1 files changed, 146 insertions, 0 deletions
diff --git a/devtools/client/shared/sourceeditor/codemirror/addon/accessibleTextarea.js b/devtools/client/shared/sourceeditor/codemirror/addon/accessibleTextarea.js
new file mode 100644
index 0000000000..6119ca0818
--- /dev/null
+++ b/devtools/client/shared/sourceeditor/codemirror/addon/accessibleTextarea.js
@@ -0,0 +1,146 @@
+/*
+ * 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;
+    }
+  };
+});