DFlex DnD
Installation
npm install @dflex/dnd
API
DFlex DnD depends on three principles to achieve DOM interactivity:
- Register element in the store.
- Start dragging when mouse is down.
- End dragging to release element when mouse is up.
import { store, DnD } from "@dflex/dnd";
Register element
Each element should be registered in DFlex DnD Store in order to be active for drag and drop later.
store.register(RegisterInputOpts): void;
Where RegisterInputOpts
is an object with the following properties:
-
id: string
Targeted element-id. -
depth?: number
The depth of targeted element starting from zero (The default value is zero). -
readonly?: boolean
True for elements that won't be transformed during DnD but belongs to the same interactive container.
Create Drag and Drop Session
The responsive drag and drop session should be created when onmousedown
is
fired. So it can initialize the element and its siblings before start dragging.
const dflexDnD = new DnD(id, coordinate, opts);
-
id: string
registered element-id in the store. -
coordinate: AxesPoint
is an object with{x: number, y: number}
contains the coordinates of the mouse/touch click. -
opts?: DFlexDnDOpts
is DnD options object. You can see DFlex DnD options full documentation by clicking here.
Start responsive dragging
dflexDnD.dragAt(x, y);
-
x: number
is event.clientX, the horizontal click coordinate. -
y: number
is event.clientY, the vertical click coordinate.
End Drag and Drop Session
dflexDnD.endDragging();
Cleanup element
It's necessary to cleanup the element from store when the element won't be used or will be removed/unmounted from the DOM to prevent any potential memory leaks.
store.unregister(id: string): void
Options
You can pass options when creating a DnD instance that controls each element individually. So your options can be different from each other.
Dragging Threshold
The threshold object defines when the dragging event should be fired and triggers the response of other sibling elements.
Threshold Interface
interface ThresholdPercentages {
/** vertical threshold in percentage from 0-100 */
vertical: number;
/** horizontal threshold in percentage from 0-100 */
horizontal: number;
}
Threshold Definition
interface DFlexDnDOpts {
// ... other options.
threshold?: Partial<ThresholdPercentages>;
}
Threshold Default Value
{
"threshold": {
"vertical": 60,
"horizontal": 60
}
}
Commit changes to DOM
DFlex is built to manipulate DOM elements with transformation indefinitely. This means you can always drag and drop elements without reconstruction of the DOM. Still, it comes with a reconciler that tracks elements' changes and only reconciles the elements that have changed their position from their origin.
Commit Interface
interface CommitInterface {
enableAfterEndingDrag: boolean;
enableForScrollOnly: boolean;
}
Commit Definition
interface DFlexDnDOpts {
// ... other options.
commit?: Partial<CommitInterface>;
}
Commit Default Value
{
"commit": {
"enableAfterEndingDrag": true,
"enableForScrollOnly": true
}
}
Dragging Restrictions
You can define the dragging restrictions for each element relative:
- Element position.
- Element parent container.
- Screen viewport (automatically enabled).
Restrictions Interface
interface Restrictions {
self: {
allowLeavingFromTop: boolean;
allowLeavingFromBottom: boolean;
allowLeavingFromLeft: boolean;
allowLeavingFromRight: boolean;
};
container: {
allowLeavingFromTop: boolean;
allowLeavingFromBottom: boolean;
allowLeavingFromLeft: boolean;
allowLeavingFromRight: boolean;
};
}
Restrictions Definition
interface DFlexDnDOpts {
// ... other options.
restrictions?: {
self?: Partial<Restrictions["self"]>;
container?: Partial<Restrictions["container"]>;
};
}
Restrictions Default Value
{
"restrictions": {
"self": {
"allowLeavingFromTop": true,
"allowLeavingFromBottom": true,
"allowLeavingFromLeft": true,
"allowLeavingFromRight": true
},
"container": {
"allowLeavingFromTop": true,
"allowLeavingFromBottom": true,
"allowLeavingFromLeft": true,
"allowLeavingFromRight": true
}
}
}
Auto-Scroll
Auto-Scroll Interface
interface ScrollOptions {
enable?: boolean;
initialSpeed?: number;
threshold?: Partial<ThresholdPercentages>;
}
Auto-Scroll Definition
interface DFlexDnDOpts {
// ... other options.
scroll?: Partial<ScrollOptions>;
}
Auto-Scroll Default Value
{
"scroll": {
"enable": true,
"initialSpeed": 10,
"threshold": {
"vertical": 15,
"horizontal": 15
}
}
}
Events
DFlex has three (3) types of custom events.
