Curses: support cycling through long lists of possible auto-completions and optimized screen refreshing/redrawing

 * pressing e.g. TAB when the popup is showing a list of auto-completions
   will show the next page, eventually beginning at the first one again.
 * do not redraw curses windows in the UI methods directly. this resulted
   in flickering during command-line editing macros and ordinary macro calls
   because the physical screen was updated immediately.
   Instead, window refreshing and updated is done centrally in
   event_loop_iter() only after a key has been processed.
   Also we use wnoutrefresh() and doupdate() to send as little to the
   terminal (emulator) as possible.

5 files changed, 153 insertions, 67 deletions

diff --git a/src/cmdline.cpp b/src/cmdline.cpp
index 0907106..b0f5155 100644
--- a/src/cmdline.cpp
+++ b/src/cmdline.cpp
@@ -74,13 +74,13 @@ cmdline_keypress(gchar key)
 	gchar *echo;
 
 	/*
-	 * Cleanup messages, popups, etc...
+	 * Cleanup messages,etc...
 	 */
-	interface.popup_clear();
 	interface.msg_clear();
 
 	/*
-	 * Process immediate editing commands
+	 * Process immediate editing commands.
+	 * It may clear/hide the popup.
 	 */
 	insert = process_edit_cmd(key);
 
@@ -149,6 +149,7 @@ process_edit_cmd(gchar key)
 {
 	static gchar insert[255];
 	gint cmdline_len = cmdline ? strlen(cmdline) : 0;
+	bool clear_popup = true;
 
 	insert[0] = key;
 	insert[1] = '\0';
@@ -197,10 +198,19 @@ process_edit_cmd(gchar key)
 
 	case CTL_KEY('T'):
 		if (States::is_string()) {
+			*insert = '\0';
+			if (interface.popup_is_shown()) {
+				/* cycle through popup pages */
+				interface.popup_show();
+				clear_popup = false;
+				break;
+			}
+
 			const gchar *filename = last_occurrence(strings[0]);
 			gchar *new_chars = filename_complete(filename);
 
-			*insert = '\0';
+			clear_popup = !interface.popup_is_shown();
+
 			if (new_chars)
 				g_stpcpy(insert, new_chars);
 			g_free(new_chars);
@@ -209,32 +219,61 @@ process_edit_cmd(gchar key)
 
 	case '\t':
 		if (States::is_file()) {
+			*insert = '\0';
+			if (interface.popup_is_shown()) {
+				/* cycle through popup pages */
+				interface.popup_show();
+				clear_popup = false;
+				break;
+			}
+
 			gchar complete = escape_char == '{' ? ' ' : escape_char;
 			gchar *new_chars = filename_complete(strings[0], complete);
 
-			*insert = '\0';
+			clear_popup = !interface.popup_is_shown();
+
 			if (new_chars)
 				g_stpcpy(insert, new_chars);
 			g_free(new_chars);
 		} else if (States::current == &States::executecommand) {
 			/*
 			 * In the EC command, <TAB> completes files just like ^T
+			 * TODO: Implement shell-command completion by iterating
+			 * executables in $PATH
 			 */
+			*insert = '\0';
+			if (interface.popup_is_shown()) {
+				/* cycle through popup pages */
+				interface.popup_show();
+				clear_popup = false;
+				break;
+			}
+
 			const gchar *filename = last_occurrence(strings[0]);
 			gchar *new_chars = filename_complete(filename);
 
-			*insert = '\0';
+			clear_popup = !interface.popup_is_shown();
+
 			if (new_chars)
 				g_stpcpy(insert, new_chars);
 			g_free(new_chars);
 		} else if (States::current == &States::scintilla_symbols) {
+			*insert = '\0';
+			if (interface.popup_is_shown()) {
+				/* cycle through popup pages */
+				interface.popup_show();
+				clear_popup = false;
+				break;
+			}
+
 			const gchar *symbol = last_occurrence(strings[0], ",");
 			SymbolList &list = symbol == strings[0]
 						? Symbols::scintilla
 						: Symbols::scilexer;
 			gchar *new_chars = symbol_complete(list, symbol, ',');
 
-			*insert = '\0';
+			clear_popup = !interface.popup_is_shown();
+
 			if (new_chars)
 				g_stpcpy(insert, new_chars);
 			g_free(new_chars);
@@ -286,6 +325,9 @@ process_edit_cmd(gchar key)
 #endif
 	}
 
