[Files.app] Split the JavaScript files into subdirectories: common, background, and foreground

chrome/browser/resources/file_manager/js/metadata/exif_parser.js

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-'use strict';
-
-var EXIF_MARK_SOI = 0xffd8;  // Start of image data.
-var EXIF_MARK_SOS = 0xffda;  // Start of "stream" (the actual image data).
-var EXIF_MARK_SOF = 0xffc0;  // Start of "frame"
-var EXIF_MARK_EXIF = 0xffe1;  // Start of exif block.
-
-var EXIF_ALIGN_LITTLE = 0x4949;  // Indicates little endian exif data.
-var EXIF_ALIGN_BIG = 0x4d4d;  // Indicates big endian exif data.
-
-var EXIF_TAG_TIFF = 0x002a;  // First directory containing TIFF data.
-var EXIF_TAG_GPSDATA = 0x8825;  // Pointer from TIFF to the GPS directory.
-var EXIF_TAG_EXIFDATA = 0x8769;  // Pointer from TIFF to the EXIF IFD.
-var EXIF_TAG_SUBIFD = 0x014a;  // Pointer from TIFF to "Extra" IFDs.
-
-var EXIF_TAG_JPG_THUMB_OFFSET = 0x0201;  // Pointer from TIFF to thumbnail.
-var EXIF_TAG_JPG_THUMB_LENGTH = 0x0202;  // Length of thumbnail data.
-
-var EXIF_TAG_ORIENTATION = 0x0112;
-var EXIF_TAG_X_DIMENSION = 0xA002;
-var EXIF_TAG_Y_DIMENSION = 0xA003;
-
-function ExifParser(parent) {
-  ImageParser.call(this, parent, 'jpeg', /\.jpe?g$/i);
-}
-
-ExifParser.prototype = {__proto__: ImageParser.prototype};
-
-/**
- * @param {File} file  // TODO(JSDOC).
- * @param {Object} metadata  // TODO(JSDOC).
- * @param {function} callback  // TODO(JSDOC).
- * @param {function} errorCallback  // TODO(JSDOC).
- */
-ExifParser.prototype.parse = function(file, metadata, callback, errorCallback) {
-  this.requestSlice(file, callback, errorCallback, metadata, 0);
-};
-
-/**
- * @param {File} file  // TODO(JSDOC).
- * @param {function} callback  // TODO(JSDOC).
- * @param {function} errorCallback  // TODO(JSDOC).
- * @param {Object} metadata  // TODO(JSDOC).
- * @param {number} filePos  // TODO(JSDOC).
- * @param {number=} opt_length  // TODO(JSDOC).
- */
-ExifParser.prototype.requestSlice = function(
-    file, callback, errorCallback, metadata, filePos, opt_length) {
-  // Read at least 1Kb so that we do not issue too many read requests.
-  opt_length = Math.max(1024, opt_length || 0);
-
-  var self = this;
-  var reader = new FileReader();
-  reader.onerror = errorCallback;
-  reader.onload = function() { self.parseSlice(
-      file, callback, errorCallback, metadata, filePos, reader.result);
-  };
-  reader.readAsArrayBuffer(file.slice(filePos, filePos + opt_length));
-};
-
-/**
- * @param {File} file  // TODO(JSDOC).
- * @param {function} callback  // TODO(JSDOC).
- * @param {function} errorCallback  // TODO(JSDOC).
- * @param {Object} metadata  // TODO(JSDOC).
- * @param {number} filePos  // TODO(JSDOC).
- * @param {ArrayBuffer} buf  // TODO(JSDOC).
- */
-ExifParser.prototype.parseSlice = function(
-    file, callback, errorCallback, metadata, filePos, buf) {
-  try {
-    var br = new ByteReader(buf);
-
-    if (!br.canRead(4)) {
-      // We never ask for less than 4 bytes. This can only mean we reached EOF.
-      throw new Error('Unexpected EOF @' + (filePos + buf.byteLength));
-    }
-
-    if (filePos == 0) {
-      // First slice, check for the SOI mark.
