Bilibili-Evolved/registry/lib/components/video/danmaku/converter/danmaku-stack.ts
2021-10-26 13:19:37 +08:00

225 lines
7.6 KiB
TypeScript

import { fixed } from '@/core/utils'
import { DanmakuType } from './danmaku-type'
import { Resolution, Duration, FontStyles } from './ass-danmaku'
import { Danmaku } from './danmaku-data'
interface TrackItem {
start: number
end: number
trackNumber: number
}
interface HorizontalTrackItem extends TrackItem {
width: number
visible: number
}
type Track = TrackItem[]
type TagStack = { tags: string }[]
interface TagData {
targetTrack: Track
initTrackNumber: number
nextTrackNumber: number
willOverlay: (trackItem: TrackItem, trackNumber: number, width: number) => boolean
getTrackItem: (trackNumber: number, width: number, visibleTime: number) => TrackItem
getTag: (info: { trackNumber: number, x: number, y: number }) => string
}
export class DanmakuStack {
static readonly danmakuType = {
[DanmakuType.Normal]: 'normal',
[DanmakuType.Normal2]: 'normal',
[DanmakuType.Normal3]: 'normal',
[DanmakuType.Bottom]: 'bottom',
[DanmakuType.Top]: 'top',
[DanmakuType.Reversed]: 'reversed',
[DanmakuType.Special]: 'special',
[DanmakuType.Special2]: 'special',
}
static readonly margin = 4
static readonly nextDanmakuDelay = 0.05
horizontalStack: TagStack
horizontalTrack: Track
verticalStack: TagStack
verticalTrack: Track
resolution: Resolution
duration: Duration
canvas: HTMLCanvasElement
context: CanvasRenderingContext2D
fontSizes: FontStyles
bottomMarginPercent: number
danmakuHeight: number
trackHeight: number
trackCount: number
constructor(
font: string,
resolution: Resolution,
duration: Duration,
bottomMarginPercent: number,
) {
this.horizontalStack = []
this.horizontalTrack = []
this.verticalStack = []
this.verticalTrack = []
this.resolution = resolution
this.duration = duration
this.canvas = document.createElement('canvas')
this.context = this.canvas.getContext('2d')
// XML字体大小到实际大小的表
this.fontSizes = {
30: `64px ${font}`,
25: `52px ${font}`,
18: `36px ${font}`,
45: `90px ${font}`,
}
this.bottomMarginPercent = bottomMarginPercent
this.generateTracks()
}
generateTracks() {
const height = 52
this.danmakuHeight = height
this.trackHeight = DanmakuStack.margin * 2 + height
this.trackCount = parseInt(
fixed((this.resolution.y * (1 - this.bottomMarginPercent)) / this.trackHeight, 0),
)
}
getTextSize(danmaku: Danmaku) {
this.context.font = this.fontSizes[danmaku.fontSize]
const metrics = this.context.measureText(danmaku.content)
const x = metrics.width / 2
return [x, this.danmakuHeight / 2]
}
getTags(danmaku: Danmaku, {
targetTrack, initTrackNumber, nextTrackNumber, willOverlay, getTrackItem, getTag,
}: TagData) {
const [x, y] = this.getTextSize(danmaku)
const width = x * 2
/*
x = this.resolution.x = 屏幕宽度
d = this.duration(danmaku) = 当前弹幕总持续时长(从出现到完全消失)
w = width = 当前弹幕的宽度
delay = DanmakuStack.nextDanmakuDelay = 相邻弹幕间最小的时间间隔
当前弹幕的速度 v = (x + w) / d
完全进入屏幕所需时间 = visibleTime = delay + w / v = delay + wd / (x + w)
*/
const visibleTime = (this.duration(danmaku) * width)
/ (this.resolution.x + width) + DanmakuStack.nextDanmakuDelay
let trackNumber = initTrackNumber
let overlayDanmaku = null
