com.itextpdf.kernel.pdf.canvas.parser.listener.SimpleTextExtractionStrategy Maven / Gradle / Ivy
/*
This file is part of the iText (R) project.
Copyright (c) 1998-2018 iText Group NV
Authors: Bruno Lowagie, Paulo Soares, et al.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License version 3
as published by the Free Software Foundation with the addition of the
following permission added to Section 15 as permitted in Section 7(a):
FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
OF THIRD PARTY RIGHTS
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program; if not, see http://www.gnu.org/licenses or write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA, 02110-1301 USA, or download the license from the following URL:
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The interactive user interfaces in modified source and object code versions
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Section 5 of the GNU Affero General Public License.
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a covered work must retain the producer line in every PDF that is created
or manipulated using iText.
You can be released from the requirements of the license by purchasing
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*/
package com.itextpdf.kernel.pdf.canvas.parser.listener;
import com.itextpdf.kernel.geom.LineSegment;
import com.itextpdf.kernel.geom.Vector;
import com.itextpdf.kernel.pdf.canvas.parser.data.IEventData;
import com.itextpdf.kernel.pdf.canvas.parser.EventType;
import com.itextpdf.kernel.pdf.canvas.parser.data.TextRenderInfo;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;
public class SimpleTextExtractionStrategy implements ITextExtractionStrategy {
private Vector lastStart;
private Vector lastEnd;
/** used to store the resulting String. */
private final StringBuilder result = new StringBuilder();
@Override
public void eventOccurred(IEventData data, EventType type) {
if (type.equals(EventType.RENDER_TEXT)) {
TextRenderInfo renderInfo = (TextRenderInfo)data;
boolean firstRender = result.length() == 0;
boolean hardReturn = false;
LineSegment segment = renderInfo.getBaseline();
Vector start = segment.getStartPoint();
Vector end = segment.getEndPoint();
if (!firstRender){
Vector x1 = lastStart;
Vector x2 = lastEnd;
// see http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html
float dist = (x2.subtract(x1)).cross((x1.subtract(start))).lengthSquared() / x2.subtract(x1).lengthSquared();
float sameLineThreshold = 1f; // we should probably base this on the current font metrics, but 1 pt seems to be sufficient for the time being
if (dist > sameLineThreshold)
hardReturn = true;
// Note: Technically, we should check both the start and end positions, in case the angle of the text changed without any displacement
// but this sort of thing probably doesn't happen much in reality, so we'll leave it alone for now
}
if (hardReturn){
//System.out.println("<< Hard Return >>");
appendTextChunk("\n");
} else if (!firstRender){
if (result.charAt(result.length()-1) != ' ' && renderInfo.getText().length() > 0 && renderInfo.getText().charAt(0) != ' '){ // we only insert a blank space if the trailing character of the previous string wasn't a space, and the leading character of the current string isn't a space
float spacing = lastEnd.subtract(start).length();
if (spacing > renderInfo.getSingleSpaceWidth()/2f){
appendTextChunk(" ");
//System.out.println("Inserting implied space before '" + renderInfo.getText() + "'");
}
}
} else {
//System.out.println("Displaying first string of content '" + text + "' :: x1 = " + x1);
}
//System.out.println("[" + renderInfo.getStartPoint() + "]->[" + renderInfo.getEndPoint() + "] " + renderInfo.getText());
appendTextChunk(renderInfo.getText());
lastStart = start;
lastEnd = end;
}
}
@Override
public Set getSupportedEvents() {
return Collections.unmodifiableSet(new LinkedHashSet<>(Collections.singletonList(EventType.RENDER_TEXT)));
}
/**
* Returns the result so far.
* @return a String with the resulting text.
*/
@Override
public String getResultantText() {
return result.toString();
}
/**
* Used to actually append text to the text results. Subclasses can use this to insert
* text that wouldn't normally be included in text parsing (e.g. result of OCR performed against
* image content)
* @param text the text to append to the text results accumulated so far
*/
protected final void appendTextChunk(CharSequence text){
result.append(text);
}
}