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https://issues.apache.org/jira/browse/PDFBOX-4597?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16890124#comment-16890124
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Michael Klink edited comment on PDFBOX-4597 at 7/22/19 1:53 PM:
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{quote}[~tilman] (to add to the mystery, results for non quadrant rotations are
undefined).
{quote}
Well, an attempt is made to treat transformations that dominantly are scaled
rotations (scaling in x and y directions may differ) as the underlying
rotation. This intends to select the multiple of 90° nearest to the actual
direction as long as the result is not mirrored or too badly skewed. Otherwise
there is a default of 0°.
Thus, the results are not _undefined_. For some borderline values, though, the
result might not really be intuitive...
IMO a better implementation would have been to calculate the actual text
direction angle (i.e. apply the matrix to (1,0,1) and (0,0,1) and calculate the
atan of the difference), select the nearest multiple of 90°; then calculate the
determinant; if it is negative, add 180° (mod 360°).
But now changing it might break some applications.
was (Author: mkl):
{quote}[~tilman] (to add to the mystery, results for non quadrant rotations are
undefined).
{quote}
Well, an attempt is made to treat transformations that dominantly are scaled
rotations (scaling in x and y directions may differ) as the underlying
rotation. This intends to select the multiple of 90° nearest to the actual
direction as long as the result is not mirrored or too badly skewed. Otherwise
there is a default of 0°.
Thus, the results are not _undefined_. For some borderline values, though, the
result might not really be intuitive...
IMO a better implementation would have been to calculate the actual text
direction angle (i.e. apply the matrix to (1,0,1) and calculate the atan),
select the nearest multiple of 90°; then calculate the determinant; if it is
negative, add 180° (mod 360°).
But now changing it might break some applications.
> TextPosition.getX() vs getXDirAdj()
> -----------------------------------
>
> Key: PDFBOX-4597
> URL: https://issues.apache.org/jira/browse/PDFBOX-4597
> Project: PDFBox
> Issue Type: Improvement
> Components: Documentation, Text extraction
> Affects Versions: 2.0.15
> Reporter: Gili
> Priority: Major
> Attachments: rot90.pdf
>
>
> Please explain the difference between "page rotation adjusted coordinates"
> and "text direction adjusted coordinates" as referenced by the TextPosition
> class. You can add an explanation (ideally a visual one) to the class or
> method Javadoc.
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