Connecting sources and targets to real DOM elements

Once you have created a connection, it is most useful when connected to a real DOM element.

Making a DOM element draggable

This means that events fired inside the element's bounding rectangle will start a drag. Use DragSourceDirective to do this. It's as simple as:

<div [dragSource]="source">
  drag me
</div>

source = this.dnd.dragSource("DRAGME", {
  beginDrag: () => ({ name: 'Jones McFly' }),
  // other DragSourceSpec methods
});
// constructor, unsubscribe, etc

Then, investigate using DragSourceSpec to customise the behaviour.

Making a DOM element into a drop target

This means your element will react to items being hovered or dropped within its bounding rectangle.

<div [dropTarget]="target">
  drop on me
</div>

target = this.dnd.dropTarget("DRAGME", {
    drop: monitor => {
        console.log('dropped an item:', monitor.getItem()); // => { name: 'Jones McFly' }
    }
})
// constructor, unsubscribe, etc

Then, investigate using DropTargetSpec to customise the behaviour.

Drag previews

This is a feature unique to the HTML5 backend. If you are using another backend, you will need a Drag Layer (see below) to render anything that follows the mouse.

By default, a static screenshot of the original [dragSource] element will form a drag preview and follow the mouse around.

Using a different element as the preview source

If you want another element to be the source of the preview, you can use the [dragPreview]="source" directive.

If you place a DragPreviewDirective on a different element than the [dragSource], and pass the same DragSource connection to it, the preview element will take over the job of posing for the preview screenshot.

Using a 'drag handle'

This is a common use of custom drag previews, where a box with a smaller handle within it is only draggable from the handle. This is useful for moving interactive blocks of UI (e.g. <input/> elements) around the screen, without touching the inputs / selecting text / making unwanted changes.

1. Attach [dragSource]="source" to the handle.
2. Attach [dragPreview]="source" to the overall box being dragged.
3. As always, you may consider applying CSS cursor: move or cursor: grab or similar to the handle, to make sure users can discover what the handle is for.

Using an image preview

1. Create an image element with const img = new Image(); img.src = "...";
2. Use img.onload = () => { ... } to wait for it to load. Inside the onload callback, run someDragSourceConnection.connectDragPreview(img).

See DragSource.connectDragPreview and DragPreviewOptions for options.

Next: Monitoring State.