properly overhaul edit_scroll() to update the screen on its own this

time, convert the vertical movement functions to use the new version of
it, and simplify them where possible


git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@2876 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

ChangeLog

@@ -34,6 +34,16 @@ CVS code -
 	  (DLR)
 	- 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)
 	- 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
@@ -59,6 +69,12 @@ CVS code -
 - global.c:
   shortcut_init()
 	- Simplify wording of nano_gotoline_msg. (Jordi and Ken Tyler)
+- move.c:
+  do_first_line(), do_last_line()
+	- Simplify by only using edit_redraw(). (DLR)
+  do_page_up(), do_page_down()
+	- If there's less than a page of text onscreen, just call
+	  do_(first|last)_line(). (DLR)
 - nano.c:
   usage()
 	- Properly mention the support for "[+LINE,COLUMN]" on the
@@ -118,7 +134,7 @@ CVS code -
 	  as the alternate spell checking code is now the only place
 	  where it's used. (DLR)
 - winio.c:
-  edit_scroll(), edit_redraw(), edit_refresh()
+  edit_redraw(), edit_refresh()
 	- Clean up and simplify. (DLR)
   edit_update()
 	- Since we no longer use TOP, remove references to it.  Also,

src/move.c

@@ -32,28 +32,27 @@
 
 void do_first_line(void)
 {
+    const filestruct *current_save = openfile->current;
     size_t pww_save = openfile->placewewant;
 
     openfile->current = openfile->fileage;
     openfile->current_x = 0;
     openfile->placewewant = 0;
 
-    if (openfile->edittop != openfile->fileage ||
-	need_vertical_update(pww_save))
-	edit_update(CENTER);
+    edit_redraw(current_save, pww_save);
 }
 
 void do_last_line(void)
 {
+    const filestruct *current_save = openfile->current;
     size_t pww_save = openfile->placewewant;
 
     openfile->current = openfile->filebot;
     openfile->current_x = 0;
     openfile->placewewant = 0;
+    openfile->current_y = editwinrows - 1;
 
-    if (openfile->edittop->lineno + (editwinrows / 2) !=
-	openfile->filebot->lineno || need_vertical_update(pww_save))
-	edit_update(CENTER);
+    edit_redraw(current_save, pww_save);
 }
 
 void do_home(void)
@@ -100,104 +99,82 @@ void do_end(void)
 
 void do_page_up(void)
 {
-    const filestruct *current_save = openfile->current;
-    size_t pww_save = openfile->placewewant;
-
 #ifndef DISABLE_WRAPPING
     wrap_reset();
 #endif
 
-    /* If the first line of the file is onscreen, move current up there
-     * and put the cursor at the beginning of the line. */
-    if (openfile->edittop == openfile->fileage) {
-	openfile->current = openfile->fileage;
-	openfile->placewewant = 0;
-    } else {
-	/* Scroll the edit window up a page. */
-	edit_scroll(UP, editwinrows - 2);
+    /* If there's less than a page of text left on the screen, put the
+     * cursor at the beginning of the first line of the file, and then
+     * update the edit window. */
+    if (openfile->current->lineno <= editwinrows - 2)
+	do_first_line();
+    else {
+	int i;
 
+	/* If we're not in smooth scrolling mode, put the cursor at the
+	 * beginning of the top line of the edit window, as Pico
+	 * does. */
 #ifndef NANO_SMALL
-	/* If we're in smooth scrolling mode and there's at least one
-	 * page of text left, move the current line of the edit window
-	 * up a page. */
-	if (ISSET(SMOOTH_SCROLL) && openfile->current->lineno >
-		editwinrows - 2) {
-	    int i = 0;
-
-	    for (; i < editwinrows - 2; i++)
-		openfile->current = openfile->current->prev;
-	}
-	/* If we're not in smooth scrolling mode or there isn't at least
-	 * one page of text left, put the cursor at the beginning of the
-	 * top line of the edit window, as Pico does. */
-	else {
+	if (!ISSET(SMOOTH_SCROLL)) {
 #endif
 	    openfile->current = openfile->edittop;
 	    openfile->placewewant = 0;
 #ifndef NANO_SMALL
 	}
 #endif
+
+	for (i = editwinrows - 2; i > 0 && openfile->current->prev !=
+		NULL; i--)
+	    openfile->current = openfile->current->prev;
+
+	openfile->current_x = actual_x(openfile->current->data,
+	    openfile->placewewant);
+
+	/* Scroll the edit window up a page. */
+	edit_scroll(UP, editwinrows - 2);
     }
 
