Export to PDF should support transparent background

[aparamon]

Current Behavior

Preview export to PDF always saves background rect.

Expected Behavior

There should be an option to have transparent background, like when exporting PNG.

Your Environment

• Product Version: Gephi 0.9.2 201709241107
• Java: 1.8.0_201; Java HotSpot(TM) 64-Bit Server VM 25.201-b09
• Runtime: Java(TM) SE Runtime Environment 1.8.0_201-b09
• System: Windows 10 version 10.0 running on amd64; Cp1252; en_US (gephi)
• User directory: C:\Users\paramon\AppData\Roaming.gephi\0.9.2\dev
• Cache directory: C:\Users\paramon\AppData\Roaming.gephi\0.9.2\dev\var\cache

[mbastian]

Makes sense, let me summarise.

Definition of done

• Add option to PDF configuration panel for transparent background. Makes sure this configuration is also saved in preferences like the others.
• Modify PDF export accordingly

[Meta-Ace]

To my understanding and through trial and error this feature does not seem possible! I have exported images from other programs with a "transparent" background, and when the PDF is opened, they white rectangle is drawn in. Changing the alpha to 0 and making the canvas transparent both still resulted in the white rectangle being drawn. I believe this is due to the fact that PDF requires there to be a canvas, as opposed to PNG which acts as a bitmap. This is my current understanding, if you know otherwise please feel free to reach out

[mbastian]

Thanks @Meta-Ace. How did you actually check whether the PDF has transparent background? In which program? Based on my own research it does seem that PDFs can have transparent backgrounds.

[Meta-Ace]

Come had a program that already supported exporting transparent backgrounds, I don't know which exactly and we selected transparent background for PDF and when we opened it it was a white background. I would have to ask him which program it was.

[mbastian]

Hi again, I did a bit more research and was able to create PDF with transparent background. I think you didn't have the proper software to actually check that it's transparent - hence the confusion. I found this trick with Acrobat Reader settings. If you check this it will show a grid when transparent

Then by commenting out line size.setBackgroundColor(new BaseColor(col.getRed(), col.getGreen(), col.getBlue())); on PDFExporter class you should get a transparent background.

[mbastian]

Added new checkbox in PDF config menu