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Copy pathsortable.ts
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187 lines (148 loc) · 5.01 KB
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export interface SortEndArgs {
src: {list: Element; index: number}
dst: {list: Element; index: number}
}
type SortStartHandler = (srcList: Element) => unknown
type SortEndHandler = (srcOrDst: SortEndArgs) => unknown
interface DragState {
didDrop: boolean
dragging: Element
dropzone: Element
sourceList: Element
sourceSibling: Element | null
sourceIndex: number
}
const sortHandlers = new WeakMap()
let state: DragState | null = null
export function isDragging(): boolean {
return !!state
}
export function sortable(el: HTMLElement, sortStarted: SortStartHandler, sortFinished: SortEndHandler): void {
sortHandlers.set(el, {sortStarted, sortFinished})
el.addEventListener('dragstart', onDragStart)
el.addEventListener('dragenter', onDragEnter)
el.addEventListener('dragend', onDragEnd)
el.addEventListener('drop', onDrop)
el.addEventListener('dragover', onDragOver)
}
// Determine if item2 is before item1 in the tree.
function isBefore(item1: Element, item2: Element): boolean {
if (item1.parentNode === item2.parentNode) {
let node: Element | null = item1
while (node) {
if (node === item2) return true
node = node.previousElementSibling
}
}
return false
}
function isSameContainer(item1: Element, item2: Element): boolean {
return item1.closest('task-lists') === item2.closest('task-lists')
}
function onDragStart(event: DragEvent) {
// Ignore selected text dragging within list items.
if (event.currentTarget !== event.target) return
const target = event.currentTarget
if (!(target instanceof Element)) return
const sourceList = target.closest('.contains-task-list')
if (!sourceList) return
target.classList.add('is-ghost')
// Add data to drag operation (required for Firefox).
if (event.dataTransfer) {
event.dataTransfer.setData('text/plain', (target.textContent || '').trim())
}
if (!target.parentElement) return
const siblings = Array.from(target.parentElement.children)
const sourceIndex = siblings.indexOf(target)
const handlers = sortHandlers.get(target)
if (handlers) {
handlers.sortStarted(sourceList)
}
state = {
didDrop: false,
dragging: target,
dropzone: target,
sourceList,
sourceSibling: siblings[sourceIndex + 1] || null,
sourceIndex
}
}
function onDragEnter(event: DragEvent) {
// Allow dragging task list item, not text, links, or files.
if (!state) return
const dropzone = event.currentTarget
if (!(dropzone instanceof Element)) return
if (!isSameContainer(state.dragging, dropzone)) {
event.stopPropagation()
return
}
// Necessary for dragging
event.preventDefault()
if (event.dataTransfer) {
event.dataTransfer.dropEffect = 'move'
}
// Make sure we weren't already dragging in this task list item.
if (state.dropzone === dropzone) return
// Open an empty space in the list as a drop target.
state.dragging.classList.add('is-dragging')
state.dropzone = dropzone
if (isBefore(state.dragging, dropzone)) {
dropzone.before(state.dragging)
} else {
dropzone.after(state.dragging)
}
}
function onDrop(event: DragEvent) {
// Allow dragging task list item, not text, links, or files.
if (!state) return
event.preventDefault()
event.stopPropagation()
const dropzone = event.currentTarget
if (!(dropzone instanceof Element)) return
// Notify dragend listener drag ended in a valid drop target.
state.didDrop = true
if (!state.dragging.parentElement) return
let newIndex = Array.from(state.dragging.parentElement.children).indexOf(state.dragging)
const currentList = dropzone.closest('.contains-task-list')
if (!currentList) return
// Don't notify listener if the list hasn't changed.
if (state.sourceIndex === newIndex && state.sourceList === currentList) return
// Increment insertion index when moving item down in its own list.
if (state.sourceList === currentList && state.sourceIndex < newIndex) {
newIndex++
}
const src = {list: state.sourceList, index: state.sourceIndex}
const dst = {list: currentList, index: newIndex}
const handlers = sortHandlers.get(state.dragging)
if (handlers) {
handlers.sortFinished({src, dst})
}
}
function onDragEnd() {
if (!state) return
state.dragging.classList.remove('is-dragging')
state.dragging.classList.remove('is-ghost')
// If the drag ended in a valid drop target, the drop event listener will
// have already set this flag to true. If not, it'll still be false, and
// we'll know the drag was canceled.
if (!state.didDrop) {
state.sourceList.insertBefore(state.dragging, state.sourceSibling)
}
// Reset for next drag.
state = null
}
function onDragOver(event: DragEvent) {
// Allow dragging task list item, not text, links, or files.
if (!state) return
const dropzone = event.currentTarget
if (!(dropzone instanceof Element)) return
if (!isSameContainer(state.dragging, dropzone)) {
event.stopPropagation()
return
}
// Necessary for dragging.
event.preventDefault()
if (event.dataTransfer) {
event.dataTransfer.dropEffect = 'move'
}
}