implementing extracting tables from pdf by pdfbox

build.gradle

@@ -102,14 +102,6 @@ dependencies {
     developmentOnly("org.springframework.boot:spring-boot-devtools")
     compileOnly 'org.projectlombok:lombok:1.18.28'
     annotationProcessor 'org.projectlombok:lombok:1.18.28'
-
-//// https://mvnrepository.com/artifact/technology.tabula/tabula
-//    implementation group: 'technology.tabula', name: 'tabula', version: '1.0.5'
-
-
-//    implementation files('/Users/artempetrenko/Java/Stirling-PDF/tabula-1.0.5-jar-with-dependencies.jar')
-    implementation fileTree(include: ['tabula-1.0.5-jar-with-dependencies.jar'],dir: 'libs')
-
 }
 
 

src/main/java/stirling/software/SPDF/controller/api/ExtractController.java

@@ -0,0 +1,120 @@
+package stirling.software.SPDF.controller.api;
+
+import com.opencsv.CSVWriter;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.pdmodel.PDPage;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.http.ContentDisposition;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+import stirling.software.SPDF.controller.api.strippers.PDFTableStripper;
+import stirling.software.SPDF.model.api.extract.PDFFilePage;
+
+import java.awt.*;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/v1/extract/pdf-to-csv")
+@Tag(name = "General", description = "General APIs")
+public class ExtractController {
+
+    private static final Logger logger = LoggerFactory.getLogger(CropController.class);
+
+    @PostMapping(consumes = "multipart/form-data")
+    @Operation(summary = "Extracts a PDF document to csv", description = "This operation takes an input PDF file and returns CSV file of whole page. Input:PDF Output:CSV Type:SISO")
+    public ResponseEntity<String> PdfToCsv(@ModelAttribute PDFFilePage form)
+            throws IOException {
+
+        ArrayList<String> tableData = new ArrayList<>();
+        int columnsCount = 0;
+
+        try (PDDocument document = PDDocument.load(new ByteArrayInputStream(form.getFileInput().getBytes()))) {
+            final double res = 72; // PDF units are at 72 DPI
+            PDFTableStripper stripper = new PDFTableStripper();
+            stripper.setSortByPosition(true);
+            stripper.setRegion(new Rectangle((int) Math.round(1.0 * res), (int) Math.round(1 * res), (int) Math.round(6 * res), (int) Math.round(9.0 * res)));
+
+            PDPage pdPage = document.getPage(form.getPageId() - 1);
+            stripper.extractTable(pdPage);
+            columnsCount = stripper.getColumns();
+
+            for (int c = 0; c < columnsCount; ++c) {
+                for(int r=0; r<stripper.getRows(); ++r) {
+                    tableData.add(stripper.getText(r, c));
+                }
+            }
+        }
+
+        ArrayList<String> notEmptyColumns = new ArrayList<>();
+
+        for (String item: tableData) {
+            if(!item.trim().isEmpty()){
+                notEmptyColumns.add(item);
+            }else{
+                columnsCount--;
+            }
+        }
+
+        List<String> fullTable  =  notEmptyColumns.stream().map((entity)->
+            entity.replace('\n',' ').replace('\r',' ').trim().replaceAll("\\s{2,}", "|")).toList();
+
+        int rowsCount = fullTable.get(0).split("\\|").length;
+
+        ArrayList<String> headersList = getTableHeaders(columnsCount,fullTable);
+        ArrayList<String> recordList = getRecordsList(rowsCount,fullTable);
+
+
+        StringWriter writer = new StringWriter();
+        try (CSVWriter csvWriter = new CSVWriter(writer)) {
+            csvWriter.writeNext(headersList.toArray(new String[0]));
+            for (String record : recordList) {
+                csvWriter.writeNext(record.split("\\|"));
+            }
+        }
+
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentDisposition(ContentDisposition.builder("attachment").filename(form.getFileInput().getOriginalFilename().replaceFirst("[.][^.]+$", "") + "_extracted.csv").build());
+        headers.setContentType(MediaType.parseMediaType("text/csv"));
+
+        return ResponseEntity.ok()
+                .headers(headers)
+                .body(writer.toString());
+    }
+
+    private ArrayList<String> getRecordsList( int rowsCounts ,List<String> items){
+        ArrayList<String> recordsList = new ArrayList<>();
+
+            for (int b=1; b<rowsCounts;b++) {
+                StringBuilder strbldr = new StringBuilder();
+
+                for (int i=0;i<items.size();i++){
+                    String[] parts = items.get(i).split("\\|");
+                    strbldr.append(parts[b]);
+                    if (i!= items.size()-1){
+                        strbldr.append("|");
+                    }
+                }
+                recordsList.add(strbldr.toString());
+            }
+
+        return recordsList;
+    }
+    private ArrayList<String> getTableHeaders(int columnsCount, List<String> items){
+        ArrayList<String> resultList = new ArrayList<>();
+        for (int i=0;i<columnsCount;i++){
+            String[] parts = items.get(i).split("\\|");
+            resultList.add(parts[0]);
+        }
+
+        return resultList;
+    }
+}

