draggable

Mark a html element as draggable.

The draggable tag is used in conjunction with the {% droppable %} tag to implement drag & drop. Elements that are marked as draggable can be dropped on elements marked as droppable. Drag & drop generates dragdrop events that are sent to the controller or the delegate.

For example:

<div id="drag1">Drag me</div>
{% draggable id="drag1" tag="drag-one" %}

Now the div with id “drag1” can be dragged. When it is dropped then event/2 of the controller or delegate Erlang module is called signaling the drag (and also the drop to the module receiving the droppable events):

event({drag, Drag, Drop}, Context).

Where both Drag and Drop are #dragdrop records:

-record(dragdrop, {tag, delegate, id}).

The draggable tag accepts the following arguments:

Argument Description Example
id The id of the element that becomes draggable. id=”drag1”
tag The tag of the draggable that is sent as part of the drag and drop events. This can be any value, including a tuple. tag={subject_list id=42 changed=false}
clone Clone the element when dragging or drag the element itself. Defaults to false. clone=true
revert When the element has to revert to its starting position. Defaults to “invalid”, i.e. when the drop was above an invalid position. Other options are true, false and “valid”. revert=false
axis Constrain the drag movement to either the x or y direction. Normally the drag is not constrained. Acceptable values are “x” or “y” axis=”x”  
handle The css selector that is the handle to drag with. Defaults to the whole element. handle=”handleclass”
group The name of this drag group, for use in the droppable element’s “accept” argument. Multiple groups are allowed. group=”edges”
opacity Change the opacity while dragging. Defaults to “0.8”. opacity=”0.5”
delegate The Erlang module that will receive the drag event after a successful drop.  

See also

the droppable tag.

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