<s>
A	O
virtual	B-Device
keyboard	I-Device
is	O
a	O
software	O
component	O
that	O
allows	O
the	O
input	B-Device
of	I-Device
characters	I-Device
without	O
the	O
need	O
for	O
physical	O
keys	O
.	O
</s>
<s>
The	O
interaction	O
with	O
the	O
virtual	B-Device
keyboard	I-Device
happens	O
mostly	O
via	O
a	O
touchscreen	B-Device
interface	I-Device
,	O
but	O
can	O
also	O
take	O
place	O
in	O
a	O
different	O
form	O
in	O
virtual	B-Application
or	O
augmented	B-General_Concept
reality	I-General_Concept
.	O
</s>
<s>
On	O
a	O
desktop	B-Device
computer	I-Device
,	O
a	O
virtual	B-Device
keyboard	I-Device
might	O
provide	O
an	O
alternative	O
input	O
mechanism	O
for	O
users	O
with	O
disabilities	O
who	O
cannot	O
use	O
a	O
conventional	O
keyboard	B-Device
,	O
or	O
for	O
bi	O
-	O
or	O
multi-lingual	O
users	O
who	O
switch	O
frequently	O
between	O
different	O
character	O
sets	O
or	O
alphabets	O
,	O
which	O
may	O
be	O
confusing	O
over	O
time	O
.	O
</s>
<s>
Although	O
hardware	O
keyboards	B-Device
are	O
available	O
with	O
dual	O
keyboard	B-Device
layouts	O
(	O
e.g.	O
</s>
<s>
Cyrillic/Latin	O
letters	O
in	O
various	O
national	O
layouts	O
)	O
,	O
the	O
on-screen	B-Device
keyboard	I-Device
provides	O
a	O
handy	O
substitute	O
while	O
working	O
at	O
different	O
stations	O
or	O
on	O
laptops	O
,	O
which	O
seldom	O
come	O
with	O
dual	O
layouts	O
.	O
</s>
<s>
Virtual	B-Device
keyboards	I-Device
can	O
be	O
categorized	O
by	O
the	O
following	O
aspects	O
:	O
</s>
<s>
Keyboard	B-Device
software	O
may	O
include	O
a	O
number	O
pad	O
feature	O
to	O
facilitate	O
typing	O
numbers	O
.	O
</s>
<s>
On	O
the	O
Internet	O
,	O
various	O
JavaScript	B-Language
virtual	B-Device
keyboards	I-Device
have	O
been	O
created	O
,	O
allowing	O
users	O
to	O
type	O
their	O
own	O
languages	O
on	O
foreign	O
keyboards	B-Device
,	O
particularly	O
in	O
Internet	O
cafes	O
.	O
</s>
<s>
Multitouch	B-Application
screens	O
allow	O
the	O
possibility	O
to	O
create	O
virtual	B-Application
chorded	B-Device
keyboards	I-Device
for	O
tablet	B-Device
computers	I-Device
,	O
touchscreens	B-Device
,	O
touchpads	B-Application
and	O
wired	B-General_Concept
gloves	I-General_Concept
.	O
</s>
<s>
Virtual	B-Device
keyboards	I-Device
are	O
commonly	O
used	O
as	O
an	O
on-screen	O
input	B-General_Concept
method	I-General_Concept
in	O
devices	O
with	O
no	O
physical	O
keyboard	B-Device
,	O
where	O
there	O
is	O
no	O
room	O
for	O
one	O
,	O
such	O
as	O
a	O
pocket	B-Device
computer	I-Device
,	O
personal	B-Application
digital	I-Application
assistant	I-Application
(	O
PDA	B-Application
)	O
,	O
tablet	B-Device
computer	I-Device
or	O
touchscreen-equipped	O
mobile	O
phone	O
.	O
</s>
<s>
Text	O
is	O
commonly	O
inputted	O
either	O
by	O
tapping	O
a	O
virtual	B-Device
keyboard	I-Device
or	O
finger-tracing	O
.	O
</s>
<s>
Virtual	B-Device
keyboards	I-Device