src/main/java/stirling/software/SPDF/controller/api/strippers/PDFTableStripper.java

@@ -0,0 +1,354 @@
+package stirling.software.SPDF.controller.api.strippers;
+
+import org.apache.fontbox.util.BoundingBox;
+import org.apache.pdfbox.pdmodel.PDPage;
+import org.apache.pdfbox.pdmodel.common.PDRectangle;
+import org.apache.pdfbox.pdmodel.font.PDFont;
+import org.apache.pdfbox.pdmodel.font.PDType3Font;
+import org.apache.pdfbox.text.PDFTextStripper;
+import org.apache.pdfbox.text.PDFTextStripperByArea;
+import org.apache.pdfbox.text.TextPosition;
+
+import java.awt.*;
+import java.awt.geom.AffineTransform;
+import java.awt.geom.Rectangle2D;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.util.List;
+import java.util.*;
+
+/**
+ *
+ * Class to extract tabular data from a PDF.
+ * Works by making a first pass of the page to group all nearby text items
+ * together, and then inferring a 2D grid from these regions. Each table cell
+ * is then extracted using a PDFTextStripperByArea object.
+ *
+ * Works best when
+ * headers are included in the detected region, to ensure representative text
+ * in every column.
+ *
+ * Based upon DrawPrintTextLocations PDFBox example
+ * (https://svn.apache.org/viewvc/pdfbox/trunk/examples/src/main/java/org/apache/pdfbox/examples/util/DrawPrintTextLocations.java)
+ *
+ * @author Beldaz
+ */
+public class PDFTableStripper extends PDFTextStripper
+{
+
+    /**
+     * This will print the documents data, for each table cell.
+     *
+     * @param args The command line arguments.
+     *
+     * @throws IOException If there is an error parsing the document.
+     */
+    /*
+     *  Used in methods derived from DrawPrintTextLocations
+     */
+    private AffineTransform flipAT;
+    private AffineTransform rotateAT;
+
+    /**
+     *  Regions updated by calls to writeString
+     */
+    private Set<Rectangle2D> boxes;
+
+    // Border to allow when finding intersections
+    private double dx = 1.0; // This value works for me, feel free to tweak (or add setter)
+    private double dy = 0.000; // Rows of text tend to overlap, so need to extend
+
+    /**
+     *  Region in which to find table (otherwise whole page)
+     */
+    private Rectangle2D regionArea;
+
+    /**
+     * Number of rows in inferred table
+     */
+    private int nRows=0;
+
+    /**
+     * Number of columns in inferred table
+     */
+    private int nCols=0;
+
+    /**
+     * This is the object that does the text extraction
+     */
+    private PDFTextStripperByArea regionStripper;
+
+    /**
+     * 1D intervals - used for calculateTableRegions()
+     * @author Beldaz
+     *
+     */
+    public static class Interval {
+        double start;
+        double end;
+        public Interval(double start, double end) {
+            this.start=start; this.end = end;
+        }
+        public void add(Interval col) {
+            if(col.start<start)
+                start = col.start;
+            if(col.end>end)
+                end = col.end;
+        }
+        public static void addTo(Interval x, LinkedList<Interval> columns) {
+            int p = 0;
+            Iterator<Interval> it = columns.iterator();
+            // Find where x should go
+            while(it.hasNext()) {
+                Interval col = it.next();
+                if(x.end>=col.start) {
+                    if(x.start<=col.end) { // overlaps
+                        x.add(col);
+                        it.remove();
+                    }
+                    break;
+                }
+                ++p;
+            }
+            while(it.hasNext()) {
+                Interval col = it.next();
+                if(x.start>col.end)
+                    break;
+                x.add(col);
+                it.remove();
+            }
+            columns.add(p, x);
+        }
+
+    }
+
+
+    /**
+     * Instantiate a new PDFTableStripper object.
