src/Zend/Filter/Compress/Gz.php
public function compress($content)
    {
        $archive = $this->getArchive();
        if (!empty($archive)) {
            $file = gzopen($archive, 'w' . $this->getLevel());
            if (!$file) {

                throw new Zend_Filter_Exception("Error opening the archive '" . $this->_options['archive'] . "'");
            }

            gzwrite($file, $content);
            gzclose($file);
            $compressed = true;
        } else if ($this->_options['mode'] == 'deflate') {
            $compressed = gzdeflate($content, $this->getLevel());
        } else {
            $compressed = gzcompress($content, $this->getLevel());
        }

        if (!$compressed) {

            throw new Zend_Filter_Exception('Error during compression');
        }

        return $compressed;
    }
public function compress($content)
    {
        $archive = $this->getArchive();
        if (!empty($archive)) {
            $file = gzopen($archive, 'w' . $this->getLevel());
            if (!$file) {

                throw new Zend_Filter_Exception("Error opening the archive '" . $this->_options['archive'] . "'");
            }

            gzwrite($file, $content);
            gzclose($file);
            $compressed = true;
        } else if ($this->_options['mode'] == 'deflate') {
            $compressed = gzdeflate($content, $this->getLevel());
        } else {
            $compressed = gzcompress($content, $this->getLevel());
        }

        if (!$compressed) {

            throw new Zend_Filter_Exception('Error during compression');
        }

        return $compressed;
    }
Compresses the given content

@param  string $content
@return string