are	O
also	O
used	O
as	O
features	O
of	O
emulation	B-Architecture
software	I-Architecture
for	O
systems	O
that	O
have	O
fewer	O
buttons	O
than	O
a	O
computer	B-Device
keyboard	I-Device
would	O
have	O
.	O
</s>
<s>
The	O
four	O
main	O
approaches	O
to	O
enter	O
text	O
into	O
a	O
PDA	B-Application
were	O
:	O
virtual	B-Device
keyboards	I-Device
operated	O
by	O
a	O
stylus	O
,	O
external	O
USB	O
keyboards	B-Device
,	O
handwritten	O
keyboards	B-Device
,	O
and	O
stroke	O
recognition	O
.	O
</s>
<s>
Many	O
early	O
PDAs	B-Application
were	O
not	O
primarily	O
focused	O
on	O
virtual	B-Device
keyboards	I-Device
.	O
</s>
<s>
Microsoft	O
's	O
mobile	O
operating	O
system	O
approach	O
was	O
to	O
simulate	O
a	O
complete	O
functional	O
keyboard	B-Device
,	O
which	O
resulted	O
in	O
a	O
slightly	O
overloaded	O
keyboard	B-Device
layout	O
.	O
</s>
<s>
The	O
main	O
problem	O
that	O
early	O
PDAs	B-Application
faced	O
was	O
support	O
for	O
multi-touch	B-Application
technology	I-Application
,	O
and	O
as	O
a	O
result	O
,	O
usability	O
problems	O
for	O
the	O
user	O
.	O
</s>
<s>
When	O
Apple	O
presented	O
the	O
first	B-Operating_System
iPhone	I-Operating_System
in	O
2007	O
,	O
the	O
decision	O
not	O
to	O
include	O
a	O
physical	O
keyboard	B-Device
was	O
seen	O
as	O
a	O
detriment	O
to	O
the	O
device	O
.	O
</s>
<s>
But	O
Apple	O
brought	O
the	O
multi-touch	B-Application
technology	I-Application
into	O
their	O
new	O
device	O
,	O
which	O
enabled	O
them	O
to	O
overcome	O
the	O
usability	O
problems	O
of	O
PDAs	B-Application
.	O
</s>
<s>
Apple	O
's	O
virtual	B-Device
keyboard	I-Device
design	O
pattern	O
has	O
become	O
a	O
standard	O
on	O
mobile	O
devices	O
today	O
.	O
</s>
<s>
Both	O
most	O
common	O
mobile	O
operating	O
systems	O
,	O
Android	B-Application
and	O
iOS	B-Application
,	O
give	O
the	O
developer	O
community	O
the	O
possibility	O
to	O
individually	O
develop	O
custom	O
virtual	B-Device
keyboards	I-Device
.	O
</s>
<s>
The	O
Android	B-Application
SDK	O
provides	O
a	O
so-called	O
InputMethodService	O
.	O
</s>
<s>
This	O
service	O
provides	O
a	O
standard	O
implementation	O
of	O
an	O
input	B-General_Concept
method	I-General_Concept
,	O
which	O
final	O
implementations	O
can	O
derive	O
from	O
and	O
customize	O
,	O
enabling	O
the	O
Android	B-Application
development	O
community	O
to	O
implement	O
their	O
own	O
keyboard	B-Device
layouts	O
.	O
</s>
<s>
The	O
InputMethodService	O
ships	O
with	O
it	O
on	O
Keyboard	B-Device
View	O
.	O
</s>
<s>
While	O
the	O
InputMethod	O
Service	O
can	O
be	O
used	O
to	O
customize	O
key	O
and	O
gesture	O
inputs	O
,	O
the	O
Keyboard	B-Device
Class	O
loads	O
an	O
XML	B-Protocol
description	O
of	O
a	O
keyboard	B-Device
and	O
stores	O
the	O
attributes	O
of	O
the	O
keys	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
it	O
is	O
possible	O
to	O
install	O
different	O
