From 105e3c63d14fff1326efd4e84ae4b73a6e69e124 Mon Sep 17 00:00:00 2001
From: reugenio <yo@reugenio.com>
Date: Tue, 16 Dec 2025 13:25:17 +0100
Subject: [PATCH] fix: UTF-8 support in TTF drawText
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

- drawText now decodes UTF-8 codepoints instead of iterating bytes
- Fixes rendering of accented characters (á, é, í, ó, ú, ñ, etc.)
- Uses std.unicode.utf8ByteSequenceLength + utf8Decode
- Invalid UTF-8 sequences are gracefully skipped

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 src/render/ttf.zig | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/src/render/ttf.zig b/src/render/ttf.zig
index fa0d571..5d53dfd 100644
--- a/src/render/ttf.zig
+++ b/src/render/ttf.zig
@@ -861,25 +861,41 @@ pub const TtfFont = struct {
         var cx = x;
         const baseline_y = y + self.ascent();
 
-        for (text) |c| {
-            if (c == '\n') continue;
-            if (c == ' ') {
-                const metrics = self.getGlyphMetrics(c);
+        // UTF-8 iteration: decode codepoints instead of iterating bytes
+        var i: usize = 0;
+        while (i < text.len) {
+            // Get UTF-8 sequence length
+            const cp_len = std.unicode.utf8ByteSequenceLength(text[i]) catch {
+                i += 1; // Skip invalid byte
+                continue;
+            };
+            if (i + cp_len > text.len) break; // Not enough bytes
+
+            // Decode codepoint
+            const cp: u32 = std.unicode.utf8Decode(text[i..][0..cp_len]) catch {
+                i += cp_len;
+                continue;
+            };
+            i += cp_len;
+
+            if (cp == '\n') continue;
+            if (cp == ' ') {
+                const metrics = self.getGlyphMetrics(cp);
                 cx += @intCast(metrics.advance);
                 continue;
             }
 
             // Try to get cached glyph or rasterize
-            const cache_key = makeCacheKey(c, self.render_size);
+            const cache_key = makeCacheKey(cp, self.render_size);
 
             if (self.glyph_cache.get(cache_key)) |cached| {
                 // Draw cached glyph
                 self.drawGlyphBitmap(fb, cx, baseline_y, cached, color, clip);
-                const metrics = self.getGlyphMetrics(c);
+                const metrics = self.getGlyphMetrics(cp);
                 cx += @intCast(metrics.advance);
             } else {
                 // Rasterize and cache
-                const glyph_index = self.getGlyphIndex(c);
+                const glyph_index = self.getGlyphIndex(cp);
                 if (self.getGlyphOutline(glyph_index)) |outline| {
                     defer {
                         var outline_copy = outline;
@@ -895,9 +911,9 @@ pub const TtfFont = struct {
                                 .height = @intCast(bitmap.height),
                                 .bearing_x = @intCast(bitmap.bearing_x),
                                 .bearing_y = @intCast(bitmap.bearing_y),
-                                .advance = self.getGlyphMetrics(c).advance,
+                                .advance = self.getGlyphMetrics(cp).advance,
                             },
-                            .codepoint = c,
+                            .codepoint = cp,
                         };
 
                         self.glyph_cache.put(cache_key, cached_glyph) catch {};
@@ -905,7 +921,7 @@ pub const TtfFont = struct {
                     }
                 }
 
-                const metrics = self.getGlyphMetrics(c);
+                const metrics = self.getGlyphMetrics(cp);
                 cx += @intCast(metrics.advance);
             }
         }