The Tor Browser: dom/inputmethod/forms.js@b8a032363ba2 (annotated)

dom/inputmethod/forms.js@b8a032363ba2 (annotated)

dom/inputmethod/forms.js

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- /
 /* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 dump("###################################### forms.js loaded\n");
 let Ci = Components.interfaces;
 let Cc = Components.classes;
 let Cu = Components.utils;
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import('resource://gre/modules/XPCOMUtils.jsm');
 XPCOMUtils.defineLazyServiceGetter(Services, "fm",
                                    "@mozilla.org/focus-manager;1",
                                    "nsIFocusManager");
 XPCOMUtils.defineLazyGetter(this, "domWindowUtils", function () {
   return content.QueryInterface(Ci.nsIInterfaceRequestor)
                 .getInterface(Ci.nsIDOMWindowUtils);
 });
 const RESIZE_SCROLL_DELAY = 20;
 // In content editable node, when there are hidden elements such as <br>, it
 // may need more than one (usually less than 3 times) move/extend operations
 // to change the selection range. If we cannot change the selection range
 // with more than 20 opertations, we are likely being blocked and cannot change
 // the selection range any more.
 const MAX_BLOCKED_COUNT = 20;
 let HTMLDocument = Ci.nsIDOMHTMLDocument;
 let HTMLHtmlElement = Ci.nsIDOMHTMLHtmlElement;
 let HTMLBodyElement = Ci.nsIDOMHTMLBodyElement;
 let HTMLIFrameElement = Ci.nsIDOMHTMLIFrameElement;
 let HTMLInputElement = Ci.nsIDOMHTMLInputElement;
 let HTMLTextAreaElement = Ci.nsIDOMHTMLTextAreaElement;
 let HTMLSelectElement = Ci.nsIDOMHTMLSelectElement;
 let HTMLOptGroupElement = Ci.nsIDOMHTMLOptGroupElement;
 let HTMLOptionElement = Ci.nsIDOMHTMLOptionElement;
 let FormVisibility = {
   /**
    * Searches upwards in the DOM for an element that has been scrolled.
    *
    * @param {HTMLElement} node element to start search at.
    * @return {Window|HTMLElement|Null} null when none are found window/element otherwise.
    */
   findScrolled: function fv_findScrolled(node) {
     let win = node.ownerDocument.defaultView;
     while (!(node instanceof HTMLBodyElement)) {
       // We can skip elements that have not been scrolled.
       // We only care about top now remember to add the scrollLeft
       // check if we decide to care about the X axis.
       if (node.scrollTop !== 0) {
         // the element has been scrolled so we may need to adjust
         // where we think the root element is located.
         //
         // Otherwise it may seem visible but be scrolled out of the viewport
         // inside this scrollable node.
         return node;
       } else {
         // this node does not effect where we think
         // the node is even if it is scrollable it has not hidden
         // the element we are looking for.
         node = node.parentNode;
         continue;
       }
     }
     // we also care about the window this is the more
     // common case where the content is larger then
     // the viewport/screen.
     if (win.scrollMaxX || win.scrollMaxY) {
       return win;
     }
     return null;
   },
   /**
    * Checks if "top  and "bottom" points of the position is visible.
    *
    * @param {Number} top position.
    * @param {Number} height of the element.
    * @param {Number} maxHeight of the window.
    * @return {Boolean} true when visible.
    */
   yAxisVisible: function fv_yAxisVisible(top, height, maxHeight) {
     return (top > 0 && (top + height) < maxHeight);
   },
   /**
    * Searches up through the dom for scrollable elements
    * which are not currently visible (relative to the viewport).
    *
    * @param {HTMLElement} element to start search at.
    * @param {Object} pos .top, .height and .width of element.
    */
   scrollablesVisible: function fv_scrollablesVisible(element, pos) {
     while ((element = this.findScrolled(element))) {
       if (element.window && element.self === element)
         break;
       // remember getBoundingClientRect does not care
       // about scrolling only where the element starts
       // in the document.
       let offset = element.getBoundingClientRect();
       // the top of both the scrollable area and
       // the form element itself are in the same document.
       // We  adjust the "top" so if the elements coordinates
       // are relative to the viewport in the current document.
       let adjustedTop = pos.top - offset.top;
       let visible = this.yAxisVisible(
         adjustedTop,
         pos.height,
         pos.width
       );
       if (!visible)
         return false;
       element = element.parentNode;
     }
     return true;
   },
   /**
    * Verifies the element is visible in the viewport.
    * Handles scrollable areas, frames and scrollable viewport(s) (windows).
