TWAIN-SANE Interface for macOS

Introduction

This repository aggregates the source code components available at ellert.se/twain-sane for the purpose of setting up a Git workspace for the project of getting the TWAIN SANE Interface running in 64-bit for current versions of macOS.

The contents of this repository do not currently compile.

I do not anticipate making progress on this project myself in the foreseeable future, as, among other things, I have very little experience with Cocoa and Objective-C, and learning macOS development is not a current focus for me.

Please feel free to fork this repository as a base for working on it yourself, and please do tag me if you make any progress!

— Elsie Hupp (@elsiehupp) September 2021

Repository Contents

This repository includes three subdirectories:

./TwainSaneInterface

This package is the core of Mattias Ellert's project. It maps SANE's API to a TWAIN API and provides a graphical user interface for use within Apple Image Capture and macOS applications that use Image Capture as a scanner or camera interface. (This package does not compile and has not been adapted to Homebrew-installed sane-backends.)

The contents of TwainSaneInterface are licensed under the GPLv2.

./SanePreferencePane

This optional Preference Pane package from Mattias Ellert's project makes it easier to configure the sane-backends drivers. If you don’t install this package you can still configure the sane-backends using a text editor in the Terminal. (This package does not compile and has not been adapted to Homebrew-installed sane-backends. Oddly, the compiled version of this did run correctly under macOS 11, even though the compiled TwainSaneInterface did not. I think this may just be due to how Preference Panes work.)

The contents of SanePreferencePane are licensed under the GPLv2.

./VirtualScanner

This is a sample project from Apple's Developer documentation archive. I have included it because does not seem to depend on Carbon.framework, though it still does not compile (albeit for different reasons.).

The contents of VirtualScanner are licensed under Apple's version of the MIT License.

External Requirements

After doing some further digging, I have simplified the contents of this repository to exclude the dependencies available through Homebrew. Rather than including an ancient version of the source code for sane-backends, I would encourage you to install the fully maintained Homebrew version using the following Terminal commands:

1. Install Homebrew (if you haven't already):

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

2. Install sane-backends:

brew install sane-backends

The advantage with this approach is that the version you have installed will be completely up-to-date. I have not updated any of the code to dynamically linking to the Homebrew version, though, because I'm not sure exactly what would be involved.

Problem Statement

Mattias Ellert's original code no longer compiles on current versions of macOS due to two prerequisite Apple libraries never making the jump to 64-bit:

1. Carbon.framework (Yes, we knew this fourteen years ago.)
2. ICADevices.framework (Depends on Carbon.framework)

Additionally, TWAIN.framework doesn't appear in Apple's current Developer documentation, but I checked on my Mac (running macOS 12.1), and /System/Library/Frameworks/TWAIN.framework is still there, so seemingly it's still current.

Regardless, Apple no longer provides any current references for creating scanner drivers in particular. As best I can tell, approaches that might work for modernizing the TWAIN-SANE Interface are as follows:

• At the very least, port the existing TwainSaneInterface (and maybe SanePreferencePane) code to access sane-backends dynamically, and port it from Carbon.framework to Cocoa.framework (or even SwiftUI).
• Maybe create a wrapper for sane-backends using DriverKit, specifically USBDriverKit (though this would rule out sane-backends using parallel, SCSI, or any other non-USB interface)?
• Maybe port the TwainSaneInterface from using TWAIN.framework to using ImageCaptureCore directly? (It's unclear to me whether ImageCaptureCore is only for client applicaitons or if it's for drivers, as well.)

Note that TwainSaneInterface is written entirely in C and C++, not Objective-C. The only Objective-C file in the entire project is in TwainSaneInterface (though the VirtualScanner sample project is written in Objective-C). TWAIN is (as far as I can tell) basically a set of C headers, so any code accessing them would need to accept these. In order to access both TWAIN and Cocoa in the same project, it may be necessary to use Objective-C++, which is just its own weird, weird beast.

Anyway, I hope this updated commentary is helpful!

— Elsie Hupp (@elsiehupp) January 2022