From 486a6c2150055f50061220ac01b4f26d68618c1a Mon Sep 17 00:00:00 2001
From: John Darrington <john@darrington.wattle.id.au>
Date: Fri, 21 Nov 2008 08:23:08 +0900
Subject: [PATCH] Prevent sheet from stepping outside its valid cell range.

---
 lib/gtksheet/gtksheet.c | 11 +++++++++++
 src/libpspp/misc.h      | 19 +++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/lib/gtksheet/gtksheet.c b/lib/gtksheet/gtksheet.c
index ba59e677..4728891b 100644
--- a/lib/gtksheet/gtksheet.c
+++ b/lib/gtksheet/gtksheet.c
@@ -58,6 +58,7 @@
 #include "gtksheet.h"
 #include "gtkextra-marshal.h"
 #include "gsheetmodel.h"
+#include <libpspp/misc.h>
 
 /* sheet flags */
 enum
@@ -4371,6 +4372,16 @@ step_sheet (GtkSheet *sheet, GtkScrollType dir)
       break;
     }
 
+
+  maximize_int (&new_row, 0);
+  maximize_int (&new_col, 0);
+
+  minimize_int (&new_row,
+		g_sheet_row_get_row_count (sheet->row_geometry) - 1);
+
+  minimize_int (&new_col,
+		g_sheet_column_get_column_count (sheet->column_geometry) - 1);
+
   g_signal_emit (sheet, sheet_signals[TRAVERSE], 0,
 		 current_row, current_col,
 		 &new_row, &new_col, &forbidden);
diff --git a/src/libpspp/misc.h b/src/libpspp/misc.h
index 3b025157..c2f865d9 100644
--- a/src/libpspp/misc.h
+++ b/src/libpspp/misc.h
@@ -77,4 +77,23 @@ maximize (double *dest, double src)
     *dest = src;
 }
 
+
+/* Set *DEST to the lower of *DEST and SRC */
+static inline void
+minimize_int (int *dest, int src)
+{
+  if (src < *dest)
+    *dest = src;
+}
+
+
+/* Set *DEST to the greater of *DEST and SRC */
+static inline void
+maximize_int (int *dest, int src)
+{
+  if (src > *dest)
+    *dest = src;
+}
+
+
 #endif /* libpspp/misc.h */
-- 
2.30.2