From 8c507fc471cfeae6805ad7021f124ff40c51b799 Mon Sep 17 00:00:00 2001
From: Ryan Phillips <ryan.a.phill@gmail.com>
Date: Fri, 6 Jul 2018 20:27:22 -0400
Subject: [PATCH] Fix undo/redo exception when there are no stored elements

- undoaction and redoaction would push undefined onto storedUndo
and storedElement respectively if the other was empty when the
action was triggered. This would cause an exception on redo during
the redraw.
- Fixes undo and redo buttons not being disabled by using find
instead of children because they are not direct children of $tool.
- Adds annotate-undo and annotate-redo to the respective buttons
when the tool does not use bootstrap.
---
 djaodjin-annotate.js | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/djaodjin-annotate.js b/djaodjin-annotate.js
index 716ca6a..bedd223 100644
--- a/djaodjin-annotate.js
+++ b/djaodjin-annotate.js
@@ -115,7 +115,7 @@ MIT License
           '</div></div>';
       } else {
         self.$tool = '<div id="" style="display:inline-block">' +
-          '<button id="undoaction">UNDO</button>';
+          '<button id="undoaction" class="annotate-undo">UNDO</button>';
         if (self.options.unselectTool) {
           self.$tool += '<input type="radio" name="' + self.toolOptionId +
             '" data-tool="null">NO TOOL SELECTED';
@@ -128,7 +128,7 @@ MIT License
           '<input type="radio" name="' + self.toolOptionId +
           '" data-tool="arrow">ARROW<input type="radio" name="' +
           self.toolOptionId + '" data-tool="pen">PEN' +
-          '<button id="redoaction"' +
+          '<button id="redoaction" class="annotate-redo"' +
           'title="Redo the last undone annotation">REDO</button>' +
           '</div>';
       }
@@ -339,17 +339,24 @@ MIT License
     },
     checkUndoRedo: function() {
       var self = this;
-      self.$tool.children('.annotate-redo').attr('disabled', self.storedUndo
-        .length === 0);
-      self.$tool.children('.annotate-undo').attr('disabled', self.storedElement
-        .length === 0);
+      self.$tool.find('.annotate-redo').attr(
+        'disabled',
+        self.storedUndo.length === 0
+      );
+      self.$tool.find('.annotate-undo').attr(
+        'disabled',
+        self.storedElement.length === 0
+      );
     },
     undoaction: function(event) {
       event.preventDefault();
       var self = this;
-      self.storedUndo.push(self.storedElement[self.storedElement.length -
-        1]);
-      self.storedElement.pop();
+      var action = self.storedElement.pop();
+
+      if (action) {
+        self.storedUndo.push(action);
+      }
+
       self.checkUndoRedo();
       self.clear();
       self.redraw();
@@ -357,8 +364,12 @@ MIT License
     redoaction: function(event) {
       event.preventDefault();
       var self = this;
-      self.storedElement.push(self.storedUndo[self.storedUndo.length - 1]);
-      self.storedUndo.pop();
+      var action = self.storedUndo.pop();
+
+      if (action) {
+        self.storedElement.push(action);
+      }
+
       self.checkUndoRedo();
       self.clear();
       self.redraw();