Add image filter operation

src/core/config/Categories.json

@@ -368,7 +368,8 @@
             "Flip Image",
             "Crop Image",
             "Image Brightness / Contrast",
-            "Image Opacity"
+            "Image Opacity",
+            "Image Filter"
         ]
     },
     {

src/core/operations/ImageFilter.mjs

@@ -0,0 +1,90 @@
+/**
+ * @author j433866 [j433866@gmail.com]
+ * @copyright Crown Copyright 2019
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import OperationError from "../errors/OperationError";
+import Magic from "../lib/Magic";
+import { toBase64 } from "../lib/Base64.mjs";
+import jimp from "jimp";
+
+/**
+ * Image Filter operation
+ */
+class ImageFilter extends Operation {
+
+    /**
+     * ImageFilter constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Image Filter";
+        this.module = "Image";
+        this.description = "Applies a greyscale or sepia filter to an image.";
+        this.infoURL = "";
+        this.inputType = "byteArray";
+        this.outputType = "byteArray";
+        this.presentType = "html";
+        this.args = [
+            {
+                name: "Filter type",
+                type: "option",
+                value: [
+                    "Greyscale",
+                    "Sepia"
+                ]
+            }
+        ];
+    }
+
+    /**
+     * @param {byteArray} input
+     * @param {Object[]} args
+     * @returns {byteArray}
+     */
+    async run(input, args) {
+        const [filterType] = args;
+        const type = Magic.magicFileType(input);
+        if (!type || type.mime.indexOf("image") !== 0){
+            throw new OperationError("Invalid file type.");
+        }
+
+        const image = await jimp.read(Buffer.from(input));
+
+        if (filterType === "Greyscale") {
+            image.greyscale();
+        } else {
+            image.sepia();
+        }
+
+        const imageBuffer = await image.getBufferAsync(jimp.AUTO);
+        return [...imageBuffer];
+    }
+
+    /**
+     * Displays the blurred image using HTML for web apps
+     * @param {byteArray} data
+     * @returns {html}
+     */
+    present(data) {
+        if (!data.length) return "";
+
+        let dataURI = "data:";
+        const type = Magic.magicFileType(data);
+        if (type && type.mime.indexOf("image") === 0){
+            dataURI += type.mime + ";";
+        } else {
+            throw new OperationError("Invalid file type.");
+        }
+        dataURI += "base64," + toBase64(data);
+
+        return "<img src='" + dataURI + "'>";
+
+    }
+
+}
+
+export default ImageFilter;