[jira] [Closed] (PDFBOX-5545) PDFTextStripper - Expose a setter for the TextPositionComparator

["Andreas Lehmkühler (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PDFBOX-5545?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andreas Lehmkühler closed PDFBOX-5545.
--------------------------------------
    Assignee: Andreas Lehmkühler

> PDFTextStripper - Expose a setter for the TextPositionComparator
> ----------------------------------------------------------------
>
>                 Key: PDFBOX-5545
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-5545
>             Project: PDFBox
>          Issue Type: Improvement
>          Components: Text extraction
>    Affects Versions: 3.0.0 PDFBox
>            Reporter: Owen McGovern
>            Assignee: Andreas Lehmkühler
>            Priority: Minor
>
> I process a lot of medical related PDF files with a lot of superscripts, subscripts, out of order characters etc.
> We tend to have trouble with the sortByPosition flag in PDFTextStripper.
> If it's not enabled, we end up with characters which are out of order in some PDFs.
> If we do enable it it sometimes messes up superscript and subscript positions.
> Can you expose a setter for the comparator instance, so that I can try to correct it ? E.g. 
>  
> {code:java}
> private Comparator<TextPosition> textPositionComparator = new TextPositionComparator();
>     /**
>      *
>      * @param newTextPositionComparator
>      */
>     public void setTextPositionComparator(final Comparator<TextPosition> newTextPositionComparator) {
>         this.textPositionComparator = newTextPositionComparator;
>     }
>  {code}
> Then in the writePage() method, just use that comparator?
>  
> Users can then potentially inject their own comparator implementation in.
> I want to try to implement a comparator that fixes sorting with subscript/superscript tolerances, eg. something like this (in Kotlin)
>  
> {code:java}
> import mu.KLogging
> import org.apache.pdfbox.text.TextPosition
> import kotlin.math.abs
> class TextPositionSubscriptComparator : Comparator<TextPosition>, KLogging() {
>     override fun compare(pos1: TextPosition, pos2: TextPosition): Int {
>         val textDir = pos1.dir.compareTo(pos2.dir)
>         return if (textDir != 0) {
>             textDir
>         } else {
>             val x1 = pos1.xDirAdj
>             val x2 = pos2.xDirAdj
>             val pos1YBottom = pos1.yDirAdj
>             val pos2YBottom = pos2.yDirAdj
>             val yDifference = abs(pos1YBottom - pos2YBottom)
>             val result = if (yDifference < 0.1f) {
>                 x1.compareTo(x2)
>             } else {
>                 val range1 = Pair(pos1.yDirAdj - OUT_OF_LINE_TOLERANCE, pos1.yDirAdj + pos1.heightDir + OUT_OF_LINE_TOLERANCE)
>                 val range2 = Pair(pos2.yDirAdj - OUT_OF_LINE_TOLERANCE, pos2.yDirAdj + pos2.heightDir + OUT_OF_LINE_TOLERANCE)
>                 if (range1.overlap(range2) || range2.overlap(range1)) {
>                     x1.compareTo(x2)
>                 } else {
>                     if (pos1YBottom < pos2YBottom) -1 else 1
>                 }
>             }
> //            logger.info { "result = $result, [${pos1.unicode}], x1=${pos1.x}, y1=${pos1.y} ---- [${pos2.unicode}], x2=${pos2.x}, y2=${pos1.y}"  }
>             return result
>         }
>     }
>     companion object {
>         private const val OUT_OF_LINE_TOLERANCE = 2f
>     }
> }
> /**
>  * Checks whether a numeric range overlaps with another
>  */
> fun Pair<Float, Float>.overlap(other: Pair<Float, Float>) =
>         !(first > other.second || second < other.first)
> {code}
>  
> It could greatly help if the sorting comparator was configurable.
>  
> regards,
> Owen
>  



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