Support ScreenCapture loopback

Cargo.toml

@@ -53,6 +53,7 @@ mach2 = "0.4" # For access to mach_timebase type.
 
 [target.'cfg(target_os = "macos")'.dependencies]
 coreaudio-rs = { version = "0.11", default-features = false, features = ["audio_unit", "core_audio"] }
+cidre = { git = "https://github.com/yury/cidre.git", rev = "f05c428" }
 
 [target.'cfg(target_os = "ios")'.dependencies]
 coreaudio-rs = { version = "0.11", default-features = false, features = ["audio_unit", "core_audio", "audio_toolbox"] }

src/host/mod.rs

@@ -24,6 +24,8 @@ pub(crate) mod jack;
 pub(crate) mod null;
 #[cfg(target_os = "android")]
 pub(crate) mod oboe;
+#[cfg(target_os = "macos")]
+pub(crate) mod screencapturekit;
 #[cfg(windows)]
 pub(crate) mod wasapi;
 #[cfg(all(target_arch = "wasm32", feature = "wasm-bindgen"))]

src/host/screencapturekit/enumerate.rs

@@ -0,0 +1,60 @@
+use std::vec::IntoIter as VecIntoIter;
+
+use cidre::sc;
+
+use crate::{BackendSpecificError, DevicesError, SupportedStreamConfigRange};
+
+use super::Device;
+
+pub struct Devices(VecIntoIter<Device>);
+
+impl Devices {
+    pub fn new() -> Result<Self, DevicesError> {
+        let (tx, rx) = std::sync::mpsc::channel();
+        sc::ShareableContent::current_with_ch(move |sc, e| {
+            let res = if let Some(err) = e {
+                Result::Err(BackendSpecificError {
+                    description: format!("{err}"),
+                })
+            } else if let Some(sc) = sc {
+                Result::Ok(sc.retained())
+            } else {
+                Result::Err(BackendSpecificError {
+                    description: "Failed to get current shareable content".to_string(),
+                })
+            };
+            tx.send(res).unwrap();
+        });
+        let sc_shareable_content = rx.recv().unwrap()?;
+
+        let mut res = Vec::new();
+        for display in sc_shareable_content.displays().iter() {
+            res.push(Device::new(display.retained()));
+        }
+
+        Ok(Devices(res.into_iter()))
+    }
+}
+
+unsafe impl Send for Devices {}
+unsafe impl Sync for Devices {}
+
+impl Iterator for Devices {
+    type Item = Device;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next()
+    }
+}
+
+pub fn default_input_device() -> Option<Device> {
+    let devices = Devices::new().ok()?;
+    devices.into_iter().next()
+}
+
+pub fn default_output_device() -> Option<Device> {
+    None
+}
+
+pub type SupportedInputConfigs = VecIntoIter<SupportedStreamConfigRange>;
+pub type SupportedOutputConfigs = VecIntoIter<SupportedStreamConfigRange>;