Move AppKit (macOS) backend to winit-appkit (#4248)

winit-appkit/src/util.rs

@@ -0,0 +1,44 @@
+use objc2_core_graphics::CGError;
+use tracing::trace;
+use winit_core::error::OsError;
+
+macro_rules! os_error {
+    ($error:expr) => {{
+        winit_core::error::OsError::new(line!(), file!(), $error)
+    }};
+}
+
+macro_rules! trace_scope {
+    ($s:literal) => {
+        let _crate = $crate::util::TraceGuard::new(module_path!(), $s);
+    };
+}
+
+pub(crate) struct TraceGuard {
+    module_path: &'static str,
+    called_from_fn: &'static str,
+}
+
+impl TraceGuard {
+    #[inline]
+    pub(crate) fn new(module_path: &'static str, called_from_fn: &'static str) -> Self {
+        trace!(target = module_path, "Triggered `{}`", called_from_fn);
+        Self { module_path, called_from_fn }
+    }
+}
+
+impl Drop for TraceGuard {
+    #[inline]
+    fn drop(&mut self) {
+        trace!(target = self.module_path, "Completed `{}`", self.called_from_fn);
+    }
+}
+
+#[track_caller]
+pub(crate) fn cgerr(err: CGError) -> Result<(), OsError> {
+    if err == CGError::Success {
+        Ok(())
+    } else {
+        Err(os_error!(format!("CGError {err:?}")))
+    }
+}