Gipphe / elm-ui / Element

Basic Elements


type alias Element msg =
Internal.Model.Element msg

The basic building block of your layout.

howdy : Element msg
howdy =
    Element.el [] (Element.text "Howdy!")

none : Element msg

When you want to render exactly nothing.

text : String -> Element msg

Create some plain text.

text "Hello, you stylish developer!"

Note text does not wrap by default. In order to get text to wrap, check out paragraph!

el : List (Attribute msg) -> Element msg -> Element msg

The basic building block of your layout.

You can think of an el as a div, but it can only have one child.

If you want multiple children, you'll need to use something like row or column

import Element exposing (Element, rgb)
import Element.Background as Background
import Element.Border as Border

myElement : Element msg
myElement =
    Element.el
        [ Background.color (rgb 0 0.5 0)
        , Border.color (rgb 0 0.7 0)
        ]
        (Element.text "You've made a stylish element!")

Rows and Columns

When we want more than one child on an element, we want to be specific about how they will be laid out.

So, the common ways to do that would be row and column.

row : List (Attribute msg) -> List (Element msg) -> Element msg

wrappedRow : List (Attribute msg) -> List (Element msg) -> Element msg

Same as row, but will wrap if it takes up too much horizontal space.

column : List (Attribute msg) -> List (Element msg) -> Element msg

Text Layout

Text layout needs some specific considerations.

paragraph : List (Attribute msg) -> List (Element msg) -> Element msg

A paragraph will layout all children as wrapped, inline elements.

import Element exposing (el, paragraph, text)
import Element.Font as Font

view =
    paragraph []
        [ text "lots of text ...."
        , el [ Font.bold ] (text "this is bold")
        , text "lots of text ...."
        ]

This is really useful when you want to markup text by having some parts be bold, or some be links, or whatever you so desire.

Also, if a child element has alignLeft or alignRight, then it will be moved to that side and the text will flow around it, (ah yes, float behavior).

This makes it particularly easy to do something like a dropped capital.

import Element exposing (alignLeft, el, padding, paragraph, text)
import Element.Font as Font

view =
    paragraph []
        [ el
            [ alignLeft
            , padding 5
            ]
            (text "S")
        , text "o much text ...."
        ]

Which will look something like

A paragraph where the first letter is twice the height of the others

Note spacing on a paragraph will set the pixel spacing between lines.

textColumn : List (Attribute msg) -> List (Element msg) -> Element msg

Now that we have a paragraph, we need some way to attach a bunch of paragraph's together.

To do that we can use a textColumn.

The main difference between a column and a textColumn is that textColumn will flow the text around elements that have alignRight or alignLeft, just like we just saw with paragraph.

In the following example, we have a textColumn where one child has alignLeft.

Element.textColumn [ spacing 10, padding 10 ]
    [ paragraph [] [ text "lots of text ...." ]
    , el [ alignLeft ] none
    , paragraph [] [ text "lots of text ...." ]
    ]

Which will result in something like:

A text layout where an image is on the left.

Data Table


type alias Column record msg =
{ header : Element msg
, width : Length
, view : record -> Element msg 
}

table : List (Attribute msg) -> { data : List records, columns : List (Column records msg) } -> Element msg

Show some tabular data.

Start with a list of records and specify how each column should be rendered.

So, if we have a list of persons:

type alias Person =
    { firstName : String
    , lastName : String
    }

persons : List Person
persons =
    [ { firstName = "David"
      , lastName = "Bowie"
      }
    , { firstName = "Florence"
      , lastName = "Welch"
      }
    ]

We could render it using

Element.table []
    { data = persons
    , columns =
        [ { header = Element.text "First Name"
          , width = fill
          , view =
                \person ->
                    Element.text person.firstName
          }
        , { header = Element.text "Last Name"
          , width = fill
          , view =
                \person ->
                    Element.text person.lastName
          }
        ]
    }

Note: Sometimes you might not have a list of records directly in your model. In this case it can be really nice to write a function that transforms some part of your model into a list of records before feeding it into Element.table.


type alias IndexedColumn record msg =
{ header : Element msg
, width : Length
, view : Basics.Int -> record -> Element msg 
}

indexedTable : List (Attribute msg) -> { data : List records, columns : List (IndexedColumn records msg) } -> Element msg

Same as Element.table except the view for each column will also receive the row index as well as the record.

