allow scrolling more than editwinrows lines via edit_scroll(), take 2

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2912 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

ChangeLog

@@ -36,15 +36,15 @@ CVS code -
 	- Consistently make the flags global and any variables used to
 	  hold it longs. (DLR)
 	- Make edit_scroll() sophisticated enough to keep track of
-	  current and current_x and update the lines before and after
-	  the scrolled region, and change the movement functions that
-	  use edit_scroll() to (a) set current and current_x before
-	  calling it, and (b) no longer call edit_redraw() afterward,
-	  since it's now unnecessary.  These changes eliminate
-	  redundant screen updates when the mark is on, since the mark
-	  display depends on current and current_x.  Changes to
-	  edit_scroll(), do_page_up(), do_page_down(), do_up(), and
-	  do_down(). (DLR)
+	  current and current_x, update the lines before and after the
+	  scrolled region, and properly scroll more than editwinrows
+	  lines; and change the movement functions that use
+	  edit_scroll() to (a) set current and current_x before calling
+	  it, and (b) no longer call edit_redraw() afterward, as it's
+	  now unnecessary.  These changes eliminate redundant screen
+	  updates when the mark is on, since the mark display depends on
+	  current and current_x.  Changes to edit_scroll(),
+	  do_page_up(), do_page_down(), do_up(), and do_down(). (DLR)
 	- Consistently make the fg and bg colortype struct entries and
 	  any variables used to hold them shorts.  Changes to
 	  do_colorinit() (renamed color_init()), color_to_int() (renamed

src/winio.c

@@ -3496,11 +3496,13 @@ void edit_scroll(updown direction, int nlines)
     const filestruct *foo;
     int i;
 
-    /* Scrolling less than one line or more than editwinrows lines is
-     * redundant, so don't allow it. */
-    if (nlines < 1 || nlines > editwinrows)
+    /* Don't bother scrolling less than one line. */
+    if (nlines < 1)
 	return;
 
+    /* Part 1: nlines is the number of lines we're going to scroll the
+     * text of the edit window. */
+
     /* Move the top line of the edit window up or down (depending on the
      * value of direction) nlines lines, or as many lines as we can if
      * there are fewer than nlines lines available. */
@@ -3516,22 +3518,28 @@ void edit_scroll(updown direction, int nlines)
 	}
     }
 
-    /* Scroll the text on the screen up or down nlines lines, depending
-     * on the value of direction. */
+    /* Limit nlines to the number of lines in the edit window. */
+    if (nlines > editwinrows)
+	nlines = editwinrows;
+
+    /* Scroll the text of the edit window up or down nlines lines,
+     * depending on the value of direction. */
     scrollok(edit, TRUE);
     wscrl(edit, (direction == UP) ? -nlines : nlines);
     scrollok(edit, FALSE);
 
+    /* Part 2: nlines is the number of lines in the scrolled region of
+     * the edit window that we need to draw. */
+
     /* If we scrolled up, we couldn't scroll up all nlines lines, and
-     * we're now at the top of the file, we need to treat the entire
-     * screen as the scrolled region, instead of just the top nlines
-     * lines. */
+     * we're now at the top of the file, we need to draw the entire edit
+     * window instead of just its top nlines lines. */
     if (direction == UP && i > 0 && openfile->edittop ==
 	openfile->fileage)
-	nlines = editwinrows;
+	nlines = editwinrows - 2;
 
-    /* Make nlines account for the lines before and after the scrolled
-     * region, if they're onsccreen. */
+    /* If the lines before and after the scrolled region are visible in
+     * the edit window, we need to draw them too. */
     nlines += 2;
     if (nlines > editwinrows)
 	nlines = editwinrows;