java/src/main/com/google/appengine/api/conversion/ConversionProtoConverter.java

   1 // Copyright 2011 Google Inc. All Rights Reserved.
   2
   3 package com.google.appengine.api.conversion;
   4
   5 import com.google.appengine.api.conversion.ConversionServicePb.ConversionInput;
   6 import com.google.common.base.Converter;
   7 import com.google.common.base.Preconditions;
   8 import com.google.common.base.StringUtil;
   9
  10 /**
  11  * A reversible converter between {@link Conversion} and its corresponding
  12  * protocol buffer.
  13  *
  14  */
  15 class ConversionProtoConverter extends Converter<Conversion, ConversionInput> {
  16
  17   private static final String IMAGE_WIDTH_FLAG = "imageWidth";
  18   private static final String FIRST_PAGE_FLAG = "firstPage";
  19   private static final String LAST_PAGE_FLAG = "lastPage";
  20   private static final String INPUT_LANGUAGE_FLAG = "input_language_hint";
  21
  22   private final DocumentProtoConverter documentProtoConverter = new DocumentProtoConverter();
  23
  24   /**
  25    * Converts a {@link Conversion} to its corresponding protocol buffer.
  26    *
  27    * @throws IllegalArgumentException if output mime type or additional asset
  28    *         name is null, empty or comprises only whitespace characters
  29    */
  30   @Override
  31   public ConversionInput doForward(Conversion conversion) {
  32     ConversionHelper.validateInputDoc(conversion.getInputDoc());
  33     Preconditions.checkArgument(!StringUtil.isEmptyOrWhitespace(conversion.getOutputMimeType()),
  34         "Output mime type should not be null, empty or comprises only whitespace characters");
  35
  36     ConversionInput.Builder builder = ConversionInput.newBuilder();
  37     builder.setInput(documentProtoConverter.convert(conversion.getInputDoc()))
  38         .setOutputMimeType(conversion.getOutputMimeType());
  39     ConversionOptions options = conversion.getOptions();
  40     builder.addFlag(createAuxData(IMAGE_WIDTH_FLAG, Integer.toString(options.getImageWidth())));
  41     builder.addFlag(createAuxData(FIRST_PAGE_FLAG, Integer.toString(options.getFirstPage())));
  42     builder.addFlag(createAuxData(LAST_PAGE_FLAG, Integer.toString(options.getLastPage())));
  43
  44     if (options.getOcrInputLanguage() != null) {
  45       builder.addFlag(createAuxData(INPUT_LANGUAGE_FLAG, options.getOcrInputLanguage()));
  46     }
  47     return builder.build();
  48   }
  49
  50   @Override
  51   public Conversion doBackward(ConversionInput conversionPb) {
  52     return new Conversion(
  53         documentProtoConverter.reverse(conversionPb.getInput()), conversionPb.getOutputMimeType());
  54   }
  55
  56   /**
  57    * Returns a converter-specific auxiliary flag with specified key and value.
  58    */
  59   private static ConversionInput.AuxData.Builder createAuxData(String key, String value) {
  60     return ConversionInput.AuxData.newBuilder()
  61         .setKey(key)
  62         .setValue(value);
  63   }
  64 }