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https://issues.apache.org/jira/browse/PDFBOX-1960?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13922745#comment-13922745
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John Hewson commented on PDFBOX-1960:
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{quote}
The only reason is that you are comparing with AffineTransform and the
expectation that it should behave the same, which it can’t because of it’s
different definition. A Matrix is defined in the PDF spec, the AffineTransform
is not. It’s a Java AWT concept not a PDF one.
{quote}
Maruan, let's be clear, these two matrices _are doing the exact same thing_,
just transposed. It's the same as turning your head 90 degrees and solving the
same equation. The difference which this does cause however is that flipping
rows and columns means that pre/post multiply flip their meaning.
AffineTransform does things the smart way by making it impossible to do the
multiplication (concatenation) wrong, we should do the same.
> Matrix and AffineTransform have confusing differences
> -----------------------------------------------------
>
> Key: PDFBOX-1960
> URL: https://issues.apache.org/jira/browse/PDFBOX-1960
> Project: PDFBox
> Issue Type: Improvement
> Affects Versions: 2.0.0
> Reporter: John Hewson
> Assignee: Maruan Sahyoun
> Priority: Minor
>
> I've been driven insane recently by trying to get pattern fills to render
> correctly. Patterns have their own matrix which is concatenated to the CTM
> and no matter how I applied the transformation, the results were wrong.
> It turns out that org.apache.pdfbox.util.Matrix is not behaving as expected,
> here's an example from a pattern I'm working on. I performed the same
> concatenation (i.e. multiplication) using our Matrix and Java's
> AffineTransform, the results are as follows:
> Java AffineTransform:
> [[2.0, 0.0, 1.251E-12], [0.0, 2.0, 1684.0]] *
> [[0.6, 0.0, 302.6], [0.0, 0.6, 1091.38]] =
> [[1.2, 0.0, 605.2000000000013], [0.0, 1.2, 3866.76]]
> PDFBox Matrix:
> [[2.0,0.0,0.0][0.0,2.0,0.0][1.251E-12,1684.0,1.0]] *
> [[0.6,0.0,0.0][0.0,0.6,0.0][302.6,1091.38,1.0]] =
> [[1.2,0.0,0.0][0.0,1.2,0.0][302.6,2101.78,1.0]]
> I suggest that we remove Matrix and replace it with AffineTransform.
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