 26px 4px rgba(0, 0, 0, 0.12); }
.md-whiteframe-15dp {
box-shadow: 0px 8px 9px -5px rgba(0, 0, 0, 0.2),
0px 15px 22px 2px rgba(0, 0, 0, 0.14),
0px 6px 28px 5px rgba(0, 0, 0, 0.12); }
.md-whiteframe-16dp {
box-shadow: 0px 8px 10px -5px rgba(0, 0, 0, 0.2),
0px 16px 24px 2px rgba(0, 0, 0, 0.14),
0px 6px 30px 5px rgba(0, 0, 0, 0.12); }
.md-whiteframe-17dp {
box-shadow: 0px 8px 11px -5px rgba(0, 0, 0, 0.2),
0px 17px 26px 2px rgba(0, 0, 0, 0.14),
0px 6px 32px 5px rgba(0, 0, 0, 0.12); }
.md-whiteframe-18dp {
box-shadow: 0px 9px 11px -5px rgba(0, 0, 0, 0.2),
0px 18px 28px 2px rgba(0, 0, 0, 0.14),
0px 7px 34px 6px rgba(0, 0, 0, 0.12); }
.md-whiteframe-19dp {
box-shadow: 0px 9px 12px -6px rgba(0, 0, 0, 0.2),
0px 19px 29px 2px rgba(0, 0, 0, 0.14),
0px 7px 36px 6px rgba(0, 0, 0, 0.12); }
.md-whiteframe-20dp {
box-shadow: 0px 10px 13px -6px rgba(0, 0, 0, 0.2),
0px 20px 31px 3px rgba(0, 0, 0, 0.14),
0px 8px 38px 7px rgba(0, 0, 0, 0.12); }
.md-whiteframe-21dp {
box-shadow: 0px 10px 13px -6px rgba(0, 0, 0, 0.2),
0px 21px 33px 3px rgba(0, 0, 0, 0.14),
0px 8px 40px 7px rgba(0, 0, 0, 0.12); }
.md-whiteframe-22dp {
box-shadow: 0px 10px 14px -6px rgba(0, 0, 0, 0.2),
0px 22px 35px 3px rgba(0, 0, 0, 0.14),
0px 8px 42px 7px rgba(0, 0, 0, 0.12); }
.md-whiteframe-23dp {
box-shadow: 0px 11px 14px -7px rgba(0, 0, 0, 0.2),
0px 23px 36px 3px rgba(0, 0, 0, 0.14),
0px 9px 44px 8px rgba(0, 0, 0, 0.12); }
.md-whiteframe-24dp {
box-shadow: 0px 11px 15px -7px rgba(0, 0, 0, 0.2),
0px 24px 38px 3px rgba(0, 0, 0, 0.14),
0px 9px 46px 8px rgba(0, 0, 0, 0.12); }
这是我想出的一个函数，它给出了一个很好的结果，我相信：
(Javascript)
function getShadow(object, dp)
{
if (dp <= 0)
{
panel.style.boxShadow = "none";
return;
}
panel.style.boxShadow = "0px " + dp + "px " + dp + "px " + "rgba(0, 0, 0, .38)";
}
一个 jfiddle：https ://jsfiddle.net/crkb906z/
基本上，与基础层的距离是阴影顶部的距离，我对模糊使用相同的值，以使其随着材质的升高而变得更加模糊。
我将这个结果与聚合物使用的 3 个阴影进行了比较，它们非常具有可比性。由于我什至无法找到大多数人提供的 5 层阴影之间的一致性，我想它的确切计算方式并不那么重要。
编辑
好的，在研究了 5 个深度的可用框阴影之后（它们起源于这里，但谷歌已经从文档中删除了它），我想出了一个更复杂的公式，它产生的阴影看起来更像该链接中的示例：
function applyShadow(element, dp)
{
if (dp == 0)
{
element.style.boxShadow = "none";
}
else
{
var shadow = "0px ";
var ambientY = dp;
var ambientBlur = dp == 1 ? 3 : dp * 2;
var ambientAlpha = (dp + 10 + (dp / 9.38)) / 100;
shadow += ambientY + "px " + ambientBlur + "px rgba(0, 0, 0, " + ambientAlpha + "), 0px ";
var directY = (dp < 10 ? (dp % 2 == 0 ? dp - ((dp / 2) - 1) : (dp - ((dp - 1) / 2))) : dp - 4);
var directBlur = dp == 1 ? 3 : dp * 2;
var directAlpha = (24 - Math.round(dp / 10)) / 100;
shadow += directY + "px " + directBlur + "px rgba(0, 0, 0, " + directAlpha + ")";
