From 6f451f22bb6fea80d9fdb805e51b5150457fdf5c Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 14 Dec 2022 21:39:45 -0800
Subject: [PATCH] terminal: only clear wide spacer head if wide char is not on
 first line

---
 src/terminal/Terminal.zig | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/terminal/Terminal.zig b/src/terminal/Terminal.zig
index 8cca30fa5..1ab9bb80c 100644
--- a/src/terminal/Terminal.zig
+++ b/src/terminal/Terminal.zig
@@ -672,7 +672,7 @@ fn printCell(self: *Terminal, unmapped_c: u21) *Screen.Cell {
         const spacer_cell = row.getCellPtr(x);
         spacer_cell.attrs.wide_spacer_tail = false;
 
-        if (self.screen.cursor.x <= 1) {
+        if (self.screen.cursor.y > 0 and self.screen.cursor.x <= 1) {
             self.clearWideSpacerHead();
         }
     } else if (cell.attrs.wide_spacer_tail) {
@@ -1415,6 +1415,18 @@ test "Terminal: zero-width character at start" {
     try testing.expectEqual(@as(usize, 0), t.screen.cursor.x);
 }
 
+test "Terminal: print over wide char at 0,0" {
+    var t = try init(testing.allocator, 80, 80);
+    defer t.deinit(testing.allocator);
+
+    try t.print(0x1F600); // Smiley face
+    t.setCursorPos(0, 0);
+    try t.print('A'); // Smiley face
+
+    try testing.expectEqual(@as(usize, 0), t.screen.cursor.y);
+    try testing.expectEqual(@as(usize, 1), t.screen.cursor.x);
+}
+
 test "Terminal: soft wrap" {
     var t = try init(testing.allocator, 3, 80);
     defer t.deinit(testing.allocator);