keyboard	B-Device
versions	O
on	O
an	O
Android	B-Application
device	O
,	O
and	O
that	O
the	O
keyboard	B-Device
is	O
only	O
an	O
application	O
;	O
a	O
simple	O
activation	O
over	O
the	O
Android	B-Application
settings	O
menu	O
is	O
possible	O
.	O
</s>
<s>
Apple	O
also	O
provides	O
the	O
possibility	O
for	O
the	O
community	O
to	O
develop	O
custom	O
keyboards	B-Device
,	O
but	O
does	O
not	O
give	O
any	O
access	O
to	O
the	O
dictionary	B-Operating_System
or	O
general	O
keyboard	B-Device
settings	O
.	O
</s>
<s>
Further	O
iOS	B-Application
is	O
automatically	O
switching	O
between	O
system	O
and	O
custom	O
keyboards	B-Device
,	O
if	O
the	O
user	O
enters	O
text	O
into	O
the	O
text	O
input	O
field	O
.	O
</s>
<s>
The	O
UIInputViewController	O
is	O
the	O
primary	O
view	O
controller	O
for	O
a	O
custom	O
keyboard	B-Device
app	O
extension	O
.	O
</s>
<s>
This	O
controller	O
provides	O
different	O
methods	O
for	O
the	O
implementation	O
of	O
a	O
custom	O
keyboard	B-Device
,	O
such	O
as	O
a	O
user	O
interface	O
for	O
a	O
custom	O
keyboard	B-Device
,	O
obtaining	O
a	O
supplementary	O
lexicon	O
or	O
changing	O
the	O
primary	O
language	O
of	O
a	O
custom	O
keyboard	B-Device
.	O
</s>
<s>
Next	O
to	O
the	O
classic	O
virtual	B-Device
keyboard	I-Device
implementation	O
Android	B-Application
,	O
iOS	B-Application
and	O
custom	O
keyboards	B-Device
,	O
such	O
as	O
SwiftKey	B-Device
for	O
example	O
,	O
are	O
providing	O
different	O
features	O
to	O
improve	O
the	O
usability	O
and	O
the	O
efficiency	O
of	O
their	O
keyboards	B-Device
.	O
</s>
<s>
The	O
Android	B-Application
platform	I-Application
offers	O
a	O
spelling	O
checker	O
framework	O
that	O
offers	O
the	O
possibility	O
to	O
implement	O
and	O
access	O
spell	O
checking	O
in	O
the	O
application	O
itself	O
.	O
</s>
<s>
The	O
framework	O
is	O
one	O
of	O
the	O
Text	O
Service	O
APIs	B-Application
offered	O
by	O
the	O
Android	B-Application
platform	I-Application
.	O
</s>
<s>
iOS	B-Application
is	O
using	O
the	O
class	O
UITextChecker	O
,	O
an	O
object	O
used	O
to	O
check	O
a	O
string	O
(	O
usually	O
the	O
text	O
of	O
a	O
document	O
)	O
for	O
misspelled	O
words	O
,	O
commonly	O
known	O
as	O
Apple	O
's	O
autocorrection	O
.	O
</s>
<s>
Users	O
may	O
be	O
able	O
to	O
add	O
a	O
custom	O
dictionary	B-Operating_System
of	O
whitelisted	O
terms	O
that	O
are	O
treated	O
by	O
auto	O
correction	O
as	O
usual	O
words	O
,	O
and	O
specify	O
"	O
aliases	O
"	O
or	O
"	O
text	O
shortcuts	O
"	O
,	O
where	O
entering	O
a	O
specified	O
text	O
string	O
causes	O
it	O
to	O
get	O
replaced	O
with	O
a	O
target	O
text	O
string	O
,	O
or	O
the	O
target	O
text	O
string	O
appears	O
as	O
suggestion	O
.	O
</s>
<s>
Diverse	O
scientific	O
papers	O
at	O
the	O
beginning	O
of	O
the	O
2000s	O
showed	O
even	O
before	O
the	O
invention	O
of	O
smart	B-Application
phones	I-Application
