<s>
QML	B-Language
(	O
Qt	B-Language
Modeling	I-Language
Language	I-Language
)	O
is	O
a	O
user	B-Language
interface	I-Language
markup	I-Language
language	I-Language
.	O
</s>
<s>
It	O
is	O
a	O
declarative	B-Language
language	I-Language
(	O
similar	O
to	O
CSS	B-Language
and	O
JSON	B-General_Concept
)	O
for	O
designing	O
user	O
interface	O
–	O
centric	O
applications	O
.	O
</s>
<s>
Inline	O
JavaScript	B-Language
code	O
handles	O
imperative	O
aspects	O
.	O
</s>
<s>
It	O
is	O
associated	O
with	O
Qt	B-Language
Quick	I-Language
,	O
the	O
UI	O
creation	O
kit	O
originally	O
developed	O
by	O
Nokia	O
within	O
the	O
Qt	B-Language
framework	I-Language
.	O
</s>
<s>
Qt	B-Language
Quick	I-Language
is	O
used	O
for	O
mobile	O
applications	O
where	O
touch	O
input	O
,	O
fluid	O
animations	O
and	O
user	O
experience	O
are	O
crucial	O
.	O
</s>
<s>
QML	B-Language
is	O
also	O
used	O
with	O
Qt3D	O
to	O
describe	O
a	O
3D	O
scene	O
and	O
a	O
"	O
frame	O
graph	O
"	O
rendering	O
methodology	O
.	O
</s>
<s>
A	O
QML	B-Language
document	O
describes	O
a	O
hierarchical	O
object	O
tree	O
.	O
</s>
<s>
QML	B-Language
modules	O
shipped	O
with	O
Qt	B-Language
include	O
primitive	O
graphical	O
building	O
blocks	O
(	O
e.g.	O
,	O
Rectangle	O
,	O
Image	O
)	O
,	O
modeling	O
components	O
(	O
e.g.	O
,	O
FolderListModel	O
,	O
XmlListModel	O
)	O
,	O
behavioral	O
components	O
(	O
e.g.	O
,	O
TapHandler	O
,	O
DragHandler	O
,	O
State	O
,	O
Transition	O
,	O
Animation	O
)	O
,	O
and	O
more	O
complex	O
controls	O
(	O
e.g.	O
,	O
Button	O
,	O
Slider	O
,	O
Drawer	O
,	O
Menu	O
)	O
.	O
</s>
<s>
QML	B-Language
elements	O
can	O
be	O
augmented	O
by	O
standard	O
JavaScript	B-Language
both	O
inline	O
and	O
via	O
included	O
.js	B-Language
files	O
.	O
</s>
<s>
Elements	O
can	O
also	O
be	O
seamlessly	O
integrated	O
and	O
extended	O
by	O
C++	B-Language
components	O
using	O
the	O
Qt	B-Language
framework	I-Language
.	O
</s>
<s>
QML	B-Language
is	O
the	O
language	O
;	O
its	O
JavaScript	B-Language
runtime	O
is	O
the	O
custom	O
V4	O
engine	O
,	O
since	O
Qt	B-Language
5.2	O
;	O
and	O
Qt	B-Language
Quick	I-Language
is	O
the	O
2D	O
scene	B-Data_Structure
graph	I-Data_Structure
and	O
the	O
UI	O
framework	O
based	O
on	O
it	O
.	O
</s>
<s>
These	O
are	O
all	O
part	O
of	O
the	O
Qt	B-Language
Declarative	B-Language
module	O
,	O
while	O
the	O
technology	O
is	O
no	O
longer	O
called	O
Qt	B-Language
Declarative	B-Language
.	O
</s>
<s>
QML	B-Language
and	O
JavaScript	B-Language
code	O
can	O
be	O
compiled	O
into	O
native	O
C++	B-Language
binaries	O
with	O
the	O
Qt	B-Language
Quick	I-Language
Compiler	O
.	O
</s>
<s>
Alternatively	O
there	O
is	O
a	O
QML	B-Language
cache	O
file	O
format	O
which	O
stores	O
a	O
compiled	O
version	O
of	O
QML	B-Language
dynamically	O
for	O
faster	O
startup	O
the	O
next	O
time	O
it	O
is	O
run	O
.	O
</s>
<s>
A	O
property	O
binding	B-General_Concept
specifies	O
the	O
value	O
of	O
a	O
property	O
in	O
a	O
declarative	B-Language
way	O
.	O
</s>
<s>
The	O
property	O
value	O
is	O
automatically	O
updated	O
if	O
