Merge branch 'charset-shift-fixes'

CHANGELOG.md

@@ -61,6 +61,8 @@
   _Private Usage Area_ codepoints to be treated as double-width
   characters.
 * OSC 9 desktop notifications (iTerm2 compatible).
+* Support for LS2 and LS3 (locking shift) escape sequences
+  (https://codeberg.org/dnkl/foot/issues/581).
 
 
 ### Changed
@@ -166,6 +168,8 @@
 * Restore `SIGHUP` in spawned processes.
 * Text reflow performance (https://codeberg.org/dnkl/foot/issues/504).
 * IL+DL (`CSI Ps L` + `CSI Ps M`) now moves the cursor to column 0.
+* SS2 and SS3 (single shift) escape sequences behaving like locking
+  shifts (https://codeberg.org/dnkl/foot/issues/580).
 
 
 ### Security

terminal.c

@@ -1606,11 +1606,11 @@ term_reset(struct terminal *term, bool hard)
     term->bell_action_enabled = true;
     term->mouse_tracking = MOUSE_NONE;
     term->mouse_reporting = MOUSE_NORMAL;
-    term->charsets.selected = 0;
+    term->charsets.selected = G0;
-    term->charsets.set[0] = CHARSET_ASCII;
+    term->charsets.set[G0] = CHARSET_ASCII;
-    term->charsets.set[1] = CHARSET_ASCII;
+    term->charsets.set[G1] = CHARSET_ASCII;
-    term->charsets.set[2] = CHARSET_ASCII;
+    term->charsets.set[G2] = CHARSET_ASCII;
-    term->charsets.set[3] = CHARSET_ASCII;
+    term->charsets.set[G3] = CHARSET_ASCII;
     term->saved_charsets = term->charsets;
     tll_free_and_free(term->window_title_stack, free);
     term_set_window_title(term, term->conf->title);
@@ -2839,6 +2839,14 @@ ascii_printer_fast(struct terminal *term, wchar_t wc)
         xassert(!term->grid->cursor.lcf);
 }
 
+static void
+ascii_printer_single_shift(struct terminal *term, wchar_t wc)
+{
+    ascii_printer_generic(term, wc);
+    term->charsets.selected = term->charsets.saved;
+    term_update_ascii_printer(term);
+}
+
 void
 term_update_ascii_printer(struct terminal *term)
 {
@@ -2860,6 +2868,14 @@ term_update_ascii_printer(struct terminal *term)
     term->ascii_printer = new_printer;
 }
 
+void
+term_single_shift(struct terminal *term, enum charset_designator idx)
+{
+    term->charsets.saved = term->charsets.selected;
+    term->charsets.selected = idx;
+    term->ascii_printer = &ascii_printer_single_shift;
+}
+
 enum term_surface
 term_surface_kind(const struct terminal *term, const struct wl_surface *surface)
 {

terminal.h

@@ -189,9 +189,11 @@ enum cursor_origin { ORIGIN_ABSOLUTE, ORIGIN_RELATIVE };
 enum cursor_keys { CURSOR_KEYS_DONTCARE, CURSOR_KEYS_NORMAL, CURSOR_KEYS_APPLICATION };
 enum keypad_keys { KEYPAD_DONTCARE, KEYPAD_NUMERICAL, KEYPAD_APPLICATION };
 enum charset { CHARSET_ASCII, CHARSET_GRAPHIC };
+enum charset_designator { G0, G1, G2, G3 };
 
 struct charsets {
-    int selected;
+    enum charset_designator selected;
+    enum charset_designator saved;
     enum charset set[4]; /* G0-G3 */
 };
 
@@ -605,6 +607,7 @@ bool term_shutdown(struct terminal *term);
 int term_destroy(struct terminal *term);
 
 void term_update_ascii_printer(struct terminal *term);
+void term_single_shift(struct terminal *term, enum charset_designator idx);
 
 void term_reset(struct terminal *term, bool hard);
 bool term_to_slave(struct terminal *term, const void *data, size_t len);

vt.c

@@ -234,13 +234,13 @@ action_execute(struct terminal *term, uint8_t c)
 
     case '\x0e':
         /* SO - shift out */
-        term->charsets.selected = 1; /* G1 */
+        term->charsets.selected = G1;
         term_update_ascii_printer(term);
         break;
 
     case '\x0f':
         /* SI - shift in */
-        term->charsets.selected = 0; /* G0 */
+        term->charsets.selected = G0;
         term_update_ascii_printer(term);
         break;
 
@@ -426,6 +426,18 @@ action_esc_dispatch(struct terminal *term, uint8_t final)
             term_reset(term, true);
             break;
 
+        case 'n':
+            /* LS2 - Locking Shift 2 */
+            term->charsets.selected = G2;
+            term_update_ascii_printer(term);
+            break;
+
+        case 'o':
+            /* LS3 - Locking Shift 3 */
+            term->charsets.selected = G3;
+            term_update_ascii_printer(term);
+            break;
+
         case 'D':
             term_linefeed(term);
             break;
@@ -452,14 +464,12 @@ action_esc_dispatch(struct terminal *term, uint8_t final)
 
         case 'N':
             /* SS2 - Single Shift 2 */
-            term->charsets.selected = 2; /* G2 */
+            term_single_shift(term, G2);
-            term_update_ascii_printer(term);
             break;
 
         case 'O':
             /* SS3 - Single Shift 3 */
-            term->charsets.selected = 3; /* G3 */
+            term_single_shift(term, G3);
-            term_update_ascii_printer(term);
             break;
 
         case '\\':
@@ -488,7 +498,7 @@ action_esc_dispatch(struct terminal *term, uint8_t final)
         switch (final) {
         case '0': {
             size_t idx = term->vt.private - '(';
-            xassert(idx <= 3);
+            xassert(idx <= G3);
             term->charsets.set[idx] = CHARSET_GRAPHIC;
             term_update_ascii_printer(term);
             break;
@@ -496,7 +506,7 @@ action_esc_dispatch(struct terminal *term, uint8_t final)
 
         case 'B': {
             size_t idx = term->vt.private - '(';
-            xassert(idx <= 3);
+            xassert(idx <= G3);
             term->charsets.set[idx] = CHARSET_ASCII;
             term_update_ascii_printer(term);
             break;