Add support for application fonts

Needed to run the sliding puzzle demo

sixtyfps_runtime/corelib/Cargo.toml

@@ -43,6 +43,7 @@ auto_enums = "0.7"
 stretch = "0.3.2"
 weak-table =  "0.3"
 femtovg = { git = "https://github.com/femtovg/femtovg", branch = "master", optional = true }
+fontdb = "0.5.1"
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 instant = { version = "0.1", features = [ "wasm-bindgen", "now" ] }

sixtyfps_runtime/corelib/graphics.rs

@@ -28,7 +28,7 @@ use crate::{Callback, SharedString};
 use auto_enums::auto_enum;
 use const_field_offset::FieldOffsets;
 use sixtyfps_corelib_macros::*;
-use std::rc::Rc;
+use std::{cell::RefCell, rc::Rc};
 
 /// 2D Rectangle
 pub type Rect = euclid::default::Rect<f32>;
@@ -688,22 +688,17 @@ pub(crate) mod ffi {
     }
 }
 
+thread_local! {
+    /// Database used to keep track of fonts added by the application
+    pub static APPLICATION_FONTS: RefCell<fontdb::Database> = RefCell::new(fontdb::Database::new())
+}
+
 /// This function can be used to register a custom TrueType font with SixtyFPS,
 /// for use with the `font-family` property. The provided slice must be a valid TrueType
 /// font.
 pub fn register_application_font_from_memory(
     data: &'static [u8],
 ) -> Result<(), Box<dyn std::error::Error>> {
-    /*
-    let platform_font = PlatformFont::new_from_slice(data).map_err(Box::new)?;
-
-    FONT_CACHE.with(|fc| {
-        fc.application_fonts
-            .borrow_mut()
-            .insert(platform_font.family_name(), FontMatch::new(platform_font))
-    });
-
+    APPLICATION_FONTS.with(|fontdb| fontdb.borrow_mut().load_font_data(data.into()));
     Ok(())
-    */
-    todo!()
 }

sixtyfps_runtime/rendering_backends/gl/Cargo.toml

@@ -34,6 +34,7 @@ by_address = "1.0.4"
 femtovg = { git = "https://github.com/femtovg/femtovg", branch = "master" }
 euclid = "0.22.1"
 pin-weak = "1"
+fontdb = "0.5.1"
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 web_sys = { version = "0.3", package = "web-sys", features=["console", "WebGlContextAttributes"] }

sixtyfps_runtime/rendering_backends/gl/lib.rs

@@ -58,11 +58,35 @@ impl Default for FontDatabase {
     }
 }
 
-impl FontDatabase {
-    fn font(&mut self, canvas: &CanvasRc, request: FontRequest) -> Rc<GLFont> {
-        self.0
-            .entry(FontCacheKey::new(&request))
-            .or_insert_with(|| {
+fn try_load_app_font(canvas: &CanvasRc, request: &FontRequest) -> Option<GLFont> {
+    let family = if request.family.is_empty() {
+        fontdb::Family::SansSerif
+    } else {
+        fontdb::Family::Name(&request.family)
+    };
+    let query = fontdb::Query {
+        families: &[family],
+        weight: fontdb::Weight(request.weight as u16),
+        ..Default::default()
+    };
+    sixtyfps_corelib::graphics::APPLICATION_FONTS.with(|font_db| {
+        let font_db = font_db.borrow();
+        font_db.query(&query).and_then(|id| font_db.face_source(id)).map(|(source, _index)| {
+            GLFont {
+                // pass index to femtovg once femtovg/femtovg/pull/21 is merged
+                font_id: match source.as_ref() {
+                    fontdb::Source::Binary(data) => {
+                        canvas.borrow_mut().add_font_mem(&data).unwrap()
+                    }
+                    fontdb::Source::File(path) => canvas.borrow_mut().add_font(path).unwrap(),
+                },
+                canvas: canvas.clone(),
+            }
+        })
+    })
+}
+
+fn load_system_font(canvas: &CanvasRc, request: &FontRequest) -> GLFont {
     let family_name = if request.family.len() == 0 {
         font_kit::family_name::FamilyName::SansSerif
     } else {
@@ -77,16 +101,28 @@ impl FontDatabase {
         )
         .unwrap();
 
+    // pass index to femtovg once femtovg/femtovg/pull/21 is merged
     let canvas_font = match handle {
-                    font_kit::handle::Handle::Path { path, font_index } => {
+        font_kit::handle::Handle::Path { path, font_index: _ } => {
             canvas.borrow_mut().add_font(path)
         }
-                    font_kit::handle::Handle::Memory { bytes, font_index } => {
+        font_kit::handle::Handle::Memory { bytes, font_index: _ } => {
             canvas.borrow_mut().add_font_mem(bytes.as_slice())
         }
     }
     .unwrap();
-                Rc::new(GLFont { font_id: canvas_font, canvas: canvas.clone() })
+    GLFont { font_id: canvas_font, canvas: canvas.clone() }
+}
+
+impl FontDatabase {
+    fn font(&mut self, canvas: &CanvasRc, request: FontRequest) -> Rc<GLFont> {
+        self.0
+            .entry(FontCacheKey::new(&request))
+            .or_insert_with(|| {
+                Rc::new(
+                    try_load_app_font(canvas, &request)
+                        .unwrap_or_else(|| load_system_font(canvas, &request)),
+                )
             })
             .clone()
     }