【前端】智能库房综合管理系统前端项目
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import { Fill } from '../../utils'
export default class CanvasRenderer {
/** @type {HTMLCanvasElement} */
canvas
/**
*
* @param {import('../../types').PlayerOptions} options
*/
constructor(options) {
this.canvas = options.canvas ?? document.createElement('canvas')
this.width = this.canvas.width
this.height = this.canvas.height
this.enabled = true
this.context = this.canvas.getContext('2d')
}
destroy() {
// Nothing to do here
}
clear() {
if (!this.context) return
const w = this.canvas.width
const h = this.canvas.height
this.context.fillStyle = '#000'
this.context.fillRect(0, 0, w, h)
}
resize(width, height) {
this.width = width | 0
this.height = height | 0
this.canvas.width = this.width
this.canvas.height = this.height
this.imageData = this.context.getImageData(0, 0, this.width, this.height)
Fill(this.imageData.data, 255)
}
renderProgress(progress) {
const w = this.canvas.width
const h = this.canvas.height
const ctx = this.context
ctx.fillStyle = '#222'
ctx.fillRect(0, 0, w, h)
ctx.fillStyle = '#fff'
ctx.fillRect(0, h - h * progress, w, h * progress)
}
render(y, cb, cr) {
this.YCbCrToRGBA(y, cb, cr, this.imageData.data)
this.context.putImageData(this.imageData, 0, 0)
}
YCbCrToRGBA(y, cb, cr, rgba) {
if (!this.enabled) {
return
}
// Chroma values are the same for each block of 4 pixels, so we proccess
// 2 lines at a time, 2 neighboring pixels each.
// I wish we could use 32bit writes to the RGBA buffer instead of writing
// each byte separately, but we need the automatic clamping of the RGBA
// buffer.
const w = ((this.width + 15) >> 4) << 4
const w2 = w >> 1
let yIndex1 = 0
let yIndex2 = w
const yNext2Lines = w + (w - this.width)
let cIndex = 0
const cNextLine = w2 - (this.width >> 1)
let rgbaIndex1 = 0
let rgbaIndex2 = this.width * 4
const rgbaNext2Lines = this.width * 4
const cols = this.width >> 1
const rows = this.height >> 1
let ccb, ccr, r, g, b
for (let row = 0; row < rows; row++) {
for (let col = 0; col < cols; col++) {
ccb = cb[cIndex]
ccr = cr[cIndex]
cIndex++
r = ccb + ((ccb * 103) >> 8) - 179
g = ((ccr * 88) >> 8) - 44 + ((ccb * 183) >> 8) - 91
b = ccr + ((ccr * 198) >> 8) - 227
// Line 1
const y1 = y[yIndex1++]
const y2 = y[yIndex1++]
rgba[rgbaIndex1] = y1 + r
rgba[rgbaIndex1 + 1] = y1 - g
rgba[rgbaIndex1 + 2] = y1 + b
rgba[rgbaIndex1 + 4] = y2 + r
rgba[rgbaIndex1 + 5] = y2 - g
rgba[rgbaIndex1 + 6] = y2 + b
rgbaIndex1 += 8
// Line 2
const y3 = y[yIndex2++]
const y4 = y[yIndex2++]
rgba[rgbaIndex2] = y3 + r
rgba[rgbaIndex2 + 1] = y3 - g
rgba[rgbaIndex2 + 2] = y3 + b
rgba[rgbaIndex2 + 4] = y4 + r
rgba[rgbaIndex2 + 5] = y4 - g
rgba[rgbaIndex2 + 6] = y4 + b
rgbaIndex2 += 8
}
yIndex1 += yNext2Lines
yIndex2 += yNext2Lines
rgbaIndex1 += rgbaNext2Lines
rgbaIndex2 += rgbaNext2Lines
cIndex += cNextLine
}
}
}