daylily
71 lines
2.7 KiB
TypeScript
71 lines
2.7 KiB
TypeScript
import { DEVICE_HEIGHT, DEVICE_WIDTH } from '$lib/constants'
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import type { ConversionConfig } from '$lib/contexts/config.svelte'
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import type { FilesContext } from '$lib/contexts/files.svelte'
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import { imageIsCorrectRatio, type ImageContext } from '$lib/contexts/image.svelte'
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export function freshContext(el: HTMLCanvasElement) {
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const ctx = el.getContext('2d')!
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ctx.imageSmoothingEnabled = false
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return ctx
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}
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export function makeAltText(filesCtx: FilesContext, imageCtx: ImageContext, config: ConversionConfig): string {
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if (filesCtx.files.length < 1) return 'No image selected for e-paper preview'
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const file = filesCtx.files[0]
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const output = [`${DEVICE_WIDTH}-by-${DEVICE_HEIGHT}-pixels e-paper preview of "${file.name}"`]
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if (!imageIsCorrectRatio(imageCtx)) {
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if (config.scaleMode === 'fit') output.push('letterboxed')
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else if (config.scaleMode === 'crop') output.push('cropped to fit')
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else if (config.scaleMode === 'distort') output.push('stretched to fit')
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}
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if (config.transform.side === 'reverse') output.push('flipped horizontally')
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if (config.transform.rotation !== 0) output.push(`rotated ${config.transform.rotation} degrees`)
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if (config.ditheringKernel === null) output.push('no dithering')
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else output.push('with dithering')
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if (config.ditheringKernel !== null) {
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if (config.contrast >= 0.75) output.push('with very high contrast')
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else if (config.contrast >= 0.25) output.push('with high contrast')
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}
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if (config.contrast > 0 || config.ditheringKernel === null) {
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const biasScaleFactor = config.ditheringKernel === null ? 1 : config.contrast
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const scaledBias = config.bias * biasScaleFactor
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if (scaledBias >= 0.5) output.push('extremely biased towards black')
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else if (scaledBias >= 0.25) output.push('biased towards black')
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else if (scaledBias >= 0.1) output.push('slightly biased towards black')
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if (scaledBias <= -0.5) output.push('extremely biased towards white')
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else if (scaledBias <= -0.25) output.push('biased towards white')
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else if (scaledBias <= -0.1) output.push('slightly biased towards white')
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}
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return output.join(', ')
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}
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export function drawQuantizedData(ctx: CanvasRenderingContext2D, data: number[]) {
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const imageData = ctx.createImageData(DEVICE_WIDTH, DEVICE_HEIGHT)
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for (let y = 0; y < DEVICE_HEIGHT; y++) {
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for (let x = 0; x < DEVICE_WIDTH; x++) {
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const dataIx = y * DEVICE_WIDTH + x
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const bitmapIx = dataIx * 4
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const colorIx = data.at(dataIx)
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const color = colorIx === 0 ? 0xcc : 0x11
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imageData.data[bitmapIx] = color
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imageData.data[bitmapIx + 1] = color
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imageData.data[bitmapIx + 2] = color
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imageData.data[bitmapIx + 3] = 0xff
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}
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}
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ctx.putImageData(imageData, 0, 0)
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}
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