Craft\ImagerService::_saveAsWebp PHP Method

    private function _saveAsWebp($imageInstance, $path, $sourceExtension, $saveOptions)
    {
        if ($this->getSetting('useCwebp')) {
            // save temp file
            $tempFile = $this->_saveTemporaryFile($imageInstance, $sourceExtension);
            // convert to webp with cwebp
            $command = escapeshellcmd($this->getSetting('cwebpPath') . ' ' . $this->getSetting('cwebpOptions') . ' -q ' . $saveOptions['webp_quality'] . ' ' . $tempFile . ' -o ' . $path);
            $r = shell_exec($command);
            if (!IOHelper::fileExists($path)) {
                throw new Exception(Craft::t('Save operation failed'));
            }
            // delete temp file
            IOHelper::deleteFile($tempFile);
        } else {
            if ($this->imageDriver === 'gd') {
                $instance = $imageInstance->getGdResource();
                if (false === \imagewebp($instance, $path, $saveOptions['webp_quality'])) {
                    throw new Exception(Craft::t('Save operation failed'));
                }
                // Fix for corrupt file bug (http://stackoverflow.com/questions/30078090/imagewebp-php-creates-corrupted-webp-files)
                if (filesize($path) % 2 == 1) {
                    file_put_contents($path, "", FILE_APPEND);
                }
            }
            if ($this->imageDriver === 'imagick') {
                $instance = $imageInstance->getImagick();
                $instance->setImageFormat('webp');
                $instance->setImageAlphaChannel(\Imagick::ALPHACHANNEL_ACTIVATE);
                $instance->setBackgroundColor(new \ImagickPixel('transparent'));
                $instance->setImageCompressionQuality($saveOptions['webp_quality']);
                $imagickOptions = $saveOptions['webp_imagick_options'];
                if ($imagickOptions && count($imagickOptions) > 0) {
                    foreach ($imagickOptions as $key => $val) {
                        $instance->setOption('webp:' . $key, $val);
                    }
                }
                $instance->writeImage($path);
            }
        }
    }