Fix camera release on Windows

Author: yushulx

examples/barcode-scanner/include/Camera.h

@@ -29,6 +29,7 @@
 #include <wrl/client.h>
 #include <dshow.h>
 
+using Microsoft::WRL::ComPtr;
 #elif __linux__
 #include <linux/videodev2.h>
 #include <fcntl.h>
@@ -106,7 +107,7 @@ class CAMERA_API Camera
 private:
 #ifdef _WIN32
     void *reader;
-
+    ComPtr<IMFMediaSource> ms;
     bool initialized;
     void InitializeMediaFoundation();
     void ShutdownMediaFoundation();

examples/barcode-scanner/litecam.jar

@@ -117,6 +117,12 @@ void Camera::ShutdownMediaFoundation()
 {
     if (initialized)
     {
+        if (ms)
+        {
+            ms->Shutdown();
+            ms.Reset();
+        }
+
         MFShutdown();
         initialized = false;
     }
@@ -164,6 +170,8 @@ bool Camera::Open(int cameraIndex)
     if (FAILED(hr))
         return false;
 
+    this->ms = mediaSource;
+
     ComPtr<IMFSourceReader> mfReader;
     hr = MFCreateSourceReaderFromMediaSource(mediaSource.Get(), nullptr, &mfReader);
     if (FAILED(hr))
@@ -200,6 +208,8 @@ void Camera::Release()
     {
         ComPtr<IMFSourceReader> mfReader(static_cast<IMFSourceReader *>(reader));
         reader = nullptr;
+
+        ShutdownMediaFoundation();
     }
 }