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      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   // TODO(aboxhall): i18n
     91   var showAltInfoText = document.createElement('span');
     92   showAltInfoText.textContent = 'Images have been replaced by their alt text.';
     93   showAltInfoText.setAttribute('role', 'status');
     94   showAltInfoContent.appendChild(showAltInfoText);
     95 
     96   var undoButton = document.createElement('button');
     97   undoButton.className = 'link-button';
     98   undoButton.textContent = 'Undo';
     99   undoButton.addEventListener('click', toggleEnabled);
    100 
    101   var closeButton = document.createElement('button');
    102 
    103   showAltInfoContent.appendChild(undoButton);
    104   showAltInfobar.appendChild(showAltInfoContent);
    105 
    106   document.body.insertBefore(showAltInfobar, document.body.firstChild);
    107 }
    108