csi: implement private modes 2034 + 2038

2034 enables window resize notifications, with the notifications being
in pixels.

2038 does the same, but in characters instead of pixels.

See
https://gist.github.com/rockorager/e695fb2924d36b2bcf1fff4a3704bd83
for specification

CHANGELOG.md

@@ -61,6 +61,8 @@
   will now utilize the new single-pixel buffer protocol. This mainly
   reduces the memory usage, but should also be slightly faster.
 * Support for high-res mouse wheel scroll events ([#1738][1738]).
+* Support for private modes 2034 and 2038 ([in-band window resize
+  notifications](https://gist.github.com/rockorager/e695fb2924d36b2bcf1fff4a3704bd83)).
 
 [1707]: https://codeberg.org/dnkl/foot/issues/1707
 [1738]: https://codeberg.org/dnkl/foot/issues/1738

csi.c

@@ -500,6 +500,20 @@ decset_decrst(struct terminal *term, unsigned param, bool enable)
         term->grapheme_shaping = enable;
         break;
 
+    case 2034:
+        if (enable)
+            term_enable_size_notifications_pixels(term);
+        else
+            term_disable_size_notifications_pixels(term);
+        break;
+
+    case 2038:
+        if (enable)
+            term_enable_size_notifications_chars(term);
+        else
+            term_disable_size_notifications_chars(term);
+        break;
+
     case 8452:
         term->sixel.cursor_right_of_graphics = enable;
         break;
@@ -587,6 +601,8 @@ decrqm(const struct terminal *term, unsigned param)
     case 2027: return term->conf->tweak.grapheme_width_method != GRAPHEME_WIDTH_DOUBLE
         ? DECRPM_PERMANENTLY_RESET
         : decrpm(term->grapheme_shaping);
+    case 2034: return decrpm(term->size_notifications_pixels);
+    case 2038: return decrpm(term->size_notifications_chars);
     case 8452: return decrpm(term->sixel.cursor_right_of_graphics);
     case 737769: return decrpm(term_ime_is_enabled(term));
     }
@@ -631,6 +647,8 @@ xtsave(struct terminal *term, unsigned param)
     case 2004: term->xtsave.bracketed_paste = term->bracketed_paste; break;
     case 2026: term->xtsave.app_sync_updates = term->render.app_sync_updates.enabled; break;
     case 2027: term->xtsave.grapheme_shaping = term->grapheme_shaping; break;
+    case 2034: term->xtsave.size_notifications_pixels = term->size_notifications_pixels; break;
+    case 2038: term->xtsave.size_notifications_chars = term->size_notifications_chars; break;
     case 8452: term->xtsave.sixel_cursor_right_of_graphics = term->sixel.cursor_right_of_graphics; break;
     case 737769: term->xtsave.ime = term_ime_is_enabled(term); break;
     }
@@ -674,6 +692,8 @@ xtrestore(struct terminal *term, unsigned param)
     case 2004: enable = term->xtsave.bracketed_paste; break;
     case 2026: enable = term->xtsave.app_sync_updates; break;
     case 2027: enable = term->xtsave.grapheme_shaping; break;
+    case 2034: enable = term->xtsave.size_notifications_pixels; break;
+    case 2038: enable = term->xtsave.size_notifications_chars; break;
     case 8452: enable = term->xtsave.sixel_cursor_right_of_graphics; break;
     case 737769: enable = term->xtsave.ime; break;
 
@@ -1204,33 +1224,10 @@ csi_dispatch(struct terminal *term, uint8_t final)
                 break;
             }
 
-            case 14: { /* report window size in pixels */
+            case 14: { /* report window/text-area size in pixels */
-                int width = -1;
-                int height = -1;
-
                 switch (vt_param_get(term, 1, 0)) {
-                case 0:
+                case 0: term_report_window_size_pixels(term, false); break;
-                    /* text area size */
+                case 2: term_report_window_size_pixels(term, true); break;
-                    width = term->width - term->margins.left - term->margins.right;
-                    height = term->height - term->margins.top - term->margins.bottom;
-                    break;
-
-                case 2:
-                    /* window size */
-                    width = term->width;
-                    height = term->height;
-                    break;
-
-                default:
-                    UNHANDLED();
-                    break;
-                }
-
-                if (width >= 0 && height >= 0) {
-                    char reply[64];
-                    size_t n = xsnprintf(
-                        reply, sizeof(reply), "\033[4;%d;%dt", height, width);
-                    term_to_slave(term, reply, n);
                 }
                 break;
             }
@@ -1259,10 +1256,7 @@ csi_dispatch(struct terminal *term, uint8_t final)
             }
 