    *
    * @param {HTMLElement} element to verify.
    * @return {Boolean} true when visible.
    */
   isVisible: function fv_isVisible(element) {
     // scrollable frames can be ignored we just care about iframes...
     let rect = element.getBoundingClientRect();
     let parent = element.ownerDocument.defaultView;
     // used to calculate the inner position of frames / scrollables.
     // The intent was to use this information to scroll either up or down.
     // scrollIntoView(true) will _break_ some web content so we can't do
     // this today. If we want that functionality we need to manually scroll
     // the individual elements.
     let pos = {
       top: rect.top,
       height: rect.height,
       width: rect.width
     };
     let visible = true;
     do {
       let frame = parent.frameElement;
       visible = visible &&
                 this.yAxisVisible(pos.top, pos.height, parent.innerHeight) &&
                 this.scrollablesVisible(element, pos);
       // nothing we can do about this now...
       // In the future we can use this information to scroll
       // only the elements we need to at this point as we should
       // have all the details we need to figure out how to scroll.
       if (!visible)
         return false;
       if (frame) {
         let frameRect = frame.getBoundingClientRect();
         pos.top += frameRect.top + frame.clientTop;
       }
     } while (
       (parent !== parent.parent) &&
       (parent = parent.parent)
     );
     return visible;
   }
 };
 let FormAssistant = {
   init: function fa_init() {
     addEventListener("focus", this, true, false);
     addEventListener("blur", this, true, false);
     addEventListener("resize", this, true, false);
     addEventListener("submit", this, true, false);
     addEventListener("pagehide", this, true, false);
     addEventListener("beforeunload", this, true, false);
     addEventListener("input", this, true, false);
     addEventListener("keydown", this, true, false);
     addEventListener("keyup", this, true, false);
     addMessageListener("Forms:Select:Choice", this);
     addMessageListener("Forms:Input:Value", this);
     addMessageListener("Forms:Select:Blur", this);
     addMessageListener("Forms:SetSelectionRange", this);
     addMessageListener("Forms:ReplaceSurroundingText", this);
     addMessageListener("Forms:GetText", this);
     addMessageListener("Forms:Input:SendKey", this);
     addMessageListener("Forms:GetContext", this);
     addMessageListener("Forms:SetComposition", this);
     addMessageListener("Forms:EndComposition", this);
   },
   ignoredInputTypes: new Set([
     'button', 'file', 'checkbox', 'radio', 'reset', 'submit', 'image',
     'range'
   ]),
   isKeyboardOpened: false,
   selectionStart: -1,
   selectionEnd: -1,
   textBeforeCursor: "",
   textAfterCursor: "",
   scrollIntoViewTimeout: null,
   _focusedElement: null,
   _focusCounter: 0, // up one for every time we focus a new element
   _observer: null,
   _documentEncoder: null,
   _editor: null,
   _editing: false,
   get focusedElement() {
     if (this._focusedElement && Cu.isDeadWrapper(this._focusedElement))
       this._focusedElement = null;
     return this._focusedElement;
   },
   set focusedElement(val) {
     this._focusCounter++;
     this._focusedElement = val;
   },
   setFocusedElement: function fa_setFocusedElement(element) {
     let self = this;
     if (element === this.focusedElement)
       return;
     if (this.focusedElement) {
       this.focusedElement.removeEventListener('mousedown', this);
       this.focusedElement.removeEventListener('mouseup', this);
       this.focusedElement.removeEventListener('compositionend', this);
       if (this._observer) {
         this._observer.disconnect();
         this._observer = null;
       }
       if (!element) {
         this.focusedElement.blur();
       }
     }
     this._documentEncoder = null;
     if (this._editor) {
       // When the nsIFrame of the input element is reconstructed by
       // CSS restyling, the editor observers are removed. Catch
       // [nsIEditor.removeEditorObserver] failure exception if that
       // happens.
       try {
         this._editor.removeEditorObserver(this);
       } catch (e) {}
       this._editor = null;
     }
     if (element) {
       element.addEventListener('mousedown', this);
       element.addEventListener('mouseup', this);
       element.addEventListener('compositionend', this);
       if (isContentEditable(element)) {
         this._documentEncoder = getDocumentEncoder(element);
       }
       this._editor = getPlaintextEditor(element);
       if (this._editor) {
         // Add a nsIEditorObserver to monitor the text content of the focused
         // element.