Size


type alias Attribute msg =
Internal.Model.Attribute () msg

An attribute that can be attached to an Element

width : Length -> Attribute msg

height : Length -> Attribute msg


type alias Length =
Internal.Model.Length

px : Basics.Int -> Length

shrink : Length

Shrink an element to fit its contents.

fill : Length

Fill the available space. The available space will be split evenly between elements that have width fill.

fillPortion : Basics.Int -> Length

Sometimes you may not want to split available space evenly. In this case you can use fillPortion to define which elements should have what portion of the available space.

So, two elements, one with width (fillPortion 2) and one with width (fillPortion 3). The first would get 2 portions of the available space, while the second would get 3.

Also: fill == fillPortion 1

maximum : Basics.Int -> Length -> Length

Add a maximum to a length.

el
    [ height
        (fill
            |> maximum 300
        )
    ]
    (text "I will stop at 300px")

minimum : Basics.Int -> Length -> Length

Similarly you can set a minimum boundary.

 el
    [ height
        (fill
            |> maximum 300
            |> minimum 30
        )

    ]
    (text "I will stop at 300px")

Debugging

explain : Todo -> Attribute msg

Highlight the borders of an element and it's children below. This can really help if you're running into some issue with your layout!

Note This attribute needs to be handed Debug.todo in order to work, even though it won't do anything with it. This is a safety measure so you don't accidently ship code with explain in it, as Elm won't compile with --optimize if you still have a Debug statement in your code.

el
    [ Element.explain Debug.todo
    ]
    (text "Help, I'm being debugged!")

Padding and Spacing

There's no concept of margin in elm-ui, instead we have padding and spacing.

Padding is the distance between the outer edge and the content, and spacing is the space between children.

So, if we have the following row, with some padding and spacing.

Element.row [ padding 10, spacing 7 ]
    [ Element.el [] none
    , Element.el [] none
    , Element.el [] none
    ]

Here's what we can expect:

Three boxes spaced 7 pixels apart. There's a 10 pixel distance from the edge of the parent to the boxes.

Note spacing set on a paragraph, will set the pixel spacing between lines.

padding : Basics.Int -> Attribute msg

paddingXY : Basics.Int -> Basics.Int -> Attribute msg

Set horizontal and vertical padding.

paddingEach : { top : Basics.Int, right : Basics.Int, bottom : Basics.Int, left : Basics.Int } -> Attribute msg

If you find yourself defining unique paddings all the time, you might consider defining

edges =
    { top = 0
    , right = 0
    , bottom = 0
    , left = 0
    }

And then just do

paddingEach { edges | right = 5 }

spacing : Basics.Int -> Attribute msg

spacingXY : Basics.Int -> Basics.Int -> Attribute msg

In the majority of cases you'll just need to use spacing, which will work as intended.

However for some layouts, like textColumn, you may want to set a different spacing for the x axis compared to the y axis.

spaceEvenly : Attribute msg

Alignment

Alignment can be used to align an Element within another Element.

Element.el [ centerX, alignTop ] (text "I'm centered and aligned top!")

If alignment is set on elements in a layout such as row, then the element will push the other elements in that direction. Here's an example.

Element.row []
    [ Element.el [] Element.none
    , Element.el [ alignLeft ] Element.none
    , Element.el [ centerX ] Element.none
    , Element.el [ alignRight ] Element.none
    ]

will result in a layout like

|-|-|    |-|    |-|

Where there are two elements on the left, one on the right, and one in the center of the space between the elements on the left and right.

