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https://issues.apache.org/jira/browse/PDFBOX-577?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12883860#action_12883860
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Karl Ward commented on PDFBOX-577:
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Not so much copied as implied from. I doubt that would be an issue.
But thanks for pointing out the existing methods. It's a shame
PDFontDescriptorDictionary#getDescent() does not account for the common problem
of an incorrectly positive value. Perhaps a reading of prior work, such as
xpdf, would have been beneficial here.
> TextPosition should expose its bounding box
> -------------------------------------------
>
> Key: PDFBOX-577
> URL: https://issues.apache.org/jira/browse/PDFBOX-577
> Project: PDFBox
> Issue Type: Improvement
> Reporter: Villu Ruusmann
> Attachments:
> 0001-PDFont.java-Add-methods-to-retreive-the-Ascent-and-D.patch,
> AFM-getHeight.png, AFM-getUpperRightY.png
>
>
> It does not seem to be possible to calculate the bounding box of a
> TextPosition.
> IIUC, TextPosition#getY is the baseline of the text and
> TextPosition#getHeight is the absolute height of the text. When I subtract
> the latter from the former I get a top line, but this is only correct if the
> text does not contain descender characters.
> Below is a screenshot (AFM-getHeight.png) which shows the bounding boxes of
> TextPositions calculated as {#getX(), #getY() - #getHeight, #getWidth,
> #getHeight} painted in random colors. For example, the bounding boxes of
> parentheses are severely misplaced, which makes the line-by-line text
> extraction impossible.
> Right now I've solved the problem by tweaking AFM FontMetrics code so that it
> returns BoundingBox#getUpperRightY instead of BoundingBox#getHeight when
> queried via PDSimpleFont#getFontHeight(byte[], int, int). Another screenshot
> (AFM-getUpperRightY.png) shows how this restores the previously broken text
> extraction ability.
> It seems like a good idea to rework TextPosition so that it would be aware of
> its bounding box:
> *) Replace methods PDSimpleFont#getFontWidth(byte[], int, int) and
> PDSimpleFont#getFontHeight(byte[], int, int) with a single method
> PDSimpleFont#getFontBoundingBox(byte[], int, int)
> *) Replace the constructor TextPosition(Matrix, Matrix) with
> TextPosition(Matrix, BoundingBox)
> *) Add new methods TextPosition#getBoundingBox,
> TextPosition#getBoundingBoxDir. This shouldn't affect existing application
> clients, because TextPosition#getY and TextPosition#getHeight remain in place.
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