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

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

import GIF from 'js-binary-schema-parser/lib/schemas/gif';
import { parse } from 'js-binary-schema-parser';
import { buildStream } from 'js-binary-schema-parser/lib/parsers/uint8';
import { deinterlace } from './deinterlace';
import { lzw } from './lzw';
export const parseGIF = arrayBuffer => {
    const byteData = new Uint8Array(arrayBuffer);
    return parse(buildStream(byteData), GIF);
};
const generatePatch = image => {
    const totalPixels = image.pixels.length;
    const patchData = new Uint8ClampedArray(totalPixels * 4);
    for (var i = 0; i < totalPixels; i++) {
        const pos = i * 4;
        const colorIndex = image.pixels[i];
        const color = image.colorTable[colorIndex];
        patchData[pos] = color[0];
        patchData[pos + 1] = color[1];
        patchData[pos + 2] = color[2];
        patchData[pos + 3] = colorIndex !== image.transparentIndex ? 255 : 0;
    }
    return patchData;
};
export const decompressFrame = (frame, gct, buildImagePatch) => {
    if (!frame.image) {
        console.warn('gif frame does not have associated image.');
        return;
    }
    const { image } = frame;
    // get the number of pixels
    const totalPixels = image.descriptor.width * image.descriptor.height;
    // do lzw decompression
    var pixels = lzw(image.data.minCodeSize, image.data.blocks, totalPixels);
    // deal with interlacing if necessary
    if (image.descriptor.lct.interlaced) {
        pixels = deinterlace(pixels, image.descriptor.width);
    }
    const resultImage = {
        pixels: pixels,
        dims: {
            top: frame.image.descriptor.top,
            left: frame.image.descriptor.left,
            width: frame.image.descriptor.width,
            height: frame.image.descriptor.height
        }
    };
    // color table
    if (image.descriptor.lct && image.descriptor.lct.exists) {
        resultImage.colorTable = image.lct;
    }
    else {
        resultImage.colorTable = gct;
    }
    // add per frame relevant gce information
    if (frame.gce) {
        resultImage.delay = (frame.gce.delay || 10) * 10; // convert to ms
        resultImage.disposalType = frame.gce.extras.disposal;
        // transparency
        if (frame.gce.extras.transparentColorGiven) {
            resultImage.transparentIndex = frame.gce.transparentColorIndex;
        }
    }
    // create canvas usable imagedata if desired
    if (buildImagePatch) {
        resultImage.patch = generatePatch(resultImage);
    }
    return resultImage;
};
export const decompressFrames = (parsedGif, buildImagePatches) => {
    return parsedGif.frames
        .filter(f => f.image)
        .map(f => decompressFrame(f, parsedGif.gct, buildImagePatches));
};