[Files app] ES6 class for image_parsers.js

Bug: 778674
Change-Id: I4f545b2c914adc2dff16489610f4134b062609e8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1647494
Commit-Queue: François Degros <fdegros@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Auto-Submit: François Degros <fdegros@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666563}

ui/file_manager/file_manager/foreground/js/metadata/image_parsers.js

@@ -5,29 +5,28 @@
 /**
  * Base class for image metadata parsers that only need to look at a short
  * fragment at the start of the file.
- * @param {MetadataParserLogger} parent Parent object.
+ * @abstract
+ */
+class SimpleImageParser extends ImageParser {
+  /**
+   * @param {!MetadataParserLogger} parent Parent object.
    * @param {string} type Image type.
- * @param {RegExp} urlFilter RegExp to match URLs.
+   * @param {!RegExp} urlFilter RegExp to match URLs.
    * @param {number} headerSize Size of header.
- * @constructor
- * @struct
- * @extends {ImageParser}
    */
-function SimpleImageParser(parent, type, urlFilter, headerSize) {
-  ImageParser.call(this, parent, type, urlFilter);
+  constructor(parent, type, urlFilter, headerSize) {
+    super(parent, type, urlFilter);
+    /** @public @const {number} */
     this.headerSize = headerSize;
-}
-
-SimpleImageParser.prototype.__proto__ = ImageParser.prototype;
+  }
 
-/**
+  /**
    * @param {File} file File to be parses.
    * @param {Object} metadata Metadata object of the file.
    * @param {function(Object)} callback Success callback.
    * @param {function(string)} errorCallback Error callback.
    */
-SimpleImageParser.prototype.parse = function(
-    file, metadata, callback, errorCallback) {
+  parse(file, metadata, callback, errorCallback) {
     const self = this;
     MetadataParser.readFileBytes(file, 0, this.headerSize, (file, br) => {
       try {
@@ -37,34 +36,33 @@ SimpleImageParser.prototype.parse = function(
         errorCallback(e.toString());
       }
     }, errorCallback);
-};
+  }
 
-/**
+  /**
    * Parse header of an image. Inherited class must implement this.
+   * @abstract
    * @param {Object} metadata Dictionary to store the parsed metadata.
    * @param {ByteReader} byteReader Reader for header binary data.
    */
-SimpleImageParser.prototype.parseHeader = (metadata, byteReader) => {};
+  parseHeader(metadata, byteReader) {}
+}
 
 /**
  * Parser for the header of png files.
- * @param {MetadataParserLogger} parent Parent object.
- * @extends {SimpleImageParser}
- * @constructor
- * @struct
+ * @final
  */
-function PngParser(parent) {
-  SimpleImageParser.call(this, parent, 'png', /\.png$/i, 24);
-}
-
-PngParser.prototype = {
-  __proto__: SimpleImageParser.prototype
-};
+class PngParser extends SimpleImageParser {
+  /**
+   * @param {!MetadataParserLogger} parent Parent object.
+   */
+  constructor(parent) {
+    super(parent, 'png', /\.png$/i, 24);
+  }
 
-/**
+  /**
    * @override
    */
-PngParser.prototype.parseHeader = (metadata, br) => {
+  parseHeader(metadata, br) {
     br.setByteOrder(ByteReader.BIG_ENDIAN);
 
     const signature = br.readString(8);
@@ -80,29 +78,27 @@ PngParser.prototype.parseHeader = (metadata, br) => {
 
     metadata.width = br.readScalar(4);
     metadata.height = br.readScalar(4);
-};
+  }
+}
 
 registerParserClass(PngParser);
 
 /**
  * Parser for the header of bmp files.
- * @param {MetadataParserLogger} parent Parent object.
- * @constructor
- * @extends {SimpleImageParser}
- * @struct
+ * @final
  */
-function BmpParser(parent) {
-  SimpleImageParser.call(this, parent, 'bmp', /\.bmp$/i, 28);
-}
-
-BmpParser.prototype = {
-  __proto__: SimpleImageParser.prototype
-};
+class BmpParser extends SimpleImageParser {
+  /**
+   * @param {!MetadataParserLogger} parent Parent object.
+   */
+  constructor(parent) {
+    super(parent, 'bmp', /\.bmp$/i, 28);
+  }
 
