From c916d0ace30a3bc686570a0813e4131538524251 Mon Sep 17 00:00:00 2001
From: Jinhao <cnjinhao@hotmail.com>
Date: Thu, 22 Sep 2016 08:03:30 +0800
Subject: [PATCH] add textbox::set_undo_queue_length

a new method for setting the undo queue length
---
 include/nana/gui/widgets/skeletons/text_editor.hpp | 9 +++++++++
 include/nana/gui/widgets/textbox.hpp               | 6 ++++++
 source/gui/widgets/skeletons/text_editor.cpp       | 5 +++++
 source/gui/widgets/textbox.cpp                     | 8 ++++++++
 4 files changed, 28 insertions(+)

diff --git a/include/nana/gui/widgets/skeletons/text_editor.hpp b/include/nana/gui/widgets/skeletons/text_editor.hpp
index 22e099e4..a6904e2e 100644
--- a/include/nana/gui/widgets/skeletons/text_editor.hpp
+++ b/include/nana/gui/widgets/skeletons/text_editor.hpp
@@ -52,7 +52,15 @@ namespace nana{	namespace widgets
 			{
 				max_steps_ = maxs;
 				if (maxs && (commands_.size() >= maxs))
+				{
+					auto move = commands_.size() - pos_;
 					commands_.erase(commands_.begin(), commands_.begin() + (commands_.size() - maxs + 1));
+					pos_ = commands_.size() - std::min(move, commands_.size());
+				}
+				else if (0 == maxs)
+				{
+					clear();
+				}
 			}
 
 			std::size_t max_steps() const
@@ -258,6 +266,7 @@ namespace nana{	namespace widgets
 			void del();
 			void backspace(bool record_undo = true);
 			void undo(bool reverse);
+			void set_undo_queue_length(std::size_t len);
 			void move_ns(bool to_north);	//Moves up and down
 			void move_left();
 			void move_right();
diff --git a/include/nana/gui/widgets/textbox.hpp b/include/nana/gui/widgets/textbox.hpp
index 12008c37..b10425f7 100644
--- a/include/nana/gui/widgets/textbox.hpp
+++ b/include/nana/gui/widgets/textbox.hpp
@@ -228,6 +228,12 @@ namespace nana
 		/// E.g. Whether caret moves to left of selected content or moves to left of last position when left arrow key is pressed.
 		/// @param move_to_end determines whether to move caret to left of selected_content or to left of last position.
 		void select_behavior(bool move_to_end);
+
+		/// Sets the undo/redo queue length
+		/**
+		 * @param len The length of the queue. If this parameter is zero, the undo/redo is disabled.
+		 */
+		void set_undo_queue_length(std::size_t len);
 	protected:
 		//Overrides widget's virtual functions
 		native_string_type _m_caption() const throw() override;
diff --git a/source/gui/widgets/skeletons/text_editor.cpp b/source/gui/widgets/skeletons/text_editor.cpp
index a030471a..3cda2d81 100644
--- a/source/gui/widgets/skeletons/text_editor.cpp
+++ b/source/gui/widgets/skeletons/text_editor.cpp
@@ -2348,6 +2348,11 @@ namespace nana{	namespace widgets
 			_m_scrollbar();
 		}
 
+		void text_editor::set_undo_queue_length(std::size_t len)
+		{
+			undo_.max_steps(len);
+		}
+
 		void text_editor::move_ns(bool to_north)
 		{
 			const bool redraw_required = _m_cancel_select(0);
diff --git a/source/gui/widgets/textbox.cpp b/source/gui/widgets/textbox.cpp
index 76aed3ac..dcc2b702 100644
--- a/source/gui/widgets/textbox.cpp
+++ b/source/gui/widgets/textbox.cpp
@@ -606,6 +606,14 @@ namespace drawerbase {
 				editor->select_behavior(move_to_end);
 		}
 
+		void textbox::set_undo_queue_length(std::size_t len)
+		{
+			internal_scope_guard lock;
+			auto editor = get_drawer_trigger().editor();
+			if (editor)
+				editor->set_undo_queue_length(len);
+		}
+
 		//Override _m_caption for caption()
 		auto textbox::_m_caption() const throw() -> native_string_type
 		{