commit 1a195beadf101b5b3e4c36c1cd632326ef8c5c5e
parent a1dc959104b9f6d69d7917a23d514a535401d062
Author: Claudio Alessi <smoppy@gmail.com>
Date: Sat, 24 Jan 2026 21:32:02 +0100
Refactoring TUI for improved cross-VTs compatibility.
Going deeper into the rabbit hole: cross-VTs compatibility is a
nightmare and drove me to make the code a little bit messy.
Simple basic automatic detection of terminal capabilities has been
implemented, running once at startup. This lets the editor knows if it's
running on a modern or legacy terminal.
This allowed, among the other things, to restore the ZWNJ hack, which
was removed in a1dc959.
The editor now supports color modifiers, variation selectors and
regional indicator symbols in way which is 99% coherent between VTs in
compat mode (strict mode free the power of modern terminals by allowing
composed emoji).
One notable exception is the skin tone modifier: since it's not properly
rendered in terminals like kitty, I currently decide not to attempt to
draw the square at all. Instead, the hex code is shown (for example,
<1f3fe>) similar to how 0x200D is handled.
Further refactoring and cleanups are expected.
Diffstat:
| M | edo.c | | | 2 | +- |
| M | tui.c | | | 205 | +++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------- |
| M | ui.h | | | 1 | + |
| M | utf8.h | | | 6 | ++++++ |
4 files changed, 146 insertions(+), 68 deletions(-)
diff --git a/edo.c b/edo.c
@@ -337,7 +337,7 @@ view_idx2col(View *v, Line *line, int target_idx) {
if (target_idx > line->len) target_idx = line->len;
- while (i < target_idx) {
+ while(i < target_idx) {
len = ui->text_len(line->buf + i, line->len - i);
x += ui->text_width(line->buf + i, len, x);
i += len;
diff --git a/tui.c b/tui.c
@@ -3,9 +3,10 @@
#include <wchar.h>
#include <assert.h>
+#include <locale.h>
+#include <poll.h>
#include <stdarg.h>
#include <stdio.h>
-#include <locale.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
@@ -34,6 +35,8 @@ struct termios origti;
struct winsize ws;
Abuf frame;
int compat_mode;
+int is_modern;
+int vs16_double = 1;
/* TODO: edo.h? */
extern void *ecalloc(size_t nmemb, size_t size);
@@ -151,10 +154,16 @@ tui_text_width(char *s, int len, int x) {
}
wc = -1;
- if(compat_mode) {
- if(IS_RIS(cp)) wc = 2;
- } else {
- /* force 2 cells width for emoji followed by VS16 */
+
+ /* force RIS to be 2-cells wide */
+ if(compat_mode && IS_RIS(cp)) wc = 2;
+
+ /* color modifier is zero-width in modern terminals while legacy
+ * VTs are able to see the square color modifiers */
+ if(is_modern && IS_CMOD(cp)) wc = 0;
+
+ /* force 2 cells width for emoji followed by VS16 */
+ if(vs16_double && is_modern && wc == -1) {
int nxi = i + step;
if(nxi < len) {
unsigned int nxcp;
@@ -206,86 +215,91 @@ tui_draw_line_compat(UI *ui, int x, int y, Cell *cells, int count) {
for(i = 0; i < count; i++) {
txt = cell_get_text(cells + i, ui->pool.data);
- unsigned int cp;
+ int w = 0;
int o = 0;
- int vw = 0;
- while(o < cells[i].len) {
+ while(o < cells[i].len && w < cells[i].width) {
+ unsigned int cp;
int step = utf8_decode(txt + o, cells[i].len - o, &cp);
- int cw = cells[i].width;
- int neederase = cells[i].len > 1 && (cells[i].width == 1);
- switch(cp) {
- case '\t':
- for(int t = 0; t < cells[i].width; t++)
+ if(cp == '\t') {
+ while(w++ < cells[i].width)
ab_write(&frame, " ", 1);
break;
- default:
- cw = wcwidth(cp);
- if(cw < 0) break;
-
- if(!cw) {
- if(!cells[i].width) break;
-
- char tag[16];
- snprintf(tag, sizeof tag, "<%0x>", cp);
-
- if(cells[i].flags & CELL_TRUNC_L) {
- cw = tui_text_width(txt + o, cells[i].len, 0);
- o = cw - cells[i].width;
