From 75177c194cba8c32f49c449f8c7e3d061558096d Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Thu, 17 Jul 2014 12:58:04 -0600
Subject: [PATCH] graphics/nxconsole/nxcon_scroll.c:  Fix scrolling in the
 NxConsole for the case of the framebuffer device.  In this case, the logic
 for clearing the vacated region at the bottom was missing so garbage up from
 the last, uncleared line

---
 graphics/nxconsole/nxcon_scroll.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/graphics/nxconsole/nxcon_scroll.c b/graphics/nxconsole/nxcon_scroll.c
index e537be0cfc..3276fc6502 100644
--- a/graphics/nxconsole/nxcon_scroll.c
+++ b/graphics/nxconsole/nxcon_scroll.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * nuttx/graphics/nxconsole/nxcon_scroll.c
  *
- *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2012, 2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -118,7 +118,7 @@ static inline void nxcon_movedisplay(FAR struct nxcon_state_s *priv,
       ret = priv->ops->fill(priv, &rect, priv->wndo.wcolor);
       if (ret < 0)
         {
-          gdbg("fill failed: %d\n", errno);
+          gdbg("Fill failed: %d\n", errno);
         }
 
       /* Fill each character that might lie within in the bounding box */
@@ -133,7 +133,7 @@ static inline void nxcon_movedisplay(FAR struct nxcon_state_s *priv,
         }
     }
 
-  /* Finally, clear the bottom part of the display */
+  /* Finally, clear the vacated part of the display */
 
   rect.pt1.y = bottom;
   rect.pt2.y = priv->wndo.wsize.h- 1;
@@ -141,7 +141,7 @@ static inline void nxcon_movedisplay(FAR struct nxcon_state_s *priv,
   ret = priv->ops->fill(priv, &rect, priv->wndo.wcolor);
   if (ret < 0)
     {
-      gdbg("nxcon_movedisplay: fill failed: %d\n", errno);
+      gdbg("Fill failed: %d\n", errno);
     }
 }
 #else
@@ -152,6 +152,10 @@ static inline void nxcon_movedisplay(FAR struct nxcon_state_s *priv,
   struct nxgl_point_s offset;
   int ret;
 
+  /* Add the line separation value to the scroll height */
+
+  scrollheight += CONFIG_NXCONSOLE_LINESEPARATION;
+
   /* Move the display in the range of 0-height up one scrollheight.  The
    * line at the bottom will be reset to the background color automatically.
    *
@@ -159,7 +163,7 @@ static inline void nxcon_movedisplay(FAR struct nxcon_state_s *priv,
    */
 
   rect.pt1.x = 0;
-  rect.pt1.y = scrollheight + CONFIG_NXCONSOLE_LINESEPARATION;
+  rect.pt1.y = scrollheight;
   rect.pt2.x = priv->wndo.wsize.w - 1;
   rect.pt2.y = priv->wndo.wsize.h - 1;
 
@@ -168,12 +172,22 @@ static inline void nxcon_movedisplay(FAR struct nxcon_state_s *priv,
   offset.x   = 0;
   offset.y   = -scrollheight;
 
-  /* Move the source rectangle */
+  /* Move the source rectangle upward by the scrollheight */
 
   ret = priv->ops->move(priv, &rect, &offset);
   if (ret < 0)
     {
-      gdbg("move failed: %d\n", errno);
+      gdbg("Move failed: %d\n", errno);
+    }
+
+  /* Finally, clear the vacated bottom part of the display */
+
+  rect.pt1.y = priv->wndo.wsize.h - scrollheight;
+
+  ret = priv->ops->fill(priv, &rect, priv->wndo.wcolor);
+  if (ret < 0)
+    {
+      gdbg("Fill failed: %d\n", errno);
     }
 }
 #endif