-      var firstMark = this.readMark(br);
-      if (firstMark != EXIF_MARK_SOI)
-        throw new Error('Invalid file header: ' + firstMark.toString(16));
-    }
-
-    var self = this;
-    var reread = function(opt_offset, opt_bytes) {
-      self.requestSlice(file, callback, errorCallback, metadata,
-          filePos + br.tell() + (opt_offset || 0), opt_bytes);
-    };
-
-    while (true) {
-      if (!br.canRead(4)) {
-        // Cannot read the mark and the length, request a minimum-size slice.
-        reread();
-        return;
-      }
-
-      var mark = this.readMark(br);
-      if (mark == EXIF_MARK_SOS)
-        throw new Error('SOS marker found before SOF');
-
-      var markLength = this.readMarkLength(br);
-
-      var nextSectionStart = br.tell() + markLength;
-      if (!br.canRead(markLength)) {
-        // Get the entire section.
-        if (filePos + br.tell() + markLength > file.size) {
-          throw new Error(
-              'Invalid section length @' + (filePos + br.tell() - 2));
-        }
-        reread(-4, markLength + 4);
-        return;
-      }
-
-      if (mark == EXIF_MARK_EXIF) {
-        this.parseExifSection(metadata, buf, br);
-      } else if (ExifParser.isSOF_(mark)) {
-        // The most reliable size information is encoded in the SOF section.
-        br.seek(1, ByteReader.SEEK_CUR); // Skip the precision byte.
-        var height = br.readScalar(2);
-        var width = br.readScalar(2);
-        ExifParser.setImageSize(metadata, width, height);
-        callback(metadata);  // We are done!
-        return;
-      }
-
-      br.seek(nextSectionStart, ByteReader.SEEK_BEG);
-    }
-  } catch (e) {
-    errorCallback(e.toString());
-  }
-};
-
-/**
- * @private
- * @param {number} mark  // TODO(JSDOC).
- * @return {boolean}  // TODO(JSDOC).
- */
-ExifParser.isSOF_ = function(mark) {
-  // There are 13 variants of SOF fragment format distinguished by the last
-  // hex digit of the mark, but the part we want is always the same.
-  if ((mark & ~0xF) != EXIF_MARK_SOF) return false;
-
-  // If the last digit is 4, 8 or 12 it is not really a SOF.
-  var type = mark & 0xF;
-  return (type != 4 && type != 8 && type != 12);
-};
-
-/**
- * @param {Object} metadata  // TODO(JSDOC).
- * @param {ArrayBuffer} buf  // TODO(JSDOC).
- * @param {ByteReader} br  // TODO(JSDOC).
- */
-ExifParser.prototype.parseExifSection = function(metadata, buf, br) {
-  var magic = br.readString(6);
-  if (magic != 'Exif\0\0') {
-    // Some JPEG files may have sections marked with EXIF_MARK_EXIF
-    // but containing something else (e.g. XML text). Ignore such sections.
-    this.vlog('Invalid EXIF magic: ' + magic + br.readString(100));
-    return;
-  }
-
-  // Offsets inside the EXIF block are based after the magic string.
-  // Create a new ByteReader based on the current position to make offset
-  // calculations simpler.
-  br = new ByteReader(buf, br.tell());
-
-  var order = br.readScalar(2);
-  if (order == EXIF_ALIGN_LITTLE) {
-    br.setByteOrder(ByteReader.LITTLE_ENDIAN);
-  } else if (order != EXIF_ALIGN_BIG) {
-    this.log('Invalid alignment value: ' + order.toString(16));
-    return;
-  }
-
-  var tag = br.readScalar(2);
-  if (tag != EXIF_TAG_TIFF) {
-    this.log('Invalid TIFF tag: ' + tag.toString(16));
-    return;
-  }
-
-  metadata.littleEndian = (order == EXIF_ALIGN_LITTLE);
-  metadata.ifd = {
-    image: {},
-    thumbnail: {}
-  };
-  var directoryOffset = br.readScalar(4);
-
-  // Image directory.
-  this.vlog('Read image directory.');
-  br.seek(directoryOffset);
-  directoryOffset = this.readDirectory(br, metadata.ifd.image);
-  metadata.imageTransform = this.parseOrientation(metadata.ifd.image);
-
-  // Thumbnail Directory chained from the end of the image directory.
