andlabs-ui/events_notdarwin.go

// +build !darwin
// Mac OS X uses its own set of position-independent key codes

// 29 march 2014

package ui

/*
For position independence across international keyboard layouts, typewriter keys are read using scancodes (which are always set 1).
Windows provides the scancodes directly in the LPARAM.
GTK+ provides the scancodes directly from the underlying window system via GdkEventKey.hardware_keycode.
On X11, this is scancode + 8 (because X11 keyboard codes have a range of [8,255]).
Wayland is guaranteed to give the same result (thanks ebassi in irc.gimp.net/#gtk+).
On Linux, where evdev is used instead of polling scancodes directly from the keyboard, evdev's typewriter section key code constants are the same as scancodes anyway, so the rules above apply.
Typewriter section scancodes are the same across international keyboards with some exceptions that have been accounted for (see KeyEvent's documentation); see http://www.quadibloc.com/comp/scan.htm for details.
Non-typewriter keys can be handled safely using constants provided by the respective backend API.

Because GTK+ keysyms may or may not obey Num Lock, we also handle the 0-9 and . keys on the numeric keypad with scancodes (they match too).
*/

// use uintptr to be safe; the size of the scancode/hardware key code field on each platform is different
var scancodeKeys = map[uintptr]byte{
	0x02:	'1',
	0x03:	'2',
	0x04:	'3',
	0x05:	'4',
	0x06:	'5',
	0x07:	'6',
	0x08:	'7',
	0x09:	'8',
	0x0A:	'9',
	0x0B:	'0',
	0x0C:	'-',
	0x0D:	'=',
	0x0E:	'\b',		// seems to be safe on GTK+; TODO safe on windows?
	0x0F:	'\t',		// seems to be safe on GTK+; TODO safe on windows?
	0x10:	'q',
	0x11:	'w',
	0x12:	'e',
	0x13:	'r',
	0x14:	't',
	0x15:	'y',
	0x16:	'u',
	0x17:	'i',
	0x18:	'o',
	0x19:	'p',
	0x1A:	'[',
	0x1B:	']',
	0x1C:	'\n',		// seems to be safe on GTK+; TODO safe on windows?
	0x1E:	'a',
	0x1F:	's',
	0x20:	'd',
	0x21:	'f',
	0x22:	'g',
	0x23:	'h',
	0x24:	'j',
	0x25:	'k',
	0x26:	'l',
	0x27:	';',
	0x28:	'\'',
	0x29:	'`',
	0x2B:	'\\',
	0x2C:	'z',
	0x2D:	'x',
	0x2E:	'c',
	0x2F:	'v',
	0x30:	'b',
	0x31:	'n',
	0x32:	'm',
	0x33:	',',
	0x34:	'.',
	0x35:	'/',
	0x39:	' ',
}

var scancodeExtKeys = map[uintptr]ExtKey{
	0x47:	N7,
	0x48:	N8,
	0x49:	N9,
	0x4B:	N4,
	0x4C:	N5,
	0x4D:	N6,
	0x4F:	N1,
	0x50:	N2,
	0x51:	N3,
	0x52:	N0,
	0x53:	NDot,
}

func fromScancode(scancode uintptr) (ke KeyEvent, ok bool) {
	if key, ok := scancodeKeys[scancode]; ok {
		ke.Key = key
		return ke, true
	}
	if extkey, ok := scancodeExtKeys[scancode]; ok {
		ke.ExtKey = extkey
		return ke, true
	}
	return ke, false
}