         this._editor.addEditorObserver(this);
       }
       // If our focusedElement is removed from DOM we want to handle it properly
       let MutationObserver = element.ownerDocument.defaultView.MutationObserver;
       this._observer = new MutationObserver(function(mutations) {
         var del = [].some.call(mutations, function(m) {
           return [].some.call(m.removedNodes, function(n) {
             return n.contains(element);
           });
         });
         if (del && element === self.focusedElement) {
           // item was deleted, fake a blur so all state gets set correctly
           self.handleEvent({ target: element, type: "blur" });
         }
       });
       this._observer.observe(element.ownerDocument.body, {
         childList: true,
         subtree: true
       });
     }
     this.focusedElement = element;
   },
   get documentEncoder() {
     return this._documentEncoder;
   },
   // Get the nsIPlaintextEditor object of current input field.
   get editor() {
     return this._editor;
   },
   // Implements nsIEditorObserver get notification when the text content of
   // current input field has changed.
   EditAction: function fa_editAction() {
     if (this._editing) {
       return;
     }
     this.sendKeyboardState(this.focusedElement);
   },
   handleEvent: function fa_handleEvent(evt) {
     let target = evt.target;
     let range = null;
     switch (evt.type) {
       case "focus":
         if (!target) {
           break;
         }
         // Focusing on Window, Document or iFrame should focus body
         if (target instanceof HTMLHtmlElement) {
           target = target.document.body;
         } else if (target instanceof HTMLDocument) {
           target = target.body;
         } else if (target instanceof HTMLIFrameElement) {
           target = target.contentDocument ? target.contentDocument.body
                                           : null;
         }
         if (!target) {
           break;
         }
         if (isContentEditable(target)) {
           this.showKeyboard(this.getTopLevelEditable(target));
           this.updateSelection();
           break;
         }
         if (this.isFocusableElement(target)) {
           this.showKeyboard(target);
           this.updateSelection();
         }
         break;
       case "pagehide":
       case "beforeunload":
         // We are only interested to the pagehide and beforeunload events from
         // the root document.
         if (target && target != content.document) {
           break;
         }
         // fall through
       case "blur":
       case "submit":
         if (this.focusedElement) {
           this.hideKeyboard();
           this.selectionStart = -1;
           this.selectionEnd = -1;
         }
         break;
       case 'mousedown':
          if (!this.focusedElement) {
           break;
         }
         // We only listen for this event on the currently focused element.
         // When the mouse goes down, note the cursor/selection position
         this.updateSelection();
         break;
       case 'mouseup':
         if (!this.focusedElement) {
           break;
         }
         // We only listen for this event on the currently focused element.
         // When the mouse goes up, see if the cursor has moved (or the
         // selection changed) since the mouse went down. If it has, we
         // need to tell the keyboard about it
         range = getSelectionRange(this.focusedElement);
         if (range[0] !== this.selectionStart ||
             range[1] !== this.selectionEnd) {
           this.updateSelection();
         }
         break;
       case "resize":
         if (!this.isKeyboardOpened)
           return;
         if (this.scrollIntoViewTimeout) {
           content.clearTimeout(this.scrollIntoViewTimeout);
           this.scrollIntoViewTimeout = null;
         }
         // We may receive multiple resize events in quick succession, so wait
         // a bit before scrolling the input element into view.
         if (this.focusedElement) {
           this.scrollIntoViewTimeout = content.setTimeout(function () {
             this.scrollIntoViewTimeout = null;
             if (this.focusedElement && !FormVisibility.isVisible(this.focusedElement)) {
               scrollSelectionOrElementIntoView(this.focusedElement);
             }
           }.bind(this), RESIZE_SCROLL_DELAY);
         }
         break;
       case "input":
         if (this.focusedElement) {
           // When the text content changes, notify the keyboard
           this.updateSelection();
         }
         break;
       case "keydown":
         if (!this.focusedElement) {
           break;
         }
         CompositionManager.endComposition('');
         // We use 'setTimeout' to wait until the input element accomplishes the
         // change in selection range.