-    /* Get the equivalent x-coordinate of the current line. */
-    openfile->current_x = actual_x(openfile->current->data,
-	openfile->placewewant);
-
-    /* Update the screen. */
-    edit_redraw(current_save, pww_save);
-
     check_statusblank();
 }
 
 void do_page_down(void)
 {
-    const filestruct *current_save = openfile->current;
-    size_t pww_save = openfile->placewewant;
-
 #ifndef DISABLE_WRAPPING
     wrap_reset();
 #endif
 
-    /* If the last line of the file is onscreen, move current down
-     * there and put the cursor at the beginning of the line. */
-    if (openfile->edittop->lineno + editwinrows >
-	openfile->filebot->lineno) {
-	openfile->current = openfile->filebot;
-	openfile->placewewant = 0;
-    } else {
-	/* Scroll the edit window down a page. */
-	edit_scroll(DOWN, editwinrows - 2);
+    /* If there's less than a page of text left on the screen, put the
+     * cursor at the beginning of the last line of the file, and then
+     * update the edit window. */
+    if (openfile->current->lineno + editwinrows - 2 >=
+	openfile->filebot->lineno)
+	do_last_line();
+    else {
+	/* If we're not in smooth scrolling mode, put the cursor at the
+	 * beginning of the top line of the edit window, as Pico
+	 * does. */
+	int i;
 
 #ifndef NANO_SMALL
-	/* If we're in smooth scrolling mode and there's at least one
-	 * page of text left, move the current line of the edit window
-	 * down a page. */
-	if (ISSET(SMOOTH_SCROLL) && openfile->current->lineno +
-		editwinrows - 2 <= openfile->filebot->lineno) {
-	    int i = 0;
-
-	    for (; i < editwinrows - 2; i++)
-		openfile->current = openfile->current->next;
-	}
-	/* If we're not in smooth scrolling mode or there isn't at least
-	 * one page of text left, put the cursor at the beginning of the
-	 * top line of the edit window, as Pico does. */
-	else {
+	if (!ISSET(SMOOTH_SCROLL)) {
 #endif
 	    openfile->current = openfile->edittop;
 	    openfile->placewewant = 0;
 #ifndef NANO_SMALL
 	}
 #endif
+
+	for (i = editwinrows - 2; i > 0 && openfile->current->next !=
+		NULL; i--)
+	    openfile->current = openfile->current->next;
+
+	openfile->current_x = actual_x(openfile->current->data,
+		openfile->placewewant);
+
+	/* Scroll the edit window down a page. */
+	edit_scroll(DOWN, editwinrows - 2);
     }
 
-    /* Get the equivalent x-coordinate of the current line. */
-    openfile->current_x = actual_x(openfile->current->data,
-	openfile->placewewant);
-
-    /* Update the screen. */
-    edit_redraw(current_save, pww_save);
-
     check_statusblank();
 }
 
@@ -228,13 +205,14 @@ void do_up(void)
 		ISSET(SMOOTH_SCROLL) ? 1 :
 #endif
 		editwinrows / 2);
-
     /* Update the line we were on before and the line we're on now.  The
      * former needs to be redrawn if we're not on the first page, and
      * the latter needs to be drawn unconditionally. */
-    if (need_vertical_update(0))
-	update_line(openfile->current->next, 0);
-    update_line(openfile->current, openfile->current_x);
+    else {
+	if (need_vertical_update(0))
+	    update_line(openfile->current->next, 0);
+	update_line(openfile->current, openfile->current_x);
+    }
 }
 