             case 18: { /* text area size in chars */
-                char reply[64];
+                term_report_window_size_chars(term);
-                size_t n = xsnprintf(reply, sizeof(reply), "\033[8;%d;%dt",
-                         term->rows, term->cols);
-                term_to_slave(term, reply, n);
                 break;
             }
 

doc/foot-ctlseqs.7.scd

@@ -331,6 +331,12 @@ that corresponds to one of the following modes:
 |  2027
 :  contour
 :  Grapheme cluster processing
+|  2034
+:  TODO
+:  In-band window resize notifications, in pixels
+|  2038
+:  TODO
+:  In-band window resize notifications, in characters
 |  8452
 :  xterm
 :  Position cursor to the right of sixels, instead of on the next line

render.c

@@ -3866,6 +3866,11 @@ tiocswinsz(struct terminal *term)
         {
             LOG_ERRNO("TIOCSWINSZ");
         }
+
+        if (term->size_notifications_chars)
+            term_report_window_size_chars(term);
+        if (term->size_notifications_pixels)
+            term_report_window_size_pixels(term, false);
     }
 }
 

terminal.c

@@ -44,6 +44,7 @@
 #include "util.h"
 #include "vt.h"
 #include "xmalloc.h"
+#include "xsnprintf.h"
 
 #define PTMX_TIMING 0
 
@@ -4098,3 +4099,71 @@ term_set_user_mouse_cursor(struct terminal *term, const char *cursor)
         : NULL;
     term_xcursor_update(term);
 }
+
+void
+term_enable_size_notifications_pixels(struct terminal *term)
+{
+    if (term->size_notifications_pixels)
+        return;
+
+    term->size_notifications_pixels = true;
+    term_report_window_size_pixels(term, false);
+}
+
+void
+term_disable_size_notifications_pixels(struct terminal *term)
+{
+    if (!term->size_notifications_pixels)
+        return;
+
+    term->size_notifications_chars = false;
+}
+
+void
+term_enable_size_notifications_chars(struct terminal *term)
+{
+    if (term->size_notifications_chars)
+        return;
+
+    term->size_notifications_chars = true;
+    term_report_window_size_chars(term);
+}
+
+void
+term_disable_size_notifications_chars(struct terminal *term)
+{
+    if (!term->size_notifications_chars)
+        return;
+
+    term->size_notifications_chars = false;
+}
+
+void
+term_report_window_size_pixels(struct terminal *term, bool include_padding)
+{
+    int width = -1;
+    int height = -1;
+
+    if (!include_padding) {
+        /* The text area only */
+        width = term->width - term->margins.left - term->margins.right;
+        height = term->height - term->margins.top - term->margins.bottom;
+    } else {
+        /* The entire window, including padding */
+        width = term->width;
+        height = term->height;
+    }
+
+    char reply[64];
+    size_t n = xsnprintf(reply, sizeof(reply), "\033[4;%d;%dt", height, width);
+    term_to_slave(term, reply, n);
+}
+
+void
+term_report_window_size_chars(struct terminal *term)
+{
+    char reply[64];
+    size_t n = xsnprintf(
+        reply, sizeof(reply), "\033[8;%d;%dt", term->rows, term->cols);
+    term_to_slave(term, reply, n);
+}

terminal.h

@@ -479,6 +479,9 @@ struct terminal {
         bool sixel_display_mode:1;
         bool sixel_private_palette:1;
         bool sixel_cursor_right_of_graphics:1;
+
+        bool size_notifications_pixels:1;
+        bool size_notifications_chars:1;
     } xtsave;
 
     bool window_title_has_been_set;
@@ -741,6 +744,9 @@ struct terminal {
     char *cwd;
 
     bool grapheme_shaping;
+
+    bool size_notifications_pixels;  /* Private mode 2034 */
+    bool size_notifications_chars;   /* Private mode 2038 */
 };
 
 struct config;
@@ -860,6 +866,13 @@ bool term_spawn_new(const struct terminal *term);
 void term_enable_app_sync_updates(struct terminal *term);
 void term_disable_app_sync_updates(struct terminal *term);
 
+void term_enable_size_notifications_pixels(struct terminal *term);
+void term_disable_size_notifications_pixels(struct terminal *term);
+void term_enable_size_notifications_chars(struct terminal *term);
+void term_disable_size_notifications_chars(struct terminal *term);
+void term_report_window_size_pixels(struct terminal *term, bool include_padding);
+void term_report_window_size_chars(struct terminal *term);
+
 enum term_surface term_surface_kind(
     const struct terminal *term, const struct wl_surface *surface);