From 24ca6f0262cb12b59499c6058cc402378125f2b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Kr=C3=BCger?= <valknar@pivoine.art>
Date: Sun, 9 Nov 2025 04:12:15 +0100
Subject: [PATCH] Fix text positioning by calculating visual width without ANSI
 codes
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The motion effects were appearing with incorrect row offsets because
the text width calculation included ANSI color escape sequences in
the byte length, causing misaligned centering.

Changes:
- Added utils/ansi.rs module with strip_ansi() and visual_width()
- Updated renderer to use visual_width() for offset positioning
- Updated TerminalManager::print_centered() to use visual_width()
- All text positioning now correctly ignores ANSI escape sequences

This fixes the "shifted in the rows" issue where colored text was
not properly centered due to escape sequence byte counts.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 src/animation/renderer.rs |  4 +--
 src/utils/ansi.rs         | 54 +++++++++++++++++++++++++++++++++++++++
 src/utils/mod.rs          |  1 +
 src/utils/terminal.rs     |  6 +++--
 4 files changed, 61 insertions(+), 4 deletions(-)
 create mode 100644 src/utils/ansi.rs

diff --git a/src/animation/renderer.rs b/src/animation/renderer.rs
index d2ec3bf..6feba70 100644
--- a/src/animation/renderer.rs
+++ b/src/animation/renderer.rs
@@ -1,6 +1,6 @@
 use crate::animation::{easing::EasingFunction, effects::Effect, timeline::Timeline};
 use crate::color::{apply, ColorEngine};
-use crate::utils::{ascii::AsciiArt, terminal::TerminalManager};
+use crate::utils::{ansi, ascii::AsciiArt, terminal::TerminalManager};
 use anyhow::Result;
 use tokio::time::sleep;
 
@@ -62,7 +62,7 @@ impl<'a> Renderer<'a> {
                 let (width, height) = terminal.get_size();
                 let lines: Vec<&str> = colored_text.lines().collect();
                 let text_height = lines.len() as i32;
-                let text_width = lines.iter().map(|l| l.len()).max().unwrap_or(0) as i32;
+                let text_width = lines.iter().map(|l| ansi::visual_width(l)).max().unwrap_or(0) as i32;
 
                 let base_x = (width as i32 - text_width) / 2;
                 let base_y = (height as i32 - text_height) / 2;
diff --git a/src/utils/ansi.rs b/src/utils/ansi.rs
new file mode 100644
index 0000000..0c12d5f
--- /dev/null
+++ b/src/utils/ansi.rs
@@ -0,0 +1,54 @@
+/// Strip ANSI escape sequences from a string to get visual width
+pub fn strip_ansi(text: &str) -> String {
+    let mut result = String::new();
+    let mut chars = text.chars().peekable();
+
+    while let Some(ch) = chars.next() {
+        if ch == '\x1b' {
+            // Skip ANSI escape sequence
+            if chars.peek() == Some(&'[') {
+                chars.next(); // consume '['
+                // Skip until we hit a letter (the command character)
+                while let Some(&c) = chars.peek() {
+                    chars.next();
+                    if c.is_ascii_alphabetic() {
+                        break;
+                    }
+                }
+            }
+        } else {
+            result.push(ch);
+        }
+    }
+
+    result
+}
+
+/// Get the visual width of a string (excluding ANSI codes)
+pub fn visual_width(text: &str) -> usize {
+    strip_ansi(text).chars().count()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_strip_ansi() {
+        let text = "\x1b[38;2;255;87;51mHello\x1b[0m";
+        assert_eq!(strip_ansi(text), "Hello");
+    }
+
+    #[test]
+    fn test_visual_width() {
+        let text = "\x1b[38;2;255;87;51mHi\x1b[0m";
+        assert_eq!(visual_width(text), 2);
+    }
+
+    #[test]
+    fn test_no_ansi() {
+        let text = "Plain text";
+        assert_eq!(strip_ansi(text), "Plain text");
+        assert_eq!(visual_width(text), 10);
+    }
+}
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index ebbd1ef..e7ba92a 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -1,2 +1,3 @@
+pub mod ansi;
 pub mod ascii;
 pub mod terminal;
diff --git a/src/utils/terminal.rs b/src/utils/terminal.rs
index 3c6d54e..14e5537 100644
--- a/src/utils/terminal.rs
+++ b/src/utils/terminal.rs
@@ -5,6 +5,8 @@ use crossterm::{
 };
 use std::io::{stdout, Write};
 
+use super::ansi;
+
 pub struct TerminalManager {
     width: u16,
     height: u16,
@@ -67,14 +69,14 @@ impl TerminalManager {
 
     pub fn print_centered(&self, text: &str) -> Result<()> {
         let lines: Vec<&str> = text.lines().collect();
-        let max_width = lines.iter().map(|l| l.len()).max().unwrap_or(0) as u16;
+        let max_width = lines.iter().map(|l| ansi::visual_width(l)).max().unwrap_or(0) as u16;
         let height = lines.len() as u16;
 
         let start_x = (self.width.saturating_sub(max_width)) / 2;
         let start_y = (self.height.saturating_sub(height)) / 2;
 
         for (i, line) in lines.iter().enumerate() {
-            let line_width = line.len() as u16;
+            let line_width = ansi::visual_width(line) as u16;
             let x = start_x + (max_width.saturating_sub(line_width)) / 2;
             let y = start_y + i as u16;
             self.print_at(x, y, line)?;