diff -r f54ad444594d -r 61bc0f252b2b camerauis/cameraxui/cxengine/inc/cxestatemachinebase.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/camerauis/cameraxui/cxengine/inc/cxestatemachinebase.h	Tue Aug 31 15:03:46 2010 +0300
@@ -0,0 +1,133 @@
+/*
+* Copyright (c) 2009-2010 Nokia Corporation and/or its subsidiary(-ies).
+* All rights reserved.
+* This component and the accompanying materials are made available
+* under the terms of "Eclipse Public License v1.0"
+* which accompanies this distribution, and is available
+* at the URL "http://www.eclipse.org/legal/epl-v10.html".
+*
+* Initial Contributors:
+* Nokia Corporation - initial contribution.
+*
+* Contributors:
+*
+* Description:
+*
+*/
+
+#ifndef CXESTATEMACHINEBASE_H
+#define CXESTATEMACHINEBASE_H
+
+#include <QHash>
+#include <QString>
+#include "cxeerror.h"
+
+class CxeState;
+
+/**
+* CxeStateMachineBase is used as the base class for all finite state machines in the
+* engine. It's not a fully functional state machine in the sense that it does not provide any
+* mechanism for handling events that would trigged state changes. Instead,
+* it relies on the derived class to call setState() whenever the state
+* should change. The derived class should also provide a list of states
+* and allowed transitions so that CxeStateMachineBase can verify that each state
+* change is valid. A pure virtual function, handleStateChanged() should be
+* implemented by derived classes to handle notifing other interested objects about
+* the state change. This class cannot emit the signals itself, because it does not
+* derived from QObject and it handles all state IDs as plain integers instead of the
+* preferred class specific enumerations.
+*
+* CxeStateMachineBase does not derive from QObject to make easier for the engine
+* control implementation classes to derive from it. Additionally we avoid the overhead
+* brought by QObject.
+*
+* CxeStateMachineBase class is to be used for unit testing. Engine class should derive
+* from CxeStateMachine class.
+*/
+
+class CxeStateMachineBase
+{
+public:
+    /**
+    * CxeStateMachine constructor.
+    * @sa addState setInitialState
+    * @param stateMachineName  Name for this state machine (used for debug prints)
+    */
+    CxeStateMachineBase(const char *stateMachineName);
+    virtual ~CxeStateMachineBase();
+
+protected:
+    /**
+     * Add a new state to the machine. Takes ownership of state.
+     *
+     * @param state A CxeState object defining a name, ID, and allowed transitions for the
+     * new state. The CxeState ID must be unique and not to contain overlapping bits with other
+     * state ids, since bitwise AND operator is used for the state ids.
+     * @return False if adding failed due to incorrect id.
+     */
+    virtual bool addState(CxeState *state);
+
+    /**
+     * Initiate a state transition from current state to a given state ID. In cases that
+     * current state is same as the new state, method returns without doing anything. If the state
+     * transition is invalid, this function return false.
+     *
+     * @param stateId State ID of the new state
+     * @param error   Optional error code to be associated with the transition
+     * @return False if state change fails. True if changing is allowed, or the current state is same
+     * as the new state.
+     */
+    virtual bool setState(int stateId, CxeError::Id error = CxeError::None);
+
+    /**
+     * Set the initial state of the state machine. Can be called only once.
+     * This method will panic, if initial state is unknown, or initial state has already
+     * been set.
+     *
+     * @param stateId State ID for the initial state.
+     * @return False if state to be set intial state is not known, or initial
+     * state has already been set.
+     */
+    virtual bool setInitialState(int stateId);
+
+    /**
+     * Pure virtual function to be implemented by derived classes. Called when state changes.
+     * The implementation should emit a signal informing interested parties of a state change.
+     *
+     * @param newStateId State ID for the new state
+     * @param error      An error code associated with the state transition
+     */
+    virtual void handleStateChanged(int newStateId, CxeError::Id error) = 0;
+
+    /**
+     * Get current state ID. It is recommended for derived classes to create
+     * a new method (typically called state()) which returns the current state ID
+     * typecasted into a class specific enumeration.
+     * @return Current state ID
+     */
+    int stateId() const;
+
+    /**
+     * Verify if a state transition is possible.
+     * @param newStateId  State ID of the new state.
+     * @return Whether state transition is possible.
+     */
+    bool verifyStateChange(int newStateId);
+
+private:
+
+    //! Hash table of all states. stateId as key
+    QHash<int, CxeState *> mStates;
+
+    //! All states ORed together
+    int mStateBitsUsed;
+
+    //! Current state
+    int mStateId;
+
+    //! Name of this state machine (for debug prints)
+    QString mName;
+
+};
+
+#endif // CXESTATEMACHINEBASE_H