+	if (clear_popup)
+		interface.popup_clear();
+
 	return insert;
 }
 
@@ -364,7 +406,7 @@ filename_complete(const gchar *filename, gchar completed)
 	gchar *dirname;
 	const gchar *basename, *cur_basename;
 	GDir *dir;
-	GList *files = NULL;
+	GSList *files = NULL;
 	guint files_len = 0;
 	gchar *insert = NULL;
 	gsize filename_len;
@@ -404,10 +446,10 @@ filename_complete(const gchar *filename, gchar completed)
 		if (g_file_test(cur_filename, G_FILE_TEST_IS_DIR))
 			String::append(cur_filename, G_DIR_SEPARATOR_S);
 
-		files = g_list_prepend(files, cur_filename);
+		files = g_slist_prepend(files, cur_filename);
 
-		if (g_list_next(files)) {
-			const gchar *other_file = (gchar *)g_list_next(files)->data;
+		if (g_slist_next(files)) {
+			const gchar *other_file = (gchar *)g_slist_next(files)->data;
 			gsize len = String::diff(other_file + filename_len,
 						 cur_filename + filename_len);
 			if (len < prefix_len)
@@ -425,24 +467,22 @@ filename_complete(const gchar *filename, gchar completed)
 	g_dir_close(dir);
 
 	if (!insert && files_len > 1) {
-		files = g_list_sort(files, (GCompareFunc)g_strcmp0);
+		files = g_slist_sort(files, (GCompareFunc)g_strcmp0);
 
-		for (GList *file = g_list_first(files);
-		     file != NULL;
-		     file = g_list_next(file)) {
+		for (GSList *file = files; file; file = g_slist_next(file)) {
 			InterfaceCurrent::PopupEntryType type;
-			bool in_buffer = false;
+			bool is_buffer = false;
 
 			if (filename_is_dir((gchar *)file->data)) {
 				type = InterfaceCurrent::POPUP_DIRECTORY;
 			} else {
 				type = InterfaceCurrent::POPUP_FILE;
 				/* FIXME: inefficient */
-				in_buffer = ring.find((gchar *)file->data);
+				is_buffer = ring.find((gchar *)file->data);
 			}
 
 			interface.popup_add(type, (gchar *)file->data,
-					    in_buffer);
+					    is_buffer);
 		}
 
 		interface.popup_show();
@@ -450,9 +490,7 @@ filename_complete(const gchar *filename, gchar completed)
 		String::append(insert, completed);
 	}
 
-	for (GList *file = g_list_first(files); file; file = g_list_next(file))
-		g_free(file->data);
-	g_list_free(files);
+	g_slist_free_full(files, g_free);
 
 	return insert;
 }
diff --git a/src/interface-curses.cpp b/src/interface-curses.cpp
index 6732494..1cbcef3 100644
--- a/src/interface-curses.cpp
+++ b/src/interface-curses.cpp
@@ -97,11 +97,6 @@ InterfaceCurses::main_impl(int &argc, char **&argv)
 	cmdline_window = newwin(0, 0, LINES - 1, 0);
 	cmdline_current = NULL;
 
-	draw_info();
-	/* scintilla will be refreshed in event loop */
-	msg_clear();
-	cmdline_update("");
-
 #ifdef EMSCRIPTEN
         nodelay(cmdline_window, TRUE);
 #else
@@ -163,8 +158,8 @@ InterfaceCurses::resize_all_windows(void)
 	mvwin(cmdline_window, lines - 1, 0);
 
 	draw_info();
-	/* scintilla will be refreshed in event loop */
 	msg_clear(); /* FIXME: use saved message */
+	popup_clear();
 	cmdline_update();
 }
 
@@ -193,8 +188,6 @@ InterfaceCurses::vmsg_impl(MessageType type, const gchar *fmt, va_list ap)
 	wbkgdset(msg_window, ' ' | type2attr[type]);
 	vw_printw(msg_window, fmt, ap);
 	wclrtoeol(msg_window);
-
-	wrefresh(msg_window);
 }
 
 void
@@ -206,8 +199,6 @@ InterfaceCurses::msg_clear(void)
 	wmove(msg_window, 0, 0);
 	wbkgdset(msg_window, ' ' | SCI_COLOR_ATTR(COLOR_BLACK, COLOR_WHITE));
 	wclrtoeol(msg_window);
-
-	wrefresh(msg_window);
 }
 
