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<template>
<div
v-observe-visibility="handleVisibilityChange"
class="vue-recycle-scroller"
:class="{
ready,
'page-mode': pageMode,
[`direction-${direction}`]: true,
}"
@scroll.passive="handleScroll"
>
<div
v-if="$slots.before"
class="vue-recycle-scroller__slot"
>
<slot
name="before"
/>
</div>
<div
ref="wrapper"
:style="{ [direction === 'vertical' ? 'minHeight' : 'minWidth']: totalSize + 'px' }"
class="vue-recycle-scroller__item-wrapper"
>
<div
v-for="view of pool"
:key="view.nr.id"
:style="ready ? {
transform: useTransform ? `translate${direction === 'vertical' ? 'Y' : 'X'}(${view.position}px)` : null,
top: !useTransform && direction === 'vertical' ? `${view.position}px` : null,
left: !useTransform && direction !== 'vertical' ? `${view.position}px` : null,
} : null"
class="vue-recycle-scroller__item-view"
:class="{ hover: hoverKey === view.nr.key }"
@mouseenter="hoverKey = view.nr.key"
@mouseleave="hoverKey = null"
>
<slot
:item="view.item"
:index="view.nr.index"
:active="view.nr.used"
/>
</div>
</div>
<div
v-if="$slots.after"
class="vue-recycle-scroller__slot"
>
<slot
name="after"
/>
</div>
<ResizeObserver @notify="handleResize" />
</div>
</template>
<script>
import { ResizeObserver } from 'vue-resize'
import { ObserveVisibility } from 'vue-observe-visibility'
import ScrollParent from 'scrollparent'
import config from '../config'
import { props, simpleArray } from './common'
import { supportsPassive } from '../utils'
let uid = 0
export default {
name: 'RecycleScroller',
components: {
ResizeObserver,
},
directives: {
ObserveVisibility,
},
props: {
...props,
itemSize: {
type: Number,
default: null,
},
minItemSize: {
type: [Number, String],
default: null,
},
sizeField: {
type: String,
default: 'size',
},
typeField: {
type: String,
default: 'type',
},
buffer: {
type: Number,
default: 200,
},
pageMode: {
type: Boolean,
default: false,
},
prerender: {
type: Number,
default: 0,
},
emitUpdate: {
type: Boolean,
default: false,
},
useTransform: {
type: Boolean,
default: true,
}
},
data () {
return {
pool: [],
totalSize: 0,
ready: false,
hoverKey: null,
}
},
computed: {
sizes () {
if (this.itemSize === null) {
const sizes = {
'-1': { accumulator: 0 },
}
const items = this.items
const field = this.sizeField
const minItemSize = this.minItemSize
let computedMinSize = 10000
let accumulator = 0
let current
for (let i = 0, l = items.length; i < l; i++) {
current = items[i][field] || minItemSize
if (current < computedMinSize) {
computedMinSize = current
}
accumulator += current
sizes[i] = { accumulator, size: current }
}
// eslint-disable-next-line
this.$_computedMinItemSize = computedMinSize
return sizes
}
return []
},
simpleArray,
},
watch: {
items () {
this.updateVisibleItems(true)
},
pageMode () {
this.applyPageMode()
this.updateVisibleItems(false)
},
sizes: {
handler () {
this.updateVisibleItems(false)
},
deep: true,
},
},
created () {
this.$_startIndex = 0
this.$_endIndex = 0
this.$_views = new Map()
this.$_unusedViews = new Map()
this.$_scrollDirty = false
this.$_lastUpdateScrollPosition = 0
// In SSR mode, we also prerender the same number of item for the first render
// to avoir mismatch between server and client templates
if (this.prerender) {
this.$_prerender = true
this.updateVisibleItems(false)
}
},
mounted () {
this.applyPageMode()
this.$nextTick(() => {
// In SSR mode, render the real number of visible items
this.$_prerender = false
this.updateVisibleItems(true)
this.ready = true
})
},
beforeDestroy () {
this.removeListeners()
},
methods: {
addView (pool, index, item, key, type) {
const view = {
item,
position: 0,
}
const nonReactive = {
id: uid++,
index,
used: true,
key,
type,
}
Object.defineProperty(view, 'nr', {
configurable: false,
value: nonReactive,
})
pool.push(view)
return view
},
unuseView (view, fake = false) {
const unusedViews = this.$_unusedViews
const type = view.nr.type
let unusedPool = unusedViews.get(type)
if (!unusedPool) {
unusedPool = []
unusedViews.set(type, unusedPool)
}
unusedPool.push(view)
if (!fake) {
view.nr.used = false
view.position = -9999
this.$_views.delete(view.nr.key)
}
},
handleResize () {
this.$emit('resize')
if (this.ready) this.updateVisibleItems(false)
},
handleScroll (event) {
if (!this.$_scrollDirty) {
this.$_scrollDirty = true
requestAnimationFrame(() => {
this.$_scrollDirty = false
const { continuous } = this.updateVisibleItems(false, true)
// It seems sometimes chrome doesn't fire scroll event :/
// When non continous scrolling is ending, we force a refresh
if (!continuous) {
