Scaling PDF output

Core Library Questions

Jo Wood

in Core Library Questions • 2 years ago

I need to be able to output from a sketch to PDF. The output is a mixture of vector lines and text and raster images. This in itself is not a problem using the standard approach of creating a PGraphicsPDF object:

PGraphicsPDF pdf = (PGraphicsPDF)createGraphics(pWidth, Math.round(pWidth*1.41f), PDF, "report.pdf");

In order to maintain a decent resolution for my raster images (ie greater than 72 dpi), I have to set fairly large pWidth (e.g. 2000 pixels). This will produce the desired level of detail in the PDF, but the document itself is then way bigger than the A4 I need for output.

I realise I can scale down the PDF when printing so that it fits on an A4 page, but my question is, is there any way of creating a PDF with a resolution of greater than 72 dpi that is A4 size by default?

Replies(2)

PhiLho

Re: Scaling PDF output

2 years ago

A1 is defined in iText as 1684 , 2384

Apparently , there is not such thing as DPI in PDF.

Jo Wood

Re: Scaling PDF output

2 years ago

Thanks. I was about to reply that yes, I know how many pixels would give A4 (or A1) sized output. But I see you are right about the DPI issue not being quite relevant to PDF output.

I think I was misled by the documentation for PDF output which says

Images don't look great, mostly because of the difference of expectations in how a PDF should look (scalable and high res) versus what happens when image data is written to it at 72 dpi.

Setting my PGraphicsPDF object to 595 pixels wide (A4 at a nominal 72dpi) seems to be able to display PImage objects of a much larger size. When a large PImage is drawn to fit within the PGraphicsPDF object, it would appear to preserve the detail of the image. This is exactly what I had hoped for, so perhaps the assertion in the PDF documentation above is no longer valid?

Thanks for the pointer too to iText - I didn't realise that was where the PDF stuff used by Processing was actually happening.

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