DIRECTORY
DeviceClassTypes, DeviceTypes, Rope;

FastTRAPDevice: CEDAR DEFINITIONS = BEGIN

Device: TYPE = DeviceTypes.Device;
DeviceClass: TYPE = DeviceClassTypes.DeviceClass;
DeviceState: TYPE = DeviceTypes.DeviceState;
DeviceStateChange: TYPE = DeviceTypes.DeviceStateChange;
KeyName: TYPE = {left, middle, right};

CreateFastTRAP: PROC [name: Rope.ROPE] RETURNS [device: Device];
AllocateState: PROC [device: Device] RETURNS [deviceState: DeviceState];

KeyChange: PROC [key: KeyName, down: BOOL] RETURNS [change: DeviceStateChange];
TrackballChange: PROC [deltaX, deltaY: INTEGER] RETURNS [change: DeviceStateChange];
ThumbwheelChange: PROC [delta: INTEGER] RETURNS [change: DeviceStateChange];

StateAfterChange: PROC [deviceState: DeviceState, change: DeviceStateChange] RETURNS [newDeviceState: DeviceState];

ChangeKind: TYPE = {key, trackball, wheel};
ExpandedChange: TYPE = RECORD [
contents: SELECT kind: ChangeKind FROM
key => [key: KeyName, down: BOOL],
trackball => [deltaX, deltaY: INTEGER],
wheel => [delta: INTEGER]
ENDCASE
];

UnpackChange: PROC [change: DeviceStateChange] RETURNS [expanded: ExpandedChange];

KeyNewState: PROC [deviceState: DeviceState, key: KeyName, down: BOOL] RETURNS [newDeviceState: DeviceState];
TrackballNewState: PROC [deviceState: DeviceState, deltaX, deltaY: INTEGER] RETURNS [newDeviceState: DeviceState];
ThumbwheelNewState: PROC [deviceState: DeviceState, delta: INTEGER] RETURNS [newDeviceState: DeviceState];

IsDown: PROC [deviceState: DeviceState, key: KeyName] RETURNS [BOOL];
GetTrackball: PROC [deviceState: DeviceState] RETURNS [x, y: INTEGER];
GetThumbwheel: PROC [deviceState: DeviceState] RETURNS [wheel: INTEGER];

END.

   –  
FastTRAPDevice.mesa
Copyright Ó 1991, 1992 by Xerox Corporation.  All rights reserved.
Bier, November 6, 1991 10:42 am PST
Contents:  Routines for creating instances of the FastTRAP trackball and representing the state of such a device.

Class Routines
Create a data structure representing a particular physical FastTRAP.  Calls class.create[class].
Allocates storage representing the state of this keyboard when all of its keys are up, the trackball is at 0,0, and the thumbwheel is at 0.  Each DeviceState is immutable, so they may be freely stored in long-term storage.

Representing FastTRAP State Changes
Convenience State Changes

Inspecting State

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