function emulateStrokeAlign() {
let supportsSvgStrokeAlign = CSS.supports("stroke-align", "outer") ?
true :
CSS.supports("stroke-alignment", "outer") ?
true :
false;
console.log("supportsSvgStrokeAlign", supportsSvgStrokeAlign);
if (!supportsSvgStrokeAlign) {
let ns = "http://www.w3.org/2000/svg";
let strokeAlignmentEls = document.querySelectorAll(
"*[stroke-alignment], *[stroke-align]"
);
strokeAlignmentEls.forEach((el, s) => {
let svg = el.closest("svg");
let svgID = svg.id ? svg.id : "svg_" + s;
svg.id = svgID;
let defs = svg.querySelector("defs");
if (!defs) {
defs = document.createElementNS(ns, "defs");
svg.insertBefore(defs, svg.children[0]);
}
let style = window.getComputedStyle(el);
let strokeWidth = parseFloat(style.strokeWidth);
let strokeAlignment = el.getAttribute("stroke-alignment") ?
el.getAttribute("stroke-alignment") :
el.getAttribute("stroke-align");
el.removeAttribute("stroke-align");
el.removeAttribute("stroke-alignment");
el.setAttribute("data-stroke-align", strokeAlignment);
let maskClipId = `mask-${svgID}-${s}`;
if (strokeAlignment === "outer") {
let mask = document.createElementNS(ns, "mask");
mask.id = maskClipId;
let maskEl = el.cloneNode();
mask.appendChild(maskEl);
defs.appendChild(mask);
maskEl.setAttribute("fill", "#000");
mask.setAttribute("maskUnits", "userSpaceOnUse");
maskEl.setAttribute("stroke", "#fff");
maskEl.removeAttribute("stroke-opacity");
maskEl.removeAttribute("id");
maskEl.setAttribute("paint-order", "stroke");
maskEl.style.strokeWidth = strokeWidth * 2;
let cloneStroke = el.cloneNode();
cloneStroke.style.fill = "none";
cloneStroke.style.strokeWidth = strokeWidth * 2;
cloneStroke.removeAttribute("id");
cloneStroke.removeAttribute("stroke-alignment");
cloneStroke.classList.add("cloneStrokeOuter");
cloneStroke.setAttribute("mask", `url(#${maskClipId})`);
el.parentNode.insertBefore(cloneStroke, el.nextElementSibling);
el.style.stroke = "none";
}
if (strokeAlignment === "inner") {
let clipPathEl = el.cloneNode();
let clipPath = document.createElementNS(ns, "clipPath");
clipPath.id = maskClipId;
defs.appendChild(clipPath);
clipPathEl.removeAttribute("id");
clipPath.appendChild(clipPathEl);
el.setAttribute("clip-path", `url(#${maskClipId})`);
el.style.strokeWidth = strokeWidth * 2;
}
});
}
}
body {
margin: 2em;
}
svg {
width: 100%;
height: auto;
overflow: visible;
border: 1px solid #ccc;
}
body {
margin: 2em;
}
svg {
height: 20em;
overflow: visible;
border: 1px solid #ccc;
}
<p><button onclick="emulateStrokeAlign()">Emulate stroke align</button></p>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 380 120">
<g id="myGroup" style="fill:rgb(45, 130, 255); stroke:#000; stroke-width:10; stroke-opacity:1;">
<rect id="el1" stroke-alignment="outer" x="10" y="10" width="100" height="100" />
<rect id="el2" x="140" y="10" width="100" height="100" />
<rect id="el3" stroke-alignment="inner" x="270" y="10" width="100" height="100" />
</g>
</svg>
<svg viewBox="0 0 12 6" xmlns="http://www.w3.org/2000/svg" stroke-width="0.5">
<path d="M1,5 a2,2 0,0,0 2,-3 a3,3 0 0 1 2,3.5z" fill="blue" stroke-align="outer" stroke="red" stroke-opacity="0.5" stroke-linecap="butt" />
<path d="M7,5 a2,2 0,0,0 2,-3 a3,3 0 0 1 2,3.5z" fill="blue" stroke-align="inner" stroke="red" stroke-opacity="0.5" />
</svg>
paint-order
的参数,您可以在其中指定填充应该呈现在描边的顶部,这样您就会得到 "外部对齐",请参见 https://jsfiddle.net/hne0kyLg/1/。 - Ivan Kuckirpaint-order
属性(Chrome 正在进行 SVG 2 实现,详情请见此处)。 - Mahozad