 void
@@ -236,8 +227,6 @@ InterfaceCurses::draw_info(void)
 	wbkgdset(info_window, ' ' | SCI_COLOR_ATTR(COLOR_BLACK, COLOR_WHITE));
 	waddstr(info_window, info_current);
 	wclrtoeol(info_window);
-
-	wrefresh(info_window);
 }
 
 void
@@ -283,8 +272,6 @@ InterfaceCurses::cmdline_update_impl(const gchar *cmdline)
 	waddstr(cmdline_window, line);
 	waddch(cmdline_window, ' ' | A_REVERSE);
 	wclrtoeol(cmdline_window);
-
-	wrefresh(cmdline_window);
 }
 
 void
@@ -310,21 +297,34 @@ InterfaceCurses::popup_show_impl(void)
 	int lines, cols; /* screen dimensions */
 	int popup_lines;
 	gint popup_cols;
-	gint cur_entry;
+	gint popup_colwidth;
+	gint cur_col;
 
-	if (isendwin()) /* batch mode */
-		goto cleanup;
+	if (isendwin() || !popup.length)
+		/* batch mode or nothing to display */
+		return;
 
 	getmaxyx(stdscr, lines, cols);
 
-	/* reserve 2 space characters between columns */
-	popup.longest += 2;
-	popup.list = g_slist_reverse(popup.list);
+	if (popup.window)
+		delwin(popup.window);
+	else
+		/* reverse list only once */
+		popup.list = g_slist_reverse(popup.list);
 
-	/* popup_cols = floor(cols / popup.longest) */
-	popup_cols = MAX(cols / popup.longest, 1);
-	/* popup_lines = ceil(popup.length / popup_cols) */
-	popup_lines = (popup.length+popup_cols-1) / popup_cols;
+	if (!popup.cur_list) {
+		/* start from beginning of list */
+		popup.cur_list = popup.list;
+		popup.cur_entry = 0;
+	}
+
+	/* reserve 2 spaces between columns */
+	popup_colwidth = popup.longest + 2;
+
+	/* popup_cols = floor(cols / popup_colwidth) */
+	popup_cols = MAX(cols / popup_colwidth, 1);
+	/* popup_lines = ceil((popup.length-popup.cur_entry) / popup_cols) */
+	popup_lines = (popup.length-popup.cur_entry+popup_cols-1) / popup_cols;
 	/*
 	 * Popup window can cover all but one screen row.
 	 * If it does not fit, the list of tokens is truncated
@@ -336,17 +336,22 @@ InterfaceCurses::popup_show_impl(void)
 	popup.window = newwin(popup_lines, 0, lines - 1 - popup_lines, 0);
 	wbkgd(popup.window, ' ' | SCI_COLOR_ATTR(COLOR_BLACK, COLOR_BLUE));
 
-	cur_entry = 0;
-	for (GSList *cur = popup.list; cur; cur = g_slist_next(cur)) {
-		gchar *entry = (gchar *)cur->data;
-		gint cur_line = cur_entry/popup_cols + 1;
+	/*
+	 * cur_col is the row currently written.
+	 * It does not wrap but grows indefinitely.
+	 * Therefore the real current row is (cur_col % popup_cols)
+	 */
+	cur_col = 0;
+	while (popup.cur_list) {
+		gchar *entry = (gchar *)popup.cur_list->data;
+		gint cur_line = cur_col/popup_cols + 1;
 
 		wmove(popup.window,
-		      cur_line-1, (cur_entry % popup_cols)*popup.longest);
-		cur_entry++;
+		      cur_line-1, (cur_col % popup_cols)*popup_colwidth);
+		cur_col++;
 
-		if (cur_line == popup_lines && !(cur_entry % popup_cols) &&
-		    cur_entry < popup.length) {
+		if (cur_line == popup_lines && !(cur_col % popup_cols) &&
+		    g_slist_next(popup.cur_list) != NULL) {
 			/* truncate entries in the popup's very last column */
 			(void)wattrset(popup.window, A_BOLD);
 			waddstr(popup.window, "...");
@@ -355,26 +360,34 @@ InterfaceCurses::popup_show_impl(void)
 
 		(void)wattrset(popup.window, *entry == '*' ? A_BOLD : A_NORMAL);
 		waddstr(popup.window, entry + 1);
+
+		popup.cur_list = g_slist_next(popup.cur_list);
+		popup.cur_entry++;
 	}
 