// 寻找前面已发送的弹幕中可能重叠的
const overlayDanmakuInTrack = (it: TrackItem) => willOverlay(it, trackNumber, width)
do {
overlayDanmaku = targetTrack.find(overlayDanmakuInTrack)
trackNumber += nextTrackNumber
}
while (overlayDanmaku && trackNumber <= this.trackCount && trackNumber >= 0)
// 如果弹幕过多, 此条就不显示了
if (trackNumber > this.trackCount || trackNumber < 0) {
return '\\pos(0,-999)'
}
trackNumber -= nextTrackNumber // 减回最后的自增
targetTrack.push(getTrackItem(trackNumber, width, visibleTime))
return getTag({ trackNumber, x, y })
}
getHorizontalTags(danmaku: Danmaku) {
return this.getTags(danmaku, {
targetTrack: this.horizontalTrack,
initTrackNumber: 0,
nextTrackNumber: 1,
willOverlay: (it: HorizontalTrackItem, trackNumber, width) => {
if (it.trackNumber !== trackNumber) { // 不同轨道当然不会重叠
return false
}
if (it.width < width) { // 弹幕比前面的弹幕长, 必须等前面弹幕走完
/*
x = this.resolution.x = 屏幕宽度
d = this.duration(danmaku) = 当前弹幕总持续时长(从出现到完全消失)
w = width = 当前弹幕的宽度
end = it.end = 前面的弹幕结束时间点
start = danmaku.startTime = 当前弹幕的开始时间点
当前弹幕的速度 v = (x + w) / d
当前弹幕碰到左侧边缘需要的时间 ▲t = x / v = dx / (x + w)
当前弹幕碰到左侧边缘的时间点 t = ▲t + start
如果会重叠, 则当前弹幕碰到左边缘时, 前面的弹幕还未结束
即 t <= end
也就是 start + dx / (x + w) <= end 或 dx / (x + w) <= end - start
*/
return (this.duration(danmaku) * this.resolution.x)
/ (this.resolution.x + width) <= it.end - danmaku.startTime
} // 前面弹幕完全进入屏幕的时间点晚于当前弹幕的开始时间, 就一定会重叠
return it.visible > danmaku.startTime
},
getTrackItem: (trackNumber, width, visibleTime) => ({
width,
start: danmaku.startTime,
visible: danmaku.startTime + visibleTime,
end: danmaku.startTime + this.duration(danmaku),
trackNumber,
} as HorizontalTrackItem),
getTag: ({ trackNumber, x, y }) => `\\move(${this.resolution.x + x},${trackNumber * this.trackHeight + DanmakuStack.margin + y},${-x},${trackNumber * this.trackHeight + DanmakuStack.margin + y},0,${this.duration(danmaku) * 1000})`,
})
}
getVerticalTags(danmaku: Danmaku) {
const isTop = DanmakuStack.danmakuType[danmaku.type] === 'top'
return this.getTags(danmaku, {
targetTrack: this.verticalTrack,
initTrackNumber: isTop ? 0 : this.trackCount - 1,
nextTrackNumber: isTop ? 1 : -1,
willOverlay: (it, trackNumber) => {
if (it.trackNumber !== trackNumber) {
return false
}
return it.end > danmaku.startTime
},
getTrackItem: trackNumber => ({
start: danmaku.startTime,
end: danmaku.startTime + this.duration(danmaku),
trackNumber,
}),
getTag: ({ trackNumber, y }) => {
if (isTop) {
return `\\pos(${this.resolution.x / 2},${trackNumber * this.trackHeight + DanmakuStack.margin + y})`
}
return `\\pos(${this.resolution.x / 2},${this.resolution.y - DanmakuStack.margin - y - (this.trackCount - 1 - trackNumber) * this.trackHeight})`
},
})
}
push(danmaku: Danmaku) {
let tags = ''
let stack: { tags: string }[] = []
switch (DanmakuStack.danmakuType[danmaku.type]) {
case 'normal':
case 'reversed': // 反向先鸽了, 直接当正向了
{
tags = this.getHorizontalTags(danmaku)
stack = this.horizontalStack
break
}
case 'top':
case 'bottom':
{
tags = this.getVerticalTags(danmaku)
stack = this.verticalStack
break
}
case 'special': // 高级弹幕也鸽了先
default:
{
return {
tags: '\\pos(0,-999)',
}
}
}
const info = {
tags,
}
stack.push(info)
return info
}
}