         content.setTimeout(function() {
           this.updateSelection();
         }.bind(this), 0);
         break;
       case "keyup":
         if (!this.focusedElement) {
           break;
         }
         CompositionManager.endComposition('');
         break;
       case "compositionend":
         if (!this.focusedElement) {
           break;
         }
         CompositionManager.onCompositionEnd();
         break;
     }
   },
   receiveMessage: function fa_receiveMessage(msg) {
     let target = this.focusedElement;
     let json = msg.json;
     // To not break mozKeyboard contextId is optional
     if ('contextId' in json &&
         json.contextId !== this._focusCounter &&
         json.requestId) {
       // Ignore messages that are meant for a previously focused element
       sendAsyncMessage("Forms:SequenceError", {
         requestId: json.requestId,
         error: "Expected contextId " + this._focusCounter +
                " but was " + json.contextId
       });
       return;
     }
     if (!target) {
       switch (msg.name) {
       case "Forms:GetText":
         sendAsyncMessage("Forms:GetText:Result:Error", {
           requestId: json.requestId,
           error: "No focused element"
         });
         break;
       }
       return;
     }
     this._editing = true;
     switch (msg.name) {
       case "Forms:Input:Value": {
         CompositionManager.endComposition('');
         target.value = json.value;
         let event = target.ownerDocument.createEvent('HTMLEvents');
         event.initEvent('input', true, false);
         target.dispatchEvent(event);
         break;
       }
       case "Forms:Input:SendKey":
         CompositionManager.endComposition('');
         this._editing = true;
         let doKeypress = domWindowUtils.sendKeyEvent('keydown', json.keyCode,
                                   json.charCode, json.modifiers);
         if (doKeypress) {
           domWindowUtils.sendKeyEvent('keypress', json.keyCode,
                                   json.charCode, json.modifiers);
         }
         if(!json.repeat) {
           domWindowUtils.sendKeyEvent('keyup', json.keyCode,
                                     json.charCode, json.modifiers);
         }
         this._editing = false;
         if (json.requestId && doKeypress) {
           sendAsyncMessage("Forms:SendKey:Result:OK", {
             requestId: json.requestId
           });
         }
         else if (json.requestId && !doKeypress) {
           sendAsyncMessage("Forms:SendKey:Result:Error", {
             requestId: json.requestId,
             error: "Keydown event got canceled"
           });
         }
         break;
       case "Forms:Select:Choice":
         let options = target.options;
         let valueChanged = false;
         if ("index" in json) {
           if (options.selectedIndex != json.index) {
             options.selectedIndex = json.index;
             valueChanged = true;
           }
         } else if ("indexes" in json) {
           for (let i = 0; i < options.length; i++) {
             let newValue = (json.indexes.indexOf(i) != -1);
             if (options.item(i).selected != newValue) {
               options.item(i).selected = newValue;
               valueChanged = true;
             }
           }
         }
         // only fire onchange event if any selected option is changed
         if (valueChanged) {
           let event = target.ownerDocument.createEvent('HTMLEvents');
           event.initEvent('change', true, true);
           target.dispatchEvent(event);
         }
         break;
       case "Forms:Select:Blur": {
         this.setFocusedElement(null);
         break;
       }
       case "Forms:SetSelectionRange":  {
         CompositionManager.endComposition('');
         let start = json.selectionStart;
         let end =  json.selectionEnd;
         if (!setSelectionRange(target, start, end)) {
           if (json.requestId) {
             sendAsyncMessage("Forms:SetSelectionRange:Result:Error", {
               requestId: json.requestId,
               error: "failed"
             });
           }
           break;
         }
         this.updateSelection();
         if (json.requestId) {
           sendAsyncMessage("Forms:SetSelectionRange:Result:OK", {
             requestId: json.requestId,
             selectioninfo: this.getSelectionInfo()
           });
         }
         break;
       }
       case "Forms:ReplaceSurroundingText": {
         CompositionManager.endComposition('');
         let selectionRange = getSelectionRange(target);
         if (!replaceSurroundingText(target,
                                     json.text,
                                     selectionRange[0],
                                     selectionRange[1],
                                     json.offset,
                                     json.length)) {
           if (json.requestId) {
             sendAsyncMessage("Forms:ReplaceSurroundingText:Result:Error", {
               requestId: json.requestId,
               error: "failed"
             });
           }
           break;
         }
         if (json.requestId) {
           sendAsyncMessage("Forms:ReplaceSurroundingText:Result:OK", {
             requestId: json.requestId,
             selectioninfo: this.getSelectionInfo()
           });
         }
         break;
       }
       case "Forms:GetText": {
         let value = isContentEditable(target) ? getContentEditableText(target)
                                               : target.value;
         if (json.offset && json.length) {
           value = value.substr(json.offset, json.length);
         }
         else if (json.offset) {
           value = value.substr(json.offset);
