Avoid flicker while resizing

3 files changed, 43 insertions, 5 deletions

diff --git a/src/sdtui.c b/src/sdtui.c
index b09de99..3dbcb03 100644
--- a/src/sdtui.c
+++ b/src/sdtui.c
@@ -43,6 +43,7 @@
 
 #include "config.h"
 #include "stardict.h"
+#include "utils.h"
 
 #define CTRL_KEY(x)  ((x) - 'A' + 1)
 
@@ -1186,11 +1187,7 @@ process_winch_input (GIOChannel *source,
 	char c;
 	read (g_io_channel_unix_get_fd (source), &c, 1);
 
-	// TODO: look for resizeterm() and use it if available for flicker-free
-	//   resize; endwin() escapes curses mode.
-	endwin ();
-	refresh ();
-
+	update_curses_terminal_size ();
 	app_process_resize (app);
 	return TRUE;
 }
diff --git a/src/utils.c b/src/utils.c
index 8636778..ebbd4a9 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -20,7 +20,16 @@
 
 #include <glib.h>
 #include <gio/gio.h>
+#include <stdlib.h>
+#include <errno.h>
 
+#include <curses.h>
+#include <termios.h>
+#ifndef TIOCGWINSZ
+#include <sys/ioctl.h>
+#endif  // ! TIOCGWINSZ
+
+#include "config.h"
 #include "utils.h"
 
 
@@ -61,3 +70,34 @@ stream_read_string (GDataInputStream *dis, GError **error)
 
 	return s;
 }
+
+static bool
+xstrtoul (unsigned long *out, const char *s, int base)
+{
+	char *end;
+	errno = 0;
+	*out = strtoul (s, &end, base);
+	return errno == 0 && !*end && end != s;
+}
+
+// Didn't want to have this ugly piece of code in the main source file;
+// the standard endwin/refresh sequence makes the terminal flicker.
+void
+update_curses_terminal_size (void)
+{
+#if defined (HAVE_RESIZE_TERM) && defined (TIOCGWINSZ)
+	struct winsize size;
+	if (!ioctl (STDOUT_FILENO, TIOCGWINSZ, (char *) &size))
+	{
+		char *row = getenv ("LINES");
+		char *col = getenv ("COLUMNS");
+		unsigned long tmp;
+		resize_term (
+			(row && xstrtoul (&tmp, row, 10)) ? tmp : size.ws_row,
+			(col && xstrtoul (&tmp, col, 10)) ? tmp : size.ws_col);
+	}
+#else  // HAVE_RESIZE_TERM && TIOCGWINSZ
+	endwin ();
+	refresh ();
+#endif  // HAVE_RESIZE_TERM && TIOCGWINSZ
+}
diff --git a/src/utils.h b/src/utils.h
index 61c108e..c3bdd84 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -40,5 +40,6 @@
 
 gboolean stream_read_all (GByteArray *ba, GInputStream *is, GError **error);
 gchar *stream_read_string (GDataInputStream *dis, GError **error);
+void update_curses_terminal_size (void);
 
 #endif /* ! UTILS_H */