Merge pull request LibrePDF#64 from albfernandez/extract_text_from_forms

Extract text from forms

openpdf/src/main/java/com/lowagie/text/pdf/parser/PdfContentStreamHandler.java

@@ -41,25 +41,34 @@
  */
 package com.lowagie.text.pdf.parser;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.ListIterator;
+import java.util.Map;
+import java.util.Stack;
+
+import com.lowagie.text.ExceptionConverter;
 import com.lowagie.text.error_messages.MessageLocalization;
 import com.lowagie.text.pdf.CMapAwareDocumentFont;
 import com.lowagie.text.pdf.PRIndirectReference;
+import com.lowagie.text.pdf.PRStream;
+import com.lowagie.text.pdf.PRTokeniser;
 import com.lowagie.text.pdf.PdfArray;
+import com.lowagie.text.pdf.PdfContentParser;
 import com.lowagie.text.pdf.PdfDictionary;
 import com.lowagie.text.pdf.PdfIndirectReference;
 import com.lowagie.text.pdf.PdfLiteral;
 import com.lowagie.text.pdf.PdfName;
 import com.lowagie.text.pdf.PdfNumber;
 import com.lowagie.text.pdf.PdfObject;
+import com.lowagie.text.pdf.PdfReader;
+import com.lowagie.text.pdf.PdfStream;
 import com.lowagie.text.pdf.PdfString;
 
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.Map;
-import java.util.Stack;
-
 /**
  * @author dgd
  */
@@ -631,7 +640,7 @@ public void invoke(ArrayList<PdfObject> operands,
 	public Matrix textLineMatrix;
 
 	boolean useContainerMarkup;
-
+	
 	/**
 	 * detail parser for text within a marked section. used by TextAssembler
 	 */
@@ -780,6 +789,75 @@ public void invoke(ArrayList<PdfObject> operands,
 			handler.popContext();
 		}
 	}
+
+	private  class Do implements ContentOperator {
+		/**
+		 * @see com.lowagie.text.pdf.parser.ContentOperator#getOperatorName()
+		 */
+		@Override
+		public String getOperatorName() {
+			return "Do";
+		}
+
+		@Override
+		public void invoke(ArrayList<PdfObject> operands, PdfContentStreamHandler handler, PdfDictionary resources) {
+			PdfObject firstOperand = operands.get(0);
+			if (firstOperand instanceof PdfName) {
+				PdfName name = (PdfName) firstOperand;
+				PdfDictionary dictionary = resources.getAsDict(PdfName.XOBJECT);
+				if (dictionary == null) {
+					return;
+				}
+				PdfStream stream = (PdfStream) dictionary.getDirectObject(name);
+				PdfName subType = stream.getAsName(PdfName.SUBTYPE);
+				if (PdfName.FORM.equals(subType)) {
+					PdfDictionary resources2 = stream.getAsDict(PdfName.RESOURCES);
+					byte[] data = null;
+					try {
+						data = getContentBytesFromPdfObject(stream);
+					} catch (IOException ex) {
+						throw new ExceptionConverter(ex);
+					}
+					new PushGraphicsState().invoke(operands, handler, resources);			
+					processContent(data, resources2);
+					new PopGraphicsState().invoke(operands, handler, resources);
+				}
+			}
+
+		}
+		private void processContent(byte[] contentBytes, PdfDictionary resources) {
+			try {
+				PdfContentParser ps = new PdfContentParser(new PRTokeniser(contentBytes));
+				ArrayList<PdfObject> operands = new ArrayList<PdfObject>();
+				while (ps.parse(operands).size() > 0) {
+					PdfLiteral operator = (PdfLiteral) operands.get(operands.size() - 1);
+					invokeOperator(operator, operands, resources);
+				}
+			} catch (Exception e) {
+				throw new ExceptionConverter(e);
+			}
+		}
+
+
+		private byte[] getContentBytesFromPdfObject(PdfObject object) throws IOException {
+			switch (object.type()) {
+			case PdfObject.INDIRECT:
+				return getContentBytesFromPdfObject(PdfReader.getPdfObject(object));
+			case PdfObject.STREAM:
+				return PdfReader.getStreamBytes((PRStream) PdfReader.getPdfObject(object));
+			case PdfObject.ARRAY:
+				ByteArrayOutputStream baos = new ByteArrayOutputStream();
+				ListIterator<PdfObject> iter = ((PdfArray) object).listIterator();
+				while (iter.hasNext()) {
+					PdfObject element = iter.next();
+					baos.write(getContentBytesFromPdfObject(element));
+				}
+				return baos.toByteArray();
+			default:
+				throw new IllegalStateException("Unsupported type: " + object.getClass().getCanonicalName());
+			}
+		}
+	}
 
 	/**
 	 * Loads all the supported graphics and text state operators in a map.
@@ -827,6 +905,8 @@ protected void installDefaultOperators() {
 		registerContentOperator(new BeginMarked());
 		registerContentOperator(new BeginMarkedDict());
 		registerContentOperator(new EndMarked());
+
+		registerContentOperator(new Do());
 	}
 
 	/**

openpdf/src/test/java/com/lowagie/text/pdf/parser/PdfTextExtractorTest.java

@@ -0,0 +1,67 @@
+package com.lowagie.text.pdf.parser;
+
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.lowagie.text.pdf.PdfReader;
+
+
+public class PdfTextExtractorTest {
+
+
+	@Test(expected=IOException.class)
+	public void testPageExceeded() throws Exception {
+		getString("HelloWorldMeta.pdf", 5);
+	}
+	@Test(expected=IOException.class)
+	public void testInvalidPageNumber() throws Exception {
+		getString("HelloWorldMeta.pdf", 0);
+	}
+
+
+	@Test
+	public void testConcatenateWatermark() throws Exception {
+		String result = getString("merge-acroforms.pdf", 5);
+		Assert.assertNotNull(result);
+		// html??
+		result = result.replaceAll("\\<.*?>","");		
+		// Multiple spaces betwen words??
+		Assert.assertTrue(result.contains("2.  This  is  chapter  2"));
+		Assert.assertTrue(result.contains("watermark-concatenate"));
+	}
+
+
+	private String getString(String fileName, int pageNumber) throws Exception {
+		return getString(new File("src/test/resources", fileName), pageNumber);
+	}
+	private String getString(File file, int pageNumber) throws Exception {
+		byte[] pdfBytes = readDocument(file);
+		final PdfReader pdfReader = new PdfReader(pdfBytes);
+
+		return new PdfTextExtractor(pdfReader).getTextFromPage( pageNumber);		
+	}
+
+	protected static byte[] readDocument(final File file) throws IOException {
+
+		try (ByteArrayOutputStream fileBytes = new ByteArrayOutputStream();
+				InputStream inputStream = new FileInputStream(file)) {
+			final byte[] buffer = new byte[8192];
+			while (true) {
+				final int bytesRead = inputStream.read(buffer);
+				if (bytesRead == -1) {
+					break;
+				}
+				fileBytes.write(buffer, 0, bytesRead);
+			}
+			return fileBytes.toByteArray();
+		}
+
+	}
+}