         }
         sendAsyncMessage("Forms:GetText:Result:OK", {
           requestId: json.requestId,
           text: value
         });
         break;
       }
       case "Forms:GetContext": {
         let obj = getJSON(target, this._focusCounter);
         sendAsyncMessage("Forms:GetContext:Result:OK", obj);
         break;
       }
       case "Forms:SetComposition": {
         CompositionManager.setComposition(target, json.text, json.cursor,
                                           json.clauses);
         sendAsyncMessage("Forms:SetComposition:Result:OK", {
           requestId: json.requestId,
         });
         break;
       }
       case "Forms:EndComposition": {
         CompositionManager.endComposition(json.text);
         sendAsyncMessage("Forms:EndComposition:Result:OK", {
           requestId: json.requestId,
         });
         break;
       }
     }
     this._editing = false;
   },
   showKeyboard: function fa_showKeyboard(target) {
     if (this.focusedElement === target)
       return;
     if (target instanceof HTMLOptionElement)
       target = target.parentNode;
     this.setFocusedElement(target);
     let kbOpened = this.sendKeyboardState(target);
     if (this.isTextInputElement(target))
       this.isKeyboardOpened = kbOpened;
   },
   hideKeyboard: function fa_hideKeyboard() {
     sendAsyncMessage("Forms:Input", { "type": "blur" });
     this.isKeyboardOpened = false;
     this.setFocusedElement(null);
   },
   isFocusableElement: function fa_isFocusableElement(element) {
     if (element instanceof HTMLSelectElement ||
         element instanceof HTMLTextAreaElement)
       return true;
     if (element instanceof HTMLOptionElement &&
         element.parentNode instanceof HTMLSelectElement)
       return true;
     return (element instanceof HTMLInputElement &&
             !this.ignoredInputTypes.has(element.type));
   },
   isTextInputElement: function fa_isTextInputElement(element) {
     return element instanceof HTMLInputElement ||
            element instanceof HTMLTextAreaElement ||
            isContentEditable(element);
   },
   getTopLevelEditable: function fa_getTopLevelEditable(element) {
     function retrieveTopLevelEditable(element) {
       while (element && !isContentEditable(element))
         element = element.parentNode;
       return element;
     }
     return retrieveTopLevelEditable(element) || element;
   },
   sendKeyboardState: function(element) {
     // FIXME/bug 729623: work around apparent bug in the IME manager
     // in gecko.
     let readonly = element.getAttribute("readonly");
     if (readonly) {
       return false;
     }
     sendAsyncMessage("Forms:Input", getJSON(element, this._focusCounter));
     return true;
   },
   getSelectionInfo: function fa_getSelectionInfo() {
     let element = this.focusedElement;
     let range =  getSelectionRange(element);
     let text = isContentEditable(element) ? getContentEditableText(element)
                                           : element.value;
     let textAround = getTextAroundCursor(text, range);
     let changed = this.selectionStart !== range[0] ||
       this.selectionEnd !== range[1] ||
       this.textBeforeCursor !== textAround.before ||
       this.textAfterCursor !== textAround.after;
     this.selectionStart = range[0];
     this.selectionEnd = range[1];
     this.textBeforeCursor = textAround.before;
     this.textAfterCursor = textAround.after;
     return {
       selectionStart: range[0],
       selectionEnd: range[1],
       textBeforeCursor: textAround.before,
       textAfterCursor: textAround.after,
       changed: changed
     };
   },
   // Notify when the selection range changes
   updateSelection: function fa_updateSelection() {
     if (!this.focusedElement) {
       return;
     }
     let selectionInfo = this.getSelectionInfo();
     if (selectionInfo.changed) {
       sendAsyncMessage("Forms:SelectionChange", this.getSelectionInfo());
     }
   }
 };
 FormAssistant.init();
 function isContentEditable(element) {
   if (!element) {
     return false;
   }
   if (element.isContentEditable || element.designMode == "on")
     return true;
   return element.ownerDocument && element.ownerDocument.designMode == "on";
 }
 function isPlainTextField(element) {
   if (!element) {
     return false;
   }
   return element instanceof HTMLTextAreaElement ||
          (element instanceof HTMLInputElement &&
           element.mozIsTextField(false));
 }
 function getJSON(element, focusCounter) {
   // <input type=number> has a nested anonymous <input type=text> element that
   // takes focus on behalf of the number control when someone tries to focus
   // the number control. If |element| is such an anonymous text control then we
   // need it's number control here in order to get the correct 'type' etc.:
   element = element.ownerNumberControl || element;
   let type = element.type || "";
   let value = element.value || "";
   let max = element.max || "";
   let min = element.min || "";
   // Treat contenteditble element as a special text area field
   if (isContentEditable(element)) {
     type = "textarea";
     value = getContentEditableText(element);
   }
   // Until the input type=date/datetime/range have been implemented
   // let's return their real type even if the platform returns 'text'
   let attributeType = element.getAttribute("type") || "";
   if (attributeType) {
     var typeLowerCase = attributeType.toLowerCase();
     switch (typeLowerCase) {
       case "datetime":
       case "datetime-local":
       case "range":
         type = typeLowerCase;
         break;
     }
   }
   // Gecko has some support for @inputmode but behind a preference and
   // it is disabled by default.
