[PATCH 1/2 V4] possible new feature: a position+portion indicator on the righthand side

[Benno Schulenberg]

V2: Use an array to remember what character plus attribute
    each scrollbar cell should contain.
V3: Do not use A_DIM as it does not work with a light background.
    And remove a no-longer-needed updating of the scroll bar.
V4: Draw the scroll bar before drawing any lines, so that 'bardata'
    will not be undefined when each line is drawn.

[This scrollbar is optionless for the moment, for ease of testing.]

This fulfills https://savannah.gnu.org/bugs/?57956.

Original-patch-by: Marco Diego Aurélio Mesquita <address@hidden>
---
 src/global.c |  4 ++++
 src/help.c   | 10 +++++-----
 src/nano.c   | 21 +++++++++++++++++----
 src/proto.h  |  2 ++
 src/winio.c  | 33 +++++++++++++++++++++++++++++++--
 5 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/src/global.c b/src/global.c
index 84103d26..0138ee80 100644
--- a/src/global.c
+++ b/src/global.c
@@ -131,7 +131,11 @@ int editwincols = -1;
                /* The number of usable columns in the edit window: COLS - 
margin. */
 int margin = 0;
                /* The amount of space reserved at the left for line numbers. */
+int thebar = 0;
+               /* Becomes 1 when a scrollbar is shown. */
 #ifndef NANO_TINY
+int *bardata = NULL;
+               /* An array of characters that together depict the scrollbar. */
 ssize_t stripe_column = 0;
                /* The column at which a vertical bar will be drawn. */
 #endif
diff --git a/src/help.c b/src/help.c
index afd1f453..4a2aa5b2 100644
--- a/src/help.c
+++ b/src/help.c
@@ -44,7 +44,7 @@ void wrap_help_text_into_buffer(void)
 {
        size_t sum = 0;
        /* Avoid overtight and overwide paragraphs in the introductory text. */
-       size_t wrapping_point = (COLS < 40) ? 40 : (COLS > 74) ? 74 : COLS;
+       size_t wrapping_point = ((COLS < 40) ? 40 : (COLS > 74) ? 74 : COLS) - 
thebar;
        const char *ptr = start_of_body;
 
        make_new_buffer();
@@ -55,7 +55,7 @@ void wrap_help_text_into_buffer(void)
                char *oneline;
 
                if (ptr == end_of_intro)
-                       wrapping_point = (COLS < 40) ? 40 : COLS;
+                       wrapping_point = ((COLS < 40) ? 40 : COLS) - thebar;
 
                if (ptr < end_of_intro || *(ptr - 1) == '\n') {
                        length = break_line(ptr, wrapping_point, TRUE);
@@ -63,7 +63,7 @@ void wrap_help_text_into_buffer(void)
                        shim = (*(ptr + length - 1) == ' ') ? 0 : 1;
                        snprintf(oneline, length + shim, "%s", ptr);
                } else {
-                       length = break_line(ptr, (COLS < 40) ? 22 : COLS - 18, 
TRUE);
+                       length = break_line(ptr, ((COLS < 40) ? 22 : COLS - 18) 
- thebar, TRUE);
                        oneline = nmalloc(length + 5);
                        snprintf(oneline, length + 5, "\t\t  %s", ptr);
                }
@@ -145,7 +145,7 @@ void show_help(void)
 
 #ifdef ENABLE_LINENUMBERS
        UNSET(LINE_NUMBERS);
-       editwincols = COLS;
+       editwincols = COLS - thebar;
        margin = 0;
 #endif
        tabsize = 8;
@@ -250,7 +250,7 @@ void show_help(void)
 
 #ifdef ENABLE_LINENUMBERS
        margin = was_margin;
-       editwincols = COLS - margin;
+       editwincols = COLS - margin - thebar;
 #endif
        tabsize = was_tabsize;
 #ifdef ENABLE_COLOR
diff --git a/src/nano.c b/src/nano.c
index 363d67ca..a30ec912 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1037,7 +1037,11 @@ void regenerate_screen(void)
        COLS = win.ws_col;
        LINES = win.ws_row;
 #endif
-       editwincols = COLS - margin;
+#ifndef NANO_TINY
+       thebar = (LINES > 5 && COLS > 9 && !ISSET(SOFTWRAP)) ? 1 : 0;
+       bardata = nrealloc(bardata, LINES * sizeof(int));
+#endif
+       editwincols = COLS - margin - thebar;
 
        /* Ensure that firstcolumn is the starting column of its chunk. */
        ensure_firstcolumn_is_aligned();
@@ -1078,8 +1082,13 @@ void do_toggle(int flag)
                        signal_init();
                        break;
                case SOFTWRAP:
-                       if (!ISSET(SOFTWRAP))
+                       if (!ISSET(SOFTWRAP)) {
+                               thebar = (LINES > 5 && COLS > 9) ? 1 : 0;
+                               bardata = nrealloc(bardata, LINES * 
sizeof(int));
                                openfile->firstcolumn = 0;
+                       } else
+                               thebar  = 0;
+                       editwincols = COLS - margin - thebar;
                        refresh_needed = TRUE;
                        break;
                case WHITESPACE_DISPLAY:
@@ -1242,7 +1251,7 @@ void confirm_margin(void)
 
        if (needed_margin != margin) {
                margin = needed_margin;
-               editwincols = COLS - margin;
+               editwincols = COLS - margin - thebar;
 
