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      1 // Copyright (c) 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 var mode;
      6 var enabled = false;
      7 var scheme = '';
      8 var timeoutId = null;
      9 
     10 var filterMap = {
     11   '0': 'url("#hc_extension_off")',
     12   '1': 'url("#hc_extension_highcontrast")',
     13   '2': 'url("#hc_extension_grayscale")',
     14   '3': 'url("#hc_extension_invert")',
     15   '4': 'url("#hc_extension_invert_grayscale")',
     16   '5': 'url("#hc_extension_yellow_on_black")'
     17 };
     18 
     19 var svgContent = '<svg xmlns="http://www.w3.org/2000/svg" version="1.1"><defs><filter id="hc_extension_off"><feComponentTransfer><feFuncR type="table" tableValues="0 1"/><feFuncG type="table" tableValues="0 1"/><feFuncB type="table" tableValues="0 1"/></feComponentTransfer></filter><filter id="hc_extension_highcontrast"><feComponentTransfer><feFuncR type="gamma" exponent="3.0"/><feFuncG type="gamma" exponent="3.0"/><feFuncB type="gamma" exponent="3.0"/></feComponentTransfer></filter><filter id="hc_extension_highcontrast_back"><feComponentTransfer><feFuncR type="gamma" exponent="0.33"/><feFuncG type="gamma" exponent="0.33"/><feFuncB type="gamma" exponent="0.33"/></feComponentTransfer></filter><filter id="hc_extension_grayscale"><feColorMatrix type="matrix" values="0.2126 0.7152 0.0722 0 0 0.2126 0.7152 0.0722 0 0 0.2126 0.7152 0.0722 0 0 0 0 0 1 0"/><feComponentTransfer><feFuncR type="gamma" exponent="3"/><feFuncG type="gamma" exponent="3"/><feFuncB type="gamma" exponent="3"/></feComponentTransfer></filter><filter id="hc_extension_grayscale_back"><feComponentTransfer><feFuncR type="gamma" exponent="0.33"/><feFuncG type="gamma" exponent="0.33"/><feFuncB type="gamma" exponent="0.33"/></feComponentTransfer></filter><filter id="hc_extension_invert"><feComponentTransfer><feFuncR type="gamma" amplitude="-1" exponent="3" offset="1"/><feFuncG type="gamma" amplitude="-1" exponent="3" offset="1"/><feFuncB type="gamma" amplitude="-1" exponent="3" offset="1"/></feComponentTransfer></filter><filter id="hc_extension_invert_back"><feComponentTransfer><feFuncR type="table" tableValues="1 0"/><feFuncG type="table" tableValues="1 0"/><feFuncB type="table" tableValues="1 0"/></feComponentTransfer><feComponentTransfer><feFuncR type="gamma" exponent="1.7"/><feFuncG type="gamma" exponent="1.7"/><feFuncB type="gamma" exponent="1.7"/></feComponentTransfer></filter><filter id="hc_extension_invert_grayscale"><feColorMatrix type="matrix" values="0.2126 0.7152 0.0722 0 0 0.2126 0.7152 0.0722 0 0 0.2126 0.7152 0.0722 0 0 0 0 0 1 0"/><feComponentTransfer><feFuncR type="gamma" amplitude="-1" exponent="3" offset="1"/><feFuncG type="gamma" amplitude="-1" exponent="3" offset="1"/><feFuncB type="gamma" amplitude="-1" exponent="3" offset="1"/></feComponentTransfer></filter><filter id="hc_extension_yellow_on_black"><feComponentTransfer><feFuncR type="gamma" amplitude="-1" exponent="3" offset="1"/><feFuncG type="gamma" amplitude="-1" exponent="3" offset="1"/><feFuncB type="gamma" amplitude="-1" exponent="3" offset="1"/></feComponentTransfer><feColorMatrix type="matrix" values="0.3 0.5 0.2 0 0 0.3 0.5 0.2 0 0 0 0 0 0 0 0 0 0 1 0"/></filter><filter id="hc_extension_yellow_on_black_back"><feComponentTransfer><feFuncR type="table" tableValues="1 0"/><feFuncG type="table" tableValues="1 0"/><feFuncB type="table" tableValues="1 0"/></feComponentTransfer><feComponentTransfer><feFuncR type="gamma" exponent="0.33"/><feFuncG type="gamma" exponent="0.33"/><feFuncB type="gamma" exponent="0.33"/></feComponentTransfer></filter></defs></svg>';