- if(o < 0) o = 0;
- }
- { const char t[] = ESC"[48;5;233m"; ab_write(&frame, t, sizeof t - 1); }
- cw = ab_printf(&frame, "%.*s", cells[i].width, tag + o);
- { const char t[] = ESC"[0m"; ab_write(&frame, t, sizeof t - 1); }
- break;
- }
+ }
+
+ int cw = wcwidth(cp);
+ if(cw < 0) break;
+
+ int showhex = !cw && !IS_CMOD(cp) && !IS_VAR(cp) && !utf8_is_combining(cp) ? 1 : 0;
+
+ if(!showhex && is_modern && compat_mode && IS_CMOD(cp)) showhex = 1;
+
+ if(showhex) {
+ char tag[16];
+ snprintf(tag, sizeof tag, "<%0x>", cp);
if(cells[i].flags & CELL_TRUNC_L) {
- ab_write(&frame, "<", 1);
- cw = 1;
- break;
- }
- if(cells[i].flags & CELL_TRUNC_R) {
- ab_write(&frame, ">", 1);
- cw = 1;
- break;
+ cw = tui_text_width(txt + o, cells[i].len - o, 0);
+ o = cw - cells[i].width;
+ if(o < 0) o = 0;
}
+ { const char t[] = ESC"[48;5;233m"; ab_write(&frame, t, sizeof t - 1); }
- if(neederase) {
- const char t[] = ESC"[48;5;232m";
- ab_write(&frame, t, sizeof t - 1);
- }
+ int j = 0;
- ab_write(&frame, txt + o, step);
-#if 0
- /* to preserve coherence between terminals always split RIS
- * so that we can see individual components. */
- if(IS_RIS(cp))
- ab_write(&frame, ZWNJ, sizeof ZWNJ - 1);
-#endif
- if(neederase) {
- const char t[] = ESC"[0m";
- ab_write(&frame, t, sizeof t - 1);
+ while(w < cells[i].width && x+w < ws.ws_col) {
+ ab_write(&frame, tag + o + j++, 1);
+ ++w;
}
+
+ { const char t[] = ESC"[0m"; ab_write(&frame, t, sizeof t - 1); }
break;
}
- vw += cw;
- /* stop processing after truncation */
- if(cells[i].flags & (CELL_TRUNC_L | CELL_TRUNC_R)) break;
+ /* to preserve coherence between terminals always split
+ * RIS so that we can see individual components. */
+ if(is_modern && IS_RIS(cp))
+ ab_write(&frame, ZWNJ, sizeof ZWNJ - 1);
+
+ if(!cw) {
+ ab_write(&frame, txt + o, step);
+ o += step;
+ continue;
+ }
- /* no more visual characters expected for this cell */
- if(neederase) break;
+
+ if(cells[i].flags & CELL_TRUNC_L) {
+ ab_write(&frame, "<", 1);
+ ++w;
+ while(w++ < cells[i].width) ab_write(&frame, ".", 1);
+ break;
+ }
+ if(cells[i].flags & CELL_TRUNC_R) {
+ ab_write(&frame, ">", 1);
+ ++w;
+ while(w++ < cells[i].width) ab_write(&frame, ".", 1);
+ break;
+ }
+
+ if(x+cw > ws.ws_col) break;
+ ab_write(&frame, txt + o, step);
o += step;
+ w += cw;
+ }
+ //ab_write(&frame, txt, cells[i].len);
+
+ /* pad to ensure we always honor cells[i].width
+ * should only happens with RIS on legacy VTs */
+ if(!is_modern && w < cells[i].width) {
+ while(w < cells[i].width && x+w < ws.ws_col) {
+ ab_write(&frame, " ", 1);
+ ++w;
+ }
}
- /* pad glyph having unexpected width */
- if(vw < cells[i].width)
- while(vw++ < cells[i].width) ab_write(&frame, " ", 1);
-
- x += cells[i].width;
+ x += w;
}
if(x < ws.ws_col) ab_write(&frame, CLEARRIGHT, strlen(CLEARRIGHT));
@@ -310,7 +324,8 @@ tui_draw_line(UI *ui, int x, int y, Cell *cells, int count) {
/* TODO: temp code for testing, we'll se how to deal with this later */
if(txt[0] == '\t') {
- ab_printf(&frame, "%*s", cells[i].width, " ");
+ for(int t = 0; t < cells[i].width; t++)
+ ab_write(&frame, " ", 1);
continue;
}
@@ -329,6 +344,7 @@ tui_draw_line(UI *ui, int x, int y, Cell *cells, int count) {
ab_write(&frame, txt, cells[i].len);
}
+
ab_write(&frame, CLEARRIGHT, strlen(CLEARRIGHT));
}
@@ -345,6 +361,50 @@ tui_draw_symbol(int c, int r, Symbol sym) {
ab_printf(&frame, "%c" CLEARRIGHT, symch);
}
+int
+detect_width(char *buf, int sz) {
+ int w = 1; /* default for legacy VTs */
+ int len = 0;
+ char *s, *e = NULL;
+
+ /* write an emoji which should be width=1 on legacy VTs and 2 on modern
+ * ones.
