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refactor(ui5-list, ui5-tree): extract drag-and-drop logic into reusable mixin
- Create DragAndDropMixin.ts with configurable callbacks for component-specific behavior - Unify drag-and-drop initialization patterns between List and Tree components - Add proper memory cleanup mechanisms in onExitDOM lifecycle hooks - Eliminate duplicated drag-and-drop code - Maintain 100% backward compatibility with existing APIs - Preserve all existing functionality including event names and behavior Benefits: - Single source of truth for drag-and-drop logic - Easier maintenance and bug fixes across components - Consistent behavior between List and Tree - Simplified addition of drag-and-drop to future components - Better memory management with cleanup on component destruction Fixes #11120
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‎packages/base/src/util/dragAndDrop/DragAndDropMixin.ts‎

Lines changed: 126 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,126 @@
1+
import type UI5Element from "../../UI5Element.js";
2+
import type MovePlacement from "../../types/MovePlacement.js";
3+
import Orientation from "../../types/Orientation.js";
4+
import type { DragAndDropSettings } from "./DragRegistry.js";
5+
import DragRegistry from "./DragRegistry.js";
6+
import handleDrop from "./handleDrop.js";
7+
import handleDragOver from "./handleDragOver.js";
8+
import { findClosestPosition } from "./findClosestPosition.js";
9+
10+
type DragAndDropCallbacks = {
11+
getItemsForDragDrop: () => Array<HTMLElement>;
12+
getOrientation: () => Orientation;
13+
getDropIndicator: () => { targetReference: HTMLElement | null; placement: any } | null;
14+
setDropIndicator: (targetReference: HTMLElement | null, placement?: any) => void;
15+
shouldContainsDraggedElement?: (draggedElement: HTMLElement, targetElement: HTMLElement) => boolean;
16+
getDragAndDropSettings?: () => DragAndDropSettings;
17+
getTargetFromPosition?: (element: HTMLElement) => HTMLElement;
18+
};
19+
20+
type DragAndDropMixinInstance = {
21+
_ondragenter: (e: DragEvent) => void;
22+
_ondragleave: (e: DragEvent) => void;
23+
_ondragover: (e: DragEvent) => void;
24+
_ondrop: (e: DragEvent) => void;
25+
_cleanupDragAndDrop: () => void;
26+
};
27+
28+
function createDragAndDropMixin<T extends UI5Element>(callbacks: DragAndDropCallbacks): DragAndDropMixinInstance {
29+
// Store bound methods to enable proper cleanup
30+
let boundMethods: DragAndDropMixinInstance | null = null;
31+
32+
const methods = {
33+
_ondragenter(this: T, e: DragEvent) {
34+
e.preventDefault();
35+
},
36+
37+
_ondragleave(this: T, e: DragEvent) {
38+
if (e.relatedTarget instanceof Node && this.shadowRoot!.contains(e.relatedTarget)) {
39+
return;
40+
}
41+
42+
callbacks.setDropIndicator(null);
43+
},
44+
45+
_ondragover(this: T, e: DragEvent) {
46+
const draggedElement = DragRegistry.getDraggedElement();
47+
const items = callbacks.getItemsForDragDrop();
48+
49+
if (!(e.target instanceof HTMLElement) || !items.length) {
50+
callbacks.setDropIndicator(null);
51+
return;
52+
}
53+
54+
const orientation = callbacks.getOrientation();
55+
const clientPosition = orientation === Orientation.Vertical ? e.clientY : e.clientX;
56+
const closestPosition = findClosestPosition(items, clientPosition, orientation);
57+
58+
if (!closestPosition) {
59+
callbacks.setDropIndicator(null);
60+
return;
61+
}
62+
63+
// Allow components to transform the target element
64+
if (callbacks.getTargetFromPosition) {
65+
closestPosition.element = callbacks.getTargetFromPosition(closestPosition.element);
66+
}
67+
68+
// Check if dragged element contains the target (prevent dropping on itself or children)
69+
if (draggedElement && callbacks.shouldContainsDraggedElement) {
70+
if (callbacks.shouldContainsDraggedElement(draggedElement, closestPosition.element)) {
71+
callbacks.setDropIndicator(null);
72+
return;
73+
}
74+
}
75+
76+
// Filter out "On" placement if dropping on the dragged element itself
77+
if (closestPosition.element === draggedElement) {
78+
closestPosition.placements = closestPosition.placements.filter(placement => placement !== "On" as MovePlacement);
79+
}
80+
81+
const settings = callbacks.getDragAndDropSettings?.() || {};
82+
const { targetReference, placement } = handleDragOver(e, this, closestPosition, closestPosition.element, settings);
83+
84+
callbacks.setDropIndicator(targetReference, placement);
85+
},
86+
87+
_ondrop(this: T, e: DragEvent) {
88+
const dropIndicator = callbacks.getDropIndicator();
89+
90+
if (!dropIndicator?.targetReference || !dropIndicator?.placement) {
91+
return;
92+
}
93+
94+
const settings = callbacks.getDragAndDropSettings?.() || {};
95+
handleDrop(e, this, dropIndicator.targetReference, dropIndicator.placement as MovePlacement, settings);
96+
callbacks.setDropIndicator(null);
97+
},
98+
99+
_cleanupDragAndDrop() {
100+
// Clear all references to prevent memory leaks
101+
if (boundMethods) {
102+
boundMethods._ondragenter = () => { };
103+
boundMethods._ondragleave = () => { };
104+
boundMethods._ondragover = () => { };
105+
boundMethods._ondrop = () => { };
106+
boundMethods = null;
107+
}
108+
109+
// Clear callbacks object to break potential circular references
110+
Object.keys(callbacks).forEach(key => {
111+
delete (callbacks as any)[key];
112+
});
113+
},
114+
};
115+
116+
// Store reference for cleanup
117+
boundMethods = methods;
118+
119+
return methods;
120+
}
121+
122+
export default createDragAndDropMixin;
123+
export type {
124+
DragAndDropCallbacks,
125+
DragAndDropMixinInstance,
126+
};

