WordPress之用字母替代图片脚本

下面给大家介绍关于用字母替代图片脚本:LetterAvatar,希望对需要的朋友有所帮助!

基于canvas,通过toDataURL动态生成base64图片。目前我主题的Gravatar头像,就是利用这个LetterAvatar脚本实现未设置Gravatar头像则读取ALT标签,自动生成首字图片替代默认的头像图片。

之前已有WP爱好者制作了一款:mk-letter-avatar 字母头像插件,试了一下很好用,不过打开浏览器开者工具发现产生大量404错误,看了一下源代码,该插件是通过无头像返回404错误,触发onerror事件用自动生成的字母图片替换src图片地址,判断方式不是很合理,如果不是因为个缺点我都想直接拿来用了,如果作者再优化一下,绝对是款优秀实用的插件。

我的实现原理和插件不同,配合头像本地缓存功能,判断无头像后,直接为无头像的图片添加特定的class类,然后通过LetterAvatar脚本替换图片。

需要注意的是上面提到的插件,Gravatar头像图片必须有alt标签属性,否则不会生成正常的图片,可惜大部分主题默认Gravatar头像alt标签属性是空的.....

如果想自动为Gravatar头像添加alt标签属性,可以将下面的代码添加到当前主题函数模板functions.php中:

function zm_gravatar_alt($altgravatar) {

if (have_comments()) {

$alt = get_comment_author();

}

else {

$alt = get_the_author_meta("display_name");

}

$altgravatar= str_replace("alt=""", "alt="" . $alt . "" title="Gravatar for " . $alt . """, $altgravatar);

return $altgravatar;

}

add_filter("get_avatar", "zm_gravatar_alt");

之后,自动将评论者昵称做为alt属性。

本文只是自己做个记录,并不是教大家怎么弄这个头像,如果认为这字母头像还不错,请直接使用上面介绍的插件。

另附LetterAvatar脚本演示代码:

<!DOCTYPE html>

<html>

<h1>Letter Avatar</h1>

 

<small><strong>用法:</strong></small>

<pre>

<code>&lt;img src=&quot;&quot; class=&quot;avatar photo&quot; width=&quot;256&quot; height=&quot;256&quot; alt=&quot;知更鸟&quot; color=&quot;#c40000&quot;&gt;</code>

</pre>

 

<img src="" class="avatar photo" height="240" width="240" alt="知更鸟" color="#c40000" />

<img src="" class="avatar photo" height="240" width="240" alt="更鸟" color="#99CC66" />

<img src="" class="avatar photo" height="240" width="240" alt="鸟" color="#0D8ABC" />

 

<style>

body {

font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;

}

 

pre {

margin: 20px 0;

padding: 20px;

background: #fafafa;

}

 

.avatar { border-radius: 50%; }

</style>

<script src="https://libs.baidu.com/jquery/3.2.1/jquery.min.js "></script>

<script>

/*

* LetterAvatar

*

* Artur Heinze

* Create Letter avatar based on Initials

* based on https://gist.github.com/leecrossley/6027780

*/

(function(w, d){

function LetterAvatar (name, size, color) {

 

name  = name || "";

size  = size || 60;

 

var colours = [

"#1abc9c", "#2ecc71", "#3498db", "#9b59b6", "#34495e", "#16a085", "#27ae60", "#2980b9", "#8e44ad", "#2c3e50",

"#f1c40f", "#e67e22", "#e74c3c", "#ecf0f1", "#95a5a6", "#f39c12", "#d35400", "#c0392b", "#bdc3c7", "#7f8c8d"

],

 

nameSplit = String(name).split(" "),

initials, charIndex, colourIndex, canvas, context, dataURI;

 

 

if (nameSplit.length == 1) {

initials = nameSplit[0] ? nameSplit[0].charAt(0):"?";

} else {

initials = nameSplit[0].charAt(0) + nameSplit[1].charAt(0);

}

 

if (w.devicePixelRatio) {

size = (size * w.devicePixelRatio);

}

charIndex     = (initials == "?" ? 72 : initials.charCodeAt(0)) - 64;

colourIndex   = charIndex % 20;

canvas        = d.createElement("canvas");

canvas.width  = size;

canvas.height = size;

context       = canvas.getContext("2d");

 

context.fillStyle = color ? color : colours[colourIndex - 1];

context.fillRect (0, 0, canvas.width, canvas.height);

context.font = Math.round(canvas.width/2)+"px Arial";

context.textAlign = "center";

context.fillStyle = "#FFF";

context.fillText(initials, size / 2, size / 1.5);

 

dataURI = canvas.toDataURL();

canvas  = null;

 

return dataURI;

}

 

LetterAvatar.transform = function() {

 

Array.prototype.forEach.call(d.querySelectorAll("img[alt]"), function(img, name, color) {

name = img.getAttribute("alt");

color = img.getAttribute("color");

img.src = LetterAvatar(name, img.getAttribute("width"), color);

img.removeAttribute("avatar");

img.setAttribute("alt", name);

});

};

 

 

// AMD support

if (typeof define === "function" && define.amd) {

define(function () { return LetterAvatar; });

// CommonJS and Node.js module support.

} else if (typeof exports !== "undefined") {

// Support Node.js specific `module.exports` (which can be a function)

if (typeof module != "undefined" && module.exports) {

exports = module.exports = LetterAvatar;

}

 

// But always support CommonJS module 1.1.1 spec (`exports` cannot be a function)

exports.LetterAvatar = LetterAvatar;

 

} else {

window.LetterAvatar = LetterAvatar;

 

d.addEventListener("DOMContentLoaded", function(event) {

LetterAvatar.transform();

});

}

})(window, document);

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