feat: setup emscripten module for api layer

src/emscripten.rs

@@ -0,0 +1,31 @@
+#[allow(dead_code)]
+#[cfg(target_os = "emscripten")]
+pub mod emscripten {
+    use std::os::raw::c_uint;
+
+    extern "C" {
+        pub fn emscripten_get_now() -> f64;
+        pub fn emscripten_sleep(ms: c_uint);
+        pub fn emscripten_get_element_css_size(target: *const u8, width: *mut f64, height: *mut f64) -> i32;
+    }
+
+    // milliseconds since start of program
+    pub fn now() -> f64 {
+        unsafe { emscripten_get_now() }
+    }
+
+    pub fn sleep(ms: u32) {
+        unsafe {
+            emscripten_sleep(ms);
+        }
+    }
+
+    pub fn get_canvas_size() -> (u32, u32) {
+        let mut width = 0.0;
+        let mut height = 0.0;
+        unsafe {
+            emscripten_get_element_css_size("canvas\0".as_ptr(), &mut width, &mut height);
+        }
+        (width as u32, height as u32)
+    }
+}