Files
aklive2d/packages/libs/libs/alpha_composite.ts
2025-05-02 02:27:42 +08:00

76 lines
2.1 KiB
TypeScript

import sharp from 'sharp'
import path from 'node:path'
export type Rect = {
x: number
y: number
w: number
h: number
rotate: number
}
export const process = async (
filename: string,
maskFilename: string,
extractedDir: string
) => {
const image = sharp(path.join(extractedDir, filename)).removeAlpha()
const imageMeta = await image.metadata()
const imageBuffer = await image.toBuffer()
const mask = await sharp(path.join(extractedDir, maskFilename))
.extractChannel('blue')
.resize(imageMeta.width, imageMeta.height)
.toBuffer()
return sharp(imageBuffer).joinChannel(mask).toBuffer()
}
export const crop = async (
buffer:
| Buffer
| ArrayBuffer
| Uint8Array
| Uint8ClampedArray
| Int8Array
| Uint16Array
| Int16Array
| Uint32Array
| Int32Array
| Float32Array
| Float64Array
| string,
rect: Rect
) => {
const left = rect.y
const top = rect.x
const width = rect.h
const height = rect.w
const rotate = rect.rotate === 0 ? -90 : 0
const newImage = await sharp(buffer)
.rotate(90)
.extract({ left: left, top: top, width: width, height: height })
.resize(width, height)
.extract({ left: 0, top: 0, width: width, height: height })
.toBuffer()
return await sharp(newImage).rotate(rotate).toBuffer()
}
export const toBuffer = async (filename: string, extractedDir: string) => {
const file = path.join(extractedDir, filename)
const { data, info } = await sharp(file)
.raw()
.toBuffer({ resolveWithObject: true })
const { width, height, channels } = info
const pixelArray = new Uint8ClampedArray(data.buffer)
for (let i = 0; i < pixelArray.length; i += 4) {
const alpha = pixelArray[i + 3] / 255
pixelArray[i + 0] = pixelArray[i + 0] * alpha
pixelArray[i + 1] = pixelArray[i + 1] * alpha
pixelArray[i + 2] = pixelArray[i + 2] * alpha
}
return await sharp(pixelArray, { raw: { width, height, channels } })
.png()
.toBuffer()
}