-  if (directoryOffset) {
-    this.vlog('Read thumbnail directory.');
-    br.seek(directoryOffset);
-    this.readDirectory(br, metadata.ifd.thumbnail);
-    // If no thumbnail orientation is encoded, assume same orientation as
-    // the primary image.
-    metadata.thumbnailTransform =
-        this.parseOrientation(metadata.ifd.thumbnail) ||
-        metadata.imageTransform;
-  }
-
-  // EXIF Directory may be specified as a tag in the image directory.
-  if (EXIF_TAG_EXIFDATA in metadata.ifd.image) {
-    this.vlog('Read EXIF directory.');
-    directoryOffset = metadata.ifd.image[EXIF_TAG_EXIFDATA].value;
-    br.seek(directoryOffset);
-    metadata.ifd.exif = {};
-    this.readDirectory(br, metadata.ifd.exif);
-  }
-
-  // GPS Directory may also be linked from the image directory.
-  if (EXIF_TAG_GPSDATA in metadata.ifd.image) {
-    this.vlog('Read GPS directory.');
-    directoryOffset = metadata.ifd.image[EXIF_TAG_GPSDATA].value;
-    br.seek(directoryOffset);
-    metadata.ifd.gps = {};
-    this.readDirectory(br, metadata.ifd.gps);
-  }
-
-  // Thumbnail may be linked from the image directory.
-  if (EXIF_TAG_JPG_THUMB_OFFSET in metadata.ifd.thumbnail &&
-      EXIF_TAG_JPG_THUMB_LENGTH in metadata.ifd.thumbnail) {
-    this.vlog('Read thumbnail image.');
-    br.seek(metadata.ifd.thumbnail[EXIF_TAG_JPG_THUMB_OFFSET].value);
-    metadata.thumbnailURL = br.readImage(
-        metadata.ifd.thumbnail[EXIF_TAG_JPG_THUMB_LENGTH].value);
-  } else {
-    this.vlog('Image has EXIF data, but no JPG thumbnail.');
-  }
-};
-
-/**
- * @param {Object} metadata  // TODO(JSDOC).
- * @param {number} width  // TODO(JSDOC).
- * @param {number} height  // TODO(JSDOC).
- */
-ExifParser.setImageSize = function(metadata, width, height) {
-  if (metadata.imageTransform && metadata.imageTransform.rotate90) {
-    metadata.width = height;
-    metadata.height = width;
-  } else {
-    metadata.width = width;
-    metadata.height = height;
-  }
-};
-
-/**
- * @param {ByteReader} br  // TODO(JSDOC).
- * @return {number}  // TODO(JSDOC).
- */
-ExifParser.prototype.readMark = function(br) {
-  return br.readScalar(2);
-};
-
-/**
- * @param {ByteReader} br  // TODO(JSDOC).
- * @return {number}  // TODO(JSDOC).
- */
-ExifParser.prototype.readMarkLength = function(br) {
-  // Length includes the 2 bytes used to store the length.
-  return br.readScalar(2) - 2;
-};
-
-/**
- * @param {ByteReader} br  // TODO(JSDOC).
- * @param {Array.<Object>} tags  // TODO(JSDOC).
- * @return {number}  // TODO(JSDOC).
- */
-ExifParser.prototype.readDirectory = function(br, tags) {
-  var entryCount = br.readScalar(2);
-  for (var i = 0; i < entryCount; i++) {
-    var tagId = br.readScalar(2);
-    var tag = tags[tagId] = {id: tagId};
-    tag.format = br.readScalar(2);
-    tag.componentCount = br.readScalar(4);
-    this.readTagValue(br, tag);
-  }
-
-  return br.readScalar(4);
-};
-
-/**
- * @param {ByteReader} br  // TODO(JSDOC).
- * @param {Object} tag  // TODO(JSDOC).
