softwrap: add new functions for chunks of varying width

get_chunk_row() replaces the formula "column / editwincols".

get_chunk_leftedge() replaces "(column / editwincols) * editwincols".

get_last_chunk_row() replaces "strlenpt() / editwincols".

get_last_chunk_leftedge() replaces "(strlenpt() / editwincols) * editwincols".

This prepares us for any changes in those formulas, and for more such
functions later.

src/cut.c

@@ -270,7 +270,7 @@ void do_uncut_text(void)
     add_undo(PASTE);
 
     if (ISSET(SOFTWRAP))
-	was_leftedge = (xplustabs() / editwincols) * editwincols;
+	was_leftedge = get_chunk_leftedge(openfile->current, xplustabs());
 #endif
 
     /* Add a copy of the text in the cutbuffer to the current buffer

src/files.c

@@ -777,7 +777,7 @@ void read_file(FILE *f, int fd, const char *filename, bool undoable,
 	add_undo(INSERT);
 
     if (ISSET(SOFTWRAP))
-	was_leftedge = (xplustabs() / editwincols) * editwincols;
+	was_leftedge = get_chunk_leftedge(openfile->current, xplustabs());
 #endif
 
     /* Create an empty buffer. */

src/move.c

@@ -58,7 +58,7 @@ void get_edge_and_target(size_t *leftedge, size_t *target_column)
 	if (realspan > openfile->placewewant)
 	    realspan = openfile->placewewant;
 
-	*leftedge = (realspan / editwincols) * editwincols;
+	*leftedge = get_chunk_leftedge(openfile->current, realspan);
 	*target_column = openfile->placewewant % editwincols;
     } else
 #endif
@@ -352,9 +352,11 @@ void do_home(bool be_clever)
     bool moved = FALSE;
     size_t leftedge_x = 0;
 
-    if (ISSET(SOFTWRAP))
+    if (ISSET(SOFTWRAP)) {
-	leftedge_x = actual_x(openfile->current->data,
+	size_t leftedge = get_chunk_leftedge(openfile->current, was_column);
-			(was_column / editwincols) * editwincols);
+
+	leftedge_x = actual_x(openfile->current->data, leftedge);
+    }
 
     if (ISSET(SMART_HOME) && be_clever) {
 	size_t indent_x = indent_length(openfile->current->data);
@@ -417,9 +419,9 @@ void do_end(bool be_clever)
 
 #ifndef NANO_TINY
     if (ISSET(SOFTWRAP)) {
+	size_t leftedge = get_chunk_leftedge(openfile->current, was_column);
 	size_t rightedge_x = actual_x(openfile->current->data,
-			((was_column / editwincols) * editwincols) +
+				leftedge + (editwincols - 1));
-			(editwincols - 1));
 
 	/* If already at the right edge of the screen, move fully to
 	 * the end of the line.  Otherwise, move to the right edge. */
@@ -562,8 +564,8 @@ void do_left(void)
 {
     size_t was_column = xplustabs();
 #ifndef NANO_TINY
-    size_t was_chunk = (was_column / editwincols);
     filestruct *was_current = openfile->current;
+    size_t was_chunk = get_chunk_row(was_current, was_column);
 #endif
 
     if (openfile->current_x > 0)
@@ -582,7 +584,8 @@ void do_left(void)
      * we're now above the first line of the edit window, so scroll up. */
     if (ISSET(SOFTWRAP) && openfile->current_y == 0 &&
 		openfile->current == was_current &&
-		openfile->placewewant / editwincols != was_chunk) {
+		get_chunk_row(openfile->current,
+				openfile->placewewant) != was_chunk) {
 	edit_scroll(UPWARD, ISSET(SMOOTH_SCROLL) ? 1 : editwinrows / 2 + 1);
 	return;
     }
@@ -598,8 +601,8 @@ void do_right(void)
 {
     size_t was_column = xplustabs();
 #ifndef NANO_TINY
-    size_t was_chunk = (was_column / editwincols);
     filestruct *was_current = openfile->current;
+    size_t was_chunk = get_chunk_row(was_current, was_column);
 #endif
 
     if (openfile->current->data[openfile->current_x] != '\0')
@@ -618,7 +621,8 @@ void do_right(void)
      * we're now below the first line of the edit window, so scroll down. */
     if (ISSET(SOFTWRAP) && openfile->current_y == editwinrows - 1 &&
 		openfile->current == was_current &&
-		openfile->placewewant / editwincols != was_chunk) {
+		get_chunk_row(openfile->current,
+				openfile->placewewant) != was_chunk) {
 	edit_scroll(DOWNWARD, ISSET(SMOOTH_SCROLL) ? 1 : editwinrows / 2 + 1);
 	return;
     }

src/nano.c

@@ -1759,7 +1759,7 @@ int do_mouse(void)
 	    /* Whether the click was on the row where the cursor is. */
 
 	if (ISSET(SOFTWRAP))
-	    leftedge = (xplustabs() / editwincols) * editwincols;
+	    leftedge = get_chunk_leftedge(openfile->current, xplustabs());
 	else
 #endif
 	    leftedge = get_page_start(xplustabs());
@@ -1809,8 +1809,8 @@ void do_output(char *output, size_t output_len, bool allow_cntrls)
 
     if (ISSET(SOFTWRAP)) {
 	if (openfile->current_y == editwinrows - 1)
-	    original_row = xplustabs() / editwincols;
+	    original_row = get_chunk_row(openfile->current, xplustabs());
-	orig_rows = strlenpt(openfile->current->data) / editwincols;
+	orig_rows = get_last_chunk_row(openfile->current);
     }
 #endif
 
