115 lines
2.6 KiB
JavaScript
115 lines
2.6 KiB
JavaScript
export function load_image_from_src(src) {
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return new Promise((resolve, reject) => {
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const image = new Image();
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image.src = src;
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image.addEventListener('load', ({ target }) => {
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const canvas = document.createElement('canvas');
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const ctx = canvas.getContext('2d');
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canvas.width = target.width;
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canvas.height = target.height;
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ctx.drawImage(target, 0, 0);
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resolve(ctx.getImageData(0, 0, target.width, target.height));
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});
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});
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}
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export class Image_Row_Reference {
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constructor(sampler, row) {
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Object.assign(this, { sampler, row });
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}
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*[Symbol.iterator]() {
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yield* this.sampler.iter_row(this.row);
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}
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}
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export class RGBA_unorm8 {
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constructor(R=0, G=0, B=0, A=255) {
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Object.assign(this, { R, G, B, A });
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}
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*[Symbol.iterator]() {
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const {R, G, B, A} = this;
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yield* [R, G, B, A];
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}
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get non_zero() {
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const {R, G, B, A} = this;
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return (A > 0) && ((R > 0) || (G > 0) || (B > 0));
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}
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}
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export class Image_Data_Sampler {
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constructor(image_data) {
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Object.assign(this, { image_data });
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}
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encode_as_bitfield() {
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//TODO - add alignment option
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const { width, height } = this.image_data;
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let result = '';
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const bytes_per_row = Math.ceil(width / 8);
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for (const row of this) {
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let pending_value = 0;
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let bit_value = 1;
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for (const pixel of row) {
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if (pixel.non_zero) {
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pending_value |= bit_value;
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}
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bit_value <<= 1;
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if (bit_value === 256) {
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result += String.fromCharCode(pending_value);
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pending_value = 0;
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bit_value = 1;
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}
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}
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if (bit_value > 1) { //If we have a tail we flush it here.
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result += String.fromCharCode(pending_value);
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pending_value = 0;
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bit_value = 1;
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}
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}
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return `${width},${height},${btoa(result)}`;
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}
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*iter_row(row) {
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const { pixelFormat, data, width, height } = this.image_data;
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switch(pixelFormat) {
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case 'rgba-unorm8': {
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const pixel_offset_y = row * width;
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for (let x=0; x<width; x++) {
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const pixel_offset_x = pixel_offset_y + x;
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const data_offset = pixel_offset_x * 4;
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yield new RGBA_unorm8(...data.slice(data_offset, data_offset + 4));
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}
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break;
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}
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default:
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throw new Error(`Format ${pixelFormat} is not yet supported by ${this.constructor.name}.`);
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}
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}
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*[Symbol.iterator]() {
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const { pixelFormat, data, width, height } = this.image_data;
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switch(pixelFormat) {
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case 'rgba-unorm8': {
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for (let y=0; y<height; y++) {
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yield new Image_Row_Reference(this, y);
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}
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break;
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}
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default:
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throw new Error(`Format ${pixelFormat} is not yet supported by ${this.constructor.name}.`);
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}
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}
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} |