[jira] [Updated] (PDFBOX-615) shfill operator needs implementation

["Tilman Hausherr (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/PDFBOX-615?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tilman Hausherr updated PDFBOX-615:
-----------------------------------

    Attachment: Type4ShadingPaint.java
                Type4ShadingContext.java

Code for type 4 shading patterns (not shfill, because I don't have a test file) attached, which works for the two adobe tests. I haven't solved the background problem, I don't find anything in the specification how this should be done. It supports only DeviceRGB and not functions. If you want to use the code, first do this:

In PDShadingType4.java correct getFunction:
{code}
    public PDFunction getFunction() throws IOException
    {
        if (function == null)
        {
            COSBase dictionaryFunctionObject = getCOSDictionary().getDictionaryObject(COSName.FUNCTION);
            if (dictionaryFunctionObject != null) //TH
                function = PDFunction.create(dictionaryFunctionObject);
        }
        return function;
    }
{code}

In PDShadingPatternResources.java, insert at case PDShadingResources.SHADING_TYPE4:

{code}
            case PDShadingResources.SHADING_TYPE4:
                if (!(getShading().getColorSpace() instanceof PDDeviceRGB))
                {
                    LOG.error("can't handle Colorspace " + shading.getColorSpace());
                    return null;
                }
                paint = new Type4ShadingPaint((PDShadingType4) getShading(), ctm, pageHeight);
                break;
{code}

Get the Bitinput lib by adding this to the pdfbox pom.xml:
{code}
        <dependency>
            <groupId>com.github.jinahya</groupId>
            <artifactId>bit-io</artifactId>
            <version>1.0.3</version>
        </dependency>
{code}
That lib has an apache 2.0 license :-)

The code works for the two Adobe demo files DECAHED.pdf and TRITYP4.pdf. It does not work for ch14.pdf because 0) that pdf uses shfill 1) the vertex streams in that file don't comply with the pdf spec (however creating a new pdf from the ps file from the homepage  http://www.math.ubc.ca/~cass/graphics/manual/index.html creates a better file), 2) that pdf file has different color spaces than DeviceRGB and I need to learn about these or get help with that segment of the code.

I think that the implementation for type4 shfill would be to use the gouraud triangle mesh as a shape and pass this shape to graphics.fill() in PageDrawer.java, and then again use the existing code. Currently, PageDrawer passes the full page to graphics.fill() which is why the pages 1,13,15 and 20 are black.

I also had a look at type 5 shading spec. The only difference is that the triangles are defined differently (lattice), but the rest is the same, so I will handle this too when I have the time.

> shfill operator needs implementation
> ------------------------------------
>
>                 Key: PDFBOX-615
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-615
>             Project: PDFBox
>          Issue Type: New Feature
>          Components: PDModel
>            Reporter: Daniel Wilson
>            Assignee: Daniel Wilson
>         Attachments: Centerplan.pdf, DECAHED.pdf, Type4ShadingContext.java, Type4ShadingPaint.java, axial-input-after.png, axial-input-before.png, axial-input.pdf, bugzilla843488.pdf, bugzilla843488.pdf-1.png, color_gradient.pdf, color_gradient.pdf-1.png, decahed.pdf-1.png, decahed.pdf-1.png, input.pdf, input1.png, pdfbox-1.8.patch, pdfbox.patch, pslib-shading.pdf, radial-input-after.png, radial-input-before.png, radial-input.pdf, shading_pattern.pdf, shading_pattern.pdf-2.png, trityp4.pdf-1.png
>
>
> I have a PDF file (for which I do not yet have release permission) that uses the "sh" operator, equivalent to PostScript's shfill (per PDF spec 1.7 page 987).
> Adobe provides implementation guidance in a 78-page document at http://www.adobe.com/devnet/postscript/pdfs/TN5600.SmoothShading.pdf#17
> I will be trying to add this functionality this week, but if anyone has hints, suggestions, etc. they are most certainly welcome!



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