 void do_down(void)
@@ -264,13 +242,14 @@ void do_down(void)
 		ISSET(SMOOTH_SCROLL) ? 1 :
 #endif
 		editwinrows / 2);
-
     /* Update the line we were on before and the line we're on now.  The
      * former needs to be redrawn if we're not on the first page, and
      * the latter needs to be drawn unconditionally. */
-    if (need_vertical_update(0))
-	update_line(openfile->current->prev, 0);
-    update_line(openfile->current, openfile->current_x);
+    else {
+	if (need_vertical_update(0))
+	    update_line(openfile->current->prev, 0);
+	update_line(openfile->current, openfile->current_x);
+    }
 }
 
 void do_left(bool allow_update)

src/winio.c

@@ -3503,17 +3503,12 @@ int need_vertical_update(size_t old_pww)
 /* Scroll the edit window in the given direction and the given number
  * of lines, and draw new lines on the blank lines left after the
  * scrolling.  direction is the direction to scroll, either UP or DOWN,
- * and nlines is the number of lines to scroll.
- *
- * We assume that the topmost and bottommost lines of the scrolled
- * region are where the current line was before and will be after
- * scrolling, and hence don't draw them, since we can't know which is
- * which.  edit_redraw() should be used to draw these lines, and to
- * redraw marked lines, if applicable. */
+ * and nlines is the number of lines to scroll.  We change edittop, and
+ * assume that current and current_x are up to date. */
 void edit_scroll(updown direction, int nlines)
 {
     const filestruct *foo;
-    int i, scroll_rows = 0;
+    int i;
 
     /* Scrolling less than one line or more than editwinrows lines is
      * redundant, so don't allow it. */
@@ -3521,10 +3516,8 @@ void edit_scroll(updown direction, int nlines)
 	return;
 
     /* Move the top line of the edit window up or down (depending on the
-     * value of direction) nlines lines.  If there are fewer lines of
-     * text than that left, move it to the top or bottom line of the
-     * file (depending on the value of direction).  Keep track of
-     * how many lines we moved in scroll_rows. */
+     * value of direction) nlines lines, or as many lines as we can if
+     * there are fewer than nlines lines available. */
     for (i = nlines; i > 0; i--) {
 	if (direction == UP) {
 	    if (openfile->edittop->prev == NULL)
@@ -3535,28 +3528,34 @@ void edit_scroll(updown direction, int nlines)
 		break;
 	    openfile->edittop = openfile->edittop->next;
 	}
-
-	scroll_rows++;
     }
 
-    /* Scroll the text on the screen up or down scroll_rows lines,
-     * depending on the value of direction. */
+    /* Scroll the text on the screen up or down nlines lines, depending
+     * on the value of direction. */
     scrollok(edit, TRUE);
-    wscrl(edit, (direction == UP) ? -scroll_rows : scroll_rows);
+    wscrl(edit, (direction == UP) ? -nlines : nlines);
     scrollok(edit, FALSE);
 
+    /* Add two to nlines, to account for the lines before and after the
+     * scrolled region. */
+    nlines += 2;
+
+    /* If we scrolled up, we're on the line before the scrolled
+     * region. */
     foo = openfile->edittop;
 
+    /* If we scrolled down, move down to the line before the scrolled
+     * region. */
     if (direction == DOWN) {
-	for (i = editwinrows - scroll_rows; i > 0 && foo != NULL; i--)
+	for (i = editwinrows - nlines; i > 0 && foo != NULL; i--)
 	    foo = foo->next;
     }
 
-    /* Draw new lines on the blank top or bottom lines of the edit
-     * window, depending on the value of direction, and skipping the
-     * topmost and bottommost lines. */
-    for (; scroll_rows > 0 && foo != NULL; scroll_rows--) {
-	update_line(foo, 0);
+    /* Draw new lines on the blank lines before, inside, and after the
+     * scrolled region. */
+    for (; nlines > 0 && foo != NULL; nlines--) {
+	update_line(foo, (foo == openfile->current) ?
+		openfile->current_x : 0);
 	foo = foo->next;
     }
 }