Support ScreenCapture loopback

Cargo.toml

@@ -50,6 +50,8 @@ jack = { version = "0.11", optional = true }
 [target.'cfg(any(target_os = "macos", target_os = "ios"))'.dependencies]
 core-foundation-sys = "0.8.2" # For linking to CoreFoundation.framework and handling device name `CFString`s.
 mach2 = "0.4" # For access to mach_timebase type.
+screencapturekit = "0.2.8"
+screencapturekit-sys = "0.2.8"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 coreaudio-rs = { version = "0.11", default-features = false, features = ["audio_unit", "core_audio"] }

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 +1,46 @@
+use screencapturekit::sc_shareable_content::SCShareableContent;
+
+use std::vec::IntoIter as VecIntoIter;
+
+use crate::{BackendSpecificError, DevicesError, SupportedStreamConfigRange};
+
+use super::Device;
+
+pub struct Devices(VecIntoIter<Device>);
+
+impl Devices {
+    pub fn new() -> Result<Self, DevicesError> {
+        let sc_shareable_content = SCShareableContent::try_current()
+            .map_err(|description| BackendSpecificError { description })?;
+
+        let mut res = Vec::new();
+        for display in sc_shareable_content.displays.into_iter() {
+            res.push(Device::new(display));
+        }
+
+        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>;