Java tutorial
/* * * This file is part of the iText (R) project. Copyright (c) 1998-2019 iText Group NV * Authors: Kevin Day, 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: * http://itextpdf.com/terms-of-use/ * * The interactive user interfaces in modified source and object code versions * of this program must display Appropriate Legal Notices, as required under * Section 5 of the GNU Affero General Public License. * * In accordance with Section 7(b) of the GNU Affero General Public License, * 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 * a commercial license. Buying such a license is mandatory as soon as you * develop commercial activities involving the iText software without * disclosing the source code of your own applications. * These activities include: offering paid services to customers as an ASP, * serving PDFs on the fly in a web application, shipping iText with a closed * source product. * * For more information, please contact iText Software Corp. at this * address: sales@itextpdf.com */ package com.itextpdf.text.pdf.parser; /** * A simple text extraction renderer. * * This renderer keeps track of the current Y position of each string. If it detects * that the y position has changed, it inserts a line break into the output. If the * PDF renders text in a non-top-to-bottom fashion, this will result in the text not * being a true representation of how it appears in the PDF. * * This renderer also uses a simple strategy based on the font metrics to determine if * a blank space should be inserted into the output. * * @since 2.1.5 */ public class SimpleTextExtractionStrategy implements TextExtractionStrategy { private Vector lastStart; private Vector lastEnd; /** used to store the resulting String. */ private final StringBuffer result = new StringBuffer();; /** * Creates a new text extraction renderer. */ public SimpleTextExtractionStrategy() { } /** * @since 5.0.1 */ public void beginTextBlock() { } /** * @since 5.0.1 */ public void endTextBlock() { } /** * Returns the result so far. * @return a String with the resulting text. */ 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); } /** * Captures text using a simplified algorithm for inserting hard returns and spaces * @param renderInfo render info */ public void renderText(TextRenderInfo renderInfo) { boolean firstRender = result.length() == 0; boolean hardReturn = false; LineSegment segment = renderInfo.getBaseline(); Vector start = segment.getStartPoint(); Vector end = segment.getEndPoint(); if (!firstRender) { Vector x0 = start; Vector x1 = lastStart; Vector x2 = lastEnd; // see http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html float dist = (x2.subtract(x1)).cross((x1.subtract(x0))).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; } /** * no-op method - this renderer isn't interested in image events * @see com.itextpdf.text.pdf.parser.RenderListener#renderImage(com.itextpdf.text.pdf.parser.ImageRenderInfo) * @since 5.0.1 */ public void renderImage(ImageRenderInfo renderInfo) { // do nothing - we aren't tracking images in this renderer } }