the	O
other	O
properties	O
or	O
data	O
values	O
change	O
,	O
following	O
the	O
reactive	B-Architecture
programming	I-Architecture
paradigm	O
.	O
</s>
<s>
Property	O
bindings	O
are	O
created	O
implicitly	O
in	O
QML	B-Language
whenever	O
a	O
property	O
is	O
assigned	O
a	O
JavaScript	B-Language
expression	O
.	O
</s>
<s>
The	O
following	O
QML	B-Language
uses	O
two	O
property	O
bindings	O
to	O
connect	O
the	O
size	O
of	O
the	O
rectangle	O
to	O
that	O
of	O
otherItem	O
.	O
</s>
<s>
QML	B-Language
extends	O
a	O
standards-compliant	O
JavaScript	B-Language
engine	O
,	O
so	O
any	O
valid	O
JavaScript	B-Language
expression	O
can	O
be	O
used	O
as	O
a	O
property	O
binding	B-General_Concept
.	O
</s>
<s>
Bindings	O
can	O
access	O
object	O
properties	O
,	O
make	O
function	O
calls	O
,	O
and	O
even	O
use	O
built-in	O
JavaScript	B-Language
objects	O
like	O
Date	O
and	O
Math	O
.	O
</s>
<s>
States	B-Architecture
are	O
a	O
mechanism	O
to	O
combine	O
changes	O
to	O
properties	O
in	O
a	O
semantic	O
unit	O
.	O
</s>
<s>
Animations	O
in	O
QML	B-Language
are	O
done	O
by	O
animating	O
properties	O
of	O
objects	O
.	O
</s>
<s>
QML	B-Language
supports	O
three	O
main	O
forms	O
of	O
animation	O
:	O
basic	O
property	O
animation	O
,	O
transitions	O
,	O
and	O
property	O
behaviors	O
.	O
</s>
<s>
Usage	O
of	O
QML	B-Language
does	O
not	O
require	O
Qt/C	O
++	O
knowledge	O
to	O
use	O
,	O
but	O
it	O
can	O
be	O
easily	O
extended	O
via	O
Qt	B-Language
.	O
</s>
<s>
Any	O
C++	B-Language
class	O
derived	O
from	O
QObject	O
can	O
be	O
easily	O
registered	O
as	O
a	O
type	O
which	O
can	O
then	O
be	O
instantiated	O
in	O
QML	B-Language
.	O
</s>
<s>
QML	B-Language
provides	O
direct	O
access	O
to	O
the	O
following	O
concepts	O
from	O
Qt	B-Language
:	O
</s>
<s>
Q*Model	O
–	O
used	O
directly	O
in	O
data	B-General_Concept
binding	I-General_Concept
(	O
e.g.	O
</s>
<s>
Signal	O
handlers	O
are	O
JavaScript	B-Language
callbacks	O
which	O
allow	O
imperative	O
actions	O
to	O
be	O
taken	O
in	O
response	O
to	O
an	O
event	O
.	O
</s>
<s>
Because	O
QML	B-Language
and	O
JavaScript	B-Language
are	O
very	O
similar	O
,	O
almost	O
all	O
code	O
editors	O
supporting	O
JavaScript	B-Language
will	O
work	O
.	O
</s>
<s>
However	O
full	O
support	O
for	O
syntax	O
highlighting	O
,	O
code	O
completion	O
,	O
integrated	O
help	O
,	O
and	O
a	O
WYSIWYG	O
editor	O
are	O
available	O
in	O
the	O
free	O
cross-platform	O
IDE	O
Qt	B-Language
Creator	I-Language
since	O
version	O
2.1	O
and	O
many	O
other	O
IDEs	O
.	O
</s>
<s>
The	O
qml	B-Language
executable	O
can	O
be	O
used	O
to	O
run	O
a	O
QML	B-Language
file	O
as	O
a	O
script	O
.	O
</s>
<s>
If	O
the	O
QML	B-Language
file	O
begins	O
with	O
a	O
shebang	B-Operating_System
it	O
can	O
be	O
made	O
directly	O
executable	O
.	O
</s>
<s>
However	O
packaging	O
an	O
application	O
for	O
deployment	O
(	O
especially	O
on	O
mobile	O
platforms	O
)	O
generally	O
involves	O
writing	O
a	O
simple	O
C++	B-Language
launcher	O
and	O
packaging	O
the	O
necessary	O
QML	B-Language
files	O
as	O
resources	O
.	O
</s>
