Add Support for disabling PageScaling in supported PDF Clients

[welfare]

Most PDF clients automatically scales a document if it feels that the document won't fit within the page margins. However, some clients (such as the PDF client in iOS) does not give the user a possibility to disable the print scaling.

This commit adds support to Prawn for disabling print_scaling by supplying the option :print_scaling => :none

[plehoux]

👍

[practicingruby]

This needs documentation in order to be merged, but otherwise looks fine. Please re-open when it is documented, and I'll merge it.

[jlduran]

PrintScaling

(Optional; PDF 1.6) The page scaling option to be selected when a print dialog is displayed for this document. Valid values are None, which indicates that the print dialog should reflect no page scaling, and AppDefault, which indicates that applications should use the current print scaling. If this entry has an unrecognized value, applications should use the current print scaling. Default value: AppDefault.

Note: If the print dialog is suppressed and its parameters are provided directly by the application, the value of this entry should still be used.

@welfare @sandal

[practicingruby]

If this is a feature that is only in PDF 1.6+, I think we'd need a min_version guard in this code. Is that correct @bradediger?

[bradediger]

@sandal Correct. We'd need a min_version(1.6).

[practicingruby]

Okay... so this patch needs a few things then, IMO.

• Add a min_version call to make sure we're setting the right PDF version.
• Wrap lines cleanly at 80 chars
• Use the notes posted above from @jlduran to write appropriate API documentation
• Fix manual example to actually use the option, and set it to not produce output as we do with some of the
  other examples.
• Rewrite manual require to use require_relative
• Resolve merge conflicts

Does someone want to take this up? If you've already got commit access, pushing this code to a branch on prawnpdf and then opening a fresh pull request is the way to go.

[practicingruby]

I'm closing this out again, but will reopen if someone volunteers to work on the above feedback points.

[welfare]

Hey @sandal, I have fixed the following:

• Added a min_version(1.6) if print_scaling is set to :none
• Line wrap everywhere I found > 80 chars in my commits
• Added the notes from @jlduran to the manual
• Fixed the manual example to use the option
• Rebased and resolved conflicts

I pushed the changes to my fork but I'm quite new to github so I have no clue what to do next. Please advise :)

[practicingruby]

What you did looks OK to me. I will probably rebase down to a single commit before merging, but I think I can take it from here. Thanks!

[practicingruby]

Merged, thank you!

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