A node script that checks the current active app running in your OS, parses some customizable rules and sends the target layer index to a QMK keyboard over raw hid, so you can change layers programmatically.
My z12 micropad uses 4 layers: vim, browser, figma and default. Encoders do different things on each layer. More often than not, when working in Figma I wanted to zoom using the right encoder, but if I had the default layer active, the encoder would scroll instead. This script fixes this kind of issues, alows me to change layer automatically depending on the main app running in OSX, forgetting about having to manually switch the layer myself.
First requirement is a keyboard running QMK, and configure it to use RAW HID. See example in the section below.
This node script requires node, with three dependencies: node-hid, json-based-conditions-and-rules-logic-evaluator and active-win-cli. Since node is probably already installed, just install dependencies from the package.json:
$ npm install
The script will check the app and title options of active-win-cli every half a second, and send to the micropad the index of the layer I want to target depending on the app, using node-hid's write method.
To determine which index to send, we need to parse a set of conditions and rules, which are completely configurable using a simple JSON file. This also allows us to use multiple scripts to target multiple QMK devices at the same time.
The JSON file is an object that containes the product name, timer values for initialization, relink in case of a disconnection and runner (how often we want to check for the current app data). It also holds two objects for conditions and rules.
CONDITONS is an object that includes one object per condition to be parsed by the rules.
Follow the documentation for the CONDITONS object structure, and/or see examples of use, even the config.json used in this repo.
RULES is an array that includes one object per set of conditions.
Follow the documentation for the RULES object structure, and/or see examples of use, even the config.json used in this repo.
On the QMK side you will need to add RAW_ENABLE = yes in the rules.mk file. The write call from the node script will trigger the raw_hid_receive method on the QMK, where you can perform layer_clear(); to clean up previous calls, then layer_on(data[0]) to change to layer sent through the stream.
Note: we are sending 99 when we want to restore default layer (0), apparently layer_on(data[0]) doesn't work in raw_hid_receive when we send 0.
Example code in keymap.c:
#include "raw_hid.h"
#ifdef RAW_ENABLE
void raw_hid_receive(uint8_t* data, uint8_t length) {
layer_clear();
if (data[0] == 99) {
layer_on(_TERM);
}
else {
layer_on(data[0]);
}
}
#endifThe script checks if there is connection to the device we want to control, using using node-hid (we pass just the product name, in this case z12, and the default usagePage and usage values). It waits for a connection to be established (it retries every 2s). It also reconnects after disconnection:
$ node index.js
Default JSON file is config.json but you can use a different one and add its name as an argument to the main call:
$ node index.js otherfile.json
It can also be called from a cron job.
You need to give Terminal screenRecordingPermission in macOS, otherwise active-win will always be an empty string for the title.
- PoC
- Configuration file
- Allow different config file path
- Product name
- Timers
- Conditions and Rules
- Extract conditions and rules parsers into external repo
- Remove all external global deps, move them to local npm deps
- Documentation
- Basic use
- Configuration file
- launchd / cron
- Tests (see external repo)
- Credits
Big thanks to sindresorhus for the excellent active-win-cli, fauxpark, precondition and riblee for helping me understand node-hid connection, uint8_t* data pointer and methods to change layer programmatically. Ale Muñoz for helping me remove all global deps and move them to the package.json.