DPI presets

Set a Logitech mouse’s pointer resolution and keep an ordered list of DPI presets, backed by the HID++ 0x2201 adjustableDpi feature. The slider snaps to the values your device actually supports, and the presets can be cycled from a hardware button so you never have to open the window to change DPI.

From the GUI

Select the mouse in the device carousel; its config column has a DPI section with:

DPI slider — its range is the device’s own supported DPI list (min–max, with the step set to the smallest gap between adjacent stops). Dragging only updates the on-screen value; the new DPI is written to the mouse when you release the slider, and the value snaps to the nearest stop the device reports. A single-DPI mouse shows a fixed value instead of a slider.
Range label — reads {min}–{max} · step {n} once the device’s capabilities are known, or a status line while OpenLogi is offline, still reading, or if the read failed.
Preset chips — each preset is a clickable chip. Clicking one snaps its value to the device grid, applies it, and writes it to the mouse. The chip matching the current DPI is highlighted as active. The × on a chip removes that preset, and + Add appends the current DPI to the list.

Capabilities are discovered lazily the first time the DPI panel renders. If that discovery fails, the panel shows a clickable retry line that re-arms it for the selected device.

There is no reorder control. Presets are append-only (each + Add drops the current DPI at the end) and removed by index, and that Vec order is the cycle order. To change the order, remove and re-add, or edit the config directly. Duplicate values are allowed on purpose, so the same DPI can sit at more than one cycle position.

Cycling from a button

Two actions drive the preset list from a hardware button:

CycleDpiPresets — steps to the next preset, wrapping from the last back to the first. This is the default action for the mode-shift (DpiToggle) button, and it is the only DPI-cycle action offered in the GUI’s action picker.
SetDpiPreset — jumps straight to a preset index. It carries that index as data, so it is not in the picker; bind it by hand-editing config.toml.

An empty preset list makes both actions a no-op. Editing the presets or switching devices resets the cycle position to the first entry, since the list changed.

In the config

The list persists per device as dpi_presets under [devices.<key>] in the config:


[devices.2b042]
dpi_presets = [800, 1600, 3200]

It is an ordered array of integers, omitted entirely while empty. See Configuration for the full action vocabulary and Per-app profiles for swapping presets per application.

Quit Logi Options+ first so OpenLogi can own the device. DPI writes target sensor 0; multi-sensor mice aren’t addressed by the GUI. Mice that expose 0x2202 extendedAdjustableDpi instead of 0x2201 are not supported.

Status: macOS + Linux — the device-side DPI write works wherever HID++ does, and firing it from a button rides the OS hook (CGEventTap on macOS, evdev on Linux), which owns the side Back / Forward buttons. Windows is an untested preview. See 0x2201 adjustableDpi for the protocol detail and the roadmap for what’s wired up.