‎packages/main/src/List.ts‎

Lines changed: 37 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -22,12 +22,11 @@ import {
2222
isDown,
2323
isUp,
2424
} from "@ui5/webcomponents-base/dist/Keys.js";
25-
import handleDragOver from "@ui5/webcomponents-base/dist/util/dragAndDrop/handleDragOver.js";
26-
import handleDrop from "@ui5/webcomponents-base/dist/util/dragAndDrop/handleDrop.js";
2725
import Orientation from "@ui5/webcomponents-base/dist/types/Orientation.js";
2826
import DragRegistry from "@ui5/webcomponents-base/dist/util/dragAndDrop/DragRegistry.js";
2927
import type { MoveEventDetail } from "@ui5/webcomponents-base/dist/util/dragAndDrop/DragRegistry.js";
30-
import { findClosestPosition, findClosestPositionsByKey } from "@ui5/webcomponents-base/dist/util/dragAndDrop/findClosestPosition.js";
28+
import createDragAndDropMixin from "@ui5/webcomponents-base/dist/util/dragAndDrop/DragAndDropMixin.js";
29+
import { findClosestPositionsByKey } from "@ui5/webcomponents-base/dist/util/dragAndDrop/findClosestPosition.js";
3130
import NavigationMode from "@ui5/webcomponents-base/dist/types/NavigationMode.js";
3231
import {
3332
getAllAccessibleDescriptionRefTexts,
@@ -517,6 +516,12 @@ class List extends UI5Element {
517516
onForwardBeforeBound: (e: CustomEvent) => void;
518517
onItemTabIndexChangeBound: (e: CustomEvent) => void;
519518

