From 1cf1e40c54025fbc2b64d12681ec9e3e96c6fb7c Mon Sep 17 00:00:00 2001
From: Richard Bowman <richard.bowman@cantab.net>
Date: Mon, 8 Apr 2019 14:06:14 +0100
Subject: [PATCH] Added a lock to stop_preview for good measure

---
 openflexure_microscope/camera/pi.py | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/openflexure_microscope/camera/pi.py b/openflexure_microscope/camera/pi.py
index 634a0f11..7dd40b03 100644
--- a/openflexure_microscope/camera/pi.py
+++ b/openflexure_microscope/camera/pi.py
@@ -243,9 +243,10 @@ class StreamingCamera(BaseCamera):
 
     def stop_preview(self) -> bool:
         """Stop the on board GPU camera preview."""
-        self.camera.stop_preview()
-        self.state['preview_active'] = False
-        time.sleep(0.2)
+        with self.lock:
+            self.camera.stop_preview()
+            self.state['preview_active'] = False
+            time.sleep(0.2)
         return True
 
     def start_recording(