Event Usage
// DFlex event handler.
const onDFlexEvent = (e: DFlexEvents) => {
// Do something.
console.log(`onDFlexEvent: ${e.type}`, e.detail);
};
// Dragged Events.
const ON_OUT_CONTAINER = "$onDragOutContainer";
const ON_OUT_THRESHOLD = "$onDragOutThreshold";
// Interactivity Events.
const ON_DRAG_OVER = "$onDragOver";
const ON_DRAG_LEAVE = "$onDragLeave";
// Sibling Events.
const ON_LIFT_UP = "$onLiftUpSiblings";
const ON_MOVE_DOWN = "$onMoveDownSiblings";
// Capture DFlex event.
document.addEventListener(
ON_OUT_CONTAINER /** or another event */,
onDFlexEvent
);
// Remove it later when dragging is done.
document.removeEventListener(
ON_OUT_CONTAINER /** or another event */,
onDFlexEvent
);
Dragged Event
It's an event related to capturing dragged positions. This event is fired when
the dragged is out of its threshold position $onDragOutContainer
or out of its
container $onDragOutThreshold
.
DraggedEvent interface
interface PayloadDraggedEvent {
/** Returns element id in the registry */
id: string;
/** Returns dragged temp index */
index: number;
}
/** For dragged out of threshold or container event. */
type DFlexDraggedEvent = CustomEvent<PayloadDraggedEvent>;
Interactivity Event
It's an event related to capturing dragged interactions with other elements.
This event is fired when the dragged is over another element $onDragOver
or
when the dragged is leaving the occupied position $onDragLeave
.
InteractivityEvent interface
interface PayloadInteractivityEvent {
/** Returns element id in the registry */
id: string;
/** Returns element current index */
index: number;
/** Returns the element that triggered the event */
target: HTMLElement;
}
/** For dragged over an element or leaving an element. */
type DFlexInteractivityEvent = CustomEvent<PayloadInteractivityEvent>;
Siblings Event
It's an event related to capturing siblings' positions. This event is fired when
the siblings are lifting up $onLiftUpSiblings
or moving down $onMoveDownSiblings
SiblingsEvent interface
interface PayloadSiblingsEvent {
/** Returns the index where the dragged left */
from: number;
/** Returns the last index effected of the dragged leaving/entering */
to: number;
/** Returns an array of sibling ids in order */
siblings: string[];
}
/** When dragged movement triggers the siblings up/down. */
type DFlexSiblingsEvent = CustomEvent<PayloadSiblingsEvent>;
Listeners
DFlex listeners are more generic than the custom events and responsible for monitoring the entire layout and reporting back to you.
DFlex has two (2) types of listeners:
Listener Usage
// app/index.js
const unsubscribeLayout = store.listeners.subscribe((e) => {
console.info("new layout state", e);
}, "layoutState");
// call it later for clear listeners from memory.
unsubscribeLayout();
const unsubscribeMutation = store.listeners.subscribe((e) => {
console.info("new mutation state", e);
}, "mutation");
// call it later for clear listeners from memory.
unsubscribeMutation();
Layout state listener
Responsible for monitoring any change that happens to layout interactivity.
Layout state listener interface
type LayoutState =
| "pending" // when DnD is initiated but not activated yet.
| "ready" // When clicking over the registered element. The element is ready but not being dragged.
| "dragging" // as expected.
| "dragEnd" // as expected.
| "dragCancel"; // When releasing the drag without settling in the new position.
interface DFlexLayoutStateEvent {
type: "layoutState";
status: LayoutState;
}
Mutation listener
Responsible for monitoring DOM mutation that happens during reconciliation.
Mutation listener interface
type ElmMutationType = "committed";
interface DFlexElmMutationEvent {
type: "mutation";
status: ElmMutationType;
payload: {
target: HTMLElement; // HTML element container.
ids: string[]; // Committed Elements' id in order.
};
}
Advanced
getSerializedElm
DFlex elements are serialized and exported accordingly.
store.getSerializedElm(elmID: string): DFlexSerializedElement | null
type DFlexSerializedElement = {
type: string;
version: number;
id: string;
translate: PointNum | null;
grid: PointNum;
order: DFlexDOMGenOrder;
initialPosition: AxesPoint;
rect: BoxRectAbstract;
hasTransformedFromOrigin: boolean;
hasPendingTransformation: boolean;
isVisible: boolean;
};
getSerializedScrollContainer
DFlex scroll containers are serialized and exported accordingly. You can get any scroll container for any registered element id.
store.getSerializedScrollContainer(elmID: string): DFlexSerializedScroll | null
type DFlexSerializedScroll = {
type: string;
version: number;
key: string;
hasOverFlow: AxesPoint<boolean>;
hasDocumentAsContainer: boolean;
scrollRect: AbstractBox;
scrollContainerRect: AbstractBox;
invisibleDistance: AbstractBox;
visibleScreen: Dimensions;
};
commit
Commit changes to the DOM. commit
will always do surgical reconciliation. and
it's the same function that's used in the options
store.commit(): void
isLayoutAvailable
True when DFlex is not transforming any elements and not executing any task.
isLayoutAvailable(): boolean
unregister
safely removing element from store.
store.unregister(id: string): void
destroy
To destroy all DFlex instances. This is what you should do when you are done with DnD completely and your app is about to be closed.
store.destroy(): void;
Documentation 📖
For documentation, more information about DFlex and a live demo, be sure to visit the DFlex website https://www.dflex.dev/
License 🤝
DFlex is MIT License.