curses UI: properly truncate q-register and file names

 * format_str() will now automatically right-truncate strings (with
   formatted control characters) exceeding the window width (or provided
   maximum width of formatted characters).
   This means that Q-Register names in the info line are now properly
   truncated.
 * introduced format_filename() which takes care of canonicalizing
   control characters in a given filename and truncate the filename
   if necessary. Filenames are currently left-truncated since the file
   name proper and the directory containing it is more significant
   than the directory names closer to the root.
   On Windows, we make sure that the drive letter is not truncated.
   The truncation rules may have to be further tweaked later.
   This feature properly truncated file names in the info line and
   in the auto-completion popup.

2 files changed, 163 insertions, 80 deletions

diff --git a/src/interface-curses.cpp b/src/interface-curses.cpp
index 5180d48..b4cdf7e 100644
--- a/src/interface-curses.cpp
+++ b/src/interface-curses.cpp
@@ -77,6 +77,13 @@
 #if defined(__PDCURSES__) && defined(G_OS_WIN32) && \
     !defined(PDCURSES_WIN32A)
 #define PDCURSES_WIN32
+
+/*
+ * A_UNDERLINE is not supported by PDCurses/win32
+ * and causes weird colors, so we simply disable it globally.
+ */
+#undef  A_UNDERLINE
+#define A_UNDERLINE 0
 #endif
 
 #ifdef NCURSES_VERSION
@@ -236,6 +243,124 @@ rgb2curses(guint32 rgb)
 	return COLOR_WHITE;
 }
 
+static gsize
+format_str(WINDOW *win, const gchar *str,
+           gssize len = -1, gint max_width = -1)
+{
+	int old_x, old_y;
+	gint chars_added = 0;
+
+	getyx(win, old_y, old_x);
+
+	if (len < 0)
+		len = strlen(str);
+	if (max_width < 0)
+		max_width = getmaxx(win) - old_x;
+
+	while (len > 0) {
+		/*
+		 * NOTE: This mapping is similar to
+		 * View::set_representations()
+		 */
+		switch (*str) {
+		case CTL_KEY_ESC:
+			chars_added++;
+			if (chars_added > max_width)
+				goto truncate;
+			waddch(win, '$' | A_REVERSE);
+			break;
+		case '\r':
+			chars_added += 2;
+			if (chars_added > max_width)
+				goto truncate;
+			waddch(win, 'C' | A_REVERSE);
+			waddch(win, 'R' | A_REVERSE);
+			break;
+		case '\n':
+			chars_added += 2;
+			if (chars_added > max_width)
+				goto truncate;
+			waddch(win, 'L' | A_REVERSE);
+			waddch(win, 'F' | A_REVERSE);
+			break;
+		case '\t':
+			chars_added += 3;
+			if (chars_added > max_width)
+				goto truncate;
+			waddch(win, 'T' | A_REVERSE);
+			waddch(win, 'A' | A_REVERSE);
+			waddch(win, 'B' | A_REVERSE);
+			break;
+		default:
+			if (IS_CTL(*str)) {
+				chars_added += 2;
+				if (chars_added > max_width)
+					goto truncate;
+				waddch(win, '^' | A_REVERSE);
+				waddch(win, CTL_ECHO(*str) | A_REVERSE);
+			} else {
+				chars_added++;
+				if (chars_added > max_width)
+					goto truncate;
+				waddch(win, *str);
+			}
+		}
+
+		str++;
+		len--;
+	}
+
+	return getcurx(win) - old_x;
+
+truncate:
+	if (max_width >= 3) {
+		/*
+		 * Truncate string
+		 */
+		wattron(win, A_UNDERLINE | A_BOLD);
+		mvwaddstr(win, old_y, old_x + max_width - 3, "...");
+		wattroff(win, A_UNDERLINE | A_BOLD);
+	}
+
+	return getcurx(win) - old_x;
+}
+
+static gsize
+format_filename(WINDOW *win, const gchar *filename,
+                gint max_width = -1)
+{
+	int old_x = getcurx(win);
+
+	gchar *filename_canon = String::canonicalize_ctl(filename);
+	size_t filename_len = strlen(filename_canon);
+
+	if (max_width < 0)
+		max_width = getmaxx(win) - old_x;
+
+	if (filename_len <= (size_t)max_width) {
+		waddstr(win, filename_canon);
+	} else {
+		const gchar *keep_post = filename_canon + filename_len -
+		                         max_width + 3;
+
+#ifdef G_OS_WIN32
+		const gchar *keep_pre = g_path_skip_root(filename_canon);
+		if (keep_pre) {
+			waddnstr(win, filename_canon,
+			         keep_pre - filename_canon);
+			keep_post += keep_pre - filename_canon;
+		}
+#endif
+		wattron(win, A_UNDERLINE | A_BOLD);
+		waddstr(win, "...");
+		wattroff(win, A_UNDERLINE | A_BOLD);
+		waddstr(win, keep_post);
+	}
+
+	g_free(filename_canon);
+	return getcurx(win) - old_x;
+}
+
 void
 ViewCurses::initialize_impl(void)
 {
@@ -247,6 +372,7 @@ InterfaceCurses::InterfaceCurses() : stdout_orig(-1), stderr_orig(-1),
                                      screen(NULL),
                                      screen_tty(NULL),
                                      info_window(NULL),
+                                     info_type(INFO_TYPE_BUFFER),
                                      info_current(NULL),
                                      msg_window(NULL),
                                      cmdline_window(NULL), cmdline_pad(NULL),
@@ -318,21 +444,7 @@ InterfaceCurses::Popup::init_pad(attr_t attr)
 
