raster support in graphics devices

Its not just the time.  Its also the nuisance of having to manage files that
I never needed in the first place.

On Fri, Dec 4, 2009 at 11:01 AM, Romain Francois <romain.francois at dbmail.com

wrote:

On 12/04/2009 03:19 PM, Gabor Grothendieck wrote:

Thanks.

I am looking for the data to be just as if I had read in the png file (or
wmf file or whatever).

Hi,

You are after the binary payload of the rendered graph as a png file. So
you are going to have to go through a png file.

It would be nice to be able to render to a binary connection, like a
rawConnection, but it seems like an expensive "nice to have"


 grid.cap seems to give a bitmap and then would

require some sort of processing to get the png or wmf, etc. form.  Also
note
that I need it for classic graphics and not just grid graphics.

grid.cap does not seem to care, baptiste code uses traditional graphics


 What I have right now works just as I want it _except_ I have to create a

file and then read it back in which seems a waste.

Can you measure the time it takes to do dev.off() and readBin ?


 On Fri, Dec 4, 2009 at 9:06 AM, baptiste auguie<

baptiste.auguie at googlemail.com>  wrote:

 Hi,

You can use grid.cap,

x11()
plot(1:10)
g = grid.cap()
dev.off()
str(g)
# chr [1:672, 1:671] "white" "white" "white" "white" "white" ...

but as far as I understand in ?grid.cap and the underlying code there
is no "capGrob" equivalent that wouldn't require opening a new device
before capturing the output.

 I hope I'm mistaken.

Best,

baptiste

2009/12/4 Gabor Grothendieck<ggrothendieck at gmail.com>:

Currently I have an application that saves the current graphics image

(that

was created with classic graphics or grid graphics) to a file and then

reads

the file back in using readBin:

png("my.png")
plot(1:10)
dev.off()
raw.img<- readBin("my.png", "raw", size = 1, n = 100000000)

(I am doing this on Windows but would like to be able to do it on any
platform.)

Does the new raster functionality give me any way to get the object

raw.img

without creating the intermediate file, my.png?  If so what is the
corresponding code?


On Mon, Nov 30, 2009 at 8:17 PM, Paul Murrell<p.murrell at auckland.ac.nz
wrote:

 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 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
http://developer.r-project.org/Raster/raster-RFC.html

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/>
<http://www.stat.auckland.ac.nz/%7Epaul/>

<http://www.stat.auckland.ac.nz/%7Epaul/>

--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
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