[Rd] raster support in graphics devices
baptiste.auguie at googlemail.com
Tue Dec 1 19:38:21 CET 2009
Very nice, thank you for this great addition to R graphics! I can't
wait to see lattice and ggplot2 functions that use rasterGrob to
display images. The pdf output is so much better in every way!
Incidentally, I ran into a segfault with grid.cap on the quartz
device, but maybe it's normal at this stage.
This works fine:
cap <- grid.cap()
cap <- grid.cap()
*** caught segfault ***
address 0x18330001, cause 'memory not mapped'
1: .Call(fnname, ..., PACKAGE = "grid")
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
[R.app GUI 1.30 (5527) i386-apple-darwin9.8.0]
R version 2.11.0 Under development (unstable) (2009-11-30 r50622)
attached base packages:
 stats graphics grDevices utils datasets methods base
2009/12/1 Paul Murrell <p.murrell at auckland.ac.nz>:
> 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 sending raster images (bitmaps) to a graphics device. This
> consists mainly of two new device functions: dev_Raster() and dev_Cap().
> The R_GE_version constant (in GraphicsEngine.h) has been bumped up to 6 as a
> marker of this change.
> This means that, at a minimum, all graphics devices should be updated to
> provide dummy implementations of these new functions that just say the
> feature is not yet implemented (see for example the PicTeX and XFig devices
> in the 'grDevices' package).
> A full implementation of dev_Raster() should be able to draw a raster image
> (provided as an array of 32-bit R colors) at any size, possibly (bilinear)
> interpolated (otherwise nearest-neighbour), at any orientation, and with a
> per-pixel alpha channel. Where these are not natively supported by a
> device, the graphics engine provides some routines for scaling and rotating
> raster images (see for example the X11 device). The dev_Cap() function
> should return a representation of a raster image captured from the current
> device. This will only make sense for some devices (see for example the
> Cairo device in the 'grDevices' package).
> A little more information and a couple of small examples are provided at
> Dr Paul Murrell
> Department of Statistics
> The University of Auckland
> Private Bag 92019
> New Zealand
> 64 9 3737599 x85392
> paul at stat.auckland.ac.nz
> R-devel at r-project.org mailing list
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