element.style.boxShadow = shadow;
}
}
我更新了https://jsfiddle.net/crkb906z/1/以显示差异。
我只发布此答案是因为 Google 的官方 MDC Web 提升内容与迄今为止发布的内容不同。
这是我要复制的源文件：
谷歌官方box-shadow的海拔值（SASS mixin）：
//
// Copyright 2017 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
@import "@material/animation/variables";
$mdc-elevation-baseline-color: black;
$mdc-elevation-umbra-opacity: .2;
$mdc-elevation-penumbra-opacity: .14;
$mdc-elevation-ambient-opacity: .12;
$mdc-elevation-umbra-map: (
0: "0px 0px 0px 0px",
1: "0px 2px 1px -1px",
2: "0px 3px 1px -2px",
3: "0px 3px 3px -2px",
4: "0px 2px 4px -1px",
5: "0px 3px 5px -1px",
6: "0px 3px 5px -1px",
7: "0px 4px 5px -2px",
8: "0px 5px 5px -3px",
9: "0px 5px 6px -3px",
10: "0px 6px 6px -3px",
11: "0px 6px 7px -4px",
12: "0px 7px 8px -4px",
13: "0px 7px 8px -4px",
14: "0px 7px 9px -4px",
15: "0px 8px 9px -5px",
16: "0px 8px 10px -5px",
17: "0px 8px 11px -5px",
18: "0px 9px 11px -5px",
19: "0px 9px 12px -6px",
20: "0px 10px 13px -6px",
21: "0px 10px 13px -6px",
22: "0px 10px 14px -6px",
23: "0px 11px 14px -7px",
24: "0px 11px 15px -7px"
);
$mdc-elevation-penumbra-map: (
0: "0px 0px 0px 0px",
1: "0px 1px 1px 0px",
2: "0px 2px 2px 0px",
3: "0px 3px 4px 0px",
4: "0px 4px 5px 0px",
5: "0px 5px 8px 0px",
6: "0px 6px 10px 0px",
7: "0px 7px 10px 1px",
8: "0px 8px 10px 1px",
9: "0px 9px 12px 1px",
10: "0px 10px 14px 1px",
11: "0px 11px 15px 1px",
12: "0px 12px 17px 2px",
13: "0px 13px 19px 2px",
14: "0px 14px 21px 2px",
15: "0px 15px 22px 2px",
16: "0px 16px 24px 2px",
17: "0px 17px 26px 2px",
18: "0px 18px 28px 2px",
19: "0px 19px 29px 2px",
20: "0px 20px 31px 3px",
21: "0px 21px 33px 3px",
22: "0px 22px 35px 3px",
23: "0px 23px 36px 3px",
24: "0px 24px 38px 3px"
);
$mdc-elevation-ambient-map: (
0: "0px 0px 0px 0px",
1: "0px 1px 3px 0px",
2: "0px 1px 5px 0px",
3: "0px 1px 8px 0px",
4: "0px 1px 10px 0px",
5: "0px 1px 14px 0px",
6: "0px 1px 18px 0px",
7: "0px 2px 16px 1px",
8: "0px 3px 14px 2px",
9: "0px 3px 16px 2px",
10: "0px 4px 18px 3px",
11: "0px 4px 20px 3px",
12: "0px 5px 22px 4px",
13: "0px 5px 24px 4px",
14: "0px 5px 26px 4px",
15: "0px 6px 28px 5px",
16: "0px 6px 30px 5px",
17: "0px 6px 32px 5px",
18: "0px 7px 34px 6px",
19: "0px 7px 36px 6px",
20: "0px 8px 38px 7px",
21: "0px 8px 40px 7px",
22: "0px 8px 42px 7px",
23: "0px 9px 44px 8px",
24: "0px 9px 46px 8px"
);
/**
* The css property used for elevation. In most cases this should not be changed. It is exposed
* as a variable for abstraction / easy use when needing to reference the property directly, for
* example in a `will-change` rule.
