wehub-resource-sync
48 lines
1.5 KiB
TypeScript
48 lines
1.5 KiB
TypeScript
import { PNG } from 'pngjs'
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export type ScreenshotDiffSummary = {
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matches: boolean
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diffPixels: number
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diffRatio: number
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width: number
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height: number
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}
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export function compareTerminalScreenshots(
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baselineBuffer: Buffer,
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candidateBuffer: Buffer
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): ScreenshotDiffSummary {
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const baseline = PNG.sync.read(baselineBuffer)
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const candidate = PNG.sync.read(candidateBuffer)
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if (baseline.width !== candidate.width || baseline.height !== candidate.height) {
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return {
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matches: false,
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diffPixels: Number.POSITIVE_INFINITY,
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diffRatio: Number.POSITIVE_INFINITY,
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width: candidate.width,
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height: candidate.height
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}
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}
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let diffPixels = 0
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for (let offset = 0; offset < baseline.data.length; offset += 4) {
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const redDiff = Math.abs((baseline.data[offset] ?? 0) - (candidate.data[offset] ?? 0))
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const greenDiff = Math.abs((baseline.data[offset + 1] ?? 0) - (candidate.data[offset + 1] ?? 0))
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const blueDiff = Math.abs((baseline.data[offset + 2] ?? 0) - (candidate.data[offset + 2] ?? 0))
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const alphaDiff = Math.abs((baseline.data[offset + 3] ?? 0) - (candidate.data[offset + 3] ?? 0))
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if (redDiff + greenDiff + blueDiff + alphaDiff > 48) {
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diffPixels += 1
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}
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}
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const pixelCount = baseline.width * baseline.height
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const diffRatio = pixelCount > 0 ? diffPixels / pixelCount : Number.POSITIVE_INFINITY
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return {
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matches: diffRatio <= 0.015,
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diffPixels,
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diffRatio,
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width: baseline.width,
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height: baseline.height
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}
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}
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