Phase 7 step 1

apps/LoopThroughWithOpenGLCompositing/videoio/VideoBackendLifecycle.cpp

@@ -0,0 +1,123 @@
+#include "VideoBackendLifecycle.h"
+
+VideoBackendLifecycleState VideoBackendLifecycle::State() const
+{
+	return mState;
+}
+
+const std::string& VideoBackendLifecycle::FailureReason() const
+{
+	return mFailureReason;
+}
+
+VideoBackendLifecycleTransition VideoBackendLifecycle::TransitionTo(VideoBackendLifecycleState next, const std::string& reason)
+{
+	VideoBackendLifecycleTransition transition;
+	transition.previous = mState;
+	transition.current = next;
+	transition.reason = reason;
+	transition.accepted = CanTransition(mState, next);
+	if (!transition.accepted)
+	{
+		transition.current = mState;
+		transition.errorMessage = std::string("Invalid video backend lifecycle transition from ") +
+			StateName(mState) + " to " + StateName(next) + ".";
+		return transition;
+	}
+
+	mState = next;
+	transition.current = mState;
+	if (mState != VideoBackendLifecycleState::Failed)
+		mFailureReason.clear();
+	return transition;
+}
+
+VideoBackendLifecycleTransition VideoBackendLifecycle::Fail(const std::string& reason)
+{
+	VideoBackendLifecycleTransition transition = TransitionTo(VideoBackendLifecycleState::Failed, reason);
+	if (transition.accepted)
+		mFailureReason = reason;
+	return transition;
+}
+
+bool VideoBackendLifecycle::CanTransition(VideoBackendLifecycleState current, VideoBackendLifecycleState next)
+{
+	if (current == next)
+		return true;
+
+	switch (current)
+	{
+	case VideoBackendLifecycleState::Uninitialized:
+		return next == VideoBackendLifecycleState::Discovering ||
+			next == VideoBackendLifecycleState::Stopped ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Discovering:
+		return next == VideoBackendLifecycleState::Discovered ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Discovered:
+		return next == VideoBackendLifecycleState::Configuring ||
+			next == VideoBackendLifecycleState::Stopped ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Configuring:
+		return next == VideoBackendLifecycleState::Configured ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Configured:
+		return next == VideoBackendLifecycleState::Prerolling ||
+			next == VideoBackendLifecycleState::Stopped ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Prerolling:
+		return next == VideoBackendLifecycleState::Running ||
+			next == VideoBackendLifecycleState::Stopping ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Running:
+		return next == VideoBackendLifecycleState::Degraded ||
+			next == VideoBackendLifecycleState::Stopping ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Degraded:
+		return next == VideoBackendLifecycleState::Running ||
+			next == VideoBackendLifecycleState::Stopping ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Stopping:
+		return next == VideoBackendLifecycleState::Stopped ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Stopped:
+		return next == VideoBackendLifecycleState::Discovering ||
+			next == VideoBackendLifecycleState::Failed;
+	case VideoBackendLifecycleState::Failed:
+		return next == VideoBackendLifecycleState::Stopped ||
+			next == VideoBackendLifecycleState::Discovering;
+	default:
+		return false;
+	}
+}
+
+const char* VideoBackendLifecycle::StateName(VideoBackendLifecycleState state)
+{
+	switch (state)
+	{
+	case VideoBackendLifecycleState::Uninitialized:
+		return "uninitialized";
+	case VideoBackendLifecycleState::Discovering:
+		return "discovering";
+	case VideoBackendLifecycleState::Discovered:
+		return "discovered";
+	case VideoBackendLifecycleState::Configuring:
+		return "configuring";
+	case VideoBackendLifecycleState::Configured:
+		return "configured";
+	case VideoBackendLifecycleState::Prerolling:
+		return "prerolling";
+	case VideoBackendLifecycleState::Running:
+		return "running";
+	case VideoBackendLifecycleState::Degraded:
+		return "degraded";
+	case VideoBackendLifecycleState::Stopping:
+		return "stopping";
+	case VideoBackendLifecycleState::Stopped:
+		return "stopped";
+	case VideoBackendLifecycleState::Failed:
+		return "failed";
+	default:
+		return "unknown";
+	}
+}