+     *
+     * @param document
+     * @throws IOException If there is an error loading the properties.
+     */
+    public PDFTableStripper() throws IOException
+    {
+        super.setShouldSeparateByBeads(false);
+        regionStripper = new PDFTextStripperByArea();
+        regionStripper.setSortByPosition( true );
+    }
+
+    /**
+     * Define the region to group text by.
+     *
+     * @param rect The rectangle area to retrieve the text from.
+     */
+    public void setRegion(Rectangle2D rect )
+    {
+        regionArea = rect;
+    }
+
+    public int getRows()
+    {
+        return nRows;
+    }
+
+    public int getColumns()
+    {
+        return nCols;
+    }
+
+    /**
+     * Get the text for the region, this should be called after extractTable().
+     *
+     * @return The text that was identified in that region.
+     */
+    public String getText(int row, int col)
+    {
+        return regionStripper.getTextForRegion("el"+col+"x"+row);
+    }
+
+    public void extractTable(PDPage pdPage) throws IOException
+    {
+        setStartPage(getCurrentPageNo());
+        setEndPage(getCurrentPageNo());
+
+        boxes = new HashSet<Rectangle2D>();
+        // flip y-axis
+        flipAT = new AffineTransform();
+        flipAT.translate(0, pdPage.getBBox().getHeight());
+        flipAT.scale(1, -1);
+
+        // page may be rotated
+        rotateAT = new AffineTransform();
+        int rotation = pdPage.getRotation();
+        if (rotation != 0)
+        {
+            PDRectangle mediaBox = pdPage.getMediaBox();
+            switch (rotation)
+            {
+                case 90:
+                    rotateAT.translate(mediaBox.getHeight(), 0);
+                    break;
+                case 270:
+                    rotateAT.translate(0, mediaBox.getWidth());
+                    break;
+                case 180:
+                    rotateAT.translate(mediaBox.getWidth(), mediaBox.getHeight());
+                    break;
+                default:
+                    break;
+            }
+            rotateAT.rotate(Math.toRadians(rotation));
+        }
+        // Trigger processing of the document so that writeString is called.
+        try (Writer dummy = new OutputStreamWriter(new ByteArrayOutputStream())) {
+            super.output = dummy;
+            super.processPage(pdPage);
+        }
+
+        Rectangle2D[][] regions = calculateTableRegions();
+
+//        System.err.println("Drawing " + nCols + "x" + nRows + "="+ nRows*nCols + " regions");
+        for(int i=0; i<nCols; ++i) {
+            for(int j=0; j<nRows; ++j) {
+                final Rectangle2D region = regions[i][j];
+                regionStripper.addRegion("el"+i+"x"+j, region);
+            }
+        }
+
+        regionStripper.extractRegions(pdPage);
+    }
+
+    /**
+     * Infer a rectangular grid of regions from the boxes field.
+     *
+     * @return 2D array of table regions (as Rectangle2D objects). Note that
+     * some of these regions may have no content.
+     */
+    private Rectangle2D[][] calculateTableRegions() {
+
+        // Build up a list of all table regions, based upon the populated
+        // regions of boxes field. Treats the horizontal and vertical extents
+        // of each box as distinct
+        LinkedList<Interval> columns = new LinkedList<Interval>();
+        LinkedList<Interval> rows = new LinkedList<Interval>();
+
+        for(Rectangle2D box: boxes) {
+            Interval x = new Interval(box.getMinX(), box.getMaxX());
+            Interval y = new Interval(box.getMinY(), box.getMaxY());
+
+            Interval.addTo(x, columns);
+            Interval.addTo(y, rows);
+        }
+
+        nRows = rows.size();
+        nCols = columns.size();
+        Rectangle2D[][] regions = new Rectangle2D[nCols][nRows];
+        int i=0;
