// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
var mode;
var enabled = false;
var scheme = '';
var timeoutId = null;
var filterMap = {
'0': 'url("#hc_extension_off")',
'1': 'url("#hc_extension_highcontrast")',
'2': 'url("#hc_extension_grayscale")',
'3': 'url("#hc_extension_invert")',
'4': 'url("#hc_extension_invert_grayscale")',
'5': 'url("#hc_extension_yellow_on_black")'
};
var svgContent =
'<svg xmlns="http://www.w3.org/2000/svg" version="1.1"><defs><filter x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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 x="0" y="0" width="99999" height="99999" 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>';
var cssTemplate =
'html[hc="a0"] { filter: url("#hc_extension_off"); } html[hcx="0"] img[src*="jpg"], html[hcx="0"] img[src*="jpeg"], html[hcx="0"] svg image, html[hcx="0"] img.rg_i, html[hcx="0"] embed, html[hcx="0"] object, html[hcx="0"] video { filter: url("#hc_extension_off"); } html[hc="a1"] { filter: url("#hc_extension_highcontrast"); } html[hcx="1"] img[src*="jpg"], html[hcx="1"] img[src*="jpeg"], html[hcx="1"] img.rg_i, html[hcx="1"] svg image, html[hcx="1"] embed, html[hcx="1"] object, html[hcx="1"] video { filter: url("#hc_extension_highcontrast_back"); } html[hc="a2"] { filter: url("#hc_extension_grayscale"); } html[hcx="2"] img[src*="jpg"], html[hcx="2"] img[src*="jpeg"], html[hcx="2"] img.rg_i, html[hcx="2"] svg image, html[hcx="2"] embed, html[hcx="2"] object, html[hcx="2"] video { filter: url("#hc_extension_grayscale_back"); } html[hc="a3"] { filter: url("#hc_extension_invert"); } html[hcx="3"] img[src*="jpg"], html[hcx="3"] img[src*="jpeg"], html[hcx="3"] img.rg_i, html[hcx="3"] svg image, html[hcx="3"] embed, html[hcx="3"] object, html[hcx="3"] video { filter: url("#hc_extension_invert_back"); } html[hc="a4"] { filter: url("#hc_extension_invert_grayscale"); } html[hcx="4"] img[src*="jpg"], html[hcx="4"] img[src*="jpeg"], html[hcx="4"] img.rg_i, html[hcx="4"] svg image, html[hcx="4"] embed, html[hcx="4"] object, html[hcx="4"] video { filter: url("#hc_extension_invert_back"); } html[hc="a5"] { filter: url("#hc_extension_yellow_on_black"); } html[hcx="5"] img[src*="jpg"], html[hcx="5"] img[src*="jpeg"], html[hcx="5"] img.rg_i, html[hcx="5"] svg image, html[hcx="5"] embed, html[hcx="5"] object, html[hcx="5"] video { filter: url("#hc_extension_yellow_on_black_back"); }';
/**
* Add the elements to the pgae that make high-contrast adjustments possible.
*/
function addOrUpdateExtraElements() {
if (!enabled)
return;
// We used to include the CSS, but that doesn't work when the document
// uses the <base> element to set a relative url. So instead we
// add a <style> element directly to the document with the right
// urls hard-coded into it.
var style = document.getElementById('hc_style');
if (!style) {
var baseUrl = window.location.href.replace(window.location.hash, '');
var css = cssTemplate.replace(/#/g, baseUrl + '#');
style = document.createElement('style');
style.id = 'hc_style';
style.setAttribute('type', 'text/css');
style.innerHTML = css;
document.head.appendChild(style);
}
// Starting in Chrome 45 we can't apply a filter to the html element,
// so instead we create an element with low z-index that copies the
// body's background.
var bg = document.getElementById('hc_extension_bkgnd');
if (!bg) {
bg = document.createElement('div');
bg.id = 'hc_extension_bkgnd';
bg.style.position = 'fixed';
bg.style.left = '0px';
bg.style.top = '0px';
bg.style.right = '0px';
bg.style.bottom = '0px';
bg.style.zIndex = -1999999999;
document.body.appendChild(bg);
}
bg.style.display = 'block';
bg.style.background = window.getComputedStyle(document.body).background;
// As a special case, replace a zero-alpha background with white,
// otherwise we can't invert it.
var c = bg.style.backgroundColor;
c = c.replace(/\s\s*/g, '');
if (m = /^rgba\(([\d]+),([\d]+),([\d]+),([\d]+|[\d]*.[\d]+)\)/.exec(c)) {
if (m[4] == '0') {
bg.style.backgroundColor = '#fff';
}
}
// Add a hidden element with the SVG filters.
var wrap = document.getElementById('hc_extension_svg_filters');
if (wrap)
return;
wrap = document.createElement('span');
wrap.id = 'hc_extension_svg_filters';
wrap.setAttribute('hidden', '');
wrap.innerHTML = svgContent;
document.body.appendChild(wrap);
}
/**
* This is called on load and every time the mode might have changed
* (i.e. enabling/disabling, or changing the type of contrast adjustment
* for this page).
*/
function update() {
var html = document.documentElement;
if (enabled) {
if (!document.body) {
window.setTimeout(update, 100);
return;
}
addOrUpdateExtraElements();
if (html.getAttribute('hc') != mode + scheme)
html.setAttribute('hc', mode + scheme);
if (html.getAttribute('hcx') != scheme)
html.setAttribute('hcx', scheme);
if (window == window.top) {
window.scrollBy(0, 1);
window.scrollBy(0, -1);
}
} else {
html.setAttribute('hc', mode + '0');
html.setAttribute('hcx', '0');
window.setTimeout(function() {
html.removeAttribute('hc');
html.removeAttribute('hcx');
var bg = document.getElementById('hc_extension_bkgnd');
if (bg)
bg.style.display = 'none';
}, 0);
}
}
/**
* Called when we get a message from the background page.
*/
function onExtensionMessage(request) {
if (enabled != request.enabled || scheme != request.scheme) {
enabled = request.enabled;
scheme = request.scheme;
update();
}
}
/**
* KeyDown event handler
*/
function onKeyDown(evt) {
if (evt.keyCode == 122 /* F11 */ && evt.shiftKey) {
chrome.extension.sendRequest({'toggle_global': true});
evt.stopPropagation();
evt.preventDefault();
return false;
}
if (evt.keyCode == 123 /* F12 */ && evt.shiftKey) {
chrome.extension.sendRequest({'toggle_site': true});
evt.stopPropagation();
evt.preventDefault();
return false;
}
return true;
}
function init() {
if (window == window.top) {
mode = 'a';
} else {
mode = 'b';
}
chrome.extension.onRequest.addListener(onExtensionMessage);
chrome.extension.sendRequest({'init': true}, onExtensionMessage);
document.addEventListener('keydown', onKeyDown, false);
// Update again after a few seconds and again after load so that
// the background isn't wrong for long.
window.setTimeout(addOrUpdateExtraElements, 2000);
window.addEventListener('load', function() {
addOrUpdateExtraElements();
// Also update when the document body attributes change.
var config = {attributes: true, childList: false, characterData: false};
var observer = new MutationObserver(function(mutations) {
addOrUpdateExtraElements();
});
observer.observe(document.body, config);
});
}
init();
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