下面由WordPress技巧栏目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><img src="" class="avatar photo" width="256" height="256" alt="知更鸟" color="#c40000"></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); </script> </html>
原项目地址:https://github.com/daolavi/LetterAvatar
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