+        // Label regions from top left, rather than the transformed orientation
+        for(Interval column: columns) {
+            int j=0;
+            for(Interval row: rows) {
+                regions[nCols-i-1][nRows-j-1] = new Rectangle2D.Double(column.start, row.start, column.end - column.start, row.end - row.start);
+                ++j;
+            }
+            ++i;
+        }
+
+        return regions;
+    }
+
+    /**
+     * Register each character's bounding box, updating boxes field to maintain
+     * a list of all distinct groups of characters.
+     *
+     * Overrides the default functionality of PDFTextStripper.
+     * Most of this is taken from DrawPrintTextLocations.java, with extra steps
+     * at end of main loop
+     */
+    @Override
+    protected void writeString(String string, List<TextPosition> textPositions) throws IOException
+    {
+        for (TextPosition text : textPositions)
+        {
+            // glyph space -> user space
+            // note: text.getTextMatrix() is *not* the Text Matrix, it's the Text Rendering Matrix
+            AffineTransform at = text.getTextMatrix().createAffineTransform();
+            PDFont font = text.getFont();
+            BoundingBox bbox = font.getBoundingBox();
+
+            // advance width, bbox height (glyph space)
+            float xadvance = font.getWidth(text.getCharacterCodes()[0]); // todo: should iterate all chars
+            Rectangle2D.Float rect = new Rectangle2D.Float(0, bbox.getLowerLeftY(), xadvance, bbox.getHeight());
+
+            if (font instanceof PDType3Font)
+            {
+                // bbox and font matrix are unscaled
+                at.concatenate(font.getFontMatrix().createAffineTransform());
+            }
+            else
+            {
+                // bbox and font matrix are already scaled to 1000
+                at.scale(1/1000f, 1/1000f);
+            }
+            Shape s = at.createTransformedShape(rect);
+            s = flipAT.createTransformedShape(s);
+            s = rotateAT.createTransformedShape(s);
+
+
+            //
+            // Merge character's bounding box with boxes field
+            //
+            Rectangle2D bounds = s.getBounds2D();
+            // Pad sides to detect almost touching boxes
+            Rectangle2D hitbox = bounds.getBounds2D();
+            hitbox.add(bounds.getMinX() - dx , bounds.getMinY() - dy);
+            hitbox.add(bounds.getMaxX() + dx , bounds.getMaxY() + dy);
+
+            // Find all overlapping boxes
+            List<Rectangle2D> intersectList = new ArrayList<Rectangle2D>();
+            for(Rectangle2D box: boxes) {
+                if(box.intersects(hitbox)) {
+                    intersectList.add(box);
+                }
+            }
+
+            // Combine all touching boxes and update
+            // (NOTE: Potentially this could leave some overlapping boxes un-merged,
+            // but it's sufficient for now and get's fixed up in calculateTableRegions)
+            for(Rectangle2D box: intersectList) {
+                bounds.add(box);
+                boxes.remove(box);
+            }
+            boxes.add(bounds);
+
+        }
+
+    }
+
+    /**
+     * This method does nothing in this derived class, because beads and regions are incompatible. Beads are
+     * ignored when stripping by area.
+     *
+     * @param aShouldSeparateByBeads The new grouping of beads.
+     */
+    @Override
+    public final void setShouldSeparateByBeads(boolean aShouldSeparateByBeads)
+    {
+    }
+
+    /**
+     * Adapted from PDFTextStripperByArea
+     * {@inheritDoc}
+     */
+    @Override
+    protected void processTextPosition( TextPosition text )
+    {
+        if(regionArea!=null && !regionArea.contains( text.getX(), text.getY() ) ) {
+            // skip character
+        } else {
+            super.processTextPosition( text );
+        }
+    }
+}