clearTimeout(this.$_refreshTimout)
this.$_refreshTimout = setTimeout(this.handleScroll, 100)
}
})
}
},
handleVisibilityChange (isVisible, entry) {
if (this.ready) {
if (isVisible || entry.boundingClientRect.width !== 0 || entry.boundingClientRect.height !== 0) {
this.$emit('visible')
requestAnimationFrame(() => {
this.updateVisibleItems(false)
})
} else {
this.$emit('hidden')
}
}
},
updateVisibleItems (checkItem, checkPositionDiff = false) {
const itemSize = this.itemSize
const minItemSize = this.$_computedMinItemSize
const typeField = this.typeField
const keyField = this.simpleArray ? null : this.keyField
const items = this.items
const count = items.length
const sizes = this.sizes
const views = this.$_views
const unusedViews = this.$_unusedViews
const pool = this.pool
let startIndex, endIndex
let totalSize
if (!count) {
startIndex = endIndex = totalSize = 0
} else if (this.$_prerender) {
startIndex = 0
endIndex = this.prerender
totalSize = null
} else {
const scroll = this.getScroll()
// Skip update if use hasn't scrolled enough
if (checkPositionDiff) {
let positionDiff = scroll.start - this.$_lastUpdateScrollPosition
if (positionDiff < 0) positionDiff = -positionDiff
if ((itemSize === null && positionDiff < minItemSize) || positionDiff < itemSize) {
return {
continuous: true,
}
}
}
this.$_lastUpdateScrollPosition = scroll.start
const buffer = this.buffer
scroll.start -= buffer
scroll.end += buffer
// Variable size mode
if (itemSize === null) {
let h
let a = 0
let b = count - 1
let i = ~~(count / 2)
let oldI
// Searching for startIndex
do {
oldI = i
h = sizes[i].accumulator
if (h < scroll.start) {
a = i
} else if (i < count - 1 && sizes[i + 1].accumulator > scroll.start) {
b = i
}
i = ~~((a + b) / 2)
} while (i !== oldI)
i < 0 && (i = 0)
startIndex = i
// For container style
totalSize = sizes[count - 1].accumulator
// Searching for endIndex
for (endIndex = i; endIndex < count && sizes[endIndex].accumulator < scroll.end; endIndex++);
if (endIndex === -1) {
endIndex = items.length - 1
} else {
endIndex++
// Bounds
endIndex > count && (endIndex = count)
}
} else {
// Fixed size mode
startIndex = ~~(scroll.start / itemSize)
endIndex = Math.ceil(scroll.end / itemSize)
// Bounds
startIndex < 0 && (startIndex = 0)
endIndex > count && (endIndex = count)
totalSize = count * itemSize
}
}
if (endIndex - startIndex > config.itemsLimit) {
this.itemsLimitError()
}
this.totalSize = totalSize
let view
const continuous = startIndex <= this.$_endIndex && endIndex >= this.$_startIndex
if (this.$_continuous !== continuous) {
if (continuous) {
views.clear()
unusedViews.clear()
for (let i = 0, l = pool.length; i < l; i++) {
view = pool[i]
this.unuseView(view)
}
}
this.$_continuous = continuous
} else if (continuous) {
for (let i = 0, l = pool.length; i < l; i++) {
view = pool[i]
if (view.nr.used) {
// Update view item index
if (checkItem) {
view.nr.index = items.findIndex(
item => keyField ? item[keyField] === view.item[keyField] : item === view.item,
)
}
// Check if index is still in visible range
if (
view.nr.index === -1 ||
view.nr.index < startIndex ||
view.nr.index >= endIndex
) {
this.unuseView(view)
}
}
}
}
const unusedIndex = continuous ? null : new Map()
let item, type, unusedPool
let v
for (let i = startIndex; i < endIndex; i++) {
item = items[i]
const key = keyField ? item[keyField] : item
if (key == null) {
throw new Error(`Key is ${key} on item (keyField is '${keyField}')`)
}
view = views.get(key)
if (!itemSize && !sizes[i].size) {
if (view) this.unuseView(view)
continue
}
// No view assigned to item
if (!view) {
type = item[typeField]
unusedPool = unusedViews.get(type)
if (continuous) {
// Reuse existing view
if (unusedPool && unusedPool.length) {
view = unusedPool.pop()
view.item = item
view.nr.used = true
view.nr.index = i
view.nr.key = key
view.nr.type = type
} else {
view = this.addView(pool, i, item, key, type)
}
} else {
// Use existing view
// We don't care if they are already used
// because we are not in continous scrolling
v = unusedIndex.get(type) || 0
if (!unusedPool || v >= unusedPool.length) {
view = this.addView(pool, i, item, key, type)
this.unuseView(view, true)
unusedPool = unusedViews.get(type)
}
view = unusedPool[v]
view.item = item
view.nr.used = true
view.nr.index = i
view.nr.key = key
view.nr.type = type
unusedIndex.set(type, v + 1)
v++
}
views.set(key, view)
} else {
view.nr.used = true
view.item = item
}
// Update position
if (itemSize === null) {
view.position = sizes[i - 1].accumulator
} else {
view.position = i * itemSize
}
}