*/
$mdc-elevation-property: box-shadow !default;
/**
* The default duration value for elevation transitions.
*/
$mdc-elevation-transition-duration: 280ms !default;
/**
* The default easing value for elevation transitions.
*/
$mdc-elevation-transition-timing-function: $mdc-animation-standard-curve-timing-function !default;
elevation这是我根据上述内容整理的一个香草 ES6函数：
const umbraColor = 'rgba(0, 0, 0, 0.2)';
const penumbraColor = 'rgba(0, 0, 0, 0.14)';
const ambientColor = 'rgba(0, 0, 0, 0.12)';
const umbra = [
"0px 0px 0px 0px",
"0px 2px 1px -1px",
"0px 3px 1px -2px",
"0px 3px 3px -2px",
"0px 2px 4px -1px",
"0px 3px 5px -1px",
"0px 3px 5px -1px",
"0px 4px 5px -2px",
"0px 5px 5px -3px",
"0px 5px 6px -3px",
"0px 6px 6px -3px",
"0px 6px 7px -4px",
"0px 7px 8px -4px",
"0px 7px 8px -4px",
"0px 7px 9px -4px",
"0px 8px 9px -5px",
"0px 8px 10px -5px",
"0px 8px 11px -5px",
"0px 9px 11px -5px",
"0px 9px 12px -6px",
"0px 10px 13px -6px",
"0px 10px 13px -6px",
"0px 10px 14px -6px",
"0px 11px 14px -7px",
"0px 11px 15px -7px"
];
const penumbra = [
"0px 0px 0px 0px",
"0px 1px 1px 0px",
"0px 2px 2px 0px",
"0px 3px 4px 0px",
"0px 4px 5px 0px",
"0px 5px 8px 0px",
"0px 6px 10px 0px",
"0px 7px 10px 1px",
"0px 8px 10px 1px",
"0px 9px 12px 1px",
"0px 10px 14px 1px",
"0px 11px 15px 1px",
"0px 12px 17px 2px",
"0px 13px 19px 2px",
"0px 14px 21px 2px",
"0px 15px 22px 2px",
"0px 16px 24px 2px",
"0px 17px 26px 2px",
"0px 18px 28px 2px",
"0px 19px 29px 2px",
"0px 20px 31px 3px",
"0px 21px 33px 3px",
"0px 22px 35px 3px",
"0px 23px 36px 3px",
"0px 24px 38px 3px"
];
const ambient = [
"0px 0px 0px 0px",
"0px 1px 3px 0px",
"0px 1px 5px 0px",
"0px 1px 8px 0px",
"0px 1px 10px 0px",
"0px 1px 14px 0px",
"0px 1px 18px 0px",
"0px 2px 16px 1px",
"0px 3px 14px 2px",
"0px 3px 16px 2px",
"0px 4px 18px 3px",
"0px 4px 20px 3px",
"0px 5px 22px 4px",
"0px 5px 24px 4px",
"0px 5px 26px 4px",
"0px 6px 28px 5px",
"0px 6px 30px 5px",
"0px 6px 32px 5px",
"0px 7px 34px 6px",
"0px 7px 36px 6px",
"0px 8px 38px 7px",
"0px 8px 40px 7px",
"0px 8px 42px 7px",
"0px 9px 44px 8px",
"0px 9px 46px 8px"
];
export default (z) => (
`
box-shadow: ${umbra[z]} ${umbraColor},
${penumbra[z]} ${penumbraColor},
${ambient[z]} ${ambientColor};
`
);
这是移植到 Stylus 的 Troncoso 公式。
elevation(dp)
if dp == 0
box-shadow none
else
dp = unit(dp, px)
blur = (dp == 1 ? 3 : dp * 2)
amba = (dp + 10 + (dp / 9.38)) / 100
diry = (dp < 10 ? (dp % 2 == 0 ? dp - ((dp / 2) - 1) : (dp - ((dp - 1) / 2))) : dp - 4)
dira = (24 - (round(dp / 10))) / 100
box-shadow 0px dp blur rgba(0, 0, 0, amba), 0px diry blur rgba(0, 0, 0, dira)
有一个 scss 库：SCSS-Material-Shadows
这是演示
您可以在 scss 文件中查看整个计算。
