Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xls/Escher.php
private function readSpgrContainer()
    {
        // context is either context DgContainer or SpgrContainer

        $length = Xls::getInt4d($this->data, $this->pos + 4);
        $recordData = substr($this->data, $this->pos + 8, $length);

        // move stream pointer to next record
        $this->pos += 8 + $length;

        // record is a container, read contents
        $spgrContainer = new SpgrContainer();

        if ($this->object instanceof DgContainer) {
            // DgContainer
            $this->object->setSpgrContainer($spgrContainer);
        } else {
            // SpgrContainer
            $this->object->addChild($spgrContainer);
        }

        $reader = new self($spgrContainer);
        $escher = $reader->load($recordData);
    }
private function readSpgrContainer()
    {
        // context is either context DgContainer or SpgrContainer

        $length = Xls::getInt4d($this->data, $this->pos + 4);
        $recordData = substr($this->data, $this->pos + 8, $length);

        // move stream pointer to next record
        $this->pos += 8 + $length;

        // record is a container, read contents
        $spgrContainer = new SpgrContainer();

        if ($this->object instanceof DgContainer) {
            // DgContainer
            $this->object->setSpgrContainer($spgrContainer);
        } else {
            // SpgrContainer
            $this->object->addChild($spgrContainer);
        }

        $reader = new self($spgrContainer);
        $escher = $reader->load($recordData);
    }
Read SpgrContainer record (Shape Group Container).