Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 1

Object-oriented application development with MeVisLab and Python

Frank HeckelMichael Schwier

Heinz-Otto Peitgen

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 2

What I am going to talk about

› Development of (medical) software assistants› Issues in multilevel development approaches (MeVisLab)› Object-oriented programming

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 3

Rapid Application Prototyping with MeVisLab

› Visual development environment for medical image processing and visualization

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 4

Script

Multilevel Development Approach

› Application Level» GUI design» Application logic

› Network Level» Image processing and visualization processes» Based on library of modules

› Module » Low-level algorithm implementationC++

Visual

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 5

Module/C++ Level Network Level Script Level

C++ Module

Int Float String

Image

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 6

The typical script level problem

› They form a global layer upon the network» Practically no access limitations» No scope bound to a subnetwork or modules

› Initial intention was to use it for short code snippets» Convenience (no need to get back to C++/recompile/restart)» Short conditional logic

› Since it’s so easy …» Developers put more and more logic and processing into the script

› Applications naturally need a lot of code upon the network» Controlling the data flow» Interaction» …

› Programmers tend to take Script programming not so serious

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 7

Giving a programmer this much freedom …

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 8

Let‘s build an application

› Load a BL and/or FU dataset that have been specified in the GUI › Switch to a proper GUI configuration if successful

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 9

Example

GUI

DataProcessing

LoadData

User Interface

Data Processing

Specific ModulesbaselineFilename

followupFilename

loadButton

LoadData_filename filename

LoadData_valid valid

Import

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 10

Call-Chain

GUI DataProcessing LoadData

baselineFilename

followupFilename

loadButton

LoadData_filename filename

LoadData_valid valid

def loadButtonPressed(field): if ctx.field(“baselineFilename”).value != “” ... state = “BL_AND_FU” ...

def baseline_LoadDataDone(field):if state == “BL_AND_FU”: if not successful: ...

def filenameChanged(field):

# loading stuff ...

if loadSuccessful: ctx.field(“valid”).value = True else: ctx.field(“valid”).value = False

Event

Set

Connection

EventSet

Event

GlobalState

Connection

IMPLICIT

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 11

Networks can get complex and confusing

Can you imagine the network script?

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 12

Join Script and Module

Module

Module

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 13

Concept

DataProcessingcontext: Networkparent: ReferenceloadData: Reference…init (ctx: Network, child: Reference): voidsetParent (parent: Reference): voidgetField (field: String): String/Int/Float

loadFile (filename: String): Boolean

DataProcessing

GUI

context: Networkparent: ReferencedataProcessing: Reference…

init (ctx: Network, child: Reference): voidsetParent (parent: Reference): voidgetField (field: String): String/Int/Float

loadFile (filename: String): Boolean

LoadData

context: Networkparent: Reference…

init (ctx: Network, child: Reference): voidsetParent (parent: Reference): voidgetField (field: String): String/Int/Float

loadFile (filename: String): Boolean

GUI LoadData

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 14

Integration in MeVisLab

DataProcessingInit

## global reference to this modules instancethis = None

## access method to the global this objectdef getThis(): global this return this

## the init method creates the global object## (one class instance per module instance)def init(ctx): global this loadData = ctx.module(“LoadData”).call(“getThis”)

this = DataProcessing(ctx, loadData)

return

DataProcessing

context: Networkparent: ReferenceloadData: Reference…

init (ctx: Network, child: Reference): voidsetParent (parent: Reference): voidgetField (field: String): String/Int/Float

loadFile (filename: String): Boolean

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 15

Integration in MeVisLab

DataProcessingInit

## global reference to this modules instancethis = None

## access method to the global this objectdef getThis(): global this return this

## the init method creates the global object## (one class instance per module instance)def init(ctx): global this loadData = ctx.module(“LoadData”).call(“getThis”)

this = DataProcessing(ctx, loadData)

return

DataProcessing

context: Networkparent: ReferenceloadData: Reference…

init (ctx: Network, child: Reference): voidsetParent (parent: Reference): voidgetField (field: String): String/Int/Float

loadFile (filename: String): Boolean

## global reference to this modules instancethis = None

## access method to the global this objectdef getThis(): global this return this

## the init method creates the global object## (one class instance per module instance)def init(ctx): global this loadData= ctx.module(“LoadData”).call(“getThis”)

this = DataProcessing(ctx, loadData)

return

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 16

Call chain

GUI DataProcessing LoadData

baselineFilename

followupFilename

loadButton

def loadData(self): if self.getfield("baselineFilename").value != "" and self.getfield("follo... if self.baselineScan.loadFile( self.getfield("baselineFilename").value ): if self.followupScan.loadFile( self.getfield("followupFilename").value ): # switch to bl+fu layout... else: ...

def loadFile(self, filename): return loadData.loadFile(filename)

EXPLICIT

def loadFile(self, filename): # loading stuff ... return loadSuccessful

Event

Call Call

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 17

The Essence

Use object oriented programming (wisely) …

… even if it‘s tempting not to do it!

Fraunhofer MEVIS Institute for Medical Image Computing 01.10.2009 INFORMATIK 2009 – Softwareassistenten in der Medizin 18

The Essence

Use object oriented programming (wisely) …

… even if it‘s tempting not to do it!

The users/clinicians will profit.