Fix cursor move with wide glyphs

st would always move back 1 column,
even with wide glyhps (using more than a single column).

The glyph rune is set on its first column,
and the other ones are to 0,
so loop until we detect the start of the previous glyph.

diff --git a/st.c b/st.c
index 034954d0aa83de340560498116a75930bc1b3db9..77c3e8a8d8d16e3004760a0432af437065e41fb6 100644 (file)
--- a/st.c
+++ b/st.c
@@ -86,8 +86,8 @@ enum escape_state {
 
 typedef struct {
        Glyph attr; /* current char attributes */
-       int x;
-       int y;
+       int x; /* terminal column */
+       int y; /* terminal row */
        char state;
 } TCursor;
 
@@ -2175,12 +2175,16 @@ tstrsequence(uchar c)
 void
 tcontrolcode(uchar ascii)
 {
+       size_t i;
+
        switch (ascii) {
        case '\t':   /* HT */
                tputtab(1);
                return;
        case '\b':   /* BS */
-               tmoveto(term.c.x-1, term.c.y);
+               for (i = 1; term.c.x && term.line[term.c.y][term.c.x - i].u == 0; ++i)
+                       ;
+               tmoveto(term.c.x - i, term.c.y);
                return;
        case '\r':   /* CR */
                tmoveto(0, term.c.y);