Drag and Drop for Dart web apps with mouse and touch support.
GitHub | Pub | Demos and Examples
- Use any HTML Element as
Draggable
orDropzone
. - Mouse and Touch dragging.
- Draggable events:
dragStart
,drag
, anddragEnd
- Dropzone events:
dragEnter
,dragOver
,dragLeave
, anddrop
- Drag avatars as visual indication of a drag operation:
- Original element as drag avatar.
- Clone as drag avatar.
- Custom drag avatar.
- Support for Shadow DOM (Web Components, Custom Elements, Polymer, etc.).
- Much more... see examples.
Before you read the instructions below, you should take a look at the examples.
Create a Draggable
and give it some HTML elements; this will make them
draggable. You can either pass a single Element
to the constructor or an
ElementList
that is returned by querySelectorAll
.
If you also want to drop somewhere, you'll need a Dropzone
.
// Install draggable (no avatar).
Draggable draggable = new Draggable(querySelectorAll('.draggable'));
// Install dropzone.
Dropzone dropzone = new Dropzone(querySelector('.dropzone'));
You'll most likely want some drag avatar to show the user that a drag is
going on. There are two predefined AvatarHandler
s that you can use as follows.
But you could also provide your own implementation of AvatarHandler
.
// Draggable with clone as avatar.
Draggable draggable = new Draggable(querySelectorAll('.draggable'),
avatarHandler: new AvatarHandler.clone());
// Draggable with original element as avatar.
Draggable draggable = new Draggable(querySelectorAll('.draggable'),
avatarHandler: new AvatarHandler.original());
The following options can be passed as named parameters to the constructor of
Draggable
:
-
avatarHandler
: Is responsible for creating, position, and removing a drag avatar. A drag avatar provides visual feedback during a drag operation. Here are possible options (see above for an example):null
(the default) - will not create a drag avatarnew AvatarHandler.original()
- handler that uses the original draggable as avatar. SeeOriginalAvatarHandler
.new AvatarHandler.clone()
- handler that uses a clone of the draggable element as avatar. SeeCloneAvatarHandler
.- A custom
AvatarHandler
- you can provide your own implementation ofAvatarHandler
.
-
horizontalOnly
: If set to true, only horizontal dragging is tracked. This enables vertical touch dragging to be used for scrolling. -
verticalOnly
: If set to true, only vertical dragging is tracked. This enables horizontal touch dragging to be used for scrolling. -
handle
: If handle query String is specified, it restricts the dragging from starting unless it occurs on the specified element(s). Only elements that descend from the draggables elements are permitted. -
cancel
: If cancel query String is specified, drag starting is prevented on specified elements. -
draggingClass
: Is the css class set to the dragged element during a drag. If set to null, no such css class is added. -
draggingClassBody
: Is the css class set to the html body tag during a drag. If set to null, no such css class is added. -
minDragStartDistance
: Is the minimum distance in pixels that is needed for a drag to start. Default is4
. This allows for clicks with tiny movement.
Available event Stream
s on Draggable
:
-
onDragStart
: Fired when the user starts dragging.
Note:onDragStart
is fired not on touchStart or mouseDown but as soon as there is a drag movement. When a drag is started anonDrag
event will also be fired. -
onDrag
: Fired periodically throughout the drag operation. -
onDragEnd
: Fired when the user ends the dragging.
Note: Is also fired when the user clicks the 'esc'-key or the window loses focus.
The following options can be passed as named parameters to the constructor of
Dropzone
:
-
acceptor
: Is used to determine whichDraggable
s will be accepted by thisDropzone
. If none is specified, allDraggable
s will be accepted. -
overClass
: Is the css class set to the dropzone element when an accepted draggable is dragged over it. If set to null, no such css class is added. -
invalidClass
: Is the css class set to the dropzone element when a not-accepted draggable is dragged over it. If set to null, no such css class is added.
Available event Stream
s on Dropzone
:
-
onDragEnter
: Fired when aDraggable
enters thisDropzone
. -
onDragOver
: Fired periodically while aDraggable
is moved over aDropzone
. -
onDragLeave
: Fired when aDraggable
leaves thisDropzone
. -
onDrop
: Fired when aDraggable
is dropped inside thisDropzone
.
Note: Dropzone
events are only fired when the Draggable
is accepted by
the Acceptor
.
Web Components create a nice ecapsulation through Shadow DOM. But this creates
a problem with dropzones inside the Shadow DOM as they never receive events
because all events are captured by the host element. To make this work we need
to retarget events to the Shadow DOM children through recursive
elementFromPoint()
calls.
For performance reasons it wouldn't make sense to retarget all drag and drop
events. If you wish to retarget events to the Shadow DOM children, you must add
a dnd-retarget
attribute to the host:
// Retarget drag and drop events to Shadow DOM children.
<my-element dnd-retarget></my-element>
The Dart Drag and Drop library is inspired by
Thank you for your work!
The MIT License (MIT)