Leafer UI

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捕获/冒泡 ​

一个交互事件触发时，目标元素的所有父节点都能接受到该事件，事件流会从根节点出发，开始进入捕获阶段，到达目标元素后完成捕获，之后从目标元素出发，开始进入冒泡阶段，到达根节点完成冒泡。

图示 ​

冒泡与捕获

监听捕获事件 ​

ts
import { Leafer, Rect, PointerEvent } from 'leafer-ui'

const leafer = new Leafer({ view: window })

const rect = new Rect({ x: 100, y: 100, fill: '#32cd79', draggable: true })

leafer.add(rect)

function onEnter(e: PointerEvent) {
    (e.current as Rect).fill = '#42dd89'
}

function onLeave(e: PointerEvent) {
    (e.current as Rect).fill = '#32cd79'
}

rect.on(PointerEvent.ENTER, onEnter, true) 
rect.on(PointerEvent.LEAVE, onLeave, { capture: true })

移除捕获事件 ​

ts
import { Leafer, Rect, PointerEvent } from 'leafer-ui'

const leafer = new Leafer({ view: window })

const rect = new Rect({ x: 100, y: 100, fill: '#32cd79', draggable: true })

leafer.add(rect)

function onEnter(e: PointerEvent) {
    (e.current as Rect).fill = '#42dd89'
}

function onLeave(e: PointerEvent) {
    (e.current as Rect).fill = '#32cd79'
}

rect.on(PointerEvent.ENTER, onEnter)
rect.on(PointerEvent.LEAVE, onLeave)

rect.off(PointerEvent.ENTER, onEnter, true)  
rect.off(PointerEvent.LEAVE, onLeave, { capture: true })

事件流 ​

ts
import { Leafer, Group, Rect, PointerEvent } from 'leafer-ui'

const leafer = new Leafer({ view: window })

const group = new Group()
const parent = new Group()
const rect = new Rect({ x: 100, y: 100, fill: '#32cd79', draggable: true })

leafer.add(group)
group.add(parent)
parent.add(rect)

// 捕获 ---
group.on(PointerEvent.ENTER, function () {
    console.log('[capture] Group enter')
}, { capture: true })

parent.on(PointerEvent.ENTER, function () {
    console.log('[capture] Parent enter')
}, true)

rect.on(PointerEvent.ENTER, function () {
    console.log('[capture] Rect enter')
}, true)


// 冒泡 ---
rect.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Rect enter')
})

parent.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Parent enter')
})

group.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Group enter')
})

阻止事件流传递 ​

阻止事件向父节点传递

stop ( ) ​

ts
import { Leafer, Group, Rect, PointerEvent } from 'leafer-ui'

const leafer = new Leafer({ view: window })

const parent = new Group()
const rect = new Rect({ x: 100, y: 100, fill: '#32cd79', draggable: true })

leafer.add(parent)
parent.add(rect)

// 捕获 ---
parent.on(PointerEvent.ENTER, function (e: PointerEvent) { 
    console.log('[capture] Parent enter A')
    e.stop() 
}, true)

parent.on(PointerEvent.ENTER, function () {
    console.log('[capture] Parent enter B')
}, true)

// [capture] Parent enter A
// [capture] Parent enter B

rect.on(PointerEvent.ENTER, function () {
    console.log('[capture] Rect enter')
}, true)


// 冒泡 ---
rect.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Rect enter')
})

parent.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Parent enter')
})

立即阻止事件流传递 ​

阻止事件向父节点及同级传递

stopNow ( ) ​

ts
import { Leafer, Group, Rect, PointerEvent } from 'leafer-ui'

const leafer = new Leafer({ view: window })

const parent = new Group()
const rect = new Rect({ x: 100, y: 100, fill: '#32cd79', draggable: true })

leafer.add(parent)
parent.add(rect)

// 捕获 ---
parent.on(PointerEvent.ENTER, function (e: PointerEvent) { 
    console.log('[capture] Parent enter A')
    e.stopNow() 
}, true)

parent.on(PointerEvent.ENTER, function () {
    console.log('[capture] Parent enter B')
}, true)

// [capture] Parent enter A

rect.on(PointerEvent.ENTER, function () {
    console.log('[capture] Rect enter')
}, true)


// 冒泡 ---
rect.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Rect enter')
})

parent.on(PointerEvent.ENTER, function () {
    console.log('[bubble] Parent enter')
})

Released under the MIT License.

Copyright © 2023 Chao (Leafer) Wan