     20 
     21 function addSvgIfMissing() {
     22   var wrap = document.getElementById('hc_extension_svg_filters');
     23   if (wrap)
     24     return;
     25   wrap = document.createElement('span');
     26   wrap.id = 'hc_extension_svg_filters';
     27   wrap.setAttribute('hidden', '');
     28   wrap.innerHTML = svgContent;
     29   document.body.appendChild(wrap);
     30 }
     31 
     32 function update() {
     33   var html = document.documentElement;
     34   if (enabled) {
     35     if (!document.body) {
     36       window.setTimeout(update, 100);
     37       return;
     38     }
     39     addSvgIfMissing();
     40     if (html.getAttribute('hc') != mode + scheme)
     41       html.setAttribute('hc', mode + scheme);
     42     if (html.getAttribute('hcx') != scheme)
     43       html.setAttribute('hcx', scheme);
     44 
     45     if (window == window.top) {
     46       window.scrollBy(0, 1);
     47       window.scrollBy(0, -1);
     48     }
     49 
     50     /**
     51     if (mode == 'a') {
     52       html.style.webkitFilter = filterMap[scheme];
     53     }
     54     else {
     55       html.style.webkitFilter = 'none';
     56     }**/
     57 
     58   } else {
     59     html.setAttribute('hc', mode + '0');
     60     html.setAttribute('hcx', '0');
     61     window.setTimeout(function() {
     62       html.removeAttribute('hc');
     63       html.removeAttribute('hcx');
     64     }, 0);
     65   }
     66 }
     67 
     68 function onExtensionMessage(request) {
     69   if (enabled != request.enabled || scheme != request.scheme) {
     70     enabled = request.enabled;
     71     scheme = request.scheme;
     72     update();
     73   }
     74 }
     75 
     76 function onEvent(evt) {
     77   if (evt.keyCode == 122 /* F11 */ &&
     78       evt.shiftKey) {
     79     chrome.extension.sendRequest({'toggle_global': true});
     80     evt.stopPropagation();
     81     evt.preventDefault();
     82     return false;
     83   }
     84   if (evt.keyCode == 123 /* F12 */ &&
     85       evt.shiftKey) {
     86     chrome.extension.sendRequest({'toggle_site': true});
     87     evt.stopPropagation();
     88     evt.preventDefault();
     89     return false;
     90   }
     91   return true;
     92 }
     93 
     94 function init() {
     95   if (window == window.top) {
     96     mode = 'a';
     97   } else {
     98     mode = 'b';
     99   }
    100   chrome.extension.onRequest.addListener(onExtensionMessage);
    101   chrome.extension.sendRequest({'init': true}, onExtensionMessage);
    102   document.addEventListener('keydown', onEvent, false);
    103 
    104   // Work around bug that causes filter to be lost when the HTML element's attributes change.
    105   var html = document.documentElement;
    106   var config = { attributes: true, childList: false, characterData: false };
    107   var observer = new MutationObserver(function(mutations) {
    108     observer.disconnect();
    109     html.removeAttribute('hc');
    110     html.removeAttribute('hcx');
    111     window.setTimeout(function() {
    112       update();
    113       window.setTimeout(function() {
    114         observer.observe(html, config);
    115       }, 0);
    116     }, 0);
    117   });
    118   observer.observe(html, config);
    119 }
    120 
    121 init();
    122