Substring widthwise instead of runewise

2 files changed, 16 insertions, 2 deletions

diff --git a/tui/widget/widget.ha b/tui/widget/widget.ha
index 7c82dfa..4212eae 100644
--- a/tui/widget/widget.ha
+++ b/tui/widget/widget.ha
@@ -234,11 +234,11 @@ fn truncate_to_size(w: *widget) []str = {
 		const line = w.buf.lines[i];
 		let item = match (w.sz) {
 		case let sz: tty::ttysize =>
-			const s = if (tui::strwidth(line) > sz.columns) strings::sub(line, 0z, sz.columns) else line;
+			const s = if (tui::strwidth(line) > sz.columns) tui::subwidth(line, sz.columns) else line;
 			yield strings::rpad(s, ' ', sz.columns);
 		case void =>
 			const wsz = tty::winsize(w.state.out)!;
-			const s = if (tui::strwidth(line) > wsz.columns) strings::sub(line, 0z, wsz.columns) else line;
+			const s = if (tui::strwidth(line) > wsz.columns) tui::subwidth(line, wsz.columns) else line;
 			yield strings::dup(s);
 		};
 		append(lines, item);
diff --git a/tui/width.ha b/tui/width.ha
index 6f9631c..ed498e6 100644
--- a/tui/width.ha
+++ b/tui/width.ha
@@ -30,3 +30,17 @@ export fn strwidth(s: str) uint = {
 	};
 	return sum;
 };
+
+export fn subwidth(s: str, end: (size | strings::end)) str = {
+	const runes = strings::torunes(s);
+	defer free(runes);
+	let sum = 0u;
+	for (let i = 0z; i < len(runes); i += 1) {
+		const r = runes[i];
+		sum += runewidth(r);
+		if (sum > end: uint) {
+			return strings::sub(s, 0, i - 1);
+		};
+	};
+	return s;
+};