Add an experimental wasm shaper (#122)

Closes #117

.gitignore

@@ -3,3 +3,4 @@ Cargo.lock
 .directory
 .DS_Store
 /src/complex/*.ri
+.vscode

Cargo.toml

@@ -21,6 +21,8 @@ unicode-bidi-mirroring = "0.3.0"
 unicode-ccc = "0.3.0"
 unicode-properties = { version = "0.1.0", default-features = false, features = ["general-category"] }
 unicode-script = "0.5.2"
+wasmi = { version = "0.34.0", optional = true }
+log = "0.4.22"
 
 [dependencies.ttf-parser]
 version = "0.24.0"
@@ -36,6 +38,7 @@ features = [
 [features]
 default = ["std"]
 std = ["ttf-parser/std"]
+wasm-shaper = ["std", "dep:wasmi"]
 
 [dev-dependencies]
 pico-args = { version = "0.5", features = ["eq-separator"] }

src/hb/buffer.rs

@@ -119,7 +119,7 @@ pub struct GlyphPosition {
     /// How much the glyph moves on the Y-axis before drawing it, this should
     /// not affect how much the line advances.
     pub y_offset: i32,
-    var: u32,
+    pub(crate) var: u32,
 }
 
 unsafe impl bytemuck::Zeroable for GlyphPosition {}

src/hb/face.rs

@@ -369,13 +369,17 @@ impl<'a> hb_font_t<'a> {
 }
 
 #[derive(Clone, Copy, Default)]
+#[repr(C)]
 pub struct hb_glyph_extents_t {
     pub x_bearing: i32,
     pub y_bearing: i32,
     pub width: i32,
     pub height: i32,
 }
 
+unsafe impl bytemuck::Zeroable for hb_glyph_extents_t {}
+unsafe impl bytemuck::Pod for hb_glyph_extents_t {}
+
 fn find_best_cmap_subtable(face: &ttf_parser::Face) -> Option<u16> {
     use ttf_parser::PlatformId;
 

src/hb/mod.rs

@@ -50,6 +50,8 @@ mod ot_shaper_vowel_constraints;
 mod paint_extents;
 mod set_digest;
 pub mod shape;
+#[cfg(feature = "wasm-shaper")]
+mod shape_wasm;
 mod tag;
 mod tag_table;
 mod text_parser;

src/hb/shape.rs

@@ -54,12 +54,27 @@ pub fn shape_with_plan(
     if buffer.len > 0 {
         // Save the original direction, we use it later.
         let target_direction = buffer.direction;
-        shape_internal(&mut hb_ot_shape_context_t {
-            plan,
-            face,
-            buffer: &mut buffer,
-            target_direction,
-        });
+
+        #[cfg(feature = "wasm-shaper")]
+        {
+            super::shape_wasm::shape_with_wasm(face, plan, &mut buffer).unwrap_or_else(|| {
+                shape_internal(&mut hb_ot_shape_context_t {
+                    plan,
+                    face,
+                    buffer: &mut buffer,
+                    target_direction,
+                });
+            });
+        }
+        #[cfg(not(feature = "wasm-shaper"))]
+        {
+            shape_internal(&mut hb_ot_shape_context_t {
+                plan,
+                face,
+                buffer: &mut buffer,
+                target_direction,
+            });
+        }
     }
 
     GlyphBuffer(buffer)