-cleanup:
-	g_slist_free_full(popup.list, g_free);
-	popup.list = NULL;
-	popup.longest = popup.length = 0;
+	redrawwin(info_window);
+	/* scintilla window is redrawn by ViewCurses::refresh() */
+	redrawwin(msg_window);
 }
 
 void
 InterfaceCurses::popup_clear_impl(void)
 {
+	g_slist_free_full(popup.list, g_free);
+	popup.list = NULL;
+	popup.length = 0;
+	/* reserve at least 3 characters for "..." */
+	popup.longest = 3;
+
+	popup.cur_list = NULL;
+	popup.cur_entry = 0;
+
 	if (!popup.window)
 		return;
 
 	redrawwin(info_window);
-	wrefresh(info_window);
-	redrawwin(current_view->get_window());
-	current_view->refresh();
+	/* scintilla window is redrawn by ViewCurses::refresh() */
 	redrawwin(msg_window);
-	wrefresh(msg_window);
 
 	delwin(popup.window);
 	popup.window = NULL;
@@ -460,17 +473,29 @@ event_loop_iter()
 
 	sigint_occurred = FALSE;
 
+	wnoutrefresh(interface.info_window);
+	/* FIXME: this does wrefresh() internally */
 	interface.current_view->refresh();
+	wnoutrefresh(interface.msg_window);
+	wnoutrefresh(interface.cmdline_window);
 	if (interface.popup.window)
-		wrefresh(interface.popup.window);
+		wnoutrefresh(interface.popup.window);
+	doupdate();
 }
 
 void
 InterfaceCurses::event_loop_impl(void)
 {
-	/* initial refresh: window might have been changed in batch mode */
+	/* initial refresh */
+	/* FIXME: this does wrefresh() internally */
 	current_view->refresh();
 	draw_info();
+	wnoutrefresh(info_window);
+	msg_clear();
+	wnoutrefresh(msg_window);
+	cmdline_update("");
+	wnoutrefresh(cmdline_window);
+	doupdate();
 
 #ifdef EMSCRIPTEN
 	PDC_emscripten_set_handler(event_loop_iter, TRUE);
diff --git a/src/interface-curses.h b/src/interface-curses.h
index 35f7edb..70e5300 100644
--- a/src/interface-curses.h
+++ b/src/interface-curses.h
@@ -80,11 +80,16 @@ typedef class InterfaceCurses : public Interface<InterfaceCurses, ViewCurses> {
 
 	struct Popup {
 		WINDOW *window;
-		GSList *list;
-		gint longest;
-		gint length;
+		GSList *list;		/**! list of popup entries */
+		gint longest;		/**! size of longest entry */
+		gint length;		/**! total number of popup entries */
 
-		Popup() : window(NULL), list(NULL), longest(0), length(0) {}
+		GSList *cur_list;	/**! next entry to display */
+		gint cur_entry;	/**! next entry to display (position) */
+
+		Popup() : window(NULL), list(NULL),
+		          longest(3), length(0),
+		          cur_list(NULL), cur_entry(0) {}
 		~Popup();
 	} popup;
 
@@ -122,6 +127,12 @@ public:
 		            const gchar *name, bool highlight = false);
 	/* implementation of Interface::popup_show() */
 	void popup_show_impl(void);
+	/* implementation of Interface::popup_is_shown() */
+	inline bool
+	popup_is_shown_impl(void)
+	{
+		return popup.window != NULL;
+	}
 	/* implementation of Interface::popup_clear() */
 	void popup_clear_impl(void);
 
diff --git a/src/interface-gtk.h b/src/interface-gtk.h
index 6c8e055..ac242f2 100644
--- a/src/interface-gtk.h
+++ b/src/interface-gtk.h
@@ -116,8 +116,15 @@ public:
 	inline void
 	popup_show_impl(void)
 	{
+		/* FIXME: scroll through popup contents */
 		gtk_widget_show(popup_widget);
 	}
+	/* implementation of Interface::popup_is_shown() */
+	inline bool
+	popup_is_shown_impl(void)
+	{
+		return gtk_widget_get_visible(popup_widget);
+	}
 	/* implementation of Interface::popup_clear() */
 	void popup_clear_impl(void);
 
diff --git a/src/interface.h b/src/interface.h
index 4b5de7f..dcf72ae 100644
--- a/src/interface.h
+++ b/src/interface.h
@@ -301,6 +301,11 @@ public:
 	{
 		impl().popup_show_impl();
 	}
+	inline bool
+	popup_is_shown(void)
+	{
+		return impl().popup_is_shown_impl();
+	}
 	inline void
 	popup_clear(void)
 	{