cairoPsSurfaceDscComment: cairoPsSurfaceDscComment

Description Usage Arguments Details Author(s)

View source: R/cairoFuncs.R

Description

Emit a comment into the PostScript output for the given surface.

Usage

1

Arguments

surface

[CairoSurface] a PostScript CairoSurface

comment

[char] a comment string to be emitted into the PostScript output

Details

The comment is expected to conform to the PostScript Language Document Structuring Conventions (DSC). Please see that manual for details on the available comments and their meanings. In particular, the %IncludeFeature comment allows a device-independent means of controlling printer device features. So the PostScript Printer Description Files Specification will also be a useful reference.

The comment string must begin with a percent character (%) and the total length of the string (including any initial percent characters) must not exceed 255 characters. Violating either of these conditions will place surface into an error state. But beyond these two conditions, this function will not enforce conformance of the comment with any particular specification.

The comment string should not have a trailing newline.

The DSC specifies different sections in which particular comments can appear. This function provides for comments to be emitted within three sections: the header, the Setup section, and the PageSetup section. Comments appearing in the first two sections apply to the entire document while comments in the BeginPageSetup section apply only to a single page.

For comments to appear in the header section, this function should be called after the surface is created, but before a call to cairoPsSurfaceBeginSetup().

For comments to appear in the Setup section, this function should be called after a call to cairoPsSurfaceBeginSetup() but before a call to cairoPsSurfaceBeginPageSetup().

For comments to appear in the PageSetup section, this function should be called after a call to cairoPsSurfaceBeginPageSetup().

Note that it is only necessary to call cairoPsSurfaceBeginPageSetup() for the first page of any surface. After a call to cairoShowPage or cairoCopyPage comments are unambiguously directed to the PageSetup section of the current page. But it doesn't hurt to call this function at the beginning of every page as that consistency may make the calling code simpler.

As a final note, cairo automatically generates several comments on its own. As such, applications must not manually generate any of the following comments:

Header section: %!PS-Adobe-3.0, %Creator, %CreationDate, %Pages, %BoundingBox, %DocumentData, %LanguageLevel, %EndComments.

Setup section: %BeginSetup, %EndSetup

PageSetup section: %BeginPageSetup, %PageBoundingBox, %EndPageSetup.

Other sections: %BeginProlog, %EndProlog, %Page, %Trailer, %EOF

Here is an example sequence showing how this function might be used:

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surface <- cairoPsSurfaceCreate(filename, width, height)
# ...
surface$dscComment("%Title: My excellent document")
surface$dscComment("%Copyright: Copyright (C) 2006 Cairo Lover")
# ...
surface$dscBeginSetup()
surface$dscComment("%IncludeFeature: *MediaColor White")
# ...
surface$dscBeginPageSetup()
surface$dscComment("%IncludeFeature: *PageSize A3")
surface$dscComment("%IncludeFeature: *InputSlot LargeCapacity")
surface$dscComment("%IncludeFeature: *MediaType Glossy")
surface$dscComment("%IncludeFeature: *MediaColor Blue")
# ... draw to first page here ..
cr$showPage()
# ...
surface$dscComment(surface, "%IncludeFeature: *PageSize A5")
# ...

Since 1.2

Author(s)

Derived by RGtkGen from GTK+ documentation


RGtk2 documentation built on May 30, 2017, 5:53 a.m.