Introduction

Overview

This module, 'twain', provides an interface to the windows TWAIN sub-system. The software is available only for windows platforms. This software is designed to support scanners, digital cameras and audio equipment which conform to the twain specification.

The twain module also includes a demonstration program, called twexplore.py, which can be used to investigate the interface to your twain compatible device.

Introduction to TWAIN

TWAIN is a published API which provides an interface between an application and a scanner or other source of images. The TWAIN API is maintained and developed by TWAIN Working Group, see www.twain.org.

The application connects to and communicates with the TWAIN Source Manager program, which is implemented as twain.dll. The TWAIN Source Manager loads the program to support the device with which your application needs to communicate. The program which supports the device is called a Data Source.

The TWAIN specification defines a simple finite-state model for communicating with the TWAIN sub-system. The states are as follows:

State Name State Description Application Activities Move to next state on

1 - Pre-Session Source Manager is not Loaded None Load DLL

2 - Source Manager Loaded Source Manager DLL has been loaded. None Open Source Manager

3 - Source Manager Open Application can communicate with the source manager Can query the list of available sources Open Source

4 - Source Open The source for the appropriate device is open. Application can negotiate the details of the session, e.g. image format, number of colours etc. Request Aquisition of image

5 - Source Enabled The source is attempting to acquire data on behalf of the application None User/Source produce image

6 - Transfer Ready The source has acquired the data on behalf of the application. Begin the transfer. Transfer Started.

7 - Transfer in Progress The source is transferring the data to the application. Receive data.

References

TWAIN Specification, version 1.9 at http://www.twain.org.
TWAIN Developers Toolkit, version 1.7.0.3 at http://www.twain.org.

Acknowledgements

Riaan and the boa constructor team for the tool their great design tool, which I used to build twexplore.py.
Thomas Heller for the py2exe tool, with which I built the twexplore.exe.
Robin and the wxPython team for their wxWindows implmentation for Python
All those who produced Python and produced the great port for windows

Introduction

State Name	State Description	Application Activities	Move to next state on
1 - Pre-Session	Source Manager is not Loaded	None	Load DLL
2 - Source Manager Loaded	Source Manager DLL has been loaded.	None	Open Source Manager
3 - Source Manager Open	Application can communicate with the source manager	Can query the list of available sources	Open Source
4 - Source Open	The source for the appropriate device is open.	Application can negotiate the details of the session, e.g. image format, number of colours etc.	Request Aquisition of image
5 - Source Enabled	The source is attempting to acquire data on behalf of the application	None	User/Source produce image
6 - Transfer Ready	The source has acquired the data on behalf of the application.	Begin the transfer.	Transfer Started.
7 - Transfer in Progress	The source is transferring the data to the application.	Receive data.