通过getBoundingClientRect（）获取正确的视口坐标

Question

将完成的触摸应用于交互式信息图表，我将HTML页面上的SVG对象的对齐方式从左侧更改为居中。这一变化打破了每个州出现的小弹出窗口的位置。这是左对齐版本，它可以正常工作：

http://www.50laboratories.com/demographicclout/demographicclout-left.html

中心版本，弹出窗口错误：

http://www.50laboratories.com/demographicclout/demographicclout-centered.html

以下是使用getBoundingClientRect（）确定弹出位置的代码：

targetbackground = document.getElementById(selectedstate + mapyear);
targetwidth=targetbackground.getBoundingClientRect().width;
targetex = targetbackground.getBoundingClientRect().left + (targetwidth/2)+excorrection;
targetwye = targetbackground.getBoundingClientRect().top + wyecorrection;
d3.select("#datapopup").attr("transform", "translate(" + targetex + "," + targetwye + ")");

显然，getBoundingClientRect（）返回的距离是浏览器窗口的左上角，而不是SVG视口的左上角。如何始终获取正确的坐标值，即从视口的原点开始？

Answer 1

使用SVG的getBBox()方法：

targetbackground = document.getElementById(selectedstate + mapyear);
targetwidth = targetbackground.getBBox().width;
targetex = targetbackground.getBBox().x + (targetwidth/2) + excorrection;
targetwye = targetbackground.getBBox().y + wyecorrection;
d3.select("#datapopup").attr("transform", "translate(" + targetex + "," + targetwye + ")");