1 files changed, 163 insertions, 0 deletions
diff --git a/src/audio.rs b/src/audio.rs
new file mode 100644
index 0000000..1552292
--- /dev/null
+++ b/src/audio.rs
@@ -0,0 +1,163 @@
+//! Contains all types and implementations related to audio processing and the audio thread.
+
+use crate::{
+    RetainPluginMainThread, RetainPluginShared,
+    params::{GestureChange, RetainParamsLocal, RetainParamsShared},
+};
+use clack_extensions::{audio_ports::*, params::PluginAudioProcessorParams};
+use clack_plugin::{
+    events::event_types::{ParamGestureBeginEvent, ParamGestureEndEvent},
+    prelude::*,
+};
+
+/// Our plugin's audio processor. It lives in the audio thread.
+///
+/// It receives parameter events, and process a stereo audio signal by operating on the given audio
+/// buffer.
+pub struct RetainPluginAudioProcessor<'a> {
+    /// The local state of the parameters
+    params: RetainParamsLocal,
+    /// A reference to the plugin's shared data.
+    shared: &'a RetainPluginShared,
+    /// Our handle to the host
+    host: HostAudioProcessorHandle<'a>,
+}
+
+impl<'a> PluginAudioProcessor<'a, RetainPluginShared, RetainPluginMainThread<'a>>
+    for RetainPluginAudioProcessor<'a>
+{
+    fn activate(
+        host: HostAudioProcessorHandle<'a>,
+        _main_thread: &mut RetainPluginMainThread,
+        shared: &'a RetainPluginShared,
+        _audio_config: PluginAudioConfiguration,
+    ) -> Result<Self, PluginError> {
+        // This is where we would allocate intermediate buffers and such if we needed them.
+        Ok(Self {
+            host,
+            shared,
+            params: RetainParamsLocal::new(&shared.params),
+        })
+    }
+
+    fn process(
+        &mut self,
+        _process: Process,
+        mut audio: Audio,
+        events: Events,
+    ) -> Result<ProcessStatus, PluginError> {
+        // First, we have to make a few sanity checks.
+        // We want at least a single input/output port pair, which contains channels of `f32`
+        // audio sample data.
+        let mut port_pair = audio
+            .port_pair(0)
+            .ok_or(PluginError::Message("No input/output ports found"))?;
+
+        let mut output_channels = port_pair
+            .channels()?
+            .into_f32()
+            .ok_or(PluginError::Message("Expected f32 input/output"))?;
+
+        let mut channel_buffers = [None, None];
+
+        // Extract the buffer slices that we need, while making sure they are paired correctly and
+        // check for either in-place or separate buffers.
+        for (pair, buf) in output_channels.iter_mut().zip(&mut channel_buffers) {
+            *buf = match pair {
+                ChannelPair::InputOnly(_) | ChannelPair::OutputOnly(_) => None,
+                ChannelPair::InPlace(b) => Some(b),
+                ChannelPair::InputOutput(i, o) => {
+                    o.copy_from_slice(i);
+                    Some(o)
+                }
+            }
+        }
+
+        // Receive any param updates from the main thread and/or the GUI.
+        let has_ui_param_updates = self.params.fetch_updates(&self.shared.params);
+
+        // Now let's process the audio, while splitting the processing in batches between each
+        // sample-accurate event.
+
+        for event_batch in events.input.batch() {
+            // Process all param events in this batch
+            for event in event_batch.events() {
+                self.params.handle_event(event);
+            }
+
+            // Get the order value after all parameter changes have been handled.
+            let order = self.params.get_order();
+
+            for buf in channel_buffers.iter_mut().flatten() {
+                for sample in buf.iter_mut() {
+                    *sample = order as f32;
+                }
+            }
+        }
+
+        // Publish any parameter changes we may have received back to the GUI.
+        if self.params.push_updates(&self.shared.params) {
+            // Request the on-main-thread callback, which we use to refresh the UI if it is open
+            self.host.request_callback();
+        }
+
+        // Fetch the latest gesture status
+        let current_gesture = self
+            .params
+            .fetch_gesture(&self.shared.params, has_ui_param_updates);
+
+        // Send a Gesture Begin event, if we need to do so
+        if let Some(GestureChange::Begin | GestureChange::Both) = current_gesture {
+            let _ = events.output.try_push(ParamGestureBeginEvent::new(
+                0,
+                RetainParamsShared::PARAM_ORDER_ID,
+            ));
+        }
+
+        // If the UI sent us param updates, send them to the Host
+        if has_ui_param_updates {
+            self.params.send_param_events(events.output);
+        }
+
+        // Send a Gesture End event, if we need to do so
+        if let Some(GestureChange::End | GestureChange::Both) = current_gesture {
+            let _ = events.output.try_push(ParamGestureEndEvent::new(
+                audio.frames_count(),
+                RetainParamsShared::PARAM_ORDER_ID,
+            ));
+        }
+
+        Ok(ProcessStatus::ContinueIfNotQuiet)
+    }
+}
+
+impl PluginAudioPortsImpl for RetainPluginMainThread<'_> {
+    fn count(&mut self, _is_input: bool) -> u32 {
+        1
+    }
+
+    fn get(&mut self, index: u32, _is_input: bool, writer: &mut AudioPortInfoWriter) {
+        if index == 0 {
+            writer.set(&AudioPortInfo {
+                id: ClapId::new(0),
+                name: b"main",
+                channel_count: 2,
+                flags: AudioPortFlags::IS_MAIN,
+                port_type: Some(AudioPortType::STEREO),
+                in_place_pair: None,
+            });
+        }
+    }
+}
+
+impl PluginAudioProcessorParams for RetainPluginAudioProcessor<'_> {
+    fn flush(
+        &mut self,
+        input_parameter_changes: &InputEvents,
+        _output_parameter_changes: &mut OutputEvents,
+    ) {
+        for event in input_parameter_changes {
+            self.params.handle_event(event);
+        }
+    }
+}