Note For text alignment, check out Element.Font!

centerX : Attribute msg

centerY : Attribute msg

alignLeft : Attribute msg

alignRight : Attribute msg

alignTop : Attribute msg

alignBottom : Attribute msg

Transparency

transparent : Basics.Bool -> Attr decorative msg

Make an element transparent and have it ignore any mouse or touch events, though it will stil take up space.

alpha : Basics.Float -> Attr decorative msg

A capped value between 0.0 and 1.0, where 0.0 is transparent and 1.0 is fully opaque.

Semantically equivalent to html opacity.

pointer : Attribute msg

Set the cursor to be a pointing hand when it's hovering over this element.

Adjustment

moveUp : Basics.Float -> Attr decorative msg

moveDown : Basics.Float -> Attr decorative msg

moveRight : Basics.Float -> Attr decorative msg

moveLeft : Basics.Float -> Attr decorative msg

rotate : Basics.Float -> Attr decorative msg

Angle is given in radians. Here are some conversion functions if you want to use another unit.

scale : Basics.Float -> Attr decorative msg

Clipping and Scrollbars

Clip the content if it overflows.

clip : Attribute msg

clipX : Attribute msg

scrollbars : Attribute msg

scrollbarX : Attribute msg

scrollbarY : Attribute msg

Rendering

layout : List (Attribute msg) -> Element msg -> Html msg

This is your top level node where you can turn Element into Html.

layoutWith : { options : List Option } -> List (Attribute msg) -> Element msg -> Html msg


type alias Option =
Internal.Model.Option

noStaticStyleSheet : Option

Elm UI embeds two StyleSheets, one that is constant, and one that changes dynamically based on styles collected from the elements being rendered.

This option will stop the static/constant stylesheet from rendering.

If you're embedding multiple elm-ui layout elements, you need to guarantee that only one is rendering the static style sheet and that it's above all the others in the DOM tree.

forceHover : Option

Any hover styles, aka attributes with mouseOver in the name, will be always turned on.

This is useful for when you're targeting a platform that has no mouse, such as mobile.

noHover : Option

Disable all mouseOver styles.

focusStyle : FocusStyle -> Option


type alias FocusStyle =
{ borderColor : Maybe Color
, backgroundColor : Maybe Color
, shadow : Maybe { color : Color
, offset : ( Basics.Int
, Basics.Int )
, blur : Basics.Int
, size : Basics.Int } 
}

Links

link : List (Attribute msg) -> { url : String, label : Element msg } -> Element msg

link []
    { url = "http://fruits.com"
    , label = text "A link to my favorite fruit provider."
    }

newTabLink : List (Attribute msg) -> { url : String, label : Element msg } -> Element msg

download : List (Attribute msg) -> { url : String, label : Element msg } -> Element msg

A link to download a file.

downloadAs : List (Attribute msg) -> { label : Element msg, filename : String, url : String } -> Element msg

A link to download a file, but you can specify the filename.

Images

image : List (Attribute msg) -> { src : String, description : String } -> Element msg

Both a source and a description are required for images.

The description is used for people using screen readers.

Leaving the description blank will cause the image to be ignored by assistive technology. This can make sense for images that are purely decorative and add no additional information.

So, take a moment to describe your image as you would to someone who has a harder time seeing.

imageSet : List (Attribute msg) -> { sources : List Source, fallback : String, description : String } -> Element msg

A set of images. Can be used to provide more than one source for an image, so as to support more than one image type and/or resolution.


type Source
    = WebP String
    | PNG String
    | JPG String
    | AVIF String
    | TIFF String
    | HEIC String

A given imageSet source can be of different types. These types will be encoded in the final element as an attribute to further guide web browsers about the contained image format.

Color

In order to use attributes like Font.color and Background.color, you'll need to make some colors!


type alias Color =
Internal.Model.Color

rgba : Basics.Float -> Basics.Float -> Basics.Float -> Basics.Float -> Color

rgb : Basics.Float -> Basics.Float -> Basics.Float -> Color

Provide the red, green, and blue channels for the color.