+ *
+ * \r start of line
+ * \xe2\x9d\xa4\xef\xb8\x8f the heart emoji
+ * \x1b[6n get position
+ * \r\x1b[K back to the start and clear
+ *
+ * We do all in a single write to be more efficient and most important
+ * to prevent visual glitches. */
+ const char out[] = "\r\xe2\x9d\xa4\xef\xb8\x8f\x1b[6n\r\x1b[K";
+ write(STDOUT_FILENO, out, sizeof out - 1);
+
+ memset(buf, 0, sz);
+
+ /* quick loop max 100ms */
+ struct pollfd fd = {STDIN_FILENO, POLLIN, 0};
+ for(int i = 0; i < 10; i++) {
+ if(poll(&fd, 1, 10) <= 0) continue;
+ int n = read(STDIN_FILENO, buf + len, sz - len - 1);
+ if(n <= 0) continue;
+ len += n;
+ buf[len] = '\0';
+ if((e = strchr(buf, 'R'))) break;
+ }
+
+ s = strstr(buf, "\x1b[");
+ if(s && e) {
+ /* if col is > 2 then emoji is 2-cells wide */
+ char *sc = strchr(s, ';');
+ if(sc && atoi(sc + 1) > 2) w = 2;
+
+ /* remove our test from user buffer */
+ memmove(s, e + 1, len - (e - buf));
+ }
+ return w;
+}
+
void
tui_init(void) {
struct termios ti;
@@ -366,7 +426,18 @@ tui_init(void) {
setbuf(stdout, NULL);
ioctl(0, TIOCGWINSZ, &ws);
- compat_mode = 1; /* TODO: auto-detect but toggable (upward only) */
+ /* auto-detect VT type */
+ char user_input[1024];
+ int emoji_width = detect_width(user_input, sizeof user_input);
+
+ is_modern = emoji_width == 2;
+ if(strlen(user_input)) {
+ die("TODO: user typed while initializing...\n");
+ }
+
+ //die("Is%smodern VT (width=%d)\n", is_modern ? " " : " NOT ", emoji_width);
+ compat_mode = !is_modern; /* TODO: toggable (upward only) */
+ compat_mode = 1; /* currently forced for development */
}
int
diff --git a/ui.h b/ui.h
@@ -28,6 +28,7 @@ typedef struct {
} TextPool;
enum CellFlags {
+ CELL_DEFAULT,
CELL_TRUNC_L,
CELL_TRUNC_R
};
diff --git a/utf8.h b/utf8.h
@@ -3,6 +3,12 @@
/* Regional Indicator Symbol */
#define IS_RIS(c) ((c) >= 0x1F1E6 && (c) <= 0x1F1FF)
+/* Variation Selector */
+#define IS_VAR(c) ((c) >= 0xFE00 && (c) <= 0xFE0F)
+
+/* Color modifier */
+#define IS_CMOD(c) ((c) >= 0x1F3FB && (c) <= 0x1F3FF)
+
/* Zero-Width Non-Joiner */
#define ZWNJ "\xe2\x80\x8c"
