Image viewer

Use grid wallpaper to highlight transparent image. Support to view the large image by holding the right mouse and drag.
当前为 2019-10-28 提交的版本，查看最新版本。
换行
// ==UserScript==
// @name            Image viewer
// @name:vi         Image viewer
// @namespace       http://devs.forumvi.com/
// @description     Use grid wallpaper to highlight transparent image. Support to view the large image by holding the right mouse and drag.
// @description:vi  Sử dụng nền lưới để làm nổi bật ảnh trong suốt. Hỗ trợ xem ảnh lớn bằng cách giữ và kéo chuột phải.
// @version         2.2.2
// @icon            http://i.imgur.com/ItcjCPc.png
// @author          Zzbaivong
// @oujs:author     baivong
// @license         MIT; https://baivong.mit-license.org/license.txt
// @match           http://*/*
// @match           https://*/*
// @require         https://greasemonkey.github.io/gm4-polyfill/gm4-polyfill.js?v=a834d46
// @noframes
// @supportURL      https://github.com/lelinhtinh/Userscript/issues
// @run-at          document-start
// @grant           GM_addStyle
// @inject-into     content
// ==/UserScript==

(function() {
  'use strict';

  /**
   * Background mode
   * @type {string} dark
   *                light
   */
  var theme = 'dark';

  // Do not change the code below this line, unless you know how.
  var doc = document,
    color = theme === 'light' ? ['#eee', 'white'] : ['gray', '#444'];

  if (doc.contentType.indexOf('image/') !== 0) return;

  function scrollByDragging(container, disableH, disableV) {
    function mouseUp(e) {
      if (e.which !== 3) return;

      window.removeEventListener('mousemove', mouseMove, true);
      container.style.cursor = 'default';
    }

    function mouseDown(e) {
      if (e.which !== 3) return;

      pos = {
        x: e.clientX,
        y: e.clientY,
      };

      window.addEventListener('mousemove', mouseMove, true);
      container.style.cursor = 'move';
    }

    function mouseMove(e) {
      if (!disableH) container.scrollLeft -= -pos.x + (pos.x = e.clientX);
      if (!disableV) container.scrollTop -= -pos.y + (pos.y = e.clientY);
    }

    var pos = {
      x: 0,
      y: 0,
    };

    container.oncontextmenu = function(e) {
      e.preventDefault();
    };

    container.addEventListener('mousedown', mouseDown, false);
    window.addEventListener('mouseup', mouseUp, false);
  }

  GM_addStyle(
    'body{background-attachment: fixed !important; background-position: 0px 0px, 10px 10px !important; background-size: 20px 20px !important; background-image: linear-gradient(45deg, ' +
      color[0] +
      ' 25%, transparent 25%, transparent 75%, ' +
      color[0] +
      ' 75%, ' +
      color[0] +
      ' 100%),linear-gradient(45deg, ' +
      color[0] +
      ' 25%, ' +
      color[1] +
      ' 25%, ' +
      color[1] +
      ' 75%, ' +
      color[0] +
      ' 75%, ' +
      color[0] +
      ' 100%) !important;} body > img {background-color: transparent !important; background-image: none !important; display: block; margin: auto; position: absolute; left: 0; top: 0; right: 0; bottom: 0;} body > img:hover {background: rgba(0, 0, 0, 0.4) !important; outline: 3px solid #333;} body > img[style*="cursor: zoom-out;"], body > img.overflowing {position: relative !important;}'
  );

  scrollByDragging(doc.body);
  scrollByDragging(doc.documentElement);
})();