From 36d5a9e33252c03674e52742560caff23cdeefb7 Mon Sep 17 00:00:00 2001
From: Sebastian Schmidt <sebastian.schmidt@helsinki.fi>
Date: Mon, 9 Jun 2025 13:48:11 +0300
Subject: [PATCH] Use default SVG font rendering for sequence names in legend.

---
 lib_tsshow/src/lib.rs      |  6 +++++-
 lib_tsshow/src/svg.rs      | 17 +++--------------
 lib_tsshow/src/svg/font.rs | 15 ++++++++++++++-
 3 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/lib_tsshow/src/lib.rs b/lib_tsshow/src/lib.rs
index 41bd5a43..ebdd81de 100644
--- a/lib_tsshow/src/lib.rs
+++ b/lib_tsshow/src/lib.rs
@@ -1,3 +1,5 @@
+use resvg::usvg::Options;
+
 pub mod error;
 pub mod plain_text;
 pub mod svg;
@@ -6,7 +8,9 @@ pub mod ts_arrangement;
 pub fn svg_to_png(svg_in: &[u8], zoom: f32) -> Vec<u8> {
     log::info!("Converting SVG to PNG");
 
-    let svg = resvg::usvg::Tree::from_data(svg_in, &Default::default()).unwrap();
+    let mut options = Options::default();
+    options.fontdb_mut().load_system_fonts();
+    let svg = resvg::usvg::Tree::from_data(svg_in, &options).unwrap();
 
     let raster_image_size = svg.size();
     let raster_image_width = (raster_image_size.width().ceil() * zoom) as u32;
diff --git a/lib_tsshow/src/svg.rs b/lib_tsshow/src/svg.rs
index 425839ee..edeadad9 100644
--- a/lib_tsshow/src/svg.rs
+++ b/lib_tsshow/src/svg.rs
@@ -20,6 +20,7 @@ use svg::{
 use crate::{
     error::{Error, Result},
     plain_text::mutlipair_alignment_renderer::Character,
+    svg::font::svg_text,
     ts_arrangement::{
         TsArrangement,
         character::Char,
@@ -913,26 +914,14 @@ fn legend(reference_name: &str, query_name: &str, scale: f32) -> (Group, f32, f3
     let label_width = label_width + typewriter::FONT.character_width;
     y = headline_height;
 
-    result = result.add(svg_string(
-        reference_name
-            .chars()
-            .map(Character::<CharacterData>::new_char_with_default),
-        &SvgLocation { x: label_width, y },
-        &sans_serif_mono::FONT,
-    ));
+    result = result.add(svg_text(reference_name, &SvgLocation { x: label_width, y }));
     explanation_width = explanation_width
         .max(reference_name.chars().count() as f32 * sans_serif_mono::FONT.character_width);
     y += typewriter::FONT
         .character_height
         .max(sans_serif_mono::FONT.character_height);
 
-    result = result.add(svg_string(
-        query_name
-            .chars()
-            .map(Character::<CharacterData>::new_char_with_default),
-        &SvgLocation { x: label_width, y },
-        &sans_serif_mono::FONT,
-    ));
+    result = result.add(svg_text(query_name, &SvgLocation { x: label_width, y }));
     explanation_width = explanation_width
         .max(query_name.chars().count() as f32 * sans_serif_mono::FONT.character_width);
     y += typewriter::FONT
diff --git a/lib_tsshow/src/svg/font.rs b/lib_tsshow/src/svg/font.rs
index e3372c5e..9c5732be 100644
--- a/lib_tsshow/src/svg/font.rs
+++ b/lib_tsshow/src/svg/font.rs
@@ -1,6 +1,6 @@
 use std::{borrow::Borrow, collections::HashMap, fmt::Debug};
 
-use svg::node::element::{Group, Path};
+use svg::node::element::{Group, Path, Text};
 
 use crate::plain_text::mutlipair_alignment_renderer::{Character, NoCharacterData};
 
@@ -94,6 +94,19 @@ where
     group
 }
 
+/// Renders text with non-monospace sans-serif font.
+/// The width of the text depends on the font used by the SVG renderer.
+pub fn svg_text(text: impl Into<String>, location: &SvgLocation) -> Group {
+    let mut group = Group::new();
+    group = group.set("transform", location.as_transform());
+    group = group.add(
+        Text::new(text)
+            .set("font-family", "sans-serif")
+            .set("font-size", "3"),
+    );
+    group
+}
+
 impl CharacterData {
     pub fn new_colored(color: impl ToString) -> Self {
         #[allow(clippy::needless_update)]