Forcing a redraw of a line only when it contains a multicolumn character,

as that is the only known situation where things go wrong.  This spares
all regular text a significant slowdown.

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@5370 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

diff --git a/ChangeLog b/ChangeLog
index 763098644f9dbd5943d5518010c39210fcd50e42..983bbe70b68786c8ec83f2b713424f47b74beab9 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-09-05  Benno Schulenberg  <bensberg@justemail.net>
+       * src/winio.c (display_string, edit_draw): Force a redraw of a line
+       only when it contains a multicolumn character, to spare all regular
+       text this significant slowdown.  This fixes Savannah bug #45684
+       reported by Wyatt Ward.
+
 2015-09-04  Benno Schulenberg  <bensberg@justemail.net>
        * src/chars.c: Reverting r5354 from August 12.  This fixes Savannah
        bug #45874.  Apparently there is /some/ state somewhere after all.

diff --git a/src/winio.c b/src/winio.c
index 32f9921be760fd8056b12f812b7d730eb4bffabd..b3a9da2e8e2cdf5600c00ffb05a4dd18d506c66d 100644 (file)
--- a/src/winio.c
+++ b/src/winio.c
@@ -40,6 +40,8 @@ static int statusblank = 0;
 static bool disable_cursorpos = FALSE;
        /* Should we temporarily disable constant cursor position
         * display? */
+static bool seen_wide = FALSE;
+       /* Whether we've seen a multicolumn character in the current line. */
 
 static sig_atomic_t sigwinch_counter_save = 0;
 
@@ -1896,6 +1898,7 @@ char *display_string(const char *buf, size_t start_col, size_t len, bool
     converted = charalloc(alloc_len);
 
     index = 0;
+    seen_wide = FALSE;
 
     if (buf[start_index] != '\0' && buf[start_index] != '\t' &&
        (column < start_col || (dollars && column > 0))) {
@@ -1939,6 +1942,9 @@ char *display_string(const char *buf, size_t start_col, size_t len, bool
     while (buf[start_index] != '\0') {
        buf_mb_len = parse_mbchar(buf + start_index, buf_mb, NULL);
 
+       if (mbwidth(buf + start_index) > 1)
+           seen_wide = TRUE;
+
        /* Make sure there's enough room for the next character, whether
         * it's a multibyte control character, a non-control multibyte
         * character, a tab character, or a null terminator. */
@@ -2472,7 +2478,8 @@ void edit_draw(filestruct *fileptr, const char *converted, int
     /* Tell ncurses to really redraw the line without trying to optimize
      * for what it thinks is already there, because it gets it wrong in
      * the case of a wide character in column zero.  See bug #31743. */
-    wredrawln(edit, line, 1);
+    if (seen_wide)
+       wredrawln(edit, line, 1);
 #endif
 
 #ifndef DISABLE_COLOR