From 2b3c75b6b1c880d3db31d1d78a0bc8038aa1a738 Mon Sep 17 00:00:00 2001
From: inssein <hussein@jafferjee.ca>
Date: Wed, 3 Jun 2015 11:31:02 -0700
Subject: [PATCH] fix selection and up + down movements

---
 src/mixins/textbox_click_behavior.mixin.js | 24 ++++++++++++----------
 src/mixins/textbox_key_behavior.mixin.js   | 14 +++++++++++--
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/src/mixins/textbox_click_behavior.mixin.js b/src/mixins/textbox_click_behavior.mixin.js
index c0ef1c0e..74212c80 100644
--- a/src/mixins/textbox_click_behavior.mixin.js
+++ b/src/mixins/textbox_click_behavior.mixin.js
@@ -1,22 +1,24 @@
 (function () {
-  var getNewSelectionStartFromOffsetOverriden = fabric.IText.prototype._getNewSelectionStartFromOffset;
+  var override = fabric.IText.prototype._getNewSelectionStartFromOffset;
+
   /**
-   * Overrides the IText implementation and always sends lineIndex as 0 for Textboxes.
+   * Overrides the IText implementation and adjusts character index as there is not always a linebreak
+   *
    * @param {Number} mouseOffset
    * @param {Number} prevWidth
    * @param {Number} width
    * @param {Number} index
-   * @param {Number} lineIndex
    * @param {Number} jlen
    * @returns {Number}
    */
-  fabric.IText.prototype._getNewSelectionStartFromOffset = function (mouseOffset,
-                                                                     prevWidth, width, index, lineIndex, jlen) {
-    if (this instanceof fabric.Textbox) {
-      lineIndex = 0;
-    }
-    return getNewSelectionStartFromOffsetOverriden
-      .call(this, mouseOffset,
-      prevWidth, width, index, lineIndex, jlen);
+  fabric.IText.prototype._getNewSelectionStartFromOffset = function (mouseOffset, prevWidth, width, index, jlen) {
+    // start by getting the iText cursor location, and then figure out how many actual new lines there are
+    var cursor = this.get2DCursorLocation(index),
+      newLines = this.text.substring(0, index).split(this._reNewline).length - 1;
+
+    // adjust index by actual new lines
+    index -= cursor.lineIndex - newLines;
+
+    return override.call(this, mouseOffset, prevWidth, width, index, jlen);
   };
 })();
diff --git a/src/mixins/textbox_key_behavior.mixin.js b/src/mixins/textbox_key_behavior.mixin.js
index c1170d41..bab82dc5 100644
--- a/src/mixins/textbox_key_behavior.mixin.js
+++ b/src/mixins/textbox_key_behavior.mixin.js
@@ -2,21 +2,31 @@ fabric.util.object.extend(fabric.Textbox.prototype, /** @lends fabric.Textbox.pr
   /**
    * Overrides superclass function and adjusts cursor offset value because
    * lines do not necessarily end with a newline in Textbox.
+   *
    * @param {Event} e
    * @param {Boolean} isRight
    * @returns {Number}
    */
   getDownCursorOffset: function (e, isRight) {
-    return fabric.IText.prototype.getDownCursorOffset.apply(this, [e, isRight]) - 1;
+    var current = this.selectionStart,
+      offset = fabric.IText.prototype.getDownCursorOffset.apply(this, [e, isRight]),
+      nextNewline = this.text.indexOf('\n', current);
+
+    return nextNewline >= current && nextNewline <= current + offset ? offset : offset - 1;
   },
   /**
    * Overrides superclass function and adjusts cursor offset value because
    * lines do not necessarily end with a newline in Textbox.
+   *
    * @param {Event} e
    * @param {Boolean} isRight
    * @returns {Number}
    */
   getUpCursorOffset: function (e, isRight) {
-    return fabric.IText.prototype.getUpCursorOffset.apply(this, [e, isRight]) - 1;
+    var current = this.selectionStart,
+      offset = fabric.IText.prototype.getUpCursorOffset.apply(this, [e, isRight]),
+      previousNewLine = this.text.indexOf('\n', current - offset);
+
+    return previousNewLine >= current - offset && previousNewLine <= current ? offset : offset - 1;
   }
 });