使用d3.js使矩形绕其中心奇怪地旋转 [英] Strange rotation of rectangle around its center using d3.js

问题描述

我打算使用d3.js围绕其中心旋转一个矩形. 我的代码是

I'm planning to rotate a rectangle around its center using d3.js. My code is

var svg = d3.select("body")
  .append("svg").attr("width", 200).attr("height", 200).append("rect")
  .attr("x", 50)
  .attr("y", 50)
  .attr("fill", "black")
  .attr("width", 100)
  .attr("height", 100)
  .transition()
  .ease("linear")
  .duration(1000)
  .attr("transform", "rotate(180,100,100)");

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>

它旋转并到达矩形的原始x，y坐标，但是 在旋转过程中不会绕其中心旋转.

It rotates and comes to its original x,y coordinates of rectangle, but does not rotate around its center during rotation.

我在网上找到的正确代码是

The correct code I found on web is

var svg = d3.select("body").append("svg").attr("width", 200).attr("height", 200);

var rect = svg.append("rect")
    .attr("x", 50)
    .attr("y", 50)
    .attr("width", 100)
    .attr("height", 100);

rect.transition().duration(5000)
    .attrTween("transform", rotTween);

function rotTween() {
    var i = d3.interpolate(0, 360);
    return function(t) {
        return "rotate(" + i(t) + ",100,100)";
    };
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>

此矩形围绕其中心正确旋转.但是我看不到两个代码之间的任何区别.有什么区别?

This rectangle rotates around its center properly. But I can't see any difference between two codes. What's the difference?

推荐答案

如注释中所述，当您检查属性时，您可以清楚地看到区别...

As mentioned in the comment, you can clearly see the difference when you check the attributes...

var log = d3.ui.log("#log").style("vertical-align", "top"),
	logTween = d3.ui.log("#logTween").style("vertical-align", "top"),
    stoppedTween = false,
    stopped = false;
log.writeLine("translate\t\trotate")
logTween.writeLine("translate\t\trotate")

var rect = d3.select("body")
    .insert("svg", "#log").attr("width", 200).attr("height", 100).append("rect")
    .attr("x", 20)
    .attr("y", 20)
    .attr("fill", "black")
    .attr("width", 40)
    .attr("height", 40);

rect.transition()
    .ease("linear")
    .duration(1000)
    .attr("transform", "rotate(180,100,100)")
    .each("start", function () {
    d3.timer(function () {
        var t = d3.transform(rect.attr("transform"));
        log.writeLine([t.translate.map(f).join(","), f(t.rotate)].join("\t"))
        return stopped;
    })
})
    .each("end", function () {
    stopped = true
});
var svg = d3.select("body").insert("svg", "#logTween").attr("width", 100).attr("height", 100);

var rectTween = svg.append("rect")
    .attr("x", 20)
    .attr("y", 20)
    .attr("width", 40)
    .attr("height", 40);


rectTween.transition().duration(1000)
    .ease("linear")
    .attrTween("transform", rotTween)
    .each("start", function () {
    d3.timer(function () {
        var t = d3.transform(rectTween.attr("transform"));
        logTween.writeLine([t.translate.map(f).join(","), f(t.rotate)].join("\t"))
        return stoppedTween;
    })
})
    .each("end", function () {
    stoppedTween = true
});


function rotTween() {
    var i = d3.interpolate(0, 360);
    return function(t) {
        return "rotate(" + i(t) + ",40,40)";
    };
}

function f(x) {
    return d3.format(" >6.1f")(x)
}

div {white-space: pre;}
svg {overflow: visible;}

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.6/d3.min.js" charset="UTF-8"></script>
<script src="https://rawgit.com/cool-Blue/d3-lib/master/Output/log/log.js"></script>
<div id="log"></div>
<div id="logTween"></div>

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