519+
_ondragenter!: (e: DragEvent) => void;
520+
_ondragleave!: (e: DragEvent) => void;
521+
_ondragover!: (e: DragEvent) => void;
522+
_ondrop!: (e: DragEvent) => void;
523+
_cleanupDragAndDrop!: () => void;
524+
520525
constructor() {
521526
super();
522527

@@ -546,6 +551,30 @@ class List extends UI5Element {
546551
this.onForwardAfterBound = this.onForwardAfter.bind(this);
547552
this.onForwardBeforeBound = this.onForwardBefore.bind(this);
548553
this.onItemTabIndexChangeBound = this.onItemTabIndexChange.bind(this);
554+
555+
const dragDropMixin = createDragAndDropMixin({
556+
getItemsForDragDrop: () => this.items,
557+
getOrientation: () => Orientation.Vertical,
558+
getDropIndicator: () => (this.dropIndicatorDOM ? {
559+
targetReference: this.dropIndicatorDOM.targetReference,
560+
placement: this.dropIndicatorDOM.placement,
561+
} : null),
562+
setDropIndicator: (targetReference: HTMLElement | null, placement?: any) => {
563+
if (this.dropIndicatorDOM) {
564+
this.dropIndicatorDOM.targetReference = targetReference;
565+
if (placement !== undefined) {
566+
this.dropIndicatorDOM.placement = placement;
567+
}
568+
}
569+
},
570+
getDragAndDropSettings: () => ({ originalEvent: true }),
571+
});
572+
573+
this._ondragenter = dragDropMixin._ondragenter.bind(this);
574+
this._ondragleave = dragDropMixin._ondragleave.bind(this);
575+
this._ondragover = dragDropMixin._ondragover.bind(this);
576+
this._ondrop = dragDropMixin._ondrop.bind(this);
577+
this._cleanupDragAndDrop = dragDropMixin._cleanupDragAndDrop;
549578
}
550579

551580
/**
@@ -574,6 +603,11 @@ class List extends UI5Element {
574603
this.unobserveListEnd();
575604
ResizeHandler.deregister(this.getDomRef()!, this._handleResizeCallback);
576605
DragRegistry.unsubscribe(this);
606+
607+
// Clean up drag and drop mixin to prevent memory leaks
608+
if (this._cleanupDragAndDrop) {
609+
this._cleanupDragAndDrop();
610+
}
577611
}
578612

579613
onBeforeRendering() {
@@ -1158,49 +1192,6 @@ class List extends UI5Element {
11581192
this.setForwardingFocus(false);
11591193
}
11601194

1161-
_ondragenter(e: DragEvent) {
1162-
e.preventDefault();
1163-
}
1164-
1165-
_ondragleave(e: DragEvent) {
1166-
if (e.relatedTarget instanceof Node && this.shadowRoot!.contains(e.relatedTarget)) {
1167-
return;
1168-
}
1169-
1170-
this.dropIndicatorDOM!.targetReference = null;
1171-
}
1172-
1173-
_ondragover(e: DragEvent) {
1174-
if (!(e.target instanceof HTMLElement)) {
1175-
return;
1176-
}
1177-
1178-
const closestPosition = findClosestPosition(
1179-
this.items,
1180-
e.clientY,
1181-
Orientation.Vertical,
1182-
);
1183-
1184-
if (!closestPosition) {
1185-
this.dropIndicatorDOM!.targetReference = null;
1186-
return;
1187-
}
1188-
1189-
const { targetReference, placement } = handleDragOver(e, this, closestPosition, closestPosition.element, { originalEvent: true });
1190-
this.dropIndicatorDOM!.targetReference = targetReference;
1191-
this.dropIndicatorDOM!.placement = placement;
1192-
}
1193-
1194-
_ondrop(e: DragEvent) {
1195-
if (!this.dropIndicatorDOM?.targetReference || !this.dropIndicatorDOM?.placement) {
1196-
e.preventDefault();
1197-
return;
1198-
}
1199-
1200-
handleDrop(e, this, this.dropIndicatorDOM.targetReference, this.dropIndicatorDOM.placement, { originalEvent: true });
1201-
this.dropIndicatorDOM.targetReference = null;
1202-
}
1203-
12041195
isForwardElement(element: HTMLElement) {
12051196
const elementId = element.id;
12061197
const beforeElement = this.getBeforeElement();

