Implement pause/resume

closes #14

Author: DerFetzer

CHANGELOG.md

@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ## [Unreleased]
 
+### Added
+
+- Pause/resume camera stream
+
 ## [0.2.0] - 2025-02-19
 
 ### Added

src/camera.rs

@@ -9,7 +9,7 @@ use nokhwa::utils::{
     CameraFormat, CameraIndex, ControlValueSetter, FrameFormat, KnownCameraControl,
     RequestedFormat, RequestedFormatType, Resolution,
 };
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc, Condvar, Mutex};
 
 #[derive(Debug, Clone)]
 pub struct CameraInfo {
@@ -41,6 +41,8 @@ pub enum CameraEvent {
     StopStream,
     Config(ImageConfig),
     Controls(Vec<(KnownCameraControl, ControlValueSetter)>),
+    Pause,
+    Resume,
 }
 
 struct Exit {}
@@ -75,7 +77,11 @@ impl CameraThread {
         #[allow(clippy::type_complexity)]
         let controls: Arc<Mutex<Option<Vec<(KnownCameraControl, ControlValueSetter)>>>> =
             Arc::new(Mutex::new(None));
+
+        let pause = Arc::new((Mutex::new(false), Condvar::new()));
+
         let mut join_handle = None;
+
         while let Ok(event) = self.config_rx.recv() {
             match event {
                 CameraEvent::StartStream { id, format } => {
@@ -86,6 +92,8 @@ impl CameraThread {
                     let window_tx = self.window_tx.clone();
                     let result_tx = self.result_tx.clone();
                     let exit_rx = exit_rx.clone();
+                    let pause_thread = Arc::clone(&pause);
+
                     let hdl = std::thread::spawn(move || {
                         let mut camera = match CallbackCamera::new(
                             id,
@@ -127,7 +135,15 @@ impl CameraThread {
 
                         let mut inner_config = None;
 
+                        let (pause_lock, pause_cvar) = &*pause_thread;
+
                         loop {
+                            // Check pause request
+                            let guard = pause_cvar
+                                .wait_while(pause_lock.lock().unwrap(), |paused| *paused)
+                                .unwrap();
+                            drop(guard);
+
                             // Check exit request
                             if exit_rx.try_recv().is_ok() {
                                 return;
@@ -208,6 +224,18 @@ impl CameraThread {
                 CameraEvent::Controls(ctrls) => {
                     *controls.lock().unwrap() = Some(ctrls);
                 }
+                CameraEvent::Pause => {
+                    let (pause_lock, pause_cvar) = &*pause;
+                    let mut paused = pause_lock.lock().unwrap();
+                    *paused = true;
+                    pause_cvar.notify_one();
+                }
+                CameraEvent::Resume => {
+                    let (pause_lock, pause_cvar) = &*pause;
+                    let mut paused = pause_lock.lock().unwrap();
+                    *paused = false;
+                    pause_cvar.notify_one();
+                }
             }
         }
         log::debug!("Camera thread exiting");

src/gui/mod.rs

@@ -31,6 +31,7 @@ pub struct SpectrometerGui {
     camera_control_window: camera_control::CameraControlWindow,
     import_export_window: import_export::ImportExportWindow,
     running: bool,
+    paused: bool,
     camera_info: IndexMap<CameraIndex, crate::camera::CameraInfo>,
     camera_controls: Vec<CameraControl>,
     spectrum_container: SpectrumContainer,
@@ -61,6 +62,7 @@ impl SpectrometerGui {
             camera_control_window: camera_control::CameraControlWindow::new(),
             import_export_window: import_export::ImportExportWindow::new(),
             running: false,
+            paused: false,
             camera_info: Default::default(),
             camera_controls: Default::default(),
             spectrum_container: SpectrumContainer::new(spectrum_rx),
@@ -166,7 +168,17 @@ impl SpectrometerGui {
         }
     }
 
+    fn pause_stream(&mut self) {
+        self.camera_config_tx.send(CameraEvent::Pause).unwrap();
+    }
+
+    fn resume_stream(&mut self) {
+        self.camera_config_tx.send(CameraEvent::Resume).unwrap();
+    }
+
     fn stop_stream(&mut self) {
+        // First resume stream, otherwise the camera thread will not continue
+        self.resume_stream();
         self.camera_config_tx.send(CameraEvent::StopStream).unwrap();
     }
 
@@ -451,6 +463,7 @@ impl SpectrometerGui {
                             .clamp(camera_format.width() as f32, camera_format.height() as f32);
 
                         self.running = !self.running;
+                        self.paused = false;
                         if self.running {
                             self.start_stream();
                         } else {
@@ -463,6 +476,18 @@ impl SpectrometerGui {
                         });
                     }
                 };
+                if self.running {
+                    let pause_resume_button =
+                        ui.button(if self.paused { "Resume" } else { "Pause" });
+                    if pause_resume_button.clicked() {
+                        if self.paused {
+                            self.resume_stream();
+                        } else {
+                            self.pause_stream();
+                        }
+                        self.paused = !self.paused;
+                    }
+                }
             });
         });
     }