From 2f19d6bb7355c9957ae373ec9cdf999f7fda0c2a Mon Sep 17 00:00:00 2001
From: Daniel Wennberg <daniel.wennberg@gmail.com>
Date: Thu, 18 Sep 2025 00:03:27 -0700
Subject: [PATCH] Treat Powerline glyphs like normal characters

...not whitespace. Powerline glyphs can be considered an extension of
the Block Elements unicode block, which is neither whitespace nor
symbols (icons).

This ensures that characters immediately followed by a powerline glyph
are constrained to a single cell (unlike the current behavior where a PL
glyph is considered whitespace), while symbols (icons) immediately
preceded by a powerline glyph are not (unlike if a PL glyph were
considered a symbol). This resolves
https://discord.com/channels/1005603569187160125/1417236683266592798
---
 src/renderer/cell.zig | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/src/renderer/cell.zig b/src/renderer/cell.zig
index 3cf306f91..206bb9d81 100644
--- a/src/renderer/cell.zig
+++ b/src/renderer/cell.zig
@@ -236,8 +236,8 @@ pub fn isCovering(cp: u21) bool {
 }
 
 /// Returns true of the codepoint is a "symbol-like" character, which
-/// for now we define as anything in a private use area and anything
-/// in several unicode blocks:
+/// for now we define as anything in a private use area, except
+/// the Powerline range, and anything in several unicode blocks:
 /// - Dingbats
 /// - Emoticons
 /// - Miscellaneous Symbols
@@ -249,11 +249,13 @@ pub fn isCovering(cp: u21) bool {
 /// In the future it may be prudent to expand this to encompass more
 /// symbol-like characters, and/or exclude some PUA sections.
 pub fn isSymbol(cp: u21) bool {
-    return symbols.get(cp);
+    return symbols.get(cp) and !isPowerline(cp);
 }
 
 /// Returns the appropriate `constraint_width` for
 /// the provided cell when rendering its glyph(s).
+///
+/// Tested as part of the Screen tests.
 pub fn constraintWidth(cell_pin: terminal.Pin) u2 {
     const cell = cell_pin.rowAndCell().cell;
     const cp = cell.codepoint();
@@ -274,9 +276,7 @@ pub fn constraintWidth(cell_pin: terminal.Pin) u2 {
 
     // If we have a previous cell and it was a symbol then we need
     // to also constrain. This is so that multiple PUA glyphs align.
-    // As an exception, we ignore powerline glyphs since they are
-    // used for box drawing and we consider them whitespace.
-    if (cell_pin.x > 0) prev: {
+    if (cell_pin.x > 0) {
         const prev_cp = prev_cp: {
             var copy = cell_pin;
             copy.x -= 1;
@@ -284,9 +284,6 @@ pub fn constraintWidth(cell_pin: terminal.Pin) u2 {
             break :prev_cp prev_cell.codepoint();
         };
 
-        // We consider powerline glyphs whitespace.
-        if (isPowerline(prev_cp)) break :prev;
-
         if (isSymbol(prev_cp)) {
             return 1;
         }
@@ -300,10 +297,7 @@ pub fn constraintWidth(cell_pin: terminal.Pin) u2 {
         const next_cell = copy.rowAndCell().cell;
         break :next_cp next_cell.codepoint();
     };
-    if (next_cp == 0 or
-        isSpace(next_cp) or
-        isPowerline(next_cp))
-    {
+    if (next_cp == 0 or isSpace(next_cp)) {
         return 2;
     }