From ae28432e623d55fd495f0f456045c2509f1c8383 Mon Sep 17 00:00:00 2001
From: zuu <zuu@openttd.org>
Date: Mon, 10 Sep 2012 18:40:54 +0000
Subject: [PATCH] (svn r24518) -Codechange [FS#5203]: Refactor arrow key text
 edit movement code (sbr)

---
 src/textbuf.cpp    | 70 +++++++++++++++++++++++++++++++++++++---------
 src/textbuf_type.h |  7 +++++
 2 files changed, 64 insertions(+), 13 deletions(-)

diff --git a/src/textbuf.cpp b/src/textbuf.cpp
index a7e1d83d8f..90fd76266b 100644
--- a/src/textbuf.cpp
+++ b/src/textbuf.cpp
@@ -151,6 +151,59 @@ bool Textbuf::InsertClipboard()
 	return true;
 }
 
+/**
+ * Checks if it is possible to move carret to the left
+ * @return true if the caret can be moved to the left, otherwise false.
+ */
+bool Textbuf::CanMoveCaretLeft()
+{
+	return this->caretpos != 0;
+}
+
+/**
+ * Moves the caret to the left.
+ * @pre Ensure that Textbuf::CanMoveCaretLeft returns true
+ * @return The character under the caret.
+ */
+WChar Textbuf::MoveCaretLeft()
+{
+	assert(this->CanMoveCaretLeft());
+
+	WChar c;
+	const char *s = Utf8PrevChar(this->buf + this->caretpos);
+	Utf8Decode(&c, s);
+	this->caretpos    = s - this->buf;
+	this->caretxoffs -= GetCharacterWidth(FS_NORMAL, c);
+
+	return c;
+}
+
+/**
+ * Checks if it is possible to move carret to the right
+ * @return true if the caret can be moved to the right, otherwise false.
+ */
+bool Textbuf::CanMoveCaretRight()
+{
+	return this->caretpos < this->bytes - 1;
+}
+
+/**
+ * Moves the caret to the right.
+ * @pre Ensure that Textbuf::CanMoveCaretRight returns true
+ * @return The character under the caret.
+ */
+WChar Textbuf::MoveCaretRight()
+{
+	assert(this->CanMoveCaretRight());
+
+	WChar c;
+	this->caretpos   += (uint16)Utf8Decode(&c, this->buf + this->caretpos);
+	this->caretxoffs += GetCharacterWidth(FS_NORMAL, c);
+
+	Utf8Decode(&c, this->buf + this->caretpos);
+	return c;
+}
+
 /**
  * Handle text navigation with arrow keys left/right.
  * This defines where the caret will blink and the next characer interaction will occur
@@ -161,24 +214,15 @@ bool Textbuf::MovePos(int navmode)
 {
 	switch (navmode) {
 		case WKC_LEFT:
-			if (this->caretpos != 0) {
-				WChar c;
-				const char *s = Utf8PrevChar(this->buf + this->caretpos);
-				Utf8Decode(&c, s);
-				this->caretpos    = s - this->buf; // -= (this->buf + this->caretpos - s)
-				this->caretxoffs -= GetCharacterWidth(FS_NORMAL, c);
-
+			if (this->CanMoveCaretLeft()) {
+				this->MoveCaretLeft();
 				return true;
 			}
 			break;
 
 		case WKC_RIGHT:
-			if (this->caretpos < this->bytes - 1) {
-				WChar c;
-
-				this->caretpos   += (uint16)Utf8Decode(&c, this->buf + this->caretpos);
-				this->caretxoffs += GetCharacterWidth(FS_NORMAL, c);
-
+			if (this->CanMoveCaretRight()) {
+				this->MoveCaretRight();
 				return true;
 			}
 			break;
diff --git a/src/textbuf_type.h b/src/textbuf_type.h
index 0c4208f530..194c241ad6 100644
--- a/src/textbuf_type.h
+++ b/src/textbuf_type.h
@@ -12,6 +12,8 @@
 #ifndef TEXTBUF_TYPE_H
 #define TEXTBUF_TYPE_H
 
+#include "string_type.h"
+
 /** Helper/buffer for input fields. */
 struct Textbuf {
 	char *buf;                ///< buffer in which text is saved
@@ -38,6 +40,11 @@ struct Textbuf {
 
 private:
 	void DelChar(bool backspace);
+	bool CanMoveCaretLeft();
+	WChar MoveCaretLeft();
+	bool CanMoveCaretRight();
+	WChar MoveCaretRight();
+
 };
 
 #endif /* TEXTBUF_TYPE_H */