-/**
+  /**
    * @override
    */
-BmpParser.prototype.parseHeader = (metadata, br) => {
+  parseHeader(metadata, br) {
     br.setByteOrder(ByteReader.LITTLE_ENDIAN);
 
     const signature = br.readString(2);
@@ -113,29 +109,27 @@ BmpParser.prototype.parseHeader = (metadata, br) => {
     br.seek(18);
     metadata.width = br.readScalar(4);
     metadata.height = br.readScalar(4);
-};
+  }
+}
 
 registerParserClass(BmpParser);
 
 /**
  * Parser for the header of gif files.
- * @param {MetadataParserLogger} parent Parent object.
- * @constructor
- * @extends {SimpleImageParser}
- * @struct
+ * @final
  */
-function GifParser(parent) {
-  SimpleImageParser.call(this, parent, 'gif', /\.Gif$/i, 10);
-}
-
-GifParser.prototype = {
-  __proto__: SimpleImageParser.prototype
-};
+class GifParser extends SimpleImageParser {
+  /**
+   * @param {!MetadataParserLogger} parent Parent object.
+   */
+  constructor(parent) {
+    super(parent, 'gif', /\.Gif$/i, 10);
+  }
 
-/**
+  /**
    * @override
    */
-GifParser.prototype.parseHeader = (metadata, br) => {
+  parseHeader(metadata, br) {
     br.setByteOrder(ByteReader.LITTLE_ENDIAN);
 
     const signature = br.readString(6);
@@ -145,29 +139,27 @@ GifParser.prototype.parseHeader = (metadata, br) => {
 
     metadata.width = br.readScalar(2);
     metadata.height = br.readScalar(2);
-};
+  }
+}
 
 registerParserClass(GifParser);
 
 /**
  * Parser for the header of webp files.
- * @param {MetadataParserLogger} parent Parent object.
- * @constructor
- * @extends {SimpleImageParser}
- * @struct
+ * @final
  */
-function WebpParser(parent) {
-  SimpleImageParser.call(this, parent, 'webp', /\.webp$/i, 30);
-}
-
-WebpParser.prototype = {
-  __proto__: SimpleImageParser.prototype
-};
+class WebpParser extends SimpleImageParser {
+  /**
+   * @param {!MetadataParserLogger} parent Parent object.
+   */
+  constructor(parent) {
+    super(parent, 'webp', /\.webp$/i, 30);
+  }
 
-/**
+  /**
    * @override
    */
-WebpParser.prototype.parseHeader = (metadata, br) => {
+  parseHeader(metadata, br) {
     br.setByteOrder(ByteReader.LITTLE_ENDIAN);
 
     const riffSignature = br.readString(4);
@@ -220,28 +212,27 @@ WebpParser.prototype.parseHeader = (metadata, br) => {
       default:
         throw new Error('Invalid chunk format: ' + chunkFormat);
     }
-};
+  }
+}
 
 registerParserClass(WebpParser);
 
 /**
  * Parser for the header of .ico icon files.
- * @param {MetadataParserLogger} parent Parent metadata dispatcher object.
- * @constructor
- * @extends {SimpleImageParser}
+ * @final
  */
-function IcoParser(parent) {
-  SimpleImageParser.call(this, parent, 'ico', /\.ico$/i, 8);
-}
-
-IcoParser.prototype = {
-  __proto__: SimpleImageParser.prototype
-};
+class IcoParser extends SimpleImageParser {
+  /**
+   * @param {!MetadataParserLogger} parent Parent metadata dispatcher object.
+   */
+  constructor(parent) {
+    super(parent, 'ico', /\.ico$/i, 8);
+  }
 
-/**
+  /**
    * @override
    */
-IcoParser.prototype.parseHeader = (metadata, byteReader) => {
+  parseHeader(metadata, byteReader) {
     byteReader.setByteOrder(ByteReader.LITTLE_ENDIAN);
 
     const signature = byteReader.readString(4);
@@ -252,6 +243,7 @@ IcoParser.prototype.parseHeader = (metadata, byteReader) => {
     byteReader.seek(2);
     metadata.width = byteReader.readScalar(1);
     metadata.height = byteReader.readScalar(1);
-};
+  }
+}
 
 registerParserClass(IcoParser);