From bab3f90e2bad590ff1eb4e0124b0174d04415e6c Mon Sep 17 00:00:00 2001
From: Keith Winstein <keithw@mit.edu>
Date: Sun, 6 Feb 2011 03:52:29 -0500
Subject: [PATCH] Better cursor-handling to save explicit moves on output

---
 terminal.hpp        |  3 ++-
 terminaldisplay.cpp | 13 +++++--------
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/terminal.hpp b/terminal.hpp
index dd7e2b0..744be1f 100644
--- a/terminal.hpp
+++ b/terminal.hpp
@@ -17,11 +17,12 @@ namespace Terminal {
     bool initialized;
     Framebuffer last_frame;
     std::string current_rendition_string;
+    int cursor_x, cursor_y;
 
   public:
     Display( int width, int height )
       : initialized( false ), last_frame( width, height ),
-	current_rendition_string()
+	current_rendition_string(), cursor_x( -1 ), cursor_y( -1 )
     {}
 
     std::string new_frame( Framebuffer &f );
diff --git a/terminaldisplay.cpp b/terminaldisplay.cpp
index 5459ef6..8209861 100644
--- a/terminaldisplay.cpp
+++ b/terminaldisplay.cpp
@@ -7,7 +7,6 @@ std::string Display::new_frame( Framebuffer &f )
   f.back_color_erase();
 
   std::string screen;
-  bool cursor_was_moved = false;
 
   /* has window title changed? */
   if ( (!initialized)
@@ -41,12 +40,10 @@ std::string Display::new_frame( Framebuffer &f )
     /* clear screen */
     screen.append( "\033[0m\033[H\033[2J" );
     initialized = false;
-    cursor_was_moved = true;
+    cursor_x = cursor_y = 0;
     current_rendition_string = "\033[0m";
   }
 
-  int cursor_x = -1, cursor_y = -1;
-
   /* iterate for every cell */
   for ( int y = 0; y < f.ds.get_height(); y++ ) {
     for ( int x = 0; x < f.ds.get_width(); /* let charwidth handle advance */ ) {
@@ -62,7 +59,6 @@ std::string Display::new_frame( Framebuffer &f )
 	char curmove[ 32 ];
 	snprintf( curmove, 32, "\033[%d;%dH", y + 1, x + 1 );
 	screen.append( curmove );
-	cursor_was_moved = true;
       }
 
       cursor_x = x;
@@ -118,13 +114,14 @@ std::string Display::new_frame( Framebuffer &f )
 
   /* has cursor location changed? */
   if ( (!initialized)
-       || (f.ds.get_cursor_row() != last_frame.ds.get_cursor_row())
-       || (f.ds.get_cursor_col() != last_frame.ds.get_cursor_col())
-       || cursor_was_moved ) {
+       || (f.ds.get_cursor_row() != cursor_y)
+       || (f.ds.get_cursor_col() != cursor_x) ) {
     char curmove[ 32 ];
     snprintf( curmove, 32, "\033[%d;%dH", f.ds.get_cursor_row() + 1,
 	      f.ds.get_cursor_col() + 1 );
     screen.append( curmove );
+    cursor_x = f.ds.get_cursor_col();
+    cursor_y = f.ds.get_cursor_row();
   }
 
   /* has cursor visibility changed? */