Github user olegz commented on a diff in the pull request:
https://github.com/apache/nifi/pull/397#discussion_r65247766
--- Diff:
nifi-nar-bundles/nifi-ocr-bundle/nifi-ocr-processors/src/main/java/org/apache/nifi/processors/ocr/TesseractOCRProcessor.java
---
@@ -0,0 +1,359 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache 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://www.apache.org/licenses/LICENSE-2.0
+ *
+ * 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.apache.nifi.processors.ocr;
+
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.FileFilter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import javax.imageio.ImageIO;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.components.AllowableValue;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.components.Validator;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.AbstractProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.io.StreamCallback;
+import org.apache.nifi.processor.util.StandardValidators;
+
+import net.sourceforge.tess4j.ITesseract;
+import net.sourceforge.tess4j.Tesseract;
+import net.sourceforge.tess4j.TesseractException;
+
+@Tags({"ocr", "tesseract", "image", "text"})
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@CapabilityDescription("Extracts text from images using Optical Character
Recognition (OCR). The images are pulled from the incoming" +
+ " Flowfile's content. Supported image types are TIFF, JPEG, GIF,
PNG, BMP, and PDF. Any Flowfile that doesn't contain" +
+ " a supported image type in its content body will be routed to the
'unsupported image format' relationship and no OCR will be performed." +
+ " This processor uses Tesseract to perform its duties and part of
that requires that a valid Tesseract data (Tessdata) directory" +
+ " be specified in the 'Tessdata Directory' Property. This
processor considers a valid Tessdata directory to be an existing directory on
the" +
+ " local NiFi instance that contains one or more files ending with
the '.traineddata' extension. The list of supported languages" +
+ " is built from the Tessdata directory configured by listing all
files ending with '.traineddata' and considering those" +
+ " Tesseract language models. You can create you own Tesseract
language models and place them in your Tessedata directory" +
+ " and the processor will display it in the dropdown list of
languages available. All valid Tesseract configuration values" +
+ " may be passed to this processor by use of the 'Tesseract
configuration values' which accepts a comma separated list" +
+ " of key=value pairs representing Tesseract configurations.
'Tesseract configuration values' is where all of your tuning" +
+ " values can be passed in to help increase the accuracy of your
OCR operations based on your expected input images." +
+ " TesseractOCRProcessor only supports installations of Tesseract
version 3.0 and greater.")
+public class TesseractOCRProcessor extends AbstractProcessor {
+
+ public static Set<String> SUPPORTED_LANGUAGES;
+ private static final String TESS_LANG_EXTENSION = ".traineddata";
+ private static List<AllowableValue> PAGE_SEGMENTATION_MODES;
+ private static volatile ITesseract tesseract;
+ private static final List<PropertyDescriptor> descriptors;
+ private static final Set<Relationship> relationships;
+
+ public static final PropertyDescriptor TESS_DATA_PATH = new
PropertyDescriptor
+ .Builder().name("Tessdata Directory")
+ .description("Directory on the local NiFi instance where the
Tesseract languages and configurations are installed.")
+ .required(true)
+ .expressionLanguageSupported(true)
+
.defaultValue("/usr/local/Cellar/tesseract/3.04.00/share/tessdata")
+
.addValidator(StandardValidators.createDirectoryExistsValidator(true, false))
+ .addValidator(new TessdataDirectoryValidator())
+ .build();
+
+ /**
+ * Validates the TessData directory by ensuring that the specified
directory exists and also that at least
+ * once language is present. A language file ends with
TESS_LANG_EXTENSION
+ */
+ public static class TessdataDirectoryValidator implements Validator {
+
+ @Override
+ public ValidationResult validate(final String subject, final
String value, final ValidationContext context) {
+ if (context.isExpressionLanguageSupported(subject) &&
context.isExpressionLanguagePresent(value)) {
+ return new ValidationResult.Builder()
+
.subject(subject).input(value).explanation("Expression Language
Present").valid(true).build();
+ }
+
+ String reason = null;
+ try {
+ //There must be lanauges present to ensure the Tessdata
directory is valid.
+ File[] languages = getTesseractLanguages(value);
+ if (languages == null || languages.length == 0) {
+ reason = "No valid languages found in directory.
Languages end with '" + TESS_LANG_EXTENSION + "'";
+ }
+ } catch (final Exception e) {
+ reason = "Value is not a valid directory name";
+ }
+
+ return new
ValidationResult.Builder().subject(subject).input(value).explanation(reason).valid(reason
== null).build();
+ }
+ }
+
+ public static final PropertyDescriptor TESSERACT_LANGUAGE = new
PropertyDescriptor
+ .Builder().name("Tesseract Language")
+ .description("Language that Tesseract will use to perform OCR
on image coming in the incoming FlowFile's content")
+ .required(true)
+ .defaultValue(SUPPORTED_LANGUAGES.iterator().next())
+ .allowableValues(SUPPORTED_LANGUAGES)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor TESSERACT_PAGE_SEG_MODE = new
PropertyDescriptor
+ .Builder().name("Tesseract Page Segmentation Mode")
+ .description("Set Tesseract to only run a subset of layout
analysis and assume a certain form of image.")
