javascript - 不移动位置的 SVG 比例

Question

我想做的很简单:当使用 vanilla js 悬停同级元素时，将一些 SVG 点从 scale(0) 缩放到 scale(1) .它们是 the demo 中的红色

这是基本的 SVG 设置

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" 
      x="0px" y="0px" viewBox="0 0 720 576" style="enable-background:new 0 0 720 576;" xml:space="preserve">
    <style type="text/css">
        .st3 {
            fill:red;
        }
        * {
            -webkit-transition:.3s;
            transition:.3s;
        }
    </style>
    <g id="Layer_4">
        <!-- Shield -->
        <path class="st8" d="M601,304.7c-32.4-15.4-68.6-24-106.8-24c-40.4,0-78.5,9.6-112.3,26.6c4.9,79.7,41.9,146.7,109.5,187.6
            C559.8,454.1,597,385.6,601,304.7z" />
        <path class="st9" d="M420.1,328.7c2.1-4.7,32.5-23.9,72.5-23.9c39.9,0,73.1,20,75.5,24.3c2.4,4.3,5.7,40-12.7,74.6
                c-19.7,36.9-53.5,50.1-61.8,50.4c-6.4,0.2-41.8-14.3-62.5-51.6C411.5,367.4,418,333.4,420.1,328.7z" />
        <circle class="st10" cx="494.9" cy="373.3" r="35.5" />
    </g>
    <g id="Layer_8">
        <!-- Dots on shield -->
        <circle class="st3" cx="578.8" cy="316.2" r="4.6" />
        <circle class="st3" cx="543.4" cy="346.2" r="4.6" />
        <circle class="st3" cx="505" cy="375.5" r="4.6" />
    </g>
</svg>

问题 是 SVG 缩放基于原点位置，而不是当前位置，因此当应用变换时，除了缩放元素外，它还会移动元素。我试图通过按 BBox() 偏移进行翻译、缩放，然后再翻译回来来解决这种情况，但这似乎只是有帮助，并没有完全解决问题。

var shield = document.getElementById("Layer_4"),
    dots = document.querySelectorAll("#Layer_8 .st3");

toggleTransform(false);

shield.onmouseover = function () { toggleTransform(true); }
shield.onmouseout = function () { toggleTransform(false); }

function toggleTransform(bool) {
    if (!bool) {
        for (var i = 0; i < dots.length; i++) {
            var box = dots[i].getBBox(),
                cx = box.x + box.width / 10,
                cy = box.y + box.height / 10;
            //dots[i].setAttribute("transform", "translate(" + cx + " " + cy + ") scale(0) translate(" + cx + " " + cy + ")");
            dots[i].style.WebkitTransform = "translate(" + cx + "px, " + cy + "px) scale(0) translate(" + -cx + "px, " + -cy + "px)";
        }
    } else {
        for (var i = 0; i < dots.length; i++) {
            var box = dots[i].getBBox(),
                cx = box.x + box.width / 2,
                cy = box.y + box.height / 2;
            //dots[i].setAttribute("transform", "translate(0 0) scale(1) translate(0 0)");
            dots[i].style.WebkitTransform = "translate(0, 0) scale(1) translate(0, 0)";
        }
    }
}

我尝试同时使用 setAttribute 和 CSS 的转换(我无法让 setAttribute 进行转换，大概是因为它不能通过 CSS 设置动画)但是无法通过任何一个。我只在 Chrome 中测试过

有人知道我如何在不移动的情况下缩放红点吗？

Here's the demo如果您错过了，请再次访问

编辑

我根据 RashFlash 的回答制作了一个函数，使其使用起来非常简单，并且还考虑了偏移量和不同的变换原点

function scaleMe(elem, scaleX, scaleY, newOffsetX, newOffsetY, originX, originY) {
    newOffsetX = null ? 0 : newOffsetX;
    newOffsetY = null ? 0 : newOffsetY;
    originX = null ? "center" : originX;
    originY = null ? "center" : originY;

    var bbox = elem.getBBox(),
        cx = bbox.x + (bbox.width / 2),
        cy = bbox.y + (bbox.height / 2),        
        tx = -cx * (scaleX - 1) + newOffsetX,
        ty = -cy * (scaleY - 1) + newOffsetY;        

    if(originX === "left" || originX === "right") {
        tx = newOffsetX;
    }
    if(originY === "top" || originY === "bottom") {
        ty = newOffsetY;
    }

    var scalestr = scaleX + ',' + scaleY,
        translatestr = tx + 'px,' + ty + 'px';

    elem.style.WebkitTransformOrigin = originX + " " + originY;
    elem.style.MozTransformOrigin = originX + " " + originY;
    elem.style.msTransformOrigin = originX + " " + originY;
    elem.style.transformOrigin = originX + " " + originY;

    elem.style.WebkitTransform = "translate(" + translatestr + ") scale(" + scalestr + ")";
    elem.style.MozTransform = "translate(" + translatestr + ") scale(" + scalestr + ")";
    elem.style.msTransform = "translate(" + translatestr + ") scale(" + scalestr + ")";
    elem.style.transform = "translate(" + translatestr + ") scale(" + scalestr + ")";
}

Answer 1

Updated to work with modern browsers that support transform-box Previously, this approach worked only in Chrome. But spec changes to how transform-origin works, and the addition of transform-box now means that this works in more browsers (currently Chrome, FF, and Opera).

其实不用JS也可以实现这个效果。

.st3 {
    fill: red;
    -webkit-transform: scale(1);
    -webkit-transform-origin: 50% 50%;
    -webkit-transition:.3s;
    transform: scale(1);
    transform-origin: 50% 50%;
    transition:.3s;
    transform-box: fill-box;
}

#Layer_4:hover + g .st3 {
    -webkit-transform: scale(2);
    -webkit-transform-origin: 50% 50%;
    -webkit-transition:.3s;
    transform: scale(2);
    transform-origin: 50% 50%;
    transition:.3s;
}

Demo here