tor-browser

accessibleTextarea.js (5743B)

---

/*
* Copyright (C) 2012 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
*     * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*     * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
(function(mod) {
 mod(require("resource://devtools/client/shared/sourceeditor/codemirror/lib/codemirror.js"));
})(function(CodeMirror) {
 // CodeMirror uses an offscreen <textarea> to detect input.
 // Due to inconsistencies in the many browsers it supports, it simplifies things by
 // regularly checking if something is in the textarea, adding those characters to the
 // document, and then clearing the textarea.
 // This breaks assistive technology that wants to read from CodeMirror, because the
 // <textarea> that they interact with is constantly empty.
 // Because we target up-to-date Firefox, we can guarantee consistent input events.
 // This lets us leave the current line from the editor in our <textarea>.
 // CodeMirror still expects a mostly empty <textarea>, so we pass CodeMirror a fake
 // <textarea> that only contains the users input.
 CodeMirror.inputStyles.accessibleTextArea = class extends CodeMirror.inputStyles.textarea {
   /**
    * @override
    * @param {!Object} display
    */
   init(display) {
     super.init(display);
     this.textarea.addEventListener("compositionstart",
       this._onCompositionStart.bind(this));
   }

   _onCompositionStart() {
     if (this.textarea.selectionEnd === this.textarea.value.length) {
       return;
     }

     // CodeMirror always expects the caret to be at the end of the textarea
     // When in IME composition mode, clip the textarea to how CodeMirror expects it,
     // and then let CodeMirror do its thing.
     this.textarea.value = this.textarea.value.substring(0, this.textarea.selectionEnd);
     const length = this.textarea.value.length;
     this.textarea.setSelectionRange(length, length);
     this.prevInput = this.textarea.value;
   }

   /**
    * @override
    * @param {Boolean} typing
    */
   reset(typing) {
     if (
       typing ||
       this.contextMenuPending ||
       this.composing ||
       this.cm.somethingSelected()
     ) {
       super.reset(typing);
       return;
     }

     // When navigating around the document, keep the current visual line in the textarea.
     const cursor = this.cm.getCursor();
     let start, end;
     if (this.cm.options.lineWrapping) {
       // To get the visual line, compute the leftmost and rightmost character positions.
       const top = this.cm.charCoords(cursor, "page").top;
       start = this.cm.coordsChar({left: -Infinity, top});
       end = this.cm.coordsChar({left: Infinity, top});
     } else {
       // Limit the line to 1000 characters to prevent lag.
       const offset = Math.floor(cursor.ch / 1000) * 1000;
       start = {ch: offset, line: cursor.line};
       end = {ch: offset + 1000, line: cursor.line};
     }

     this.textarea.value = this.cm.getRange(start, end);
     const caretPosition = cursor.ch - start.ch;
     this.textarea.setSelectionRange(caretPosition, caretPosition);
     this.prevInput = this.textarea.value;
   }

   /**
    * @override
    * @return {boolean}
    */
   poll() {
     if (this.contextMenuPending || this.composing) {
       return super.poll();
     }

     const text = this.textarea.value;
     let start = 0;
     const length = Math.min(this.prevInput.length, text.length);

     while (start < length && this.prevInput[start] === text[start]) {
       ++start;
     }

     let end = 0;

     while (
       end < length - start &&
       this.prevInput[this.prevInput.length - end - 1] === text[text.length - end - 1]
     ) {
       ++end;
     }

     // CodeMirror expects the user to be typing into a blank <textarea>.
     // Pass a fake textarea into super.poll that only contains the users input.
     const placeholder = this.textarea;
     this.textarea = document.createElement("textarea");
     this.textarea.value = text.substring(start, text.length - end);
     this.textarea.setSelectionRange(
       placeholder.selectionStart - start,
       placeholder.selectionEnd - start
     );
     this.prevInput = "";
     const result = super.poll();
     this.prevInput = text;
     this.textarea = placeholder;
     return result;
   }
 };
});