 		wattrset(pad, *entry == '*' ? A_BOLD : A_NORMAL);
 
-		if ((int)strlen(entry + 1) > cols - 2) {
-			/* truncate entry */
-			waddnstr(pad, entry + 1, cols - 2 - 3);
-			wattron(pad, A_BOLD);
-			/*
-			 * A_UNDERLINE is not supported by PDCurses/win32
-			 * and causes weird colors, so we better leave it away.
-			 */
-#ifndef PDCURSES_WIN32
-			wattron(pad, A_UNDERLINE);
-#endif
-			waddstr(pad, "...");
-		} else {
-			waddstr(pad, entry + 1);
-		}
+		format_filename(pad, entry+1);
 
 		cur_col++;
 	}
@@ -817,55 +929,6 @@ InterfaceCurses::resize_all_windows(void)
 	draw_cmdline();
 }
 
-static gsize
-format_str(WINDOW *win, const gchar *str, gsize len)
-{
-	int old_x = getcurx(win);
-
-	while (len > 0) {
-		/*
-		 * NOTE: This mapping is similar to
-		 * View::set_representations()
-		 */
-		switch (*str) {
-		case CTL_KEY_ESC:
-			waddch(win, '$' | A_REVERSE);
-			break;
-		case '\r':
-			waddch(win, 'C' | A_REVERSE);
-			waddch(win, 'R' | A_REVERSE);
-			break;
-		case '\n':
-			waddch(win, 'L' | A_REVERSE);
-			waddch(win, 'F' | A_REVERSE);
-			break;
-		case '\t':
-			waddch(win, 'T' | A_REVERSE);
-			waddch(win, 'A' | A_REVERSE);
-			waddch(win, 'B' | A_REVERSE);
-			break;
-		default:
-			if (IS_CTL(*str)) {
-				waddch(win, '^' | A_REVERSE);
-				waddch(win, CTL_ECHO(*str) | A_REVERSE);
-			} else {
-				waddch(win, *str);
-			}
-		}
-
-		str++;
-		len--;
-	}
-
-	return getcurx(win) - old_x;
-}
-
-static inline gsize
-format_str(WINDOW *win, const gchar *str)
-{
-	return format_str(win, str, strlen(str));
-}
-
 void
 InterfaceCurses::vmsg_impl(MessageType type, const gchar *fmt, va_list ap)
 {
@@ -1027,7 +1090,8 @@ void
 InterfaceCurses::draw_info(void)
 {
 	short fg, bg;
-	gchar *title;
+	const gchar *info_type_str;
+	gchar *info_current_canon, *title;
 
 	if (!info_window) /* batch mode */
 		return;
@@ -1042,15 +1106,31 @@ InterfaceCurses::draw_info(void)
 
