Details
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Improvement
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Status: Closed
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Major
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Resolution: Invalid
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None
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Description
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.