 #ifndef NANO_TINY
                /* Ensure that firstcolumn is the starting column of its chunk. 
*/
@@ -2275,7 +2284,11 @@ int main(int argc, char **argv)
        window_init();
        curs_set(0);
 
-       editwincols = COLS;
+#ifndef NANO_TINY
+       thebar = (LINES > 5 && COLS > 9 && !ISSET(SOFTWRAP)) ? 1 : 0;
+       bardata = nrealloc(bardata, LINES * sizeof(int));
+#endif
+       editwincols = COLS - thebar;
 
        /* Set up the signal handlers. */
        signal_init();
diff --git a/src/proto.h b/src/proto.h
index e6f170a9..9a27ab6b 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -93,7 +93,9 @@ extern WINDOW *bottomwin;
 extern int editwinrows;
 extern int editwincols;
 extern int margin;
+extern int thebar;
 #ifndef NANO_TINY
+extern int *bardata;
 extern ssize_t stripe_column;
 #endif
 
diff --git a/src/winio.c b/src/winio.c
index 76bb775c..292e38c7 100644
--- a/src/winio.c
+++ b/src/winio.c
@@ -2412,6 +2412,9 @@ void draw_row(int row, const char *converted, linestruct 
*line, size_t from_col)
        if (is_shorter || ISSET(SOFTWRAP))
                wclrtoeol(edit);
 
+       if (thebar)
+               mvwaddch(edit, row, COLS - 1, bardata[row]);
+
 #ifdef USING_OLD_NCURSES
        /* Tell ncurses to really redraw the line without trying to optimize
         * for what it thinks is already there, because it gets it wrong in
@@ -2780,7 +2783,7 @@ int update_line(linestruct *line, size_t index)
        }
        if (has_more) {
                wattron(edit, hilite_attribute);
-               mvwaddch(edit, row, COLS - 1, '>');
+               mvwaddch(edit, row, COLS - 1 - thebar, '>');
                wattroff(edit, hilite_attribute);
        }
 
@@ -2960,6 +2963,24 @@ bool less_than_a_screenful(size_t was_lineno, size_t 
was_leftedge)
                return (openfile->current->lineno - was_lineno < editwinrows);
 }
 
+#ifndef NANO_TINY
+/* Draw a scroll bar on the righthand side of the screen. */
+void draw_scrollbar(void)
+{
+       int totalrows = openfile->filebot->lineno;
+       int lowest = ((openfile->edittop->lineno - 1) * editwinrows) / 
totalrows;
+       int highest = lowest + (editwinrows * editwinrows) / totalrows;
+
+       if (editwinrows > totalrows)
+               highest = editwinrows;
+
+       for (int row = 0; row < editwinrows; row++) {
+               bardata[row] = ' '|((row >= lowest && row <= highest) ? 
A_REVERSE : 0);
+               mvwaddch(edit, row, COLS - 1, bardata[row]);
+       }
+}
+#endif
+
 /* Scroll the edit window one row in the given direction, and
  * draw the relevant content on the resultant blank row. */
 void edit_scroll(bool direction)
@@ -2993,6 +3014,9 @@ void edit_scroll(bool direction)
                go_forward_chunks(editwinrows - nrows, &line, &leftedge);
 
 #ifndef NANO_TINY
+       if (thebar)
+               draw_scrollbar();
+
        if (ISSET(SOFTWRAP)) {
                /* Compensate for the earlier chunks of a softwrapped line. */
                nrows += chunk_for(leftedge, line);
@@ -3267,6 +3291,11 @@ void edit_refresh(void)
        if (current_is_offscreen())
                adjust_viewport((focusing || ISSET(JUMPY_SCROLLING)) ? 
CENTERING : FLOWING);
 
+#ifndef NANO_TINY
+       if (thebar)
+               draw_scrollbar();
+#endif
+
        line = openfile->edittop;
 
        while (row < editwinrows && line != NULL) {
@@ -3426,7 +3455,7 @@ void spotlight(size_t from_col, size_t to_col)
        wattron(edit, interface_color_pair[SELECTED_TEXT]);
        waddnstr(edit, word, actual_x(word, to_col));
        if (overshoots)
-               mvwaddch(edit, openfile->current_y, COLS - 1, '>');
+               mvwaddch(edit, openfile->current_y, COLS - 1 - thebar, '>');
        wattroff(edit, interface_color_pair[SELECTED_TEXT]);
 
        free(word);
-- 
2.25.4