Threepenny-gui Flexbox
Flexbox layouts for Threepenny-gui.
This library was written following the
wonderful
A Complete Guide to Flexbox and
using the equally wonderful Clay
library as a CSS domain specific language.
Usage
Properties
Ultimately we just want to set Flexbox properties on elements, both parent and
child elements. In CSS these properties would look like flex-grow: 1;
.
We collect Flexbox properties that apply to the parent element, things like
flex-direction
, in a ParentProps
data type. Flexbox properties that apply to
child elements, things like flex-grow
, are collected in a ChildProps
data
type.
If you want ChildProps
with flex-grow: 1;
you can just do:
flexGrow 1
You can define multiple properties using record syntax:
order 1 { cflexGrow = 1, cFlexShrink = 2 }
Note that in the examples above we used flexGrow
and order
to return
ChildProps
with given values set but also with default values set for all
other Flexbox properties, unless record syntax is used to override a property.
Some properties like flexGrow
simply take an Int
but others take a value
from the Clay
library. Here’s an example for ParentProps
:
display Clay.Display.inlineFlex { pFlexWrap = Clay.Flexbox.nowrap }
If you just want ParentProps
or ChildProps
with default values:
parentProps :: ParentProps
childProps :: ChildProps
Setting Properties
Once you have your properties defined you’ll want to apply them to elements. For
this you can use setFlex
which can be used with Threepenny’s reverse function
application operator #
:
UI.div # set UI.text "foo" # setFlex (flexGrow 1)
You can also convert ParentProps
or ChildProps
to a [(String, String)]
which
is
how Threepenny expects CSS.
This can be done using toStyle
which is defined in the typeclass ToStyle
:
UI.div # set UI.style (toStyle $ order 1)
‘flex’
We provide a utility function flex
(and a few variants thereof) which takes
both parent and child elements and their respective ParentProps
and
ChildProps
, applies the properties to the respective elements and then returns
the parent element with children attached.
Here is a full example, which produces the above image of three orange text
boxes in ratio 1:2:1. First done without flex_p
and then with flex_p
.
flex_p
is a variant of flex
which applies default Flexbox properties to the
parent element.
-- |Example without 'flex_p'.
example :: Window -> UI ()
example w = void $
getBody w # setFlex parentProps #+ [
foo # setFlex (flexGrow 1)
, foo # setFlex (flexGrow 2)
, foo # setFlex (flexGrow 1)
]
-- |Example with 'flex_p'.
example' :: Window -> UI ()
example' w = void $
flex_p (getBody w) [
(foo, flexGrow 1)
, (foo, flexGrow 2)
, (foo, flexGrow 1)
]
-- | Simple coloured 'div'.
foo = UI.div # set UI.text "foo"
# set UI.style [("background-color", "#F89406"),
("margin", "8px")]