From e9b0d02104bd50d002ce142d64570de11590dc29 Mon Sep 17 00:00:00 2001
From: Mark Paronyan <markparonian@gmail.com>
Date: Thu, 1 Oct 2026 15:25:28 +0300
Subject: [PATCH] refactor(vt): don't store default colors in cells when
 drawing

---
 test/test-vt.c | 17 +++++++++++++++++
 vt.c           | 16 ++++++++--------
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/test/test-vt.c b/test/test-vt.c
index 9907dd4..a8f96a6 100644
--- a/test/test-vt.c
+++ b/test/test-vt.c
@@ -114,6 +114,23 @@ static void test_term(const char *name, int red, int palette196, int rgb123, int
 	extended_pair_content(reserved, &fg, &bg);
 	CHECK(fg == COLOR_BLUE && bg == -1);
 	CHECK(vt_color_reserve(COLOR_BLUE, -1) == reserved);
+	vt_destroy(t);
+
+	/* default colors are applied when drawing, not stored in the cells */
+	t = vt_create(2, 80, 0);
+	vt_default_colors_set(t, A_NORMAL, COLOR_GREEN, -1);
+	feed(t, "a\033[31mb");
+	drawn(0, &fg, &bg);
+	CHECK(fg == COLOR_GREEN);
+	CHECK(strstr(content(t), "\033[39m\033[49ma"));
+
+	/* new defaults, e.g. from a color rule after a title change, apply to existing text */
+	vt_default_colors_set(t, A_NORMAL, COLOR_BLUE, -1);
+	vt_draw(t, pad, 0, 0);
+	drawn(0, &fg, &bg);
+	CHECK(fg == COLOR_BLUE);
+	drawn(1, &fg, &bg);
+	CHECK(fg == COLOR_RED);
 
 	vt_destroy(t);
 	delwin(pad);
diff --git a/vt.c b/vt.c
index 4ff8f95..93f3691 100644
--- a/vt.c
+++ b/vt.c
@@ -1478,9 +1478,12 @@ int vt_process(Vt *t)
 
 void vt_default_colors_set(Vt *t, attr_t attrs, int fg, int bg)
 {
+	if (t->defattrs == attrs && t->deffg == fg && t->defbg == bg)
+		return;
 	t->defattrs = attrs;
 	t->deffg = fg;
 	t->defbg = bg;
+	vt_dirty(t);
 }
 
 Vt *vt_create(int rows, int cols, int scroll_size)
@@ -1561,14 +1564,11 @@ void vt_draw(Vt *t, WINDOW *win, int srow, int scol)
 			if (!prev_cell || cell->attr != prev_cell->attr
 			    || cell->fg != prev_cell->fg
 			    || cell->bg != prev_cell->bg) {
-				if (cell->attr == A_NORMAL)
-					cell->attr = t->defattrs;
-				if (cell->fg == -1)
-					cell->fg = t->deffg;
-				if (cell->bg == -1)
-					cell->bg = t->defbg;
-				int pair = vt_color_get(t, cell->fg, cell->bg);
-				wattr_set(win, cell->attr << NCURSES_ATTR_SHIFT, pair, PAIR_OPTS(pair));
+				attr_t attr = cell->attr == A_NORMAL ? t->defattrs : cell->attr;
+				int fg = cell->fg == -1 ? t->deffg : cell->fg;
+				int bg = cell->bg == -1 ? t->defbg : cell->bg;
+				int pair = vt_color_get(t, fg, bg);
+				wattr_set(win, attr << NCURSES_ATTR_SHIFT, pair, PAIR_OPTS(pair));
 			}
 
 			if (is_utf8 && cell->text >= 128) {