this.$_startIndex = startIndex
this.$_endIndex = endIndex
if (this.emitUpdate) this.$emit('update', startIndex, endIndex)
// After the user has finished scrolling
// Sort views so text selection is correct
clearTimeout(this.$_sortTimer)
this.$_sortTimer = setTimeout(this.sortViews, 300)
return {
continuous,
}
},
getListenerTarget () {
let target = ScrollParent(this.$el)
// Fix global scroll target for Chrome and Safari
if (window.document && (target === window.document.documentElement || target === window.document.body)) {
target = window
}
return target
},
getScroll () {
const { $el: el, direction } = this
const isVertical = direction === 'vertical'
let scrollState
if (this.pageMode) {
const bounds = el.getBoundingClientRect()
const boundsSize = isVertical ? bounds.height : bounds.width
let start = -(isVertical ? bounds.top : bounds.left)
let size = isVertical ? window.innerHeight : window.innerWidth
if (start < 0) {
size += start
start = 0
}
if (start + size > boundsSize) {
size = boundsSize - start
}
scrollState = {
start,
end: start + size,
}
} else if (isVertical) {
scrollState = {
start: el.scrollTop,
end: el.scrollTop + el.clientHeight,
}
} else {
scrollState = {
start: el.scrollLeft,
end: el.scrollLeft + el.clientWidth,
}
}
return scrollState
},
applyPageMode () {
if (this.pageMode) {
this.addListeners()
} else {
this.removeListeners()
}
},
addListeners () {
this.listenerTarget = this.getListenerTarget()
this.listenerTarget.addEventListener('scroll', this.handleScroll, supportsPassive ? {
passive: true,
} : false)
this.listenerTarget.addEventListener('resize', this.handleResize)
},
removeListeners () {
if (!this.listenerTarget) {
return
}
this.listenerTarget.removeEventListener('scroll', this.handleScroll)
this.listenerTarget.removeEventListener('resize', this.handleResize)
this.listenerTarget = null
},
scrollToItem (index) {
this.$_scrollDirty = true
const { viewport, scrollDirection, scrollDistance } = this.scrollToPosition(index)
viewport[scrollDirection] = scrollDistance
setTimeout(() => {
this.$_scrollDirty = false
this.updateVisibleItems(false, true)
})
},
scrollToPosition (index) {
const getPositionOfItem = (index) => {
if (this.itemSize === null) {
return index > 0 ? this.sizes[index - 1].accumulator : 0
} else {
return index * this.itemSize
}
}
const position = getPositionOfItem(index)
const direction = this.direction === 'vertical'
? { scroll: 'scrollTop', start: 'top' }
: { scroll: 'scrollLeft', start: 'left' }
if (this.pageMode) {
const viewportEl = ScrollParent(this.$el)
// HTML doesn't overflow like other elements
const scrollTop = viewportEl.tagName === 'HTML' ? 0 : viewportEl[direction.scroll]
const viewport = viewportEl.getBoundingClientRect()
const scroller = this.$el.getBoundingClientRect()
const scrollerPosition = scroller[direction.start] - viewport[direction.start]
return {
viewport: viewportEl,
scrollDirection: direction.scroll,
scrollDistance: position + scrollTop + scrollerPosition,
}
}
return {
viewport: this.$el,
scrollDirection: direction.scroll,
scrollDistance: position,
}
},
itemsLimitError () {
setTimeout(() => {
console.log('It seems the scroller element isn\'t scrolling, so it tries to render all the items at once.', 'Scroller:', this.$el)
console.log('Make sure the scroller has a fixed height (or width) and \'overflow-y\' (or \'overflow-x\') set to \'auto\' so it can scroll correctly and only render the items visible in the scroll viewport.')
})
throw new Error('Rendered items limit reached')
},
sortViews () {
this.pool.sort((viewA, viewB) => viewA.nr.index - viewB.nr.index)
},
},
}
</script>
<style>
.vue-recycle-scroller {
position: relative;
}
.vue-recycle-scroller.direction-vertical:not(.page-mode) {
overflow-y: auto;
}
.vue-recycle-scroller.direction-horizontal:not(.page-mode) {
overflow-x: auto;
}
.vue-recycle-scroller.direction-horizontal {
display: flex;
}
.vue-recycle-scroller__slot {
flex: auto 0 0;
}
.vue-recycle-scroller__item-wrapper {
flex: 1;
box-sizing: border-box;
overflow: hidden;
position: relative;
}
.vue-recycle-scroller.ready .vue-recycle-scroller__item-view {
position: absolute;
top: 0;
left: 0;
will-change: transform;
}
.vue-recycle-scroller.direction-vertical .vue-recycle-scroller__item-wrapper {
width: 100%;
}
.vue-recycle-scroller.direction-horizontal .vue-recycle-scroller__item-wrapper {
height: 100%;
}
.vue-recycle-scroller.ready.direction-vertical .vue-recycle-scroller__item-view {
width: 100%;
}
.vue-recycle-scroller.ready.direction-horizontal .vue-recycle-scroller__item-view {
height: 100%;
}
</style>
|