Each channel takes a value between 0 and 1.

rgb255 : Basics.Int -> Basics.Int -> Basics.Int -> Color

Provide the red, green, and blue channels for the color.

Each channel takes a value between 0 and 255.

rgba255 : Basics.Int -> Basics.Int -> Basics.Int -> Basics.Float -> Color

fromRgb : { red : Basics.Float, green : Basics.Float, blue : Basics.Float, alpha : Basics.Float } -> Color

Create a color from an RGB record.

fromRgb255 : { red : Basics.Int, green : Basics.Int, blue : Basics.Int, alpha : Basics.Float } -> Color

toRgb : Color -> { red : Basics.Float, green : Basics.Float, blue : Basics.Float, alpha : Basics.Float }

Deconstruct a Color into its rgb channels.

Nearby Elements

Let's say we want a dropdown menu. Essentially we want to say: put this element below this other element, but don't affect the layout when you do.

Element.row []
    [ Element.el
        [ Element.below (Element.text "I'm below!")
        ]
        (Element.text "I'm normal!")
    ]

This will result in

|- I'm normal! -|
   I'm below

Where "I'm Below" doesn't change the size of Element.row.

This is very useful for things like dropdown menus or tooltips.

above : Element msg -> Attribute msg

below : Element msg -> Attribute msg

onRight : Element msg -> Attribute msg

onLeft : Element msg -> Attribute msg

inFront : Element msg -> Attribute msg

This will place an element in front of another.

Note: If you use this on a layout element, it will place the element as fixed to the viewport which can be useful for modals and overlays.

behindContent : Element msg -> Attribute msg

This will place an element between the background and the content of an element.

Temporary Styling


type alias Attr decorative msg =
Internal.Model.Attribute decorative msg

This is a special attribute that counts as both a Attribute msg and a Decoration.


type alias Decoration =
Internal.Model.Attribute Basics.Never Basics.Never

Only decorations

mouseOver : List Decoration -> Attribute msg

mouseDown : List Decoration -> Attribute msg

focused : List Decoration -> Attribute msg

Responsiveness

The main technique for responsiveness is to store window size information in your model.

Install the Browser package, and set up a subscription for Browser.Events.onResize.

You'll also need to retrieve the initial window size. You can either use Browser.Dom.getViewport or pass in window.innerWidth and window.innerHeight as flags to your program, which is the preferred way. This requires minor setup on the JS side, but allows you to avoid the state where you don't have window info.


type alias Device =
{ class : DeviceClass
, orientation : Orientation 
}


type DeviceClass
    = Phone
    | Tablet
    | Desktop
    | BigDesktop


type Orientation
    = Portrait
    | Landscape

classifyDevice : { window | height : Basics.Int, width : Basics.Int } -> Device

Takes in a Window.Size and returns a device profile which can be used for responsiveness.

If you have more detailed concerns around responsiveness, it probably makes sense to copy this function into your codebase and modify as needed.

Scaling

modular : Basics.Float -> Basics.Float -> Basics.Int -> Basics.Float

When designing it's nice to use a modular scale to set spacial rythms.

scaled =
    Element.modular 16 1.25

A modular scale starts with a number, and multiplies it by a ratio a number of times. Then, when setting font sizes you can use:

Font.size (scaled 1) -- results in 16

Font.size (scaled 2) -- 16 * 1.25 results in 20

Font.size (scaled 4) -- 16 * 1.25 ^ (4 - 1) results in 31.25

We can also provide negative numbers to scale below 16px.

Font.size (scaled -1) -- 16 * 1.25 ^ (-1) results in 12.8

Mapping

map : (msg -> msg1) -> Element msg -> Element msg1

mapAttribute : (msg -> msg1) -> Attribute msg -> Attribute msg1

Compatibility

html : Html msg -> Element msg

htmlAttribute : Html.Attribute msg -> Attribute msg