Initial checkin of accessibility extensions.

ui/accessibility/extensions/highcontrast/highcontrast.js

Index: ui/accessibility/extensions/highcontrast/highcontrast.js
diff --git a/ui/accessibility/extensions/highcontrast/highcontrast.js b/ui/accessibility/extensions/highcontrast/highcontrast.js
new file mode 100644
index 0000000000000000000000000000000000000000..d115d3e3fd3992bb6f73ebe23dcc6441b6883d19
--- /dev/null
+++ b/ui/accessibility/extensions/highcontrast/highcontrast.js
@@ -0,0 +1,121 @@
+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// 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 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>';
+
+function addSvgIfMissing() {
+  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);
+}
+
+function update() {
+  var html = document.documentElement;
+  if (enabled) {
+    if (!document.body) {
+      window.setTimeout(update, 100);
+      return;
+    }
+    addSvgIfMissing();
+    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);
+    }
+
+    /**
+    if (mode == 'a') {
+      html.style.webkitFilter = filterMap[scheme];
+    }
+    else {
+      html.style.webkitFilter = 'none';
+    }**/
+
+  } else {
+    html.setAttribute('hc', mode + '0');
+    html.setAttribute('hcx', '0');
+    window.setTimeout(function() {
+      html.removeAttribute('hc');
+      html.removeAttribute('hcx');
+    }, 0);
+  }
+}
+
+function onExtensionMessage(request) {
+  if (enabled != request.enabled || scheme != request.scheme) {
+    enabled = request.enabled;
+    scheme = request.scheme;
+    update();
+  }
+}
+
+function onEvent(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', onEvent, false);
+
+  // Work around bug that causes filter to be lost when the HTML element's attributes change.
+  var html = document.documentElement;
+  var config = { attributes: true, childList: false, characterData: false };
+  var observer = new MutationObserver(function(mutations) {
+    observer.disconnect();
+    html.removeAttribute('hc');
+    html.removeAttribute('hcx');
+    window.setTimeout(function() {
+      update();
+      window.setTimeout(function() {
+        observer.observe(html, config);
+      }, 0);
+    }, 0);
+  });
+  observer.observe(html, config);
+}
+
+init();