Slicer3D Wizard Workflow In KWWidgets for a year now,KWWidgets Includes State Machine Engine, Was used to port Slicer2s EMSegmentation Module (Golland,

Slicer3D Wizard WorkflowSlicer3D Wizard WorkflowIn KWWidgets for a year now,Includes State Machine Engine,Was used to port Slicer2’s

EMSegmentation Module (Golland, Pohl),

Funded by NA-MIC.

12/13/2007 1Kitware Inc. (Sébastien Barré)

What it looks likeWhat it looks like


State Machine EngineState Machine EngineBorrows design from IGSTK’s State

Machine,Uses KWWidgets/VTK framework,Provides the basis for the Wizard

Workflow.


State Machine ClassesState Machine ClassesvtkKWStateMachineState: a state vtkKWStateMachineInput: an input vtkKWStateMachineTransition: a transition vtkKWStateMachine: a state machine

Helper classes: vtkKWStateMachineCluster: a cluster of

states vtkKWStateMachineWriter: a writer

superclass vtkKWStateMachineDOTWriter: a DOT writer


State Machine StateState Machine StatevtkKWStateMachineState Id: unique state ID Name: string Description: string Enter/Leave: callbacks, events

Both callbacks and events are supported, independent of the transition, can be used to bring UI, or free resources.


State Machine InputState Machine InputvtkKWStateMachineInput Id: unique input ID Name: string


State Machine TransitionState Machine TransitionvtkKWStateMachineTransition Id: unique transition ID OriginState: vtkKWStateMachineState Input: vtkKWStateMachineInput DestinationState:

vtkKWStateMachineState Start/End: callbacks, events

Support callback and events at beginning and end of a transition.


State Machine APIState Machine APIvtkKWStateMachine AddState(state) AddInput(input) AddTransition(transition)

CreateTransition(origin_state, input, destination_state)

SetInitialState(state) GetCurrentState(state)

PushInput(input) ProcessInputs()


State Machine AlgorithmState Machine AlgorithmvtkKWStateMachine’s ProcessInputs():For each input in the queue: a transition T is searched accepting the current

state C and the input, if found:

◦ T's Start() method is triggered,◦ C's Leave() method is triggered,◦ T is pushed to the history,◦ C becomes T's DestinationState,◦ CurrentStateChangedCommand and

CurrentStateChangedEvent are invoked,◦ C (i.e. T's DestinationState)'s Enter() method is

triggered,◦ T's End() method is triggered.


State Machine ExampleState Machine ExampleFrom TestStateMachine.cxx :

vtkKWStateMachine *state_machine = vtkKWStateMachine::New();

...

vtkKWStateMachineState *state_1 = vtkKWStateMachineState::New();

state_1->SetName("Start");

state_machine->AddState(state_1);

...

vtkKWStateMachineInput *input_next = vtkKWStateMachineInput::New();

input_next->SetName("next");

state_machine->AddInput(input_next);

...

// Transition: state_1 / input_next => state_2

vtkKWStateMachineTransition *trans_a = vtkKWStateMachineTransition::New();

trans_a->SetOriginState(state_1);

trans_a->SetInput(input_next);

trans_a->SetDestinationState(state_2);

state_machine->AddTransition(trans_a);

...

// Transition: state_1 / skip => state_3

state_machine->CreateTransition(state_1, input_skip, state_3);

...

// Run the state machine

state_machine->SetInitialState(state_1);

state_machine->PushInput(input_next); // state_1 to state_2

state_machine->PushInput(input_invalid); // state_2 to state_2

state_machine->ProcessInputs();


Wizard WorkflowWizard Workflow Uses the state machine engine and provides higher-

level classes to meet the following requirements: ◦ a wizard is a linear succession of steps (most of the time),

◦ each step may need to display specific GUI elements,

◦ one may navigate from one step to the next one using a 'Next' button,

◦ one may navigate from one step to the previous one using a 'Back' button,

◦ one may navigate directly to the last step using a 'Finish' button,

◦ one needs to make sure a step is valid before navigating to the next one,

◦ one do *not* need to make sure a step is valid before navigating to the previous one.


Wizard Workflow ClassesWizard Workflow ClassesvtkKWWizardStep: a wizard step, vtkKWWizardWorkflow: a wizard workflow,vtkKWWizardWidget: a wizard widget,

embedding buttons, client area, and a wizard workflow engine,

vtkKWWizardDialog: a wizard dialog, embedding a wizard widget in a toplevel dialog.


Wizard StepWizard StepA wizard step is not a subclass of a state

machine state but an aggregation of several states, transitions and inputs that are relevant to a step.

InteractionState, ValidationState ValidationTransition, ValidationFailedTransition ValidationInput, ValidationSucceededInput,

ValidationFailedInput GoToSelfInput, GoBackToSelfInput

BUT what really needs to be re-implemented: ShowUserInterface(): brings UI Validate(): pushes inputs

Optionally: HideUserInterface() CanGoToSelf()


Wizard WorkflowWizard WorkflowA wizard workflow is a subclass of a state

machine engine. It provides additional methods that accept wizard steps as arguments and:

setup their internal elements, initialize their states, connect their transitions, Distribute/reshuffle all internal elements to the

state machine superclass. A wizard workflow can be used as a regular

state machine if you wish.


Wizard Workflow APIWizard Workflow API AddStep(step) CreateNextTransition(origin_step, next_input,

dest_step) CreateBackTransition(origin_step, dest_step) AddNextStep(step) … CreateGoToTransitionsToFinishStep()

Supports navigation and transition history.


Wizard Workflow ExampleWizard Workflow ExampleKWWidgets CVS Cxx/Examples/WizardDialog Simple wizard walks you through a

mathematical operation: Select a mathematical operator (addition, division, square

root), Select the first operand, Select the second operand *if* the operator was addition or

division, Display the result.

Exercises simple features: Skipping a step (if the operator is square root, the second

operand is not needed), Validation (if the operand is division, the second operand

should be != 0, if the operand is square root, it should be >= 0).


Wizard Workflow ExampleWizard Workflow Example Demo


Diagram without “Go To Finish” transitions.

Wizard Workflow ExampleWizard Workflow Example


Diagram with “Go To Finish” transitions.

“Complexity delusion”

Wizard Workflow ExampleWizard Workflow Example


ResourcesResourceshttp://kwwidgets.orghttp://kwwidgets.org/Wiki/KWWidgets/

Wizard_Workflow (under construction)KWWidgets CVS: Cxx/Examples/WizardDialogSlicer SVN: Modules/EMSegment/Wizard


Documents

Slicer3D Wizard Workflow In KWWidgets for a year now,KWWidgets Includes State Machine Engine, Was used to port Slicer2s EMSegmentation Module (Golland,