,	O
that	O
predicting	O
words	O
,	O
based	O
on	O
what	O
the	O
user	O
is	O
typing	O
,	O
is	O
very	O
helpful	O
to	O
increase	O
the	O
typing	O
speed	O
.	O
</s>
<s>
At	O
the	O
beginning	O
of	O
development	O
of	O
this	O
keyboard	B-Device
feature	O
,	O
prediction	O
was	O
mainly	O
based	O
on	O
static	O
dictionaries	B-Operating_System
.	O
</s>
<s>
Google	B-Application
implemented	O
the	O
predicting	O
method	O
in	O
2013	O
in	O
Android	B-Application
4.4	O
.	O
</s>
<s>
This	O
development	O
was	O
mainly	O
driven	O
by	O
third	O
party	O
keyboard	B-Device
providers	O
,	O
such	O
as	O
SwiftKey	B-Device
and	O
Swype	B-Language
.	O
</s>
<s>
In	O
2014	O
Apple	O
presented	O
iOS	B-Operating_System
8	I-Operating_System
which	O
includes	O
a	O
new	O
predictive	O
typing	O
feature	O
called	O
QuickType	O
,	O
which	O
displays	O
word	O
predictions	O
above	O
the	O
keyboard	B-Device
as	O
the	O
user	O
types	O
.	O
</s>
<s>
iOS	B-Application
and	O
Android	B-Application
allow	O
developers	O
to	O
replace	O
its	O
keyboard	B-Device
with	O
their	O
own	O
keyboard	B-Device
apps	O
.	O
</s>
<s>
This	O
has	O
led	O
to	O
experimentation	O
and	O
new	O
features	O
,	O
like	O
the	O
gesture-typing	O
feature	O
that	O
's	O
made	O
its	O
way	O
into	O
Android	B-Application
's	O
official	O
keyboard	B-Device
after	O
proving	O
itself	O
in	O
third-party	O
keyboards	B-Device
.	O
</s>
<s>
Research	O
by	O
Google	B-Application
itself	O
confirmed	O
that	O
gesture-typing	O
is	O
increasing	O
the	O
typing	O
rate	O
by	O
22%	O
and	O
is	O
decreasing	O
the	O
error	O
rate	O
near	O
to	O
0%	O
.	O
</s>
<s>
Google	B-Application
further	O
showed	O
that	O
the	O
gesture-typing	O
method	O
is	O
also	O
useful	O
on	O
smart	O
watches	O
.	O
</s>
<s>
Their	O
scientific	O
research	O
is	O
primarily	O
based	O
on	O
research	O
made	O
by	O
I	O
.	O
Scott	O
MacKenzie	O
and	O
papers	O
about	O
modeling	O
finger	B-Device
touch	I-Device
with	O
fitts’	O
law	O
.	O
</s>
<s>
Haptic	B-Device
feedback	I-Device
provides	O
for	O
tactile	O
confirmation	O
that	O
a	O
key	O
has	O
been	O
successfully	O
triggered	O
i.e.	O
</s>
<s>
In	O
this	O
case	O
,	O
there	O
is	O
an	O
initial	O
"	O
click	O
"	O
that	O
is	O
heard	O
and	O
felt	O
as	O
the	O
virtual	B-Application
key	O
is	O
pressed	O
down	O
,	O
but	O
then	O
as	O
finger	O
pressure	O
is	O
reduced	O
once	O
the	O
key	O
is	O
triggered	O
,	O
there	O
is	O
a	O
further	O
"	O
unclick	O
"	O
sound	O
and	O
sensation	O
as	O
if	O
a	O
physical	O
key	O
is	O
respringing	O
back	O
to	O
its	O
original	O
unclicked	O
state	O
.	O
</s>
<s>
This	O
behaviour	O
is	O
explained	O
in	O
Aleks	O
Oniszczak	O
&	O
Scott	O
Mackenzie	O
's	O
2004	O
paper	O
"	O
A	O
Comparison	O
of	O
Two	O
Input	B-General_Concept
Methods	I-General_Concept
for	O
Keypads	O
on	O
Mobile	O
Devices	O
"	O
which	O
first	O
introduced	O
haptic	B-Device
feedback	I-Device
