Phase 7 step 1

apps/LoopThroughWithOpenGLCompositing/videoio/VideoBackendLifecycle.h

@@ -0,0 +1,43 @@
+#pragma once
+
+#include <string>
+
+enum class VideoBackendLifecycleState
+{
+	Uninitialized,
+	Discovering,
+	Discovered,
+	Configuring,
+	Configured,
+	Prerolling,
+	Running,
+	Degraded,
+	Stopping,
+	Stopped,
+	Failed
+};
+
+struct VideoBackendLifecycleTransition
+{
+	VideoBackendLifecycleState previous = VideoBackendLifecycleState::Uninitialized;
+	VideoBackendLifecycleState current = VideoBackendLifecycleState::Uninitialized;
+	bool accepted = false;
+	std::string reason;
+	std::string errorMessage;
+};
+
+class VideoBackendLifecycle
+{
+public:
+	VideoBackendLifecycleState State() const;
+	const std::string& FailureReason() const;
+	VideoBackendLifecycleTransition TransitionTo(VideoBackendLifecycleState next, const std::string& reason);
+	VideoBackendLifecycleTransition Fail(const std::string& reason);
+
+	static bool CanTransition(VideoBackendLifecycleState current, VideoBackendLifecycleState next);
+	static const char* StateName(VideoBackendLifecycleState state);
+
+private:
+	VideoBackendLifecycleState mState = VideoBackendLifecycleState::Uninitialized;
+	std::string mFailureReason;
+};