javascript - 在 d3/js 中通过 Stamen 或 CartoDB 使用视网膜 map 图 block

Question

我想知道如何修改我的代码以检测视网膜显示并向用户提供增强的图 block 。我通常使用此代码来调用图 block :

雄蕊图 block :

.attr("xlink:href", function(d) { return "http://tile.stamen.com/toner-lite/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })

CartoDB 磁贴:

.attr("xlink:href", function(d) { return "http://" + ["a", "b", "c", "d"][Math.random() * 4 | 0] + ".basemaps.cartocdn.com/light_all/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; })

谢谢!

Answer 1

好的，通过使用它来工作:

function isRetina() {
return ((window.matchMedia && (window.matchMedia('only screen and (min-resolution: 192dpi), only screen and (min-resolution: 2dppx), only screen and (min-resolution: 75.6dpcm)').matches || window.matchMedia('only screen and (-webkit-min-device-pixel-ratio: 2), only screen and (-o-min-device-pixel-ratio: 2/1), only screen and (min--moz-device-pixel-ratio: 2), only screen and (min-device-pixel-ratio: 2)').matches)) || (window.devicePixelRatio && window.devicePixelRatio > 2)) && /(iPad|iPhone|iPod)/g.test(navigator.userAgent);}

function isRetinaDisplay() {
if (window.matchMedia) {
    var mq = window.matchMedia("only screen and (min--moz-device-pixel-ratio: 1.3), only screen and (-o-min-device-pixel-ratio: 2.6/2), only screen and (-webkit-min-device-pixel-ratio: 1.3), only screen  and (min-device-pixel-ratio: 1.3), only screen and (min-resolution: 1.3dppx)");
    if (mq && mq.matches || (window.devicePixelRatio > 1)) {
        return true;
    } else {
        return false;}
}
}

image.enter().append("image")
.attr("xlink:href", function(d) {
    if (isRetinaDisplay) {
        return "http://tile.stamen.com/toner-lite/" + d[2] + "/" + d[0] + "/" + d[1] + "@2x.png";
    } else {
        return "http://tile.stamen.com/toner-lite/" + d[2] + "/" + d[0] + "/" + d[1] + ".png";
    }
})

这是用于雄蕊图 block 的。基本上只需在文件名末尾添加“@2x”即可。