with	O
hysteresis	O
on	O
a	O
virtual	B-Device
keyboard	I-Device
.	O
</s>
<s>
Keyboards	B-Device
are	O
needed	O
in	O
different	O
digital	O
areas	O
.	O
</s>
<s>
Not	O
only	O
smartphones	B-Application
need	O
a	O
virtual	B-Device
keyboards	I-Device
,	O
also	O
devices	O
which	O
create	O
virtual	B-Application
worlds	O
,	O
for	O
example	O
virtual	B-Application
reality	I-Application
or	O
augmented	B-General_Concept
reality	I-General_Concept
glasses	I-General_Concept
,	O
need	O
to	O
provide	O
text	O
input	O
possibilities	O
.	O
</s>
<s>
An	O
optical	O
virtual	B-Device
keyboard	I-Device
was	O
invented	O
and	O
patented	O
by	O
IBM	O
engineers	O
in	O
1992	O
.	O
</s>
<s>
It	O
optically	O
detects	O
and	O
analyses	O
human	O
hand	O
and	O
finger	O
motions	O
and	O
interprets	O
them	O
as	O
operations	O
on	O
a	O
physically	O
non-existent	O
input	B-Device
device	I-Device
like	O
a	O
surface	O
having	O
painted	O
keys	O
.	O
</s>
<s>
In	O
that	O
way	O
it	O
allows	O
to	O
emulate	O
unlimited	O
types	O
of	O
manually	O
operated	O
input	B-Device
devices	I-Device
such	O
as	O
a	O
mouse	O
or	O
keyboard	B-Device
.	O
</s>
<s>
All	O
mechanical	O
input	O
units	O
can	O
be	O
replaced	O
by	O
such	O
virtual	B-Application
devices	O
,	O
optimized	O
for	O
the	O
current	O
application	O
and	O
for	O
the	O
user	O
's	O
physiology	O
maintaining	O
speed	O
,	O
simplicity	O
and	O
unambiguity	O
of	O
manual	O
data	O
input	O
.	O
</s>
<s>
The	O
basic	O
idea	O
of	O
a	O
virtual	B-Device
keyboard	I-Device
in	O
an	O
augmented	B-General_Concept
reality	I-General_Concept
environment	O
is	O
to	O
give	O
the	O
user	O
a	O
text	O
input	O
possibility	O
.	O
</s>
<s>
A	O
common	O
approach	O
is	O
to	O
render	O
a	O
flat	O
keyboard	B-Device
into	O
the	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
e.g.	O
</s>
<s>
using	O
the	O
Unity	B-Application
TouchScreenKeyboard	O
.	O
</s>
<s>
The	O
Microsoft	B-General_Concept
HoloLens	I-General_Concept
enables	O
the	O
user	O
to	O
point	O
at	O
letters	O
on	O
the	O
keyboard	B-Device
by	O
moving	O
his	O
head	O
.	O
</s>
<s>
Their	O
suggestion	O
was	O
to	O
use	O
wearables	O
to	O
track	O
the	O
finger	O
motion	O
to	O
replace	O
a	O
physical	O
keyboards	B-Device
with	O
virtual	B-Application
ones	O
.	O
</s>
<s>
The	O
Magic	B-General_Concept
Leap	I-General_Concept
1	O
from	O
Magic	B-General_Concept
Leap	I-General_Concept
implements	O
a	O
virtual	B-Device
keyboard	I-Device
with	O
augmented	B-General_Concept
reality	I-General_Concept
.	O
</s>
<s>
The	O
challenges	O
,	O
as	O
in	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
is	O
to	O
give	O
the	O
user	O
the	O
possibility	O
to	O
enter	O
text	O
in	O
a	O
completely	O
virtual	B-Application
environment	O
.	O
</s>
<s>
One	O
big	O
issue	O
is	O
that	O
most	O
augmented	B-General_Concept
reality	I-General_Concept
systems	O
on	O
the	O
market	O
