[RQt-devel] Fwd: [Rd] support for polygons with holes

[Michael Lawrence]

Does anyone think this would be useful to have in qtpaint? It would mean
adding a new primitive type, the path.

---------- Forwarded message ----------
From: Paul Murrell <p.murrell at auckland.ac.nz>
Date: Sun, Jun 27, 2010 at 2:42 PM
Subject: [Rd] support for polygons with holes
To: "r-devel at r-project.org" <r-devel at r-project.org>


Hi

This is for developers of extension packages that provide extra
*graphics devices* for R.

In the *development* version of R, support has been added to the
graphics engine for rendering polygons with holes (e.g., maps with lakes
with islands ...).

The API change is a new dev_Path() function for graphics devices.

The R_GE_version constant (in GraphicsEngine.h) has been bumped up to 8
as a marker of this change.

This means that, at a minimum, all graphics devices should be updated to
provide dummy implementations of the new functions to just say that the
feature is not yet implemented (see for example the PicTeX and XFig
devices in the 'grDevices' package).

A full implementation of dev_Path() should be able to render paths that
consist of multiple sub-paths which can be filled using either the even-odd
rule or the non-zero winding rule (see the examples in polypath() from
'graphics' or grid.path() from 'grid').

Paul
-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
paul at stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/<http://www.stat.auckland.ac.nz/%7Epaul/>

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