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I am trying to get the width and height of an image, so give a URL, what is the width and height of that image
753
I don't believe that there is a way to do this in elm. Ports are one possible solution. You can read about them here. I've written a small example of your use case which you can run your self on ellie. In this example I use the JS example you gave in your comment, but there are other possible solutions such as event listeners or querying the DOM.
port module Main exposing (main)
import Html exposing (..)
import Html.Attributes exposing (..)
main : Program Never Model Msg
main =
Html.program
{ init = init
, update = update
, view = view
, subscriptions = subscriptions
}
type alias Model =
{ imageUrl : String
, dim : Maybe ( Int, Int )
}
testImg : String
testImg =
"https://images-na.ssl-images-amazon.com/images/I/71TcaVWvBsL._SY355_.jpg"
init : ( Model, Cmd msg )
init =
Model testImg Nothing
! [ getDim testImg ]
type Msg
= UpdateDim ( Int, Int )
update : Msg -> Model -> ( Model, Cmd msg )
update msg model =
case msg of
UpdateDim xy ->
{ model | dim = Just xy } ! []
view : Model -> Html msg
view model =
case model.dim of
Nothing ->
div [] []
Just dims ->
div []
[ img [ src model.imageUrl ] []
, text <|
"size: "
++ toString dims
]
subscriptions : Model -> Sub Msg
subscriptions model =
newDim UpdateDim
-- this port handles our incomming height and width
-- and passes it to a Msg constructor
port newDim : (( Int, Int ) -> msg) -> Sub msg
-- this port passes our string out of Elm and into
-- js land
port getDim : String -> Cmd msg
<html>
<head>
<style>
/* you can style your program here */
</style>
</head>
<body>
<script>
var app = Elm.Main.fullscreen()
// you can use ports and stuff here
app.ports.getDim.subscribe(function(url){
// recieve the url for the image through
// the `getDim` port in Main.elm
let img = new Image()
img.src = url
img.onload = function() {
// send the height and width back to elm through
// the `newDim` port in Main.elm
app.ports.newDim.send([img.height, img.width])
}
})
</script>
</body>
</html>
I mentioned in a comment that if you display the image, you can do this without ports. This is the solution I was talking about:
module Main exposing (main)
import Browser
import Debug exposing (toString)
import Html exposing (Html, div, img, text)
import Html.Attributes exposing (src)
import Html.Events exposing (on)
import Json.Decode as Decode
type alias Model =
{ imageDimensions : Maybe ImgDimensions }
initialModel : Model
initialModel =
{ imageDimensions = Nothing }
type Msg
= ImgLoaded ImgDimensions
update : Msg -> Model -> Model
update msg model =
case msg of
ImgLoaded dimensions ->
{ model | imageDimensions = Just dimensions }
type alias ImgDimensions =
{ width : Int
, height : Int
}
decodeImgLoad msg =
Decode.map msg <|
Decode.field "target" <|
Decode.map2 ImgDimensions
(Decode.field "width" Decode.int)
(Decode.field "height" Decode.int)
view : Model -> Html Msg
view model =
div []
[ text <| "Image Loaded = " ++ toString model.imageDimensions
, img
[ on "load" (decodeImgLoad ImgLoaded)
, src "https://cloud.netlifyusercontent.com/assets/344dbf88-fdf9-42bb-adb4-46f01eedd629/bd07f82e-a30d-4e93-a2cf-0c16ea2b7f40/08-owl-opt.jpg"
]
[]
]
main : Program () Model Msg
main =
Browser.sandbox
{ init = initialModel
, view = view
, update = update
}
https://ellie-app.com/3FCdcDqy4gqa1
40
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