   // Gaia is then using @x-inputmode has its proprietary way to set
   // inputmode for fields. This shouldn't be used outside of pre-installed
   // apps because the attribute is going to disappear as soon as a definitive
   // solution will be find.
   let inputmode = element.getAttribute('x-inputmode');
   if (inputmode) {
     inputmode = inputmode.toLowerCase();
   } else {
     inputmode = '';
   }
   let range = getSelectionRange(element);
   let textAround = getTextAroundCursor(value, range);
   return {
     "contextId": focusCounter,
     "type": type.toLowerCase(),
     "choices": getListForElement(element),
     "value": value,
     "inputmode": inputmode,
     "selectionStart": range[0],
     "selectionEnd": range[1],
     "max": max,
     "min": min,
     "lang": element.lang || "",
     "textBeforeCursor": textAround.before,
     "textAfterCursor": textAround.after
   };
 }
 function getTextAroundCursor(value, range) {
   let textBeforeCursor = range[0] < 100 ?
     value.substr(0, range[0]) :
     value.substr(range[0] - 100, 100);
   let textAfterCursor = range[1] + 100 > value.length ?
     value.substr(range[0], value.length) :
     value.substr(range[0], range[1] - range[0] + 100);
   return {
     before: textBeforeCursor,
     after: textAfterCursor
   };
 }
 function getListForElement(element) {
   if (!(element instanceof HTMLSelectElement))
     return null;
   let optionIndex = 0;
   let result = {
     "multiple": element.multiple,
     "choices": []
   };
   // Build up a flat JSON array of the choices.
   // In HTML, it's possible for select element choices to be under a
   // group header (but not recursively). We distinguish between headers
   // and entries using the boolean "list.group".
   let children = element.children;
   for (let i = 0; i < children.length; i++) {
     let child = children[i];
     if (child instanceof HTMLOptGroupElement) {
       result.choices.push({
         "group": true,
         "text": child.label || child.firstChild.data,
         "disabled": child.disabled
       });
       let subchildren = child.children;
       for (let j = 0; j < subchildren.length; j++) {
         let subchild = subchildren[j];
         result.choices.push({
           "group": false,
           "inGroup": true,
           "text": subchild.text,
           "disabled": child.disabled || subchild.disabled,
           "selected": subchild.selected,
           "optionIndex": optionIndex++
         });
       }
     } else if (child instanceof HTMLOptionElement) {
       result.choices.push({
         "group": false,
         "inGroup": false,
         "text": child.text,
         "disabled": child.disabled,
         "selected": child.selected,
         "optionIndex": optionIndex++
       });
     }
   }
   return result;
 };
 // Create a plain text document encode from the focused element.
 function getDocumentEncoder(element) {
   let encoder = Cc["@mozilla.org/layout/documentEncoder;1?type=text/plain"]
                 .createInstance(Ci.nsIDocumentEncoder);
   let flags = Ci.nsIDocumentEncoder.SkipInvisibleContent |
               Ci.nsIDocumentEncoder.OutputRaw |
               Ci.nsIDocumentEncoder.OutputDropInvisibleBreak |
               // Bug 902847. Don't trim trailing spaces of a line.
