🎉 Implement font fallback to support multiple languages

render-wasm/src/render/fonts.rs

@@ -1,4 +1,5 @@
 use skia_safe::{self as skia, textlayout, Font, FontMgr};
+use std::collections::HashSet;
 
 use crate::shapes::{FontFamily, FontStyle};
 use crate::uuid::Uuid;
@@ -21,6 +22,7 @@ pub struct FontStore {
     font_provider: textlayout::TypefaceFontProvider,
     font_collection: textlayout::FontCollection,
     debug_font: Font,
+    fallback_fonts: HashSet<String>,
 }
 
 impl FontStore {
@@ -41,6 +43,7 @@ impl FontStore {
             font_provider,
             font_collection,
             debug_font,
+            fallback_fonts: HashSet::new(),
         }
     }
 
@@ -61,6 +64,7 @@ impl FontStore {
         family: FontFamily,
         font_data: &[u8],
         is_emoji: bool,
+        is_fallback: bool,
     ) -> Result<(), String> {
         if self.has_family(&family) {
             return Ok(());
@@ -80,6 +84,11 @@ impl FontStore {
 
         self.font_provider.register_typeface(typeface, font_name);
         self.font_collection.clear_caches();
+
+        if is_fallback {
+            self.fallback_fonts.insert(alias);
+        }
+
         Ok(())
     }
 
@@ -87,6 +96,10 @@ impl FontStore {
         let serialized = format!("{}", family);
         self.font_provider.family_names().any(|x| x == serialized)
     }
+
+    pub fn get_fallback(&self) -> &HashSet<String> {
+        &self.fallback_fonts
+    }
 }
 
 fn load_default_provider(font_mgr: &FontMgr) -> skia::textlayout::TypefaceFontProvider {

render-wasm/src/shapes/text.rs

@@ -7,10 +7,11 @@ use skia_safe::{
     paint::Paint,
     textlayout::{FontCollection, ParagraphBuilder, ParagraphStyle},
 };
+use std::collections::HashSet;
 
 use super::FontFamily;
 use crate::shapes::{self, merge_fills, set_paint_fill, Stroke, StrokeKind};
-use crate::utils::uuid_from_u32;
+use crate::utils::{get_fallback_fonts, uuid_from_u32};
 use crate::wasm::fills::parse_fills_from_bytes;
 use crate::Uuid;
 
@@ -94,6 +95,7 @@ impl TextContent {
     }
 
     pub fn to_paragraphs(&self, fonts: &FontCollection) -> Vec<Vec<skia::textlayout::Paragraph>> {
+        let fallback_fonts = get_fallback_fonts();
         let mut paragraph_group = Vec::new();
         let paragraphs = self
             .paragraphs
@@ -102,7 +104,7 @@ impl TextContent {
                 let paragraph_style = p.paragraph_to_style();
                 let mut builder = ParagraphBuilder::new(&paragraph_style, fonts);
                 for leaf in &p.children {
-                    let text_style = leaf.to_style(p, &self.bounds); // FIXME
+                    let text_style = leaf.to_style(p, &self.bounds, fallback_fonts); // FIXME
                     let text = leaf.apply_text_transform();
                     builder.push_style(&text_style);
                     builder.add_text(&text);
@@ -121,6 +123,7 @@ impl TextContent {
         bounds: &Rect,
         fonts: &FontCollection,
     ) -> Vec<Vec<skia::textlayout::Paragraph>> {
+        let fallback_fonts = get_fallback_fonts();
         let mut paragraph_group = Vec::new();
         let stroke_paints = get_text_stroke_paints(stroke, bounds);
 
@@ -130,7 +133,8 @@ impl TextContent {
                 let paragraph_style = paragraph.paragraph_to_style();
                 let mut builder = ParagraphBuilder::new(&paragraph_style, fonts);
                 for leaf in &paragraph.children {
-                    let stroke_style = leaf.to_stroke_style(paragraph, &stroke_paint);
+                    let stroke_style =
+                        leaf.to_stroke_style(paragraph, &stroke_paint, fallback_fonts);
                     let text: String = leaf.apply_text_transform();
                     builder.push_style(&stroke_style);
                     builder.add_text(&text);
@@ -336,6 +340,7 @@ impl TextLeaf {
         &self,
         paragraph: &Paragraph,
         content_bounds: &Rect,
+        fallback_fonts: &HashSet<String>,
     ) -> skia::textlayout::TextStyle {
         let mut style = skia::textlayout::TextStyle::default();
 
@@ -359,14 +364,18 @@ impl TextLeaf {
             3 => skia::textlayout::TextDecoration::OVERLINE,
             _ => skia::textlayout::TextDecoration::NO_DECORATION,
         });
-        // FIXME
+
+        // FIXME fix decoration styles
         style.set_decoration_color(paint.color());
 
-        style.set_font_families(&[
+        let mut font_families = vec![
             self.serialized_font_family(),
             default_font(),
             DEFAULT_EMOJI_FONT.to_string(),
-        ]);
+        ];
+
+        font_families.extend(fallback_fonts.iter().cloned());
+        style.set_font_families(&font_families);
 
         style
     }
@@ -375,8 +384,9 @@ impl TextLeaf {
         &self,
         paragraph: &Paragraph,
         stroke_paint: &Paint,
+        fallback_fonts: &HashSet<String>,
     ) -> skia::textlayout::TextStyle {
-        let mut style = self.to_style(paragraph, &Rect::default());
+        let mut style = self.to_style(paragraph, &Rect::default(), fallback_fonts);
         style.set_foreground_paint(stroke_paint);
         style.set_font_size(self.font_size);
         style.set_letter_spacing(paragraph.letter_spacing);

render-wasm/src/utils.rs

@@ -2,6 +2,7 @@ use crate::skia::Image;
 use crate::uuid::Uuid;
 use crate::with_state;
 use crate::STATE;
+use std::collections::HashSet;
 
 pub fn uuid_from_u32_quartet(a: u32, b: u32, c: u32, d: u32) -> Uuid {
     let hi: u64 = ((a as u64) << 32) | b as u64;
@@ -25,3 +26,8 @@ pub fn uuid_from_u32(id: [u32; 4]) -> Uuid {
 pub fn get_image(image_id: &Uuid) -> Option<&Image> {
     with_state!(state, { state.render_state().images.get(image_id) })
 }
+
+// FIXME: move to a different place ?
+pub fn get_fallback_fonts() -> &'static HashSet<String> {
+    with_state!(state, { state.render_state().fonts().get_fallback() })
+}

render-wasm/src/wasm/fonts.rs

@@ -14,19 +14,19 @@ pub extern "C" fn store_font(
     weight: u32,
     style: u8,
     is_emoji: bool,
+    is_fallback: bool,
 ) {
     with_state!(state, {
         let id = uuid_from_u32_quartet(a, b, c, d);
         let font_bytes = mem::bytes();
+
         let family = FontFamily::new(id, weight, style.into());
-        let res = state
+        let _ = state
             .render_state()
             .fonts_mut()
-            .add(family, &font_bytes, is_emoji);
+            .add(family, &font_bytes, is_emoji, is_fallback);
 
-        if let Err(msg) = res {
-            eprintln!("{}", msg);
-        }
+        mem::free_bytes();
     });
 }