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https://issues.apache.org/jira/browse/PDFBOX-2831?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14593551#comment-14593551
]
ASF subversion and git services commented on PDFBOX-2831:
---------------------------------------------------------
Commit 1686438 from [~tilman] in branch 'pdfbox/trunk'
[ https://svn.apache.org/r1686438 ]
PDFBOX-2831: avoid ArrayIndexOutOfBoundsException if diacritic on ligature
> ArrayIndexOutOfBoundsException in mergeDiacritic() on extraction of text with
> diacritic text
> --------------------------------------------------------------------------------------------
>
> Key: PDFBOX-2831
> URL: https://issues.apache.org/jira/browse/PDFBOX-2831
> Project: PDFBox
> Issue Type: Bug
> Components: Text extraction
> Affects Versions: 1.8.9, 1.8.10, 2.0.0
> Reporter: Andreas Meier
> Priority: Minor
> Attachments: PDFBOX-2831.pdf, chya31marked.jpg
>
>
> PDFBox may fail on extraction of text in method mergeDiacritic(TextPosition
> diacritic):
> {code}
> Caused by: java.lang.ArrayIndexOutOfBoundsException: 1
> at
> org.apache.pdfbox.text.TextPosition.mergeDiacritic(TextPosition.java:532)
> at
> org.apache.pdfbox.text.PDFTextStripper.processTextPosition(PDFTextStripper.java:945)
> at
> org.apache.pdfbox.text.PDFTextStreamEngine.showGlyph(PDFTextStreamEngine.java:229)
> at
> org.apache.pdfbox.contentstream.PDFStreamEngine.showText(PDFStreamEngine.java:683)
> at
> org.apache.pdfbox.contentstream.PDFStreamEngine.showTextStrings(PDFStreamEngine.java:593)
> at
> org.apache.pdfbox.contentstream.operator.text.ShowTextAdjusted.process(ShowTextAdjusted.java:38)
> at
> org.apache.pdfbox.contentstream.PDFStreamEngine.processOperator(PDFStreamEngine.java:795)
> at
> org.apache.pdfbox.contentstream.PDFStreamEngine.processStreamOperators(PDFStreamEngine.java:462)
> at
> org.apache.pdfbox.contentstream.PDFStreamEngine.processStream(PDFStreamEngine.java:438)
> at
> org.apache.pdfbox.contentstream.PDFStreamEngine.processPage(PDFStreamEngine.java:149)
> at
> org.apache.pdfbox.text.PDFTextStreamEngine.processPage(PDFTextStreamEngine.java:117)
> at
> org.apache.pdfbox.text.PDFTextStripper.processPage(PDFTextStripper.java:369)
> at
> org.apache.pdfbox.text.PDFTextStripper.processPages(PDFTextStripper.java:305)
> at
> org.apache.pdfbox.text.PDFTextStripper.writeText(PDFTextStripper.java:249)
> at
> org.apache.pdfbox.text.PDFTextStripper.getText(PDFTextStripper.java:210)
> ... 8 more
> {code}
> The exception is thrown, because variable "unicode" contains two diacritic
> signs (for example: arabic shaddah U+0651 and arabic fathah U+064E, unicode
> length = 2), while array "widths" only contains one entry at that time(
> [x.xxxxxxxx] ).
> Temporary workaround could be to check the size of the array:
> (does not address the actual problem, that unicode and widths variable drift
> apart)
> {code}
> /**
> * Merge a single character TextPosition into the current object. This is
> to be used only for
> * cases where we have a diacritic that overlaps an existing
> TextPosition. In a graphical
> * display, we could overlay them, but for text extraction we need to
> merge them. Use the
> * contains() method to test if two objects overlap.
> *
> * @param diacritic TextPosition to merge into the current TextPosition.
> */
> public void mergeDiacritic(TextPosition diacritic)
> {
> if (diacritic.getUnicode().length() > 1)
> {
> return;
> }
> float diacXStart = diacritic.getXDirAdj();
> float diacXEnd = diacXStart + diacritic.widths[0];
> float currCharXStart = getXDirAdj();
> int strLen = unicode.length();
> boolean wasAdded = false;
> for (int i = 0; i < strLen && !wasAdded; i++)
> {
> if (i <= (widths.length - 1))
> {
> float currCharXEnd = currCharXStart + widths[i];
> // this is the case where there is an overlap of the
> diacritic character with the
> // current character and the previous character. If no
> previous character, just append
> // the diacritic after the current one
> if (diacXStart < currCharXStart && diacXEnd <= currCharXEnd)
> {
> if (i == 0)
> {
> insertDiacritic(i, diacritic);
> }
> else
> {
> float distanceOverlapping1 = diacXEnd -
> currCharXStart;
> float percentage1 = distanceOverlapping1/widths[i];
> float distanceOverlapping2 = currCharXStart -
> diacXStart;
> float percentage2 = distanceOverlapping2/widths[i -
> 1];
> if (percentage1 >= percentage2)
> {
> insertDiacritic(i, diacritic);
> }
> else
> {
> insertDiacritic(i - 1, diacritic);
> }
> }
> wasAdded = true;
> }
> // diacritic completely covers this character and therefore
> we assume that this is the
> // character the diacritic belongs to
> else if (diacXStart < currCharXStart && diacXEnd >
> currCharXEnd)
> {
> insertDiacritic(i, diacritic);
> wasAdded = true;
> }
> // otherwise, The diacritic modifies this character because
> its completely
> // contained by the character width
> else if (diacXStart >= currCharXStart && diacXEnd <=
> currCharXEnd)
> {
> insertDiacritic(i, diacritic);
> wasAdded = true;
> }
> // last character in the TextPosition so we add diacritic to
> the end
> else if (diacXStart >= currCharXStart && diacXEnd >
> currCharXEnd && i == strLen - 1)
> {
> insertDiacritic(i, diacritic);
> wasAdded = true;
> }
> // couldn't find anything useful so we go to the next
> character in the TextPosition
> currCharXStart += widths[i];
> } else {
> // problem: unicode length and widths size differ
> }
> }
> }
> {code}
> This problem only happened on arabic texts so far. Since there is no evidence
> that it will occur only in arabic text I did not attach it to another issue.
> Further investigation needed.
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