Method decodeRect

systemvm/agent/noVNC/core/decoders/jpeg.js:20–87

(x, y, width, height, sock, display, depth)

    }

    decodeRect(x, y, width, height, sock, display, depth) {
        // A rect of JPEG encodings is simply a JPEG file
        while (true) {
            let segment = this._readSegment(sock);
            if (segment === null) {
                return false;
            }
            this._segments.push(segment);
            // End of image?
            if (segment[1] === 0xD9) {
                break;
            }
        }

        let huffmanTables = [];
        let quantTables = [];
        for (let segment of this._segments) {
            let type = segment[1];
            if (type === 0xC4) {
                // Huffman tables
                huffmanTables.push(segment);
            } else if (type === 0xDB) {
                // Quantization tables
                quantTables.push(segment);
            }
        }

        const sofIndex = this._segments.findIndex(
            x => x[1] == 0xC0 || x[1] == 0xC2
        );
        if (sofIndex == -1) {
            throw new Error("Illegal JPEG image without SOF");
        }

        if (quantTables.length === 0) {
            this._segments.splice(sofIndex+1, 0,
                                  ...this._cachedQuantTables);
        }
        if (huffmanTables.length === 0) {
            this._segments.splice(sofIndex+1, 0,
                                  ...this._cachedHuffmanTables);
        }

        let length = 0;
        for (let segment of this._segments) {
            length += segment.length;
        }

        let data = new Uint8Array(length);
        length = 0;
        for (let segment of this._segments) {
            data.set(segment, length);
            length += segment.length;
        }

        display.imageRect(x, y, width, height, "image/jpeg", data);

        if (huffmanTables.length !== 0) {