How to Set Up DPI Presets and Cycle DPI Presets Actions in OpenLogi

OpenLogi enables you to define a list of DPI sensitivity values in its TOML configuration and bind a single "Cycle DPI Presets" action to any mouse button, allowing instant switching between predefined sensitivity levels without opening the application window.

OpenLogi is an open-source utility for advanced Logitech device customization that communicates directly via the HID++ protocol. By configuring dpi_presets and assigning the Cycle DPI Presets action, you can toggle between distinct sensitivity modes—such as 800 DPI for precise pixel work and 3200 DPI for rapid navigation—directly from your mouse hardware.

Configuring DPI Presets in the TOML Configuration

OpenLogi reads hardware settings from a user-level TOML configuration file at startup. Defining the dpi_presets array makes specific DPI values available to the runtime action system.

Defining the dpi_presets Array

Edit your OpenLogi configuration file (see the example structure in docs/config.example.toml) to include a top-level array of integer DPI values:

# ~/.config/openlogi/config.toml

dpi_presets = [400, 800, 1600, 3200]

The array can contain any number of integer values supported by your specific Logitech mouse model. OpenLogi validates this configuration during initialization and stores the values for runtime access. The actual device communication that applies these values occurs in crates/openlogi-device/src/write/dpi.rs, which implements the HID++ write protocol for DPI changes.

Binding the Cycle DPI Presets Action

Once the presets are defined, you must bind the Cycle DPI Presets action to a physical button. OpenLogi supports both GUI-based configuration and direct TOML editing.

Assigning via the OpenLogi Interface

The OpenLogi UI exposes this action in the localization entries found at crates/openlogi-ui/locales/en.toml. To bind the action:

1. Open OpenLogi → Presets → Actions.
2. Locate Cycle DPI Presets in the available actions list.
3. Drag the action onto your desired button (for example, Button 5 on a Logitech MX Master series).
4. Save the active profile to persist the binding.

When triggered, the action handler in crates/openlogi-agent-core/src/action_ring.rs receives the command and advances to the next DPI value in your configured array.

Manual Profile Configuration

Advanced users can define the binding directly in the profile TOML by adding an entry to the actions table:

[[profile.actions]]
name = "cycle_dpi_presets"
type = "cycle_dpi_presets"
button = "button5"

The type = "cycle_dpi_presets" identifier tells the OpenLogi agent to interpret this entry as a DPI cycling command. The runtime dispatches this to the device driver, which updates the mouse sensitivity immediately upon button press.

Understanding the Cycle DPI Presets Implementation

The Cycle DPI Presets action operates through a three-stage pipeline. First, the input event reaches the action ring handler at crates/openlogi-agent-core/src/action_ring.rs, which identifies the cycle_dpi_presets command type. The handler then queries the next value from the dpi_presets array, wrapping back to the first element after reaching the end of the list. Finally, the new DPI value is serialized into a HID++ packet and transmitted to the hardware via the write implementation in crates/openlogi-device/src/write/dpi.rs. This architecture ensures sub-millisecond latency when switching sensitivity levels during active use.

Summary

• Define presets by adding a dpi_presets array to your OpenLogi TOML configuration, specifying integer DPI values in your preferred cycle order.
• Bind the action either through the UI (referenced in crates/openlogi-ui/locales/en.toml) or by adding a type = "cycle_dpi_presets" entry to your profile's actions table.
• Runtime execution occurs through crates/openlogi-agent-core/src/action_ring.rs, which dispatches changes to the HID++ writer in crates/openlogi-device/src/write/dpi.rs.
• The system cycles sequentially through your preset list and automatically returns to the first value after reaching the final entry.

Frequently Asked Questions

What configuration file format does OpenLogi use for DPI presets?

OpenLogi uses the TOML format for all configuration files. The dpi_presets array must be defined at the root level of your user configuration file (typically located at ~/.config/openlogi/config.toml or as shown in docs/config.example.toml). This array accepts only integer values representing valid DPI steps for your specific Logitech device.

How many DPI presets can I define in OpenLogi?

You can define any number of DPI presets in the dpi_presets array. The OpenLogi agent initializes the full list into memory at startup, and the Cycle DPI Presets action will sequentially iterate through every value you provide. There is no enforced upper limit within the configuration parser, though your specific mouse hardware may only support specific DPI ranges (e.g., 200-4000).

Does the Cycle DPI Presets action require the OpenLogi UI to be running?

No, the Cycle DPI Presets action functions independently of the UI. Once you save the profile configuration—whether through the interface or manual TOML editing—the openlogi-agent-core service handles the button events directly. The action ring processor (crates/openlogi-agent-core/src/action_ring.rs) intercepts the hardware input and issues the DPI change command without requiring the graphical interface to remain open.

What happens when I reach the end of the DPI presets list?

The action automatically cycles back to the first DPI value in your dpi_presets array. When the action handler in crates/openlogi-agent-core/src/action_ring.rs detects that it has reached the final index of the preset list, it resets the internal pointer to zero and applies the initial DPI value on the next button press, creating a continuous loop through your sensitivity options.

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