import Html.Events.Extra.Pointer as Pointer -- ... example usage div [ Pointer.onDown (\event -> PointerDownMsg event.pointer.offsetPos) ] [ text "click here" ]
This package aims at handling all kinds of pointer events in elm. To be more specific, this means:
MouseEvent: standard mouse events
WheelEvent: standard wheel events
DragEvent: HTML5 drag events
TouchEvent: standard touch events
PointerEvent: new pointer events
If you are looking for only one standard kind of interaction (mouse or touch),
I recommend that you use the
If however, you are designing a multi-device (desktop/tablet/mobile/...) experience,
I recommend that you use the
Pointer events are a unified interface for similar input devices (mouse, pen, touch, ...). Since maintaining both mouse and touch events for compatibility is really cumbersome, using a unified pointer events interface is a relief.
Beware though, that the pointer API is not well supported by all browsers. Firefox < 59 and Safari do not natively support pointer events. So I strongly recommend to use this package in pair with the elm-pep polyfill for compatibility with major browsers.
Pointer modules have very similar API
so I will use
Mouse as an example.
Let's say you want the coordinates of a mouse down event relative to the DOM
element that triggered it.
of the mouse event.
Using this module, these are similarly provided by the
of a mouse
import Html.Events.Extra.Mouse as Mouse -- ... type Msg = MouseDownAt ( Float, Float ) view = div [Mouse.onDown (\event -> MouseDownAt event.offsetPos)] [text "click here"]
If you are using the
it is recommended that you deactivate
to disable browsers scroll/pinch/... touch behaviors.
Also, if you are designing some kind of drawing application,
you want to be able to keep track of a pointer that leave the
drawing area to know if the pointer went up.
This is possible using what is called pointer capture.
But requires the use of ports. Look at
if you are interested in how to do this.
div [ Pointer.onDown ... , Pointer.onMove ... , Pointer.onUp ... -- no touch-action , Html.Attributes.style "touch-action" "none" ] [ -- the drawing area ]
Multi-touch interactions can be managed using the
In case you only want to handle single touch interactions,
you could do something like below:
import Html.Events.Extra.Touch as Touch -- ... type Msg = StartAt ( Float, Float ) | MoveAt ( Float, Float ) | EndAt ( Float, Float ) view = div [ Touch.onStart (StartAt << touchCoordinates) , Touch.onMove (MoveAt << touchCoordinates) , Touch.onEnd (EndAt << touchCoordinates) ] [text "touch here"] touchCoordinates : Touch.Event -> ( Float, Float ) touchCoordinates touchEvent = List.head touchEvent.changedTouches |> Maybe.map .clientPos |> Maybe.withDefault ( 0, 0 )
You can manage
Wheel events with the corresponding module.
Since it is an extension to the
Mouse module all mouse inherited properties
are also available in the attribute
To simply check for wheel rolling up or down you could do something like below:
import Html.Events.Extra.Wheel as Wheel -- ... type Msg = Scrolling Float view = div [Wheel.onWheel (\event -> Scrolling event.deltaY)] [text "scroll here"]
The API presented by this package is slightly opinionated, to mitigate most errors induced by the complicated HTML5 drag events. This API is organized around two use cases:
For dropping files, everything can be done purely in elm so the API reflects that.
Consequently it requires the use of ports.
Ports.elm are provided in the source code
of this repo to help setup things.
More info is available in the module documentation.
One example for each use case is present in the
Minimalist working examples are available for each module in the
To test one example,
cd into one of them and compile the elm file with the command:
elm make Main.elm --output Main.js
Then use any static http server like:
$ python3 -m http.server 8888
And open your browser at localhost:8888
to load the
If you are interested in contributing in any way (feedback, bug report, implementation of new functionality, ...) don't hesitate to reach out on slack (user @mattpiz) and/or open an issue. Discussion is the best way to start any contribution.
The package documentation is available on the elm package website.
This Source Code Form is subject to the terms of the Mozilla Public License,v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.