+ .required(true)
+ .defaultValue(PAGE_SEGMENTATION_MODES.get(3).getValue())
+ .allowableValues(PAGE_SEGMENTATION_MODES)
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final PropertyDescriptor TESSERACT_CONFIGS = new
PropertyDescriptor
+ .Builder().name("Tesseract configuration values")
+ .description("Comma separated list of key=value pairs that
will be used to configure the Tesseract instance." +
+ " If a Tesseract configuration file is specified that
will take precedence over these configurations. Values" +
+ " placed into this property will not be validated so
take care to pass only valid Tesseract configuration values." +
+ " EX:
textord_min_linesize=3.25,tessedit_write_images=true")
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .build();
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("success")
+ .description("successfully completed OCR on image")
+ .build();
+
+ public static final Relationship REL_UNSUPPORTED_IMAGE_FORMAT = new
Relationship.Builder()
+ .name("unsupported image format")
+ .description("The image format in the FlowFile content is not
supported by Tesseract")
+ .build();
+
+ public static final Relationship REL_ORIGINAL = new
Relationship.Builder()
+ .name("original")
+ .description("The original image that OCR was performed on")
+ .build();
+
+ public static final Relationship REL_FAILURE = new
Relationship.Builder()
+ .name("failure")
+ .description("Failed to attempt OCR on input image")
+ .build();
+
+ static {
+ SUPPORTED_LANGUAGES = new HashSet<>();
+ SUPPORTED_LANGUAGES.add("eng"); //Since this is the default value
we need to ensure it is present in the allowableValues.
+
+ PAGE_SEGMENTATION_MODES = new ArrayList<>();
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("0","0 =
Orientation and script detection (OSD) only"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("1","1 = Automatic
page segmentation with OSD"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("2","2 = Automatic
page segmentation, but no OSD, or OCR"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("3","3 = Fully
automatic page segmentation, but no OSD"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("4","4 = Assume a
single column of text of variable sizes"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("5","5 = Assume a
single uniform block of vertically aligned text"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("6","6 = Assume a
single uniform block of text"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("7","7 = Treat the
image as a single text line"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("8","8 = Treat the
image as a single word"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("9","9 = Treat the
image as a single word in a circle"));
+ PAGE_SEGMENTATION_MODES.add(new AllowableValue("10","10 = Treat
the image as a single character"));
+
+ final List<PropertyDescriptor> _descriptors = new ArrayList<>();
+ _descriptors.add(TESS_DATA_PATH);
+ _descriptors.add(TESSERACT_LANGUAGE);
+ _descriptors.add(TESSERACT_PAGE_SEG_MODE);
+ _descriptors.add(TESSERACT_CONFIGS);
+ descriptors = Collections.unmodifiableList(_descriptors);
+
+ final Set<Relationship> _relationships = new HashSet<>();
+ _relationships.add(REL_SUCCESS);
+ _relationships.add(REL_FAILURE);
+ _relationships.add(REL_UNSUPPORTED_IMAGE_FORMAT);
+ _relationships.add(REL_ORIGINAL);
+ relationships = Collections.unmodifiableSet(_relationships);
+ }
+
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return this.relationships;
+ }
+
+ @Override
+ public final List<PropertyDescriptor>
getSupportedPropertyDescriptors() {
+
+ List<PropertyDescriptor> descriptorsNew = new ArrayList<>();
+
+ descriptorsNew.add(TESS_DATA_PATH);
+ descriptorsNew.add(new PropertyDescriptor.Builder()
+ .fromPropertyDescriptor(TESSERACT_LANGUAGE)
+ .allowableValues(SUPPORTED_LANGUAGES)
+ .build());
+ descriptorsNew.add(TESSERACT_PAGE_SEG_MODE);
+ descriptorsNew.add(TESSERACT_CONFIGS);
+
+ return descriptorsNew;
+ }
+
+ @Override
+ public void onPropertyModified(PropertyDescriptor descriptor, String
oldValue, String newValue) {
+ super.onPropertyModified(descriptor, oldValue, newValue);
+
+ if (descriptor.equals(TESS_DATA_PATH)) {
+ getLogger().debug("Tesseract Install path was changed.
Building list of supported languages");
+ SUPPORTED_LANGUAGES.clear();
+ SUPPORTED_LANGUAGES.add("eng");
+ //File will always exist since the Validator will take care of
that.