 	wmove(info_window, 0, 0);
 	wbkgdset(info_window, ' ' | SCI_COLOR_ATTR(fg, bg));
-	/* same formatting as in command lines */
-	format_str(info_window, info_current);
+
+	switch (info_type) {
+	case INFO_TYPE_QREGISTER:
+		info_type_str = PACKAGE_NAME " - <QRegister> ";
+		waddstr(info_window, info_type_str);
+		/* same formatting as in command lines */
+		format_str(info_window, info_current);
+		break;
+
+	case INFO_TYPE_BUFFER:
+		info_type_str = PACKAGE_NAME " - <Buffer> ";
+		waddstr(info_window, info_type_str);
+		format_filename(info_window, info_current);
+		break;
+	}
+
 	wclrtoeol(info_window);
 
 	/*
 	 * Make sure the title will consist only of printable
 	 * characters
 	 */
-	title = String::canonicalize_ctl(info_current);
+	info_current_canon = String::canonicalize_ctl(info_current);
+	title = g_strconcat(info_type_str, info_current_canon, NIL);
+	g_free(info_current_canon);
 	set_window_title(title);
 	g_free(title);
 }
@@ -1060,8 +1140,8 @@ InterfaceCurses::info_update_impl(const QRegister *reg)
 {
 	g_free(info_current);
 	/* NOTE: will contain control characters */
-	info_current = g_strconcat(PACKAGE_NAME " - <QRegister> ",
-	                           reg->name, NIL);
+	info_type = INFO_TYPE_QREGISTER;
+	info_current = g_strdup(reg->name);
 	/* NOTE: drawn in event_loop_iter() */
 }
 
@@ -1069,9 +1149,9 @@ void
 InterfaceCurses::info_update_impl(const Buffer *buffer)
 {
 	g_free(info_current);
-	info_current = g_strconcat(PACKAGE_NAME " - <Buffer> ",
-	                           buffer->filename ? : UNNAMED_FILE,
-	                           buffer->dirty ? "*" : "", NIL);
+	info_type = INFO_TYPE_BUFFER;
+	info_current = g_strconcat(buffer->filename ? : UNNAMED_FILE,
+	                           buffer->dirty ? "*" : " ", NIL);
 	/* NOTE: drawn in event_loop_iter() */
 }
 
@@ -1102,8 +1182,6 @@ InterfaceCurses::cmdline_update_impl(const Cmdline *cmdline)
 	cmdline_len = format_str(cmdline_pad, cmdline->str, cmdline->len);
 
 	/*
-	 * Also A_UNDERLINE is not supported by PDCurses/win32
-	 * and causes weird colors, so we better leave it away.
 	 * A_BOLD should result in either a bold font or a brighter
 	 * color both on 8 and 16 color terminals.
 	 * This is not quite color-scheme-agnostic, but works
@@ -1113,12 +1191,13 @@ InterfaceCurses::cmdline_update_impl(const Cmdline *cmdline)
 	 * for rubbed out parts of the command line which will
 	 * be user-configurable.
 	 */
-#ifndef PDCURSES_WIN32
-	wattron(cmdline_pad, A_UNDERLINE);
-#endif
-	wattron(cmdline_pad, A_BOLD);
+	wattron(cmdline_pad, A_UNDERLINE | A_BOLD);
 
-	/* Format rubbed-out command line. */
+	/*
+	 * Format rubbed-out command line.
+	 * NOTE: This formatting will never be truncated since we're
+	 * writing into the pad which is large enough.
+	 */
 	cmdline_rubout_len = format_str(cmdline_pad, cmdline->str + cmdline->len,
 	                                cmdline->rubout_len);
 
diff --git a/src/interface-curses.h b/src/interface-curses.h
index 9bb17cd..ed228ee 100644
--- a/src/interface-curses.h
+++ b/src/interface-curses.h
@@ -103,6 +103,10 @@ typedef class InterfaceCurses : public Interface<InterfaceCurses, ViewCurses> {
 	FILE *screen_tty;
 
 	WINDOW *info_window;
+	enum {
+		INFO_TYPE_BUFFER = 0,
+		INFO_TYPE_QREGISTER
+	} info_type;
 	gchar *info_current;
 
 	WINDOW *msg_window;