ui/accessibility/extensions/alt/hide-images.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 function toggleEnabled(event) {
   6   if (!document.body)
   7     return;
   8   if (document.body.hasAttribute('show-alt'))
   9     document.body.removeAttribute('show-alt');
  10   else
  11     document.body.setAttribute('show-alt', '');
  12 }
  13
  14 function processImage(image) {
  15   image.style.setProperty('min-height', image.height + 'px');
  16   image.style.setProperty('min-width', image.width + 'px');
  17   var style = window.getComputedStyle(image, null);
  18   var contrastRatio =
  19       axs.utils.getContrastRatioForElementWithComputedStyle(style, image);
  20   if (contrastRatio != null && axs.utils.isLowContrast(contrastRatio, style)) {
  21     var bgColor = axs.utils.getBgColor(style, image);
  22     var fgColor = axs.utils.getFgColor(style, image, bgColor);
  23     var suggestedColors = axs.utils.suggestColors(
  24         bgColor, fgColor, contrastRatio, style);
  25     var suggestedColorsAA = suggestedColors['AA'];
  26     image.style.setProperty('color', suggestedColorsAA['fg']);
  27     image.style.setProperty(
  28         'background-color', suggestedColorsAA['bg'], 'important');
  29   }
  30   if (!image.hasAttribute('alt')) {
  31     if (image.hasAttribute('_repaired'))
  32       return;
  33     var filename = image.src.split('/').pop();
  34     image.setAttribute('_repaired', filename);
  35   }
  36 }
  37
  38 var observer = new MutationObserver(function(mutations) {
  39   mutations.forEach(function(mutation) {
  40     if (!mutation.addedNodes || mutation.addedNodes.length == 0)
  41       return;
  42     for (var i = 0; i < mutation.addedNodes.length; i++) {
  43       var addedNode = mutation.addedNodes[i];
  44       if (!(addedNode instanceof
  45           addedNode.ownerDocument.defaultView.HTMLImageElement)) {
  46         continue;
  47       }
  48       processImage(addedNode);
  49     }
  50   });
  51 });
  52 observer.observe(document, { childList: true, subtree: true });
  53
  54 var images = document.querySelectorAll('img');
  55 for (var i = 0; i < images.length; i++) {
  56   processImage(images[i]);
  57 }
  58
  59 if (!infobarDismissed)
  60     var infobarDismissed = false;
  61
  62 function createInfobar() {
  63   if (infobarDismissed)
  64       return;
  65
  66   if (!document.body)
  67     return;
  68
  69   if (document.querySelector('.show-alt-infobar'))
  70     return;
  71
  72   var showAltInfobar = document.createElement('div');
  73   showAltInfobar.className = 'show-alt-infobar';
  74
  75   var showAltInfoControls = document.createElement('div');
  76   showAltInfoControls.className = 'controls';
  77
  78   var showAltInfoCloseButton = document.createElement('button');
  79   showAltInfoCloseButton.className = 'close-button-gray';
  80   showAltInfoCloseButton.addEventListener('click', function() {
  81     document.body.removeChild(showAltInfobar);
  82     infobarDismissed = true;
  83   });
  84
  85   showAltInfoControls.appendChild(showAltInfoCloseButton);
  86   showAltInfobar.appendChild(showAltInfoControls);
  87
  88   var showAltInfoContent = document.createElement('div');
  89   showAltInfoContent.className = 'content';
  90   var showAltInfoText = document.createElement('span');
  91   showAltInfoText.textContent = chrome.i18n.getMessage('alt_infobar');
  92   showAltInfoText.setAttribute('role', 'status');
  93   showAltInfoContent.appendChild(showAltInfoText);
  94
  95   var undoButton = document.createElement('button');
  96   undoButton.className = 'link-button';
  97   undoButton.textContent = chrome.i18n.getMessage('alt_undo');
  98   undoButton.addEventListener('click', toggleEnabled);
  99
 100   var closeButton = document.createElement('button');
 101
 102   showAltInfoContent.appendChild(undoButton);
 103   showAltInfobar.appendChild(showAltInfoContent);
 104
 105   document.body.insertBefore(showAltInfobar, document.body.firstChild);
 106 }