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Human Interface Device Interfaces

Keyboard

Adds ability to read keyboard input from the system.

import {sack} from "sack.vfs"
const keys = sack.Keyboard( eventCallback );

function eventCallback( event ) {
	// gets key events.
	// return true if the event is consumed.
	return false;
}

Keys are dispached to every sack.Keyboard object created.

There is a callback on the resulting keyboard object lock(true/false) which can lock the keyboard and block any input.

the keyboard event handler can be closed with the close() method on the mouse result.

Mouse

Adds ability to read mouse input from the system.

import {sack} from "sack.vfs"
const mouse = sack.Mouse( eventCallback );

function eventCallback( event ) {
	// gets mouse events.
}

Mouse events are dispached to every sack.Keyboard object created.

Mouse Events look like {op:<event type>, wheel:<number> buttons:<number>, x:<number>, y:<number>}. op is the type of mouse event forwarded from the hook. wheel is the delta on the mouse wheel. buttons is a composite of mouse button flags. These definitions are stored on the Mouse class as a button object; for example Mouse.buttons.left === 1.

button value
left 1
right 2
middle 0x10
x1 0x20
x2 0x40
relative 0x1000000

x1 and x2 are buttons 4 and 5. The missing bits are usually MK_SHIFT(0x4), MK_CONTROL(0x8).

The flag relative is not a mouse button flag, but controls whether the x, y position specified for a event() (below) is a relative or absolute position. Default is to move to the absolute position specified.

There is an accessor on sack.Mouse that can set/get the cursor position.

const curPos = sack.Mouse.cursor;  // get the mouse

sack.Mouse.cursor = {x:123, y:456}; // set the cursor position

the mouse event handler can be closed with the close() method on the mouse result.

Mouse System Utility Methods

The Mouse() class also has some utility functions.

method args description
clickAt (x,y) Generates a left button click at position x,y.
event (x,y,b,s1,s2) Generates events for the information supplied. x and y set the position of the mouse; b sets the state of the buttons, the value of this are the buttons flags mentioned above; s1 generates up-down scroll wheel events, and is a number, a negative number goes up; s2 generates right-left scroll events, and is a floating point number, a negative number goes left(?). Default scroll size is 1, but may be a fraction of a scroll tick

In order to generate a full click, two event() calls are needed, one to click the button and another to release any buttons. Mouse position is only sent when the current system cursor position is different from the position specified.