主要用途是通过一个名为mdElevation(). 是此处mdElevationElement()找到的所有材质元素的预定义高程值的便捷实现
对于高程过渡期间的动态效果，您可以mdElevationTransition()在 scss 中添加。作为参数，使用两个海拔之间的增量。
有关更多详细信息，请访问 github 页面。
以下 JS 函数接收海拔高度，并返回非常接近 Google 的 Material 组件的结果。
export const getShadow = (elevation=1) => {
const extraEl = elevation-1
const getSize = (v1, v24) => `${v1+Math.round(((v24-v1)/23)*extraEl)}px`
const getShade = (y, blur, spread, alpha) =>
`0 ${getSize(y[0], y[1])} ${getSize(blur[0], blur[1])} ${getSize(spread[0], spread[1])} rgba(0,0,0,${alpha})`
return `box-shadow: ${getShade([2,11], [1,15], [-1,-7], 0.2)}, ${getShade([1,24], [1,38], [0,3], 0.14)}, ${getShade([1,9], [3,46], [0,8], 0.12)};`
}
const getShadow = (elevation=1) => {
const extraEl = elevation-1
const getSize = (v1, v24) => `${v1+Math.round(((v24-v1)/23)*extraEl)}px`
const getShade = (y, blur, spread, alpha) =>
`0 ${getSize(y[0], y[1])} ${getSize(blur[0], blur[1])} ${getSize(spread[0], spread[1])} rgba(0,0,0,${alpha})`
return `box-shadow: ${getShade([2,11], [1,15], [-1,-7], 0.2)}, ${getShade([1,24], [1,38], [0,3], 0.14)}, ${getShade([1,9], [3,46], [0,8], 0.12)};`
}
const appDiv = document.getElementById('app');
appDiv.innerHTML = `<div style="margin: 50px; width: 100px; height: 100px; ${getShadow(12)}">Hello world</div>`;<div id="app"></div>它使用来自第一级和最后（24 级）高程的值。
我从 Google 的 Material Design Lite 中得到了一些阴影。我认为这段代码可能会有所帮助。
.shadow--2dp {
box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.14), 0 3px 1px -2px rgba(0, 0, 0, 0.2), 0 1px 5px 0 rgba(0, 0, 0, 0.12);
}
.shadow--3dp {
box-shadow: 0 3px 4px 0 rgba(0, 0, 0, 0.14), 0 3px 3px -2px rgba(0, 0, 0, 0.2), 0 1px 8px 0 rgba(0, 0, 0, 0.12);
}
.shadow--4dp {
box-shadow: 0 4px 5px 0 rgba(0, 0, 0, 0.14), 0 1px 10px 0 rgba(0, 0, 0, 0.12), 0 2px 4px -1px rgba(0, 0, 0, 0.2);
}
.shadow--6dp {
box-shadow: 0 6px 10px 0 rgba(0, 0, 0, 0.14), 0 1px 18px 0 rgba(0, 0, 0, 0.12), 0 3px 5px -1px rgba(0, 0, 0, 0.2);
}
.shadow--8dp {
box-shadow: 0 8px 10px 1px rgba(0, 0, 0, 0.14), 0 3px 14px 2px rgba(0, 0, 0, 0.12), 0 5px 5px -3px rgba(0, 0, 0, 0.2);
}
.shadow--16dp {
box-shadow: 0 16px 24px 2px rgba(0, 0, 0, 0.14), 0 6px 30px 5px rgba(0, 0, 0, 0.12), 0 8px 10px -5px rgba(0, 0, 0, 0.2);
}
.shadow--24dp {
box-shadow: 0 9px 46px 8px rgba(0, 0, 0, 0.14), 0 11px 15px -7px rgba(0, 0, 0, 0.12), 0 24px 38px 3px rgba(0, 0, 0, 0.2);
}
这是 Sass 稍作修改的端口：
@mixin shadow($dp: 1) {
@if $dp == 0 { box-shadow: none; }
@else {
$blur: if($dp == 1, 3, $dp * 2);
$amba: ($dp + 11) / 100;
$diry: $dp - floor($dp / 4);
$dirb: floor(($dp + 5) / 2);
$dira: (24 - (round($dp / 10))) / 100;
box-shadow: 0px #{$dp + 'px'} #{$blur + 'px'} rgba(0, 0, 0, $amba), 0px #{$diry + 'px'} #{$dirb + 'px'} rgba(0, 0, 0, $dira);
}
}