‎packages/main/src/Tree.ts‎

Lines changed: 60 additions & 57 deletions
Original file line numberDiff line numberDiff line change
@@ -3,11 +3,9 @@ import customElement from "@ui5/webcomponents-base/dist/decorators/customElement
33
import property from "@ui5/webcomponents-base/dist/decorators/property.js";
44
import slot from "@ui5/webcomponents-base/dist/decorators/slot.js";
55
import DragRegistry from "@ui5/webcomponents-base/dist/util/dragAndDrop/DragRegistry.js";
6-
import handleDragOver from "@ui5/webcomponents-base/dist/util/dragAndDrop/handleDragOver.js";
7-
import handleDrop from "@ui5/webcomponents-base/dist/util/dragAndDrop/handleDrop.js";
8-
import { findClosestPosition } from "@ui5/webcomponents-base/dist/util/dragAndDrop/findClosestPosition.js";
6+
import createDragAndDropMixin from "@ui5/webcomponents-base/dist/util/dragAndDrop/DragAndDropMixin.js";
97
import Orientation from "@ui5/webcomponents-base/dist/types/Orientation.js";
10-
import MovePlacement from "@ui5/webcomponents-base/dist/types/MovePlacement.js";
8+
import type MovePlacement from "@ui5/webcomponents-base/dist/types/MovePlacement.js";
119
import event from "@ui5/webcomponents-base/dist/decorators/event-strict.js";
1210
import jsxRenderer from "@ui5/webcomponents-base/dist/renderer/JsxRenderer.js";
1311
import type DropIndicator from "./DropIndicator.js";
@@ -221,6 +219,13 @@ class Tree extends UI5Element {
221219
"move": TreeMoveEventDetail,
222220
"move-over": TreeMoveEventDetail,
223221
}
222+
223+
_ondragenter!: (e: DragEvent) => void;
224+
_ondragleave!: (e: DragEvent) => void;
225+
_ondragover!: (e: DragEvent) => void;
226+
_ondrop!: (e: DragEvent) => void;
227+
_cleanupDragAndDrop!: () => void;
228+
224229
/**
225230
* Defines the selection mode of the component. Since the tree uses a `ui5-list` to display its structure,
226231
* the tree modes are exactly the same as the list modes, and are all applicable.
@@ -311,12 +316,63 @@ class Tree extends UI5Element {
311316
@slot()
312317
header!: Array<HTMLElement>;
313318