src/main/java/stirling/software/SPDF/model/api/extract/PDFFilePage.java

@@ -0,0 +1,18 @@
+package stirling.software.SPDF.model.api.extract;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import stirling.software.SPDF.model.api.PDFFile;
+
+@Data
+@EqualsAndHashCode(callSuper=true)
+public class PDFFilePage extends PDFFile {
+
+
+    @Schema(description = "Number of chosen page", type = "number")
+    private int pageId;
+
+
+}
+

src/main/resources/templates/convert/pdf-to-csv.html

@@ -1,29 +1,158 @@
 <!DOCTYPE html>
 <html th:lang="${#locale.toString()}" th:lang-direction="#{language.direction}" xmlns:th="http://www.thymeleaf.org">
 
-<th:block th:insert="~{fragments/common :: head(title=#{PDFToXML.title})}"></th:block>
+<th:block th:insert="~{fragments/common :: head(title=#{PDFToCSV.title})}"></th:block>
+
+
 <body>
-    <th:block th:insert="~{fragments/common :: game}"></th:block>
-    <div id="page-container">
+<div id="page-container">
     <div id="content-wrap">
-            <div th:insert="~{fragments/navbar.html :: navbar}"></div>
-            <br> <br>
+
         <div class="container">
             <div class="row justify-content-center">
                 <div class="col-md-6">
                     <h2 th:text="#{PDFToCSV.header}"></h2>
-                        <form method="post" enctype="multipart/form-data" th:action="@{api/v1/convert/pdf/csv}">
+                    <form id="PDFToCSVForm" th:action="@{api/v1/extract/pdf-to-csv}" method="post" enctype="multipart/form-data">
+                        <input  id="pageId" type="hidden" name="pageId" />
                         <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=false, accept='application/pdf')}"></div>
-                            <br>
-                            <button type="submit" id="submitBtn" class="btn btn-primary" th:text="#{PDFToCSV.submit}"></button>
-
+                        <button type="submit" class="btn btn-primary" th:text="#{PDFToCSV.submit}"></button>
                     </form>
-                        <p class="mt-3" th:text="#{PDFToCSV.credit}"></p>
+                    <p id="instruction-text" style="margin: 0; display: none">Choose page to extract table</p>
+
+                    <div style="position: relative; display: inline-block;">
+                        <div>
+
+                            <div style="display:none ;margin: 3px;position: absolute;top: 0;width: 120px;justify-content:space-between;z-index: 10" id="pagination-button-container">
+                                <button id='previous-page-btn' style='opacity: 80% ; width: 50px; height: 30px; display: flex;align-items: center;justify-content: center; background: grey; color: #ffffff;  ;border: none;outline: none; border-radius: 4px;'> < </button>
+                                <button id='next-page-btn' style='opacity: 80% ; width: 50px; height: 30px; display: flex;align-items: center;justify-content: center; background: grey; color: #ffffff;  ;border: none;outline: none; border-radius: 4px;'> > </button>
+                            </div>
+
+                            <canvas id="crop-pdf-canvas" style="position: absolute; top: 0; left: 0; z-index: 1;"></canvas>
+                        </div>
+                        <canvas id="overlayCanvas" style="position: absolute; top: 0; left: 0; z-index: 2;"></canvas>
+                    </div>
+
+                    <script>
+
+                        let pdfCanvas  = document.getElementById('crop-pdf-canvas');
+                        let overlayCanvas = document.getElementById('overlayCanvas');
+                        // let paginationBtnContainer = ;
+
+                        let context = pdfCanvas.getContext('2d');
+
+                        let btn1Object = document.getElementById('previous-page-btn');
+                        let btn2Object = document.getElementById('next-page-btn');
+                        overlayCanvas.width = pdfCanvas.width;
+                        overlayCanvas.height = pdfCanvas.height;
+
+                        let fileInput = document.getElementById('fileInput-input');
+
+                        let file;
+
+                        let pdfDoc = null;
+                        let pageId = document.getElementById('pageId');
+                        let currentPage = 1;
+                        let totalPages = 0;
+
+                        let startX = 0;
+                        let startY = 0;
+                        let rectWidth = 0;
+                        let rectHeight = 0;
+
+                        btn1Object.addEventListener('click',function (e){
+
+                            if (currentPage !== 1) {