@@ -1875,9 +1875,9 @@ void do_output(char *output, size_t output_len, bool allow_cntrls)
      * of the edit window, and we moved one screen row, we're now below
      * the last line of the edit window, so we need a full refresh too. */
     if (ISSET(SOFTWRAP) && refresh_needed == FALSE &&
-		(strlenpt(openfile->current->data) / editwincols != orig_rows ||
+		(get_last_chunk_row(openfile->current) != orig_rows ||
 		(openfile->current_y == editwinrows - 1 &&
-		xplustabs() / editwincols != original_row)))
+		get_chunk_row(openfile->current, xplustabs()) != original_row)))
 	refresh_needed = TRUE;
 #endif
 

src/proto.h

@@ -666,6 +666,10 @@ void edit_scroll(scroll_dir direction, int nrows);
 size_t get_softwrap_breakpoint(const char *text, size_t leftedge,
 				bool *end_of_line);
 size_t get_chunk(filestruct *line, size_t column, size_t *leftedge);
+size_t get_chunk_row(filestruct *line, size_t column);
+size_t get_chunk_leftedge(filestruct *line, size_t column);
+size_t get_last_chunk_row(filestruct *line);
+size_t get_last_chunk_leftedge(filestruct *line);
 void ensure_firstcolumn_is_aligned(void);
 #endif
 void edit_redraw(filestruct *old_current);

src/search.c

@@ -903,7 +903,7 @@ void do_gotolinecolumn(ssize_t line, ssize_t column, bool use_answer,
 #ifndef NANO_TINY
 	if (ISSET(SOFTWRAP)) {
 	    filestruct *line = openfile->current;
-	    size_t leftedge = (xplustabs() / editwincols) * editwincols;
+	    size_t leftedge = get_chunk_leftedge(openfile->current, xplustabs());
 
 	    rows_from_tail = (editwinrows / 2) -
 			go_forward_chunks(editwinrows / 2, &line, &leftedge);

src/text.c

@@ -112,7 +112,7 @@ void do_deletion(undo_type action)
 	update_undo(action);
 
 	if (ISSET(SOFTWRAP))
-	    orig_rows = strlenpt(openfile->current->data) / editwincols;
+	    orig_rows = get_last_chunk_row(openfile->current);
 #endif
 
 	/* Move the remainder of the line "in", over the current character. */
@@ -181,7 +181,7 @@ void do_deletion(undo_type action)
     /* If the number of screen rows that a softwrapped line occupies
      * has changed, we need a full refresh. */
     if (ISSET(SOFTWRAP) && refresh_needed == FALSE &&
-		strlenpt(openfile->current->data) / editwincols != orig_rows)
+		get_last_chunk_row(openfile->current) != orig_rows)
 	refresh_needed = TRUE;
 #endif
 

src/winio.c

@@ -2295,16 +2295,16 @@ void place_the_cursor(bool forreal)
     if (ISSET(SOFTWRAP)) {
 	filestruct *line = openfile->edittop;
 
-	row -= (openfile->firstcolumn / editwincols);
+	row -= get_chunk_row(openfile->edittop, openfile->firstcolumn);
 
 	/* Calculate how many rows the lines from edittop to current use. */
 	while (line != NULL && line != openfile->current) {
-	    row += strlenpt(line->data) / editwincols + 1;
+	    row += get_last_chunk_row(line) + 1;
 	    line = line->next;
 	}
 
 	/* Add the number of wraps in the current line before the cursor. */
-	row += xpt / editwincols;
+	row += get_chunk_row(openfile->current, xpt);
 	col = xpt % editwincols;
 
 	/* If the cursor ought to be in column zero, nudge it there. */
@@ -2753,11 +2753,11 @@ int update_softwrapped_line(filestruct *fileptr)
     if (fileptr == openfile->edittop)
 	from_col = openfile->firstcolumn;
     else
-	row -= (openfile->firstcolumn / editwincols);
+	row -= get_chunk_row(openfile->edittop, openfile->firstcolumn);
 
     /* Find out on which screen row the target line should be shown. */
     while (line != fileptr && line != NULL) {
-	row += (strlenpt(line->data) / editwincols) + 1;
+	row += get_last_chunk_row(line) + 1;
 	line = line->next;
     }
 
@@ -2813,7 +2813,7 @@ int go_back_chunks(int nrows, filestruct **line, size_t *leftedge)
 
