♻️ Refactor rust/wasm code organization

render-wasm/src/render.rs

@@ -0,0 +1,86 @@
+use skia_safe as skia;
+use skia_safe::gpu::{self, gl::FramebufferInfo, DirectContext};
+
+extern "C" {
+    pub fn emscripten_GetProcAddress(
+        name: *const ::std::os::raw::c_char,
+    ) -> *const ::std::os::raw::c_void;
+}
+
+pub struct GpuState {
+    pub context: DirectContext,
+    framebuffer_info: FramebufferInfo,
+}
+
+/// This struct holds the state of the Rust application between JS calls.
+///
+/// It is created by [init] and passed to the other exported functions. Note that rust-skia data
+/// structures are not thread safe, so a state must not be shared between different Web Workers.
+pub struct State {
+    pub gpu_state: GpuState,
+    pub surface: skia::Surface,
+}
+
+impl State {
+    pub fn new(gpu_state: GpuState, surface: skia::Surface) -> Self {
+        State { gpu_state, surface }
+    }
+
+    pub fn set_surface(&mut self, surface: skia::Surface) {
+        self.surface = surface;
+    }
+}
+
+pub(crate) fn init_gl() {
+    unsafe {
+        gl::load_with(|addr| {
+            let addr = std::ffi::CString::new(addr).unwrap();
+            emscripten_GetProcAddress(addr.into_raw() as *const _) as *const _
+        });
+    }
+}
+
+/// This needs to be done once per WebGL context.
+pub(crate) fn create_gpu_state() -> GpuState {
+    let interface = skia_safe::gpu::gl::Interface::new_native().unwrap();
+    let context = skia_safe::gpu::direct_contexts::make_gl(interface, None).unwrap();
+    let framebuffer_info = {
+        let mut fboid: gl::types::GLint = 0;
+        unsafe { gl::GetIntegerv(gl::FRAMEBUFFER_BINDING, &mut fboid) };
+
+        FramebufferInfo {
+            fboid: fboid.try_into().unwrap(),
+            format: skia_safe::gpu::gl::Format::RGBA8.into(),
+            protected: skia_safe::gpu::Protected::No,
+        }
+    };
+
+    GpuState {
+        context,
+        framebuffer_info,
+    }
+}
+
+/// Create the Skia surface that will be used for rendering.
+pub(crate) fn create_surface(gpu_state: &mut GpuState, width: i32, height: i32) -> skia::Surface {
+    let backend_render_target =
+        gpu::backend_render_targets::make_gl((width, height), 1, 8, gpu_state.framebuffer_info);
+
+    gpu::surfaces::wrap_backend_render_target(
+        &mut gpu_state.context,
+        &backend_render_target,
+        skia_safe::gpu::SurfaceOrigin::BottomLeft,
+        skia_safe::ColorType::RGBA8888,
+        None,
+        None,
+    )
+    .unwrap()
+}
+
+pub(crate) fn render_rect(surface: &mut skia::Surface, rect: skia::Rect, color: skia::Color) {
+    let mut paint = skia::Paint::default();
+    paint.set_style(skia::PaintStyle::Fill);
+    paint.set_color(color);
+    paint.set_anti_alias(true);
+    surface.canvas().draw_rect(rect, &paint);
+}