+ File[] files = getTesseractLanguages(newValue);
+
+ //Guard against creating an empty list of allowable values in
case the user points to an invalid directory
+ if (files != null && files.length > 0) {
+ for (int i = 0; i < files.length; i++) {
+ if (getLogger().isDebugEnabled()) {
+ getLogger().debug("Found Tesseract supported
language: " + files[i].getName());
+ }
+
SUPPORTED_LANGUAGES.add(StringUtils.split(files[i].getName(), ".")[0]);
+ }
+ } else {
+ getLogger().debug("No languages found in user specified
Tessdata directory: '" + newValue + "'");
+ }
+
+ }
+ }
+
+ @OnScheduled
+ public void onScheduled(final ProcessContext context) {
+ //Setup the Tesseract instance once the processor is scheuled
+ tesseract = new Tesseract();
+
tesseract.setLanguage(context.getProperty(TESSERACT_LANGUAGE).getValue());
+
tesseract.setPageSegMode((context.getProperty(TESSERACT_PAGE_SEG_MODE).asInteger()));
+ }
+
+
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSession session) throws ProcessException {
+ final FlowFile flowFile = session.get();
+ if ( flowFile == null ) {
+ return;
+ }
+
+ //Transfer the original
+ session.transfer(session.clone(flowFile), REL_ORIGINAL);
+ AtomicBoolean errors = new AtomicBoolean(false);
+
+ FlowFile ff = session.write(flowFile, new StreamCallback() {
+ @Override
+ public void process(InputStream inputStream, OutputStream
outputStream) throws IOException {
+
tesseract.setDatapath(context.getProperty(TESS_DATA_PATH).evaluateAttributeExpressions(flowFile).getValue());
+
+ //Builds the list of Tesseract configs.
+ Map<String, String> configs =
buildTesseractConfigs(context.getProperty(TESSERACT_CONFIGS).getValue());
+ for (Map.Entry<String, String> entry : configs.entrySet())
{
+ getLogger().debug("Tesseract Config Key : '" +
entry.getKey()
+ + "' Tesseract Config Value : '" +
entry.getValue() + "'");
+ tesseract.setTessVariable(entry.getKey(),
entry.getValue());
+ }
+
+ try {
+ BufferedImage imBuff = ImageIO.read(inputStream);
+ outputStream.write(tesseract.doOCR(imBuff).getBytes());
+ } catch (TesseractException te) {
+ getLogger().error(te.getMessage());
+ if (te.getCause().getMessage().equals("image ==
null!")) {
+ session.transfer(flowFile,
REL_UNSUPPORTED_IMAGE_FORMAT);
+ } else {
+ session.transfer(flowFile, REL_FAILURE);
+ }
+ errors.set(true);
+
+ } catch (Exception ex) {
+ getLogger().error(ex.getMessage());
+ session.transfer(flowFile, REL_FAILURE);
+ errors.set(true);
+ }
+ }
+ });
+
+ if (!errors.get()) {
+ session.transfer(ff, REL_SUCCESS);
+ }
+
+ }
+
+
+
+ /**
+ * Build the key/value pairs of Tesseract configuration values that
will be passed to Tesseract.
+ *
+ * @param commaDelimitedConfigs
+ * Comma separated list of key=value Tesseract configuration pairs.
+ *
+ * @return
+ * Map of key/value pairs that were parsed from the incoming
commaDelimtedConfigs string.
+ */
+ private Map<String, String> buildTesseractConfigs(String
commaDelimitedConfigs) {
+ Map<String, String> configs = new HashMap<>();
+ if (!StringUtils.isEmpty(commaDelimitedConfigs)) {
+ String[] keyValuePairs =
StringUtils.split(commaDelimitedConfigs, ",");
+ if (keyValuePairs != null && keyValuePairs.length > 0) {
+ for (String kp : keyValuePairs) {
+ String[] keyValue = StringUtils.split(kp);
+ configs.put(keyValue[0], keyValue[1]);
+ }
+ }
+ }
+ return configs;
+ }
+
+ /**
+ * Traverses the TessData directory and locates all of the installed
languages so they may be
+ * presented to the user as a list of allowableValues.
+ *
+ * @param tessDataPath
+ * PropertyDescriptor String value described the path of the TessData
directory.
+ *
+ * @return
+ * Array of File references to the Tesseract language files.
+ */
+ public static File[] getTesseractLanguages(String tessDataPath) {
+ //File will always exist since the Validator will take care of
that.
+ File installFile = new File(tessDataPath);
+ File[] files = installFile.listFiles(new FileFilter() {
+ @Override
+ public boolean accept(File pathname) {
+ if (pathname.getName().endsWith(TESS_LANG_EXTENSION)) {
+ return true;
+ } else {
+ return false;
+ }
--- End diff --
I think you can simply do this
```
return pathname.getName().endsWith(TESS_LANG_EXTENSION);
```
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