 #ifndef NANO_TINY
     if (ISSET(SOFTWRAP)) {
-	size_t current_chunk = (*leftedge) / editwincols;
+	size_t current_chunk = get_chunk_row(*line, *leftedge);
 
 	/* Recede through the requested number of chunks. */
 	for (i = nrows; i > 0; i--) {
@@ -2826,7 +2826,7 @@ int go_back_chunks(int nrows, filestruct **line, size_t *leftedge)
 		break;
 
 	    *line = (*line)->prev;
-	    current_chunk = strlenpt((*line)->data) / editwincols;
+	    current_chunk = get_last_chunk_row(*line);
 	}
 
 	/* Only change leftedge when we actually could move. */
@@ -2854,8 +2854,8 @@ int go_forward_chunks(int nrows, filestruct **line, size_t *leftedge)
 
 #ifndef NANO_TINY
     if (ISSET(SOFTWRAP)) {
-	size_t current_chunk = (*leftedge) / editwincols;
+	size_t current_chunk = get_chunk_row(*line, *leftedge);
-	size_t last_chunk = strlenpt((*line)->data) / editwincols;
+	size_t last_chunk = get_last_chunk_row(*line);
 
 	/* Advance through the requested number of chunks. */
 	for (i = nrows; i > 0; i--) {
@@ -2869,7 +2869,7 @@ int go_forward_chunks(int nrows, filestruct **line, size_t *leftedge)
 
 	    *line = (*line)->next;
 	    current_chunk = 0;
-	    last_chunk = strlenpt((*line)->data) / editwincols;
+	    last_chunk = get_last_chunk_row(*line);
 	}
 
 	/* Only change leftedge when we actually could move. */
@@ -2891,7 +2891,7 @@ bool less_than_a_screenful(size_t was_lineno, size_t was_leftedge)
 #ifndef NANO_TINY
     if (ISSET(SOFTWRAP)) {
 	filestruct *line = openfile->current;
-	size_t leftedge = (xplustabs() / editwincols) * editwincols;
+	size_t leftedge = get_chunk_leftedge(openfile->current, xplustabs());
 	int rows_left = go_back_chunks(editwinrows - 1, &line, &leftedge);
 
 	return (rows_left > 0 || line->lineno < was_lineno ||
@@ -2957,11 +2957,11 @@ void edit_scroll(scroll_dir direction, int nrows)
 
 #ifndef NANO_TINY
     /* Compensate for the earlier chunks of a softwrapped line. */
-    nrows += leftedge / editwincols;
+    nrows += get_chunk_row(line, leftedge);
 
     /* Don't compensate for the chunks that are offscreen. */
     if (line == openfile->edittop)
-	nrows -= openfile->firstcolumn / editwincols;
+	nrows -= get_chunk_row(line, openfile->firstcolumn);
 #endif
 
     /* Draw new content on the blank rows inside the scrolled region
@@ -3039,6 +3039,34 @@ size_t get_chunk(filestruct *line, size_t column, size_t *leftedge)
     }
 }
 
+/* Return the row of the softwrapped chunk of the given line that column is on,
+ * relative to the first row (zero-based). */
+size_t get_chunk_row(filestruct *line, size_t column)
+{
+    return strnlenpt(line->data, column) / editwincols;
+}
+
+/* Return the leftmost column of the softwrapped chunk of the given line that
+ * column is on. */
+size_t get_chunk_leftedge(filestruct *line, size_t column)
+{
+    return (strnlenpt(line->data, column) / editwincols) * editwincols;
+}
+
+/* Return the row of the last softwrapped chunk of the given line, relative to
+ * the first row (zero-based). */
+size_t get_last_chunk_row(filestruct *line)
+{
+    return get_chunk_row(line, (size_t)-1);
+}
+
+/* Return the leftmost column of the last softwrapped chunk of the given
+ * line. */
+size_t get_last_chunk_leftedge(filestruct *line)
+{
+    return get_chunk_leftedge(line, (size_t)-1);
+}
+
 /* Ensure that firstcolumn is at the starting column of the softwrapped chunk
  * it's on.  We need to do this when the number of columns of the edit window
  * has changed, because then the width of softwrapped chunks has changed. */
@@ -3082,7 +3110,8 @@ bool current_is_below_screen(void)
 	return (go_forward_chunks(editwinrows - 1, &line, &leftedge) == 0 &&
 			(line->lineno < openfile->current->lineno ||
 			(line->lineno == openfile->current->lineno &&
-			leftedge < (xplustabs() / editwincols) * editwincols)));
+			leftedge < get_chunk_leftedge(openfile->current,
+					xplustabs()))));
     } else
 #endif
 	return (openfile->current->lineno >=
@@ -3201,7 +3230,8 @@ void adjust_viewport(update_type manner)
     openfile->edittop = openfile->current;
 #ifndef NANO_TINY
     if (ISSET(SOFTWRAP))
-	openfile->firstcolumn = (xplustabs() / editwincols) * editwincols;
+	openfile->firstcolumn = get_chunk_leftedge(openfile->current,
+							xplustabs());
 #endif
 
     /* Move edittop back goal rows, starting at current[current_x]. */