+                                currentPage = currentPage - 1;
+                                pageId.value = currentPage;
+
+                                if (file.type === 'application/pdf') {
+                                    let reader = new FileReader();
+                                    reader.onload = function (ev) {
+                                        let typedArray = new Uint8Array(reader.result);
+                                        pdfjsLib.GlobalWorkerOptions.workerSrc = 'pdfjs/pdf.worker.js'
+                                        pdfjsLib.getDocument(typedArray).promise.then(function (pdf) {
+                                            pdfDoc = pdf;
+                                            totalPages = pdf.numPages;
+                                            renderPage(currentPage);
+                                        });
+                                    };
+                                    reader.readAsArrayBuffer(file);
+                                }
+                            }
+                        });
+
+                        btn2Object.addEventListener('click',function (e){
+
+                            if (currentPage !== totalPages){
+
+                                currentPage=currentPage+1;
+                                pageId.value = currentPage;
+
+                                if (file.type === 'application/pdf') {
+                                    let reader = new FileReader();
+                                    reader.onload = function(ev) {
+                                        let typedArray = new Uint8Array(reader.result);
+                                        pdfjsLib.GlobalWorkerOptions.workerSrc = 'pdfjs/pdf.worker.js'
+                                        pdfjsLib.getDocument(typedArray).promise.then(function(pdf) {
+                                            pdfDoc = pdf;
+                                            totalPages = pdf.numPages;
+                                            renderPage(currentPage);
+                                        });
+                                    };
+                                    reader.readAsArrayBuffer(file);
+                                }
+                            }
+                        });
+
+                        fileInput.addEventListener('change', function(e) {
+
+                            file = e.target.files[0];
+                            if (file.type === 'application/pdf') {
+                                let reader = new FileReader();
+                                reader.onload = function(ev) {
+                                    let typedArray = new Uint8Array(reader.result);
+                                    pdfjsLib.GlobalWorkerOptions.workerSrc = 'pdfjs/pdf.worker.js'
+                                    pdfjsLib.getDocument(typedArray).promise.then(function(pdf) {
+                                        pdfDoc = pdf;
+                                        totalPages = pdf.numPages;
+                                        renderPage(currentPage);
+                                    });
+                                    pageId.value = currentPage;
+
+                                };
+                                reader.readAsArrayBuffer(file);
+                                document.getElementById("pagination-button-container").style.display="flex";
+                                document.getElementById("instruction-text").style.display="block";
+                            }
+                        });
+
+
+                        function renderPage(pageNumber) {
+                            pdfDoc.getPage(pageNumber).then(function(page) {
+                                let viewport = page.getViewport({ scale: 1.0 });
+                                pdfCanvas.width = viewport.width;
+                                pdfCanvas.height = viewport.height;
+
+                                overlayCanvas.width = viewport.width;  // Match overlay canvas size with PDF canvas
+                                overlayCanvas.height = viewport.height;
+
+                                let renderContext = { canvasContext: context, viewport: viewport };
+                                page.render(renderContext);
+                                pdfCanvas.classList.add("shadow-canvas");
+                            });
+                        }
+
+
+
+
+
+                    </script>
+
                 </div>
             </div>
         </div>
     </div>
     <div th:insert="~{fragments/footer.html :: footer}"></div>
-    </div>
+</div>
 </body>
 </html>