handwritten-mathematics-recogniser/utility/converter.js

Easy and abstracted way to recognise handwritten mathematics in a browser or in a web view.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
class Converter {
    static convertImageToCanvas(image) {
        const canvas = document.createElement('canvas');
        const context = canvas.getContext('2d');
        canvas.width = image[0].length;
        canvas.height = image.length;
        const array = image.reduce((arr, row) => [].concat(arr, row.reduce((concatedRow, alpha) => [].concat(concatedRow, [0, 0, 0, (1 - alpha) * 255]), [])), []);
        const clampedArray = new Uint8ClampedArray(array);
        const imageData = new ImageData(clampedArray, canvas.width, canvas.height);
        context.putImageData(imageData, 0, 0);
        return canvas;
    }
    static convertCanvasToImage(canvas) {
        const context = canvas.getContext('2d');
        const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
        const image = [];
        for (let y = 0; y < imageData.height; y++) {
            image[y] = [];
            for (let x = 0; x < imageData.width; x++) {
                const offset = y * 4 * imageData.width + 4 * x;
                const alpha = imageData.data[offset + 3];
                if (alpha === 0) {
                    imageData.data[offset] = 255;
                    imageData.data[offset + 1] = 255;
                    imageData.data[offset + 2] = 255;
                }
                imageData.data[offset + 3] = 255;
                image[y][x] = imageData.data[y * 4 * imageData.width + x * 4 + 0] / 255;
            }
        }
        return image;
    }
}
exports.Converter = Converter;

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