319+
constructor() {
320+
super();
321+
322+
const dragDropMixin = createDragAndDropMixin({
323+
getItemsForDragDrop: () => {
324+
const allLiNodesTraversed: Array<HTMLElement> = [];
325+
this.walk(item => {
326+
const liElement = item.shadowRoot?.querySelector("li");
327+
if (liElement) {
328+
allLiNodesTraversed.push(liElement);
329+
}
330+
});
331+
return allLiNodesTraversed;
332+
},
333+
getOrientation: () => Orientation.Vertical,
334+
getDropIndicator: () => (this.dropIndicatorDOM ? {
335+
targetReference: this.dropIndicatorDOM.targetReference,
336+
placement: this.dropIndicatorDOM.placement,
337+
} : null),
338+
setDropIndicator: (targetReference: HTMLElement | null, placement?: any) => {
339+
if (this.dropIndicatorDOM) {
340+
this.dropIndicatorDOM.targetReference = targetReference;
341+
if (placement !== undefined) {
342+
this.dropIndicatorDOM.placement = placement;
343+
}
344+
}
345+
},
346+
getTargetFromPosition: (element: HTMLElement) => {
347+
const rootNode = element.getRootNode();
348+
if (rootNode instanceof ShadowRoot && rootNode.host instanceof HTMLElement) {
349+
return rootNode.host;
350+
}
351+
return element; // Fallback to original element
352+
},
353+
shouldContainsDraggedElement: (draggedElement: HTMLElement, targetElement: HTMLElement) => {
354+
return draggedElement.contains(targetElement);
355+
},
356+
});
357+
358+
this._ondragenter = dragDropMixin._ondragenter.bind(this);
359+
this._ondragleave = dragDropMixin._ondragleave.bind(this);
360+
this._ondragover = dragDropMixin._ondragover.bind(this);
361+
this._ondrop = dragDropMixin._ondrop.bind(this);
362+
this._cleanupDragAndDrop = dragDropMixin._cleanupDragAndDrop;
363+
}
364+
314365
onEnterDOM() {
315366
DragRegistry.subscribe(this);
316367
}
317368

318369
onExitDOM() {
319370
DragRegistry.unsubscribe(this);
371+
372+
// Clean up drag and drop mixin to prevent memory leaks
373+
if (this._cleanupDragAndDrop) {
374+
this._cleanupDragAndDrop();
375+
}
320376
}
321377

322378
onBeforeRendering() {
@@ -345,59 +401,6 @@ class Tree extends UI5Element {
345401
return !!this.header.length;
346402
}
347403

348-
_ondragenter(e: DragEvent) {
349-
e.preventDefault();
350-
}
351-
352-
_ondragleave(e: DragEvent) {
353-
if (e.relatedTarget instanceof Node && this.shadowRoot!.contains(e.relatedTarget)) {
354-
return;
355-
}
356-
357-
this.dropIndicatorDOM!.targetReference = null;
358-
}
359-
360-
_ondragover(e: DragEvent) {
361-
const draggedElement = DragRegistry.getDraggedElement();
362-
const allLiNodesTraversed: Array<HTMLElement> = []; // use the only <li> nodes to determine positioning
363-
if (!(e.target instanceof HTMLElement) || !draggedElement) {
364-
return;
365-
}
366-
367-
this.walk(item => {
368-
allLiNodesTraversed.push(item.shadowRoot!.querySelector("li")!);
369-
});
370-
371-
const closestPosition = findClosestPosition(
372-
allLiNodesTraversed,
373-
e.clientY,
374-
Orientation.Vertical,
375-
);
376-
377-
if (!closestPosition) {
378-
this.dropIndicatorDOM!.targetReference = null;
379-
return;
380-
}
381-
382-
closestPosition.element = <HTMLElement>(<ShadowRoot>closestPosition.element.getRootNode()).host;
383-
if (draggedElement.contains(closestPosition.element)) { return; }
384-
if (closestPosition.element === draggedElement) {
385-
closestPosition.placements = closestPosition.placements.filter(placement => placement !== MovePlacement.On);
386-
}
387-
388-
const { targetReference, placement } = handleDragOver(e, this, closestPosition, closestPosition.element);
389-
this.dropIndicatorDOM!.targetReference = targetReference;
390-
this.dropIndicatorDOM!.placement = placement;
391-
}
392-
393-
_ondrop(e: DragEvent) {
394-
if (!this.dropIndicatorDOM?.targetReference || !this.dropIndicatorDOM?.placement) {
395-
return;
396-
}
397-
handleDrop(e, this, this.dropIndicatorDOM.targetReference, this.dropIndicatorDOM.placement);
398-
this.dropIndicatorDOM.targetReference = null;
399-
}
400-
401404
_onListItemStepIn(e: CustomEvent<TreeItemBaseStepInEventDetail>) {
402405
const treeItem = e.detail.item;
403406
if (treeItem.items.length > 0) {

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