TesseractTextExtractor.java

/**
 * Licensed to The Apereo Foundation under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 *
 * The Apereo Foundation licenses this file to you under the Educational
 * Community License, Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of the License
 * at:
 *
 *   http://opensource.org/licenses/ecl2.txt
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations under
 * the License.
 *
 */


package org.opencastproject.textextractor.tesseract;

import org.opencastproject.textextractor.api.TextExtractor;
import org.opencastproject.textextractor.api.TextExtractorException;
import org.opencastproject.textextractor.api.TextFrame;
import org.opencastproject.util.ProcessRunner;

import com.entwinemedia.fn.Pred;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;
import org.osgi.service.cm.ConfigurationException;
import org.osgi.service.cm.ManagedService;
import org.osgi.service.component.ComponentContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Dictionary;

/**
 * Commandline wrapper around tesseract' <code>tesseract</code> command.
 */
public class TesseractTextExtractor implements TextExtractor, ManagedService {

  /** The logging facility */
  private static final Logger logger = LoggerFactory.getLogger(TesseractTextExtractor.class);

  /** Default name of the tesseract binary */
  public static final String TESSERACT_BINARY_DEFAULT = "tesseract";

  /** Configuration property that defines the path to the tesseract binary */
  public static final String TESSERACT_BINARY_CONFIG_KEY =
    "org.opencastproject.textanalyzer.tesseract.path";

  /** Configuration property that defines additional tesseract options like the
   * language or the pagesegmode to use. This is just appended to the command
   * line when tesseract is called. */
  public static final String TESSERACT_OPTS_CONFIG_KEY =
    "org.opencastproject.textanalyzer.tesseract.options";

  /** Binary of the tesseract command */
  protected String binary = null;

  /** Additional options for the tesseract command */
  protected String addOptions = "";

  /**
   * Creates a new tesseract command wrapper that will be using the default binary.
   */
  public TesseractTextExtractor() {
    this(TESSERACT_BINARY_DEFAULT);
  }

  /**
   * Creates a new tesseract command wrapper that will be using the given binary.
   *
   * @param binary
   *          the tesseract binary
   */
  public TesseractTextExtractor(String binary) {
    this.binary = binary;
  }

  /**
   * Returns the path to the <code>tesseract</code> binary.
   *
   * @return path to the binary
   */
  public String getBinary() {
    return binary;
  }

  /**
   * Sets additional options for tesseract calls.
   *
   * @param addOptions
   */
  public void setAdditionalOptions(String addOptions) {
    this.addOptions = addOptions;
  }

  /**
   * Returns the additional options for tesseract..
   *
   * @return additional options
   */
  public String getAdditionalOptions() {
    return addOptions;
  }

  /**
   * Sets the path to the <code>tesseract</code> binary.
   *
   * @param binary
   */
  public void setBinary(String binary) {
    this.binary = binary;
  }

  /**
   * {@inheritDoc}
   *
   * @see org.opencastproject.textextractor.api.TextExtractor#extract(java.io.File)
   */
  @Override
  public TextFrame extract(File image) throws TextExtractorException {
    if (binary == null)
      throw new IllegalStateException("Binary is not set");

    InputStream is = null;
    File outputFile = null;
    File outputFileBase = new File(image.getParentFile(), FilenameUtils.getBaseName(image.getName()));
    // Run tesseract
    String opts = getAnalysisOptions(image, outputFileBase);
    logger.info("Running Tesseract: {} {}", binary, opts);
    try {
      final int exitCode = ProcessRunner.run(ProcessRunner.mk(binary, opts), fnLogDebug, new Pred<String>() {
        @Override public Boolean apply(String line) {
          if (!line.trim().startsWith("Page") && !line.trim().startsWith("Tesseract Open Source OCR Engine")) {
            logger.warn(line);
          }
          return true;
        }
      });
      if (exitCode != 0) {
        throw new TextExtractorException("Text analyzer " + binary + " exited with code " + exitCode);
      }
      // Read the tesseract output file
      outputFile = new File(outputFileBase.getAbsolutePath() + ".txt");
      is = new FileInputStream(outputFile);
      TextFrame textFrame = TesseractTextFrame.parse(is);
      is.close();
      return textFrame;
    } catch (IOException e) {
      throw new TextExtractorException("Error running text extractor " + binary, e);
    } finally {
      IOUtils.closeQuietly(is);
      FileUtils.deleteQuietly(outputFile);
    }
  }

  /**
   * The only parameter to <code>tesseract</code> is the filename, so this is what this method returns.
   *
   * @param image
   *          the image file
   * @return the options to run analysis on the image
   */
  protected String getAnalysisOptions(File image, File outputFile) {
    StringBuilder options = new StringBuilder();
    options.append(image.getAbsolutePath());
    options.append(" ");
    options.append(outputFile.getAbsolutePath());
    options.append(" ");
    options.append(this.addOptions);
    return options.toString();
  }

  @Override
  public void updated(Dictionary properties) throws ConfigurationException {
    String path = (String) properties.get(TESSERACT_BINARY_CONFIG_KEY);
    if (path != null) {
      logger.info("Setting Tesseract path to {}", path);
      this.binary = path;
    }
    /* Set additional options for tesseract (i.e. language to use) */
    String addopts = (String) properties.get(TESSERACT_OPTS_CONFIG_KEY);
    if (addopts != null) {
      logger.info("Setting additional options for Tesseract path to '{}'", addopts);
      this.addOptions = addopts;
    }
  }

  public void activate(ComponentContext cc) {
    // Configure ffmpeg
    String path = (String) cc.getBundleContext().getProperty(TESSERACT_BINARY_CONFIG_KEY);
    if (path == null) {
      logger.debug("DEFAULT " + TESSERACT_BINARY_CONFIG_KEY + ": " + TESSERACT_BINARY_DEFAULT);
    } else {
      setBinary(path);
      logger.info("Setting Tesseract path to binary from config: {}", path);
    }
    /* Set additional options for tesseract (i.e. language to use) */
    String addopts = (String) cc.getBundleContext().getProperty(TESSERACT_OPTS_CONFIG_KEY);
    if (addopts != null) {
      logger.info("Setting additional options for Tesseract to '{}'", addopts);
      this.addOptions = addopts;
    } else {
      logger.info("No additional options for Tesseract");
      this.addOptions = "";
    }
  }

  private static final Pred<String> fnLogDebug = new Pred<String>() {
    @Override public Boolean apply(String s) {
      logger.debug(s);
      return true;
    }
  };
}