add property and method for webpAdd

wire/core/ImageSizerEngine.php

@@ -69,6 +69,14 @@ abstract class ImageSizerEngine extends WireData implements Module, Configurable
 	 */
 	protected $webpQuality = 90;
 
+	/**
+	 * Also create a WebP Image with this variation?
+	 *
+	 * @var bool
+	 *
+	 */
+	protected $webpAdd = false;
+
 	/**
 	 * Image interlace setting, false or true
 	 *
@@ -915,6 +923,19 @@ abstract class ImageSizerEngine extends WireData implements Module, Configurable
 		return $this;
 	}
 
+	/**
+	 * Set flag to also create a webp file or not
+	 *
+	 * @param bool $value
+	 *
+	 * @return $this
+	 *
+	 */
+	public function setWebpAdd($value) {
+		$this->webpAdd = (bool) $value;
+		return $this;
+	}
+
 	/**
 	 * Given an unknown sharpening value, return the string representation of it
 	 *
@@ -1178,6 +1199,9 @@ abstract class ImageSizerEngine extends WireData implements Module, Configurable
 				case 'webpQuality':
 					$this->setWebpQuality($value);
 					break;
+				case 'webpAdd':
+					$this->setWebpAdd($value);
+					break;
 				case 'cropping':
 					$this->setCropping($value);
 					break;