熊田貢 <kumata-mit <at> obun.jp> writes:
>
> Hello all,
>
> I have a question about soft-mask.
> I know there is a sample code "SoftMask.java", but I
> want to know how to achieve soft-mask using gradation
> composed of path lines as mask.
>
> For example, if I have the following mask;
>
> for(int i=0; i<10; i++) {
> template.setLineWidth(10-i);
> template.setGrayStroke(1-(0.1f*i));
> template.ellipse(0, 0, 100, 100);
> template.stroke();
> }
> template.ellipse(0, 0, 100, 100);
> template.clip();
Clipping and masking are two different things.
> how to apply the mask to a photo?
> Is it impossible?
No, but it isn't directly supported by iText. You'll need to read the
PDFReference and do some direct PdfDictionary manipulation.
>
> I tried "PdfGState#setAlphaIsShape(false)", but I could
> not get good result.
>
You'll need to create an XObject Form (a PdfTemplate) with the mask shape you
want, and build a "soft mask dictionary", as defined in the Pdf Reference
(chapter 7.5, table 7.10). Something like this:
<<
/Type /Mask
/S /Luminosity
/G 999 0 R %% an indirect reference to that XObject Form I mentioned
>>
You then write this dictionary into the PdfGState's /SMask key.
The XObject Form houses your blended path for the mask. I strongly suggest you
draw it in DeviceG (gray) color. You'll need to set the PdfTemplate's
PdfTransparencyGroup.
PdfGState state = new PdfGState();
PdfDictionary maskDict = new PdfDictionary();
maskDict.put( PdfName.TYPE, PdfName.MASK );
maskDict.put( PdfName.S, new PdfName( "Luminosity" ) );
maskDict.put( PdfName.G, template.getIndirectReference() );
state.put( PdfName.SMASK, maskDict );
PdfTransparencyGroup transGroup = new PdfTransparencyGroup();
transGroup.put( PdfName.CS, PdfName.DEVICEGRAY );
template.setGroup( transGroup );
That should do it, though I'm none too certain about the DEVICEGRAY entry in the
transGroup. It may not be necessary, or it may need to be DEFAULTGRAY instead.
(hmm... I really ought to charge for this stuff ;)
--Mark Storer
Senior Software Engineer
Cardiff.com
#include <disclaimer>
typedef std::disclaimer<Cardiff> DisCard;
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