Roderick McMullen created BATIK-1379:
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Summary: Problems generating SVG with PdfBox PDFRenderer and Batik
SVGGraphics2D for PDF with extended graphics state soft mask (/SMask), stroking
alpha (/CA) and non-stroking alpha (/ca)
Key: BATIK-1379
URL: https://issues.apache.org/jira/browse/BATIK-1379
Project: Batik
Issue Type: Bug
Affects Versions: 1.18
Reporter: Roderick McMullen
Attachments: batik-alpha-issue-180.zip,
screen-capture-fully-transparent-column.png,
screen-capture-mask-applied-twice.png,
screen-capture-mask-not-shifted-up-enough.png
We subclass {{org.apache.batik.svggen.DefaultExtensionHandler}} to handle PDF
soft masks when rendering to SVG with PdfBox (2.0.33) PDFRenderer and Batik
(1.18) SVGGraphics2D.
Compared with the original PDF and rendered PNG created with pdfbox, the
generated SVG looks different:
* The computed soft mask recovered contains some unexpected, fully transparent
rows and columns. (See attachment
[^screen-capture-fully-transparent-column.png])
* The alpha mask placement is (slightly) vertically misaligned compared to the
PDF/PNG. (See attachment [^screen-capture-mask-not-shifted-up-enough.png])
How might these visual differences be avoided?
Additionally, the soft mask {{SVGPaintDescriptor}} object returned with this
extension is applied to two SVG {{g}} elements (instead of one) which results
more dramatic differences when compared to the PDF/PNG. (See attachment
[^screen-capture-mask-applied-twice.png])
To work around this, our override to {{SVGPaintDescriptor.getAttributeMap()}}
counts read attempts and returns an empty attribute map after the first use.
What correction should we make to avoid needing this workaround? Or is this a
batik issue?
Sample code, input PDF, and output SVG and PNG are included. (See attachment
[^batik-alpha-issue-180.zip])
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