Pointing Device is a generic name for a feature intended to be generic: moving the system pointer around. There are certainly other options for it - like mousekeys - but this aims to be easily modifiable and hardware driven. You can implement custom keys to control functionality, or you can gather information from other peripherals and insert it directly here - let QMK handle the processing for you.
There are a number of sensors that are supported by default. Note that only one sensor can be enabled by `POINTING_DEVICE_DRIVER` at a time. If you need to enable more than one sensor, then you need to implement it manually.
### ADNS 5050 Sensor
To use the ADNS 5050 sensor, add this to your `rules.mk`
```make
POINTING_DEVICE_DRIVER = adns5050
```
The ADNS 5050 sensor uses a serial type protocol for communication, and requires an additional light source.
This supports the Cirque Pinnacle 1CA027 Touch Controller, which is used in the TM040040, TM035035 and the TM023023 trackpads. These are I2C or SPI compatible, and both configurations are supported.
|`ROTATIONAL_TRANSFORM_ANGLE` | (Optional) Allows for the sensor data to be rotated +/- 30 degrees directly in the sensor. | `0` |
The CPI range is 100-12000, in increments of 100. Defaults to 1600 CPI.
### Custom Driver
If you have a sensor type that isn't supported here, you can manually implement it, by adding these functions (with the correct implementation for your device):
!> Ideally, new sensor hardware should be added to `drivers/sensors/` and `quantum/pointing_device_drivers.c`, but there may be cases where it's very specific to the hardware. So these functions are provided, just in case.
| `pointing_device_init_kb(void)` | Callback to allow for keyboard level initialization. Useful for additional hardware sensors. |
| `pointing_device_init_user(void)` | Callback to allow for user level initialization. Useful for additional hardware sensors. |
| `pointing_device_task_kb(mouse_report)` | Callback that sends sensor data, so keyboard code can intercept and modify the data. Returns a mouse report. |
| `pointing_device_task_user(mouse_report)` | Callback that sends sensor data, so user coe can intercept and modify the data. Returns a mouse report. |
| `pointing_device_handle_buttons(buttons, pressed, button)` | Callback to handle hardware button presses. Returns a `uint8_t`. |
| `pointing_device_get_cpi(void)` | Gets the current CPI/DPI setting from the sensor, if supported. |
| `pointing_device_set_cpi(uint16_t)` | Sets the CPI/DPI, if supported. |
| `pointing_device_get_report(void)` | Returns the current mouse report (as a `mouse_report_t` data structure). |
| `pointing_device_set_report(mouse_report)` | Sets the mouse report to the assigned `mouse_report_t` data structured passed to the function. |
| `pointing_device_send(void)` | Sends the current mouse report to the host system. Function can be replaced. |
| `has_mouse_report_changed(old, new)` | Compares the old and new `mouse_report_t` data and returns true only if it has changed. |
# Manipulating Mouse Reports
The report_mouse_t (here "mouseReport") has the following properties:
*`mouseReport.x` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing movement (+ to the right, - to the left) on the x axis.
*`mouseReport.y` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing movement (+ upward, - downward) on the y axis.
*`mouseReport.v` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing vertical scrolling (+ upward, - downward).
*`mouseReport.h` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing horizontal scrolling (+ right, - left).
*`mouseReport.buttons` - this is a uint8_t in which all 8 bits are used. These bits represent the mouse button state - bit 0 is mouse button 1, and bit 7 is mouse button 8.
*`pointing_device_send()` - Sends the mouse report to the host and zeroes out the report.
When the mouse report is sent, the x, y, v, and h values are set to 0 (this is done in `pointing_device_send()`, which can be overridden to avoid this behavior). This way, button states persist, but movement will only occur once. For further customization, both `pointing_device_init` and `pointing_device_task` can be overridden.
Additionally, by default, `pointing_device_send()` will only send a report when the report has actually changed. This prevents it from continuously sending mouse reports, which will keep the host system awake. This behavior can be changed by creating your own `pointing_device_send()` function.
Also, you use the `has_mouse_report_changed(new, old)` function to check to see if the report has changed.
In this example, a custom key is used to click the mouse and scroll 127 units vertically and horizontally, then undo all of that when released - because that's a totally useful function.
A very common implementation is to use the mouse movement to scroll instead of moving the cursor on the system. This uses the `pointing_device_task_user` callback to intercept and modify the mouse report before it's sent to the host system.
