vue-qr-test/src/lib/gifuct-js/deinterlace.js

The Vue 2.x component of Awesome-qr.js

/**
 * Deinterlace function from https://github.com/shachaf/jsgif
 */
export const deinterlace = (pixels, width) => {
    const newPixels = new Array(pixels.length);
    const rows = pixels.length / width;
    const cpRow = function (toRow, fromRow) {
        const fromPixels = pixels.slice(fromRow * width, (fromRow + 1) * width);
        newPixels.splice.apply(newPixels, [toRow * width, width].concat(fromPixels));
    };
    // See appendix E.
    const offsets = [0, 4, 2, 1];
    const steps = [8, 8, 4, 2];
    var fromRow = 0;
    for (var pass = 0; pass < 4; pass++) {
        for (var toRow = offsets[pass]; toRow < rows; toRow += steps[pass]) {
            cpRow(toRow, fromRow);
            fromRow++;
        }
    }
    return newPixels;
};