- */
-ExifParser.prototype.readTagValue = function(br, tag) {
-  var self = this;
-
-  function safeRead(size, readFunction, signed) {
-    try {
-      unsafeRead(size, readFunction, signed);
-    } catch (ex) {
-      self.log('error reading tag 0x' + tag.id.toString(16) + '/' +
-               tag.format + ', size ' + tag.componentCount + '*' + size + ' ' +
-               (ex.stack || '<no stack>') + ': ' + ex);
-      tag.value = null;
-    }
-  }
-
-  function unsafeRead(size, readFunction, signed) {
-    if (!readFunction)
-      readFunction = function(size) { return br.readScalar(size, signed) };
-
-    var totalSize = tag.componentCount * size;
-    if (totalSize < 1) {
-      // This is probably invalid exif data, skip it.
-      tag.componentCount = 1;
-      tag.value = br.readScalar(4);
-      return;
-    }
-
-    if (totalSize > 4) {
-      // If the total size is > 4, the next 4 bytes will be a pointer to the
-      // actual data.
-      br.pushSeek(br.readScalar(4));
-    }
-
-    if (tag.componentCount == 1) {
-      tag.value = readFunction(size);
-    } else {
-      // Read multiple components into an array.
-      tag.value = [];
-      for (var i = 0; i < tag.componentCount; i++)
-        tag.value[i] = readFunction(size);
-    }
-
-    if (totalSize > 4) {
-      // Go back to the previous position if we had to jump to the data.
-      br.popSeek();
-    } else if (totalSize < 4) {
-      // Otherwise, if the value wasn't exactly 4 bytes, skip over the
-      // unread data.
-      br.seek(4 - totalSize, ByteReader.SEEK_CUR);
-    }
-  }
-
-  switch (tag.format) {
-    case 1: // Byte
-    case 7: // Undefined
-      safeRead(1);
-      break;
-
-    case 2: // String
-      safeRead(1);
-      if (tag.componentCount == 0) {
-        tag.value = '';
-      } else if (tag.componentCount == 1) {
-        tag.value = String.fromCharCode(tag.value);
-      } else {
-        tag.value = String.fromCharCode.apply(null, tag.value);
-      }
-      break;
-
-    case 3: // Short
-      safeRead(2);
-      break;
-
-    case 4: // Long
-      safeRead(4);
-      break;
-
-    case 9: // Signed Long
-      safeRead(4, null, true);
-      break;
-
-    case 5: // Rational
-      safeRead(8, function() {
-        return [br.readScalar(4), br.readScalar(4)];
-      });
-      break;
-
-    case 10: // Signed Rational
-      safeRead(8, function() {
-        return [br.readScalar(4, true), br.readScalar(4, true)];
-      });
-      break;
-
-    default: // ???
-      this.vlog('Unknown tag format 0x' + Number(tag.id).toString(16) +
-                ': ' + tag.format);
-      safeRead(4);
-      break;
-  }
-
-  this.vlog('Read tag: 0x' + tag.id.toString(16) + '/' + tag.format + ': ' +
-            tag.value);
-};
-
-/**
- * TODO(JSDOC)
- * @const
- * @type {Array.<number>}
- */
-ExifParser.SCALEX = [1, -1, -1, 1, 1, 1, -1, -1];
-
-/**
- * TODO(JSDOC)
- * @const
- * @type {Array.<number>}
- */
-ExifParser.SCALEY = [1, 1, -1, -1, -1, 1, 1, -1];
-
-/**
- * TODO(JSDOC)
- * @const
- * @type {Array.<number>}
- */
-ExifParser.ROTATE90 = [0, 0, 0, 0, 1, 1, 1, 1];
-
-/**
- * Transform exif-encoded orientation into a set of parameters compatible with
- * CSS and canvas transforms (scaleX, scaleY, rotation).
- *
- * @param {Object} ifd exif property dictionary (image or thumbnail).
- * @return {Object} // TODO(JSDOC).
- */
-ExifParser.prototype.parseOrientation = function(ifd) {
-  if (ifd[EXIF_TAG_ORIENTATION]) {
-    var index = (ifd[EXIF_TAG_ORIENTATION].value || 1) - 1;
-    return {
-      scaleX: ExifParser.SCALEX[index],
-      scaleY: ExifParser.SCALEY[index],
-      rotate90: ExifParser.ROTATE90[index]
-    };
-  }
-  return null;
-};
-
-MetadataDispatcher.registerParserClass(ExifParser);