The two are very much different in operations and device definition. One reason for this is that the device drivers for touch devices often report the characteristics of touches using device-specific units. For touch pads not associated with a display , the output height equals raw. Two finger motion both fingers moving in the same direction: For example, when multiple fingers are touching the device, each finger should be assigned a distinct tracking id that is used as long as the finger remains in contact. The touch input mapper uses many configuration properties in the input device configuration file to specify calibration values.

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Touch Device Classification An input device is classified as a multi-touch device if both of the following conditions hold: If the value is nonethe pressure is unknown so it is set to 1. For touch pads not associated with a displaythe output width equals raw. Sampath 1 10 When a stylus tool is present, the orientation range may be described in a full circle range from -PI or PI.

Other times it is desirable to perform the mapping from touch androidd to key codes in software. Not all touch devices are able to sense the presence of a tool hovering above the touch device.

[Q] USB Touchscreen on Android

If the touch size is unavailable but the tool size is available, then the tool size will be set equal to the touch size. These defaults are not designed for built-in touch screens and will most likely result in incorrect behavior.


This default ensures that touch pads that have not been designated any other special purpose will serve to control the pointer. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Refer to the Linux multi-touch protocol documentation for more details. Registering excess axes or key codes may confuse the device classification algorithm or cause the system to incorrectly detect the capabilities of usbrouchscreen device. In other words, the touch screen should not be reporting minX, minY when the user’s finger is really touching outside of the active area.

The tilt angles along the X and Y axes are assumed to be specified in degrees from perpendicular. If the value is amplitudethe pressure axis is assumed to measure the signal amplitude, which is related to the size of the contact and the pressure applied. Hovering tools are reported to applications as generic motion events using MotionEvent. This raw size value would not be meaningful to applications because they usbtoucshcreen need to know about the physical size and other characteristics of the touch device sensor nodes.

When a tool becomes inactive finger goes “up”it should stop appearing in subsequent multi-touch sync reports. Values smaller than the center point represent a tilt up or to the left, values larger than the center point represent a tilt down or to the right.

Likewise, touching tools and hovering tools are reported to applications in different ways. Documentation Conventions For documentation purposes, we will use the following conventions to describe the values used by the system during the calibration process.

Pressing this button also synthesizes usbtouchscrfen key press with the key code KeyEvent.


Seems there are a lot of differences with a mouse and a touchscreen. Tracking ids may be reused when their usntouchscreen tools move out of range. If the value is pointerthe touch pad gestures are presented by way of a cursor similar to a mouse pointer. An input device is either classified as a single-touch device or as a multi-touch device, never both. Reporting distance information is optional but recommended for stylus devices.

Input Device Configuration Files Virtual Key Map Files Properties The system relies on many input device configuration properties to configure and calibrate touch device behavior.

When using the multi-touch protocol ‘B’, the tool is active as long as it has an active slot. You need to create. If the value is defaultthe system automatically detects the device type according to the anvroid algorithm.

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USB Touch Screen Monitors – USB Monitors

If a virtual key map is available, then the key layout file for the device is also loaded. The ToolMajor and ToolMinor fields describe the approximate dimensions of the tool itself in output units pixels. If the value is pointerthe touch device is a touch pad not associated with a display, and usbtouchsvreen motions are used for indirect multi-touch pointer gestures.