Writing OpenTabletDriver Configurations

Contents

Device Information
Specifications
Identifiers
- Attributes

Device Information

Generic device identification information is required for OpenTabletDriver in order for it to be able to differentiate tablets.

Property Name	Value Type	Description
Name	`string`	The name of the device. This is always the device manufacturer’s name followed by the device’s model number or product name when not applicable.

Specifications

Tablet configuration specifications provide OpenTabletDriver with information it needs in order to correctly and accurately handle the data the tablet device outputs.

Digitizer

This refers to the graphics tablet’s digitizer, which provides coordinates of where the tool is positioned. This is always required for the device to function.

Property Name	Value Type	Units	Description
Width	`double`	mm	The physical width of the digitizer in millimeters
Height	`double`	mm	The physical height of the digitizer in millimeters
`MaxX`	`double`	Device Units	The horizontal resolution of the digitizer in device units
`MaxY`	`double`	Device Units	The vertical resolution of the digitizer in device units

Pen

This refers to the pen tool for the graphics tablet. It is the source of position and typically the source of pressure data. This is almost always required.

Property Name	Value Type	Description
Max Pressure	`uint`	The maximum pressure reported by the pen in device pressure units. This is used to calculate a percentage of pressure. If there are more than pens supported by this tablet, the pen with the highest pressure value is used.
Button Count	`uint`	The amount of buttons on the pen. This does not include the eraser, if applicable. If there are more than one pens supported by this tablet, use the number of buttons on the pen with the most.

Auxiliary Buttons

This refers to any buttons located on the graphics tablet pad. This should only be enabled if there are any auxililary buttons.

Property Name	Value Type	Description
Button Count	`uint`	The amount of buttons

Touch

This refers to the touch digitizer, which may be built into the pen digitizer. This exists as the resolution of the touch digitizer can be different than the pen digitizer. This should only be enabled if the graphics tablet supports touch input.

This has the same properties as the digitizer

Mouse

This refers to an absolute positioning mouse tool. This should only be enabled if the graphics tablet supports a mouse.

This has the same properties as the auxiliary buttons

Identifiers

Device identifiers are what actually detect the tablet. Anything defined here is used in the detection process to pinpoint devices.

Property Name	Value Type	Description
Vendor ID	`ushort`	A USB-IF defined identifier that defines which vendor the device is produced by. Since this is assigned by the USB-IF it can be quite reliable for determining the manufacturer.
Product ID	`ushort`	A vendor-defined identifier for the device. This can be used to identify a device, however this can be unreliable as it depends on the vendor defining it different for all of their devices.
Input Report Length	`ushort`	The length of input reports from the device. This is always required as report parsers expect a specific report length.
Output Report Length	`ushort`	The length of output reports to the device endpoint. This is not always required, however it does help make the detection more precise.
Report Parser	`string`	The parser that will read and convert all tablet report data into a format that OpenTabletDriver understands. This is the full namespace and the class name. All supported vendor-specific report parsers can be found here.
Feature Initialization Report	`List<byte[]>`	A list of feature reports to be sent to the device to perform the device’s initialization sequence.
Output Initialization Report	`List<byte[]>`	A list of output reports to be sent to the device to perform the device’s initialization sequence.
Device Strings	`Dictionary<byte, string>`	A list of regular expressions to be matched against specific indexes of strings contained within the device’s firmware. They can be retrieved via the device string reader. This is optional, however it is commonly used to improve detection precision.
Initialization String Indexes	`byte[]`	A list of indexes to be retrieved from the device as part of the device’s initialization sequence. This is optional, and very infrequently used.
Attributes	`Dictionary<string, string>`	See Attributes table for attributes that can be used in identifiers

Byte arrays (byte[]) are serialized as Base64 in JSON.NET, the library that serializes and deserializes configurations.

Attributes

Attributes are used to provide additional optional information, commonly used within utilities or tools, or within OpenTabletDriver to help with device detection.

The type of the object is Dictionary<string, string>, e.g. { "FeatureInitDelayMs": "150", "libinputoverride": "1" }.

Some example attributes include:

Key Name	String Value	Usage in		Description
		Attributes	Identifier
`Interface`	non-negative integer	✅	✅	Specifies the USB device interface to use. For example: `"0"`. Should be used when the identifiers might be ambiguous, or if the tablet has multiple interfaces matching the used identifiers, but only has one of them usable. We suggest using the digitizer-specific `Interface` attribute instead, if possible.
`WinUsage`	[00..99]	✅	✅	(Windows only) Specifies the HID usage collection to use. String must have exactly two digits (e.g. `"01"`)
`libinputoverride`	`1`	✅	❌	(Linux only) Whether the generic tablet interface should be ignored by libinput or not. Used in udev rule generation, using the tablets VID and PID.
`FeatureInitDelayMs`	milliseconds	✅	❌	For tablets with multiple feature initialization reports (e.g. polling rate change), wait this many milliseconds between reports. This can help if later feature initialization reports are sometimes randomly not picked up by the tablet.