are	O
not	O
tracking	B-Algorithm
the	I-Algorithm
hands	I-Algorithm
of	O
the	O
user	O
.	O
</s>
<s>
In	O
September	O
2016	O
,	O
Google	B-Application
released	O
a	O
virtual	B-Device
keyboard	I-Device
app	O
for	O
their	O
Daydream	B-Application
virtual	B-Application
reality	I-Application
headset	O
.	O
</s>
<s>
To	O
enter	O
text	O
,	O
the	O
user	O
can	O
point	O
at	O
specific	O
letters	O
with	O
the	O
Daydream	B-Application
controller	O
.	O
</s>
<s>
In	O
February	O
2017	O
,	O
Logitech	O
presented	O
experimental	O
approach	O
to	O
bring	O
their	O
keyboards	B-Device
into	O
the	O
virtual	B-Application
environment	O
.	O
</s>
<s>
With	O
the	O
Vive	O
Tracker	O
and	O
the	O
Logitech	O
G	O
gaming	O
keyboard	B-Device
it	O
is	O
possible	O
to	O
exactly	O
track	O
every	O
finger	O
movement	O
,	O
without	O
wearing	O
any	O
type	O
of	O
glove	O
.	O
</s>
<s>
Virtual	B-Device
keyboards	I-Device
may	O
be	O
used	O
in	O
some	O
cases	O
to	O
reduce	O
the	O
risk	O
of	O
keystroke	O
logging	O
.	O
</s>
<s>
For	O
example	O
,	O
Westpac	O
’s	O
online	O
banking	O
service	O
uses	O
a	O
virtual	B-Device
keyboard	I-Device
for	O
the	O
password	O
entry	O
,	O
as	O
does	O
TreasuryDirect	O
(	O
see	O
picture	O
)	O
.	O
</s>
<s>
It	O
is	O
more	O
difficult	O
for	O
malware	O
to	O
monitor	O
the	O
display	O
and	O
mouse	O
to	O
obtain	O
the	O
data	O
entered	O
via	O
the	O
virtual	B-Device
keyboard	I-Device
,	O
than	O
it	O
is	O
to	O
monitor	O
real	O
keystrokes	O
.	O
</s>
<s>
However	O
it	O
is	O
possible	O
,	O
for	O
example	O
by	O
recording	O
screenshots	B-Application
at	O
regular	O
intervals	O
or	O
upon	O
each	O
mouse	O
click	O
.	O
</s>
<s>
The	O
use	O
of	O
an	O
on-screen	B-Device
keyboard	I-Device
on	O
which	O
the	O
user	O
"	O
types	O
"	O
with	O
mouse	O
clicks	O
can	O
increase	O
the	O
risk	O
of	O
password	O
disclosure	O
by	O
shoulder	O
surfing	O
,	O
because	O
:	O
</s>
<s>
An	O
observer	O
can	O
typically	O
watch	O
the	O
screen	O
more	O
easily	O
(	O
and	O
less	O
suspiciously	O
)	O
than	O
the	O
keyboard	B-Device
,	O
and	O
see	O
which	O
characters	O
the	O
mouse	O
moves	O
to	O
.	O
</s>
<s>
Some	O
implementations	O
of	O
the	O
on-screen	B-Device
keyboard	I-Device
may	O
give	O
visual	O
feedback	O
of	O
the	O
"	O
key	O
"	O
clicked	O
,	O
e.g.	O
</s>
<s>
In	O
the	O
worst	O
case	O
,	O
the	O
implementation	O
may	O
leave	O
the	O
focus	B-Application
on	O
the	O
most	O
recently	O
clicked	O
"	O
key	O
"	O
until	O
the	O
next	O
virtual	B-Application
key	O
is	O
clicked	O
,	O
thus	O
allowing	O
the	O
observer	O
time	O
to	O
read	O
each	O
character	O
even	O
after	O
the	O
mouse	O
starts	O
moving	O
to	O
the	O
next	O
character	O
.	O
</s>
<s>
A	O
user	O
may	O
not	O
be	O
able	O
to	O
"	O
point	O
and	O
click	O
"	O
as	O
fast	O
as	O
they	O
could	O
type	O
on	O
a	O
keyboard	B-Device
,	O
thus	O
making	O
it	O
easier	O
for	O
the	O
observer	O
.	O
</s>
