Scroll Reverser
Reverses the direction of macOS scrolling, with independent settings for trackpads and mice.
Web home page: https://pilotmoon.com/scrollreverser/ (Please note the home page contains additional content about the app, FAQ, changelog etc.)
Requirements
The latest build of Scroll Reverser requires macOS 10.12.6 and above, and is a univeral binary for both Intel and Apple Silicon (M1) Macs. Older versions are available for older OS versions down to OS X 10.4. See the web home page for the downloads, or the respective labelled branches for the code.
Install and run
Download the latest release, unzip, and place Scroll Reverser.app in your /Applications folder. Double-click to run.
To uninstall, simply quit the app and drag Scroll Reverser.app to trash.
Translations
Translation contributions in your language are welcome. Please submit transmations using the CrowdIn platform. ** When improving an existing translation, please add a comment and mark it as "Issue" so that it flags it up to me to approve. Otherwise I might not see it.** If you would like to open a new language, just send me an email.
License
Published under Apache License 2.0.
Please note, the name "Scroll Reverser" and the application icon are trademarks and may not be used by derivatve works (except as required to describe the origin of the work).
Building
After cloning this repo, you'll need to git submodule update --init to check out the BuildScripts submodule.
You will get errors in the build script phase. That is because you need to replace out the part of the script which specifies my code signing key with the name of your own key. (If you don't have a code signing key, you'll need to Google that...)
Viewing debug log
To display the debug window, Option(⌥)-click the Scroll Reverser menu bar icon. (Scroll Reverser does not output debug info with NSLog. This is because doing so slows down the event lap. Instead, it has some custom debug code which is more efficient to write to.)
Notes on the code
The master branch targets 10.12 and higher.
Older code targeting 10.4+ is in the 'tiger' branch and 10.7+ is in the 'lion' branch.
The real guts of the code is in MouseTap.m. Everything else is just user interface rigging.
Scroll Reverser installs an event tap, which gives access to event stream, including scrolling events and gesture events. The main documentation is Quartz Event Services Reference.
To distinguish between trackpad and mouse, Scroll Reverser essentially looks at the gesture events to determine whether there are 2 or more fingers on the trackpad. If so, it assumes it is the trackpad. If not, mouse. It's a little more complicated than that as you will see, but that is the general idea.