               Ci.nsIDocumentEncoder.OutputDontRemoveLineEndingSpaces |
               Ci.nsIDocumentEncoder.OutputLFLineBreak |
               Ci.nsIDocumentEncoder.OutputNonTextContentAsPlaceholder;
   encoder.init(element.ownerDocument, "text/plain", flags);
   return encoder;
 }
 // Get the visible content text of a content editable element
 function getContentEditableText(element) {
   if (!element || !isContentEditable(element)) {
     return null;
   }
   let doc = element.ownerDocument;
   let range = doc.createRange();
   range.selectNodeContents(element);
   let encoder = FormAssistant.documentEncoder;
   encoder.setRange(range);
   return encoder.encodeToString();
 }
 function getSelectionRange(element) {
   let start = 0;
   let end = 0;
   if (isPlainTextField(element)) {
     // Get the selection range of <input> and <textarea> elements
     start = element.selectionStart;
     end = element.selectionEnd;
   } else if (isContentEditable(element)){
     // Get the selection range of contenteditable elements
     let win = element.ownerDocument.defaultView;
     let sel = win.getSelection();
     if (sel && sel.rangeCount > 0) {
       start = getContentEditableSelectionStart(element, sel);
       end = start + getContentEditableSelectionLength(element, sel);
     } else {
       dump("Failed to get window.getSelection()\n");
     }
    }
    return [start, end];
  }
 function getContentEditableSelectionStart(element, selection) {
   let doc = element.ownerDocument;
   let range = doc.createRange();
   range.setStart(element, 0);
   range.setEnd(selection.anchorNode, selection.anchorOffset);
   let encoder = FormAssistant.documentEncoder;
   encoder.setRange(range);
   return encoder.encodeToString().length;
 }
 function getContentEditableSelectionLength(element, selection) {
   let encoder = FormAssistant.documentEncoder;
   encoder.setRange(selection.getRangeAt(0));
   return encoder.encodeToString().length;
 }
 function setSelectionRange(element, start, end) {
   let isTextField = isPlainTextField(element);
   // Check the parameters
   if (!isTextField && !isContentEditable(element)) {
     // Skip HTMLOptionElement and HTMLSelectElement elements, as they don't
     // support the operation of setSelectionRange
     return false;
   }
   let text = isTextField ? element.value : getContentEditableText(element);
   let length = text.length;
   if (start < 0) {
     start = 0;
   }
   if (end > length) {
     end = length;
   }
   if (start > end) {
     start = end;
   }
   if (isTextField) {
     // Set the selection range of <input> and <textarea> elements
     element.setSelectionRange(start, end, "forward");
     return true;
   } else {
     // set the selection range of contenteditable elements
     let win = element.ownerDocument.defaultView;
     let sel = win.getSelection();
     // Move the caret to the start position
     sel.collapse(element, 0);
     for (let i = 0; i < start; i++) {
       sel.modify("move", "forward", "character");
     }
     // Avoid entering infinite loop in case we cannot change the selection
     // range. See bug https://bugzilla.mozilla.org/show_bug.cgi?id=978918
     let oldStart = getContentEditableSelectionStart(element, sel);
     let counter = 0;
     while (oldStart < start) {
       sel.modify("move", "forward", "character");
       let newStart = getContentEditableSelectionStart(element, sel);
       if (oldStart == newStart) {
         counter++;
         if (counter > MAX_BLOCKED_COUNT) {
           return false;
         }
       } else {
         counter = 0;
         oldStart = newStart;
       }
     }
     // Extend the selection to the end position
     for (let i = start; i < end; i++) {
       sel.modify("extend", "forward", "character");
     }
     // Avoid entering infinite loop in case we cannot change the selection
     // range. See bug https://bugzilla.mozilla.org/show_bug.cgi?id=978918
     counter = 0;
     let selectionLength = end - start;
     let oldSelectionLength = getContentEditableSelectionLength(element, sel);
     while (oldSelectionLength  < selectionLength) {
       sel.modify("extend", "forward", "character");
       let newSelectionLength = getContentEditableSelectionLength(element, sel);
       if (oldSelectionLength == newSelectionLength ) {
         counter++;
         if (counter > MAX_BLOCKED_COUNT) {
           return false;
         }
       } else {
         counter = 0;
         oldSelectionLength = newSelectionLength;
       }
     }
     return true;
   }
 }
 /**
  * Scroll the given element into view.
  *
  * Calls scrollSelectionIntoView for contentEditable elements.
  */
 function scrollSelectionOrElementIntoView(element) {
   let editor = getPlaintextEditor(element);
   if (editor) {
     editor.selectionController.scrollSelectionIntoView(
       Ci.nsISelectionController.SELECTION_NORMAL,
       Ci.nsISelectionController.SELECTION_FOCUS_REGION,
       Ci.nsISelectionController.SCROLL_SYNCHRONOUS);
   } else {
       element.scrollIntoView(false);
   }
 }
 // Get nsIPlaintextEditor object from an input field
 function getPlaintextEditor(element) {
   let editor = null;
   // Get nsIEditor
   if (isPlainTextField(element)) {
     // Get from the <input> and <textarea> elements
     editor = element.QueryInterface(Ci.nsIDOMNSEditableElement).editor;
   } else if (isContentEditable(element)) {
     // Get from content editable element
     let win = element.ownerDocument.defaultView;
     let editingSession = win.QueryInterface(Ci.nsIInterfaceRequestor)
                             .getInterface(Ci.nsIWebNavigation)
                             .QueryInterface(Ci.nsIInterfaceRequestor)
                             .getInterface(Ci.nsIEditingSession);
     if (editingSession) {
       editor = editingSession.getEditorForWindow(win);
     }
   }
   if (editor) {
     editor.QueryInterface(Ci.nsIPlaintextEditor);
   }
   return editor;
 }
 function replaceSurroundingText(element, text, selectionStart, selectionEnd,
                                 offset, length) {
   let editor = FormAssistant.editor;
   if (!editor) {
     return false;
   }
   // Check the parameters.
   let start = selectionStart + offset;
   if (start < 0) {
     start = 0;
   }
   if (length < 0) {
     length = 0;
   }
   let end = start + length;
   if (selectionStart != start || selectionEnd != end) {
     // Change selection range before replacing.
     if (!setSelectionRange(element, start, end)) {
       return false;
     }
   }
   if (start != end) {
     // Delete the selected text.
     editor.deleteSelection(Ci.nsIEditor.ePrevious, Ci.nsIEditor.eStrip);
   }
   if (text) {
     // We don't use CR but LF
     // see https://bugzilla.mozilla.org/show_bug.cgi?id=902847
     text = text.replace(/\r/g, '\n');
     // Insert the text to be replaced with.
     editor.insertText(text);
   }
   return true;
 }
 let CompositionManager =  {
   _isStarted: false,
   _text: '',
   _clauseAttrMap: {
     'raw-input':
       Ci.nsICompositionStringSynthesizer.ATTR_RAWINPUT,
     'selected-raw-text':
       Ci.nsICompositionStringSynthesizer.ATTR_SELECTEDRAWTEXT,
     'converted-text':
       Ci.nsICompositionStringSynthesizer.ATTR_CONVERTEDTEXT,
     'selected-converted-text':
       Ci.nsICompositionStringSynthesizer.ATTR_SELECTEDCONVERTEDTEXT
   },
   setComposition: function cm_setComposition(element, text, cursor, clauses) {
     // Check parameters.
     if (!element) {
       return;
     }
     let len = text.length;
     if (cursor > len) {
       cursor = len;
     }
     let clauseLens = [];
     let clauseAttrs = [];
     if (clauses) {
       let remainingLength = len;
       for (let i = 0; i < clauses.length; i++) {
         if (clauses[i]) {
           let clauseLength = clauses[i].length || 0;
           // Make sure the total clauses length is not bigger than that of the
           // composition string.
           if (clauseLength > remainingLength) {
             clauseLength = remainingLength;
           }
           remainingLength -= clauseLength;
           clauseLens.push(clauseLength);
           clauseAttrs.push(this._clauseAttrMap[clauses[i].selectionType] ||
                            Ci.nsICompositionStringSynthesizer.ATTR_RAWINPUT);
         }
       }
       // If the total clauses length is less than that of the composition
       // string, extend the last clause to the end of the composition string.
       if (remainingLength > 0) {
         clauseLens[clauseLens.length - 1] += remainingLength;
       }
     } else {
       clauseLens.push(len);
       clauseAttrs.push(Ci.nsICompositionStringSynthesizer.ATTR_RAWINPUT);
     }
     // Start composition if need to.
     if (!this._isStarted) {
       this._isStarted = true;
       domWindowUtils.sendCompositionEvent('compositionstart', '', '');
       this._text = '';
     }
     // Update the composing text.
     if (this._text !== text) {
       this._text = text;
       domWindowUtils.sendCompositionEvent('compositionupdate', text, '');
     }
     let compositionString = domWindowUtils.createCompositionStringSynthesizer();
     compositionString.setString(text);
     for (var i = 0; i < clauseLens.length; i++) {
       compositionString.appendClause(clauseLens[i], clauseAttrs[i]);
     }
     if (cursor >= 0) {
       compositionString.setCaret(cursor, 0);
     }
     compositionString.dispatchEvent();
   },
   endComposition: function cm_endComposition(text) {
     if (!this._isStarted) {
       return;
     }
     // Update the composing text.
     if (this._text !== text) {
       domWindowUtils.sendCompositionEvent('compositionupdate', text, '');
     }
     let compositionString = domWindowUtils.createCompositionStringSynthesizer();
     compositionString.setString(text);
     // Set the cursor position to |text.length| so that the text will be
     // committed before the cursor position.
     compositionString.setCaret(text.length, 0);
     compositionString.dispatchEvent();
     domWindowUtils.sendCompositionEvent('compositionend', text, '');
     this._text = '';
     this._isStarted = false;
   },
   // Composition ends due to external actions.
   onCompositionEnd: function cm_onCompositionEnd() {
     if (!this._isStarted) {
       return;
     }
     this._text = '';
     this._isStarted = false;
   }
 };