Hi
Two points:
1. grid.remove() redraws the entire scene (and because the drawing is
slow you see a flicker)
2. Doing this ...
dev.hold()
grid.gremove("lastShape")
dev.flush()
... may reduce flicker for you.
Paul
On 07/25/13 06:10, Daniel Guetta wrote:> I'm designing an interactive plot using the `grid` package in R. As
> part of the interactivity, I repeatedly delete and re-create various
> parts of the plot. However, the total number of grid elements (as
> obtained using the `grid.ls()` command) stays constant; everything I
> create was previously removed.
>
> The problem is as follows - once I've gone through a few cycles of
> creation and deletion, every deletion I make to the graphic, however
> small, causes all the interactive parts of the plot (those I've been
> repeatedly deleting and creating) to flicker.
>
> Here's the simplest example I could come up with - first run this code
> to set up the `grid` graphic, and repeatedly delete and re-create
> certain elements
>
> ###############################
>
> library(grid)
>
> pushViewport(viewport())
>
> for (x in seq(0, 1, length=5))
> {
> for (y in seq(0, 1, length=5))
> {
> pushViewport(viewport(x = x, y = y, width=1/5, height=1/5,
> name=paste("foo", x, y, sep="")))
> grid.rect()
>
> pushViewport(viewport(x = 0, 0, width=1/4, height=1/4,
name="bar1"))
> grid.circle(name="testing")
> grid.text("123")
> upViewport()
>
> pushViewport(viewport(x = 1, 0, width=1/4, height=1/4,
name="bar2"))
> grid.circle(name="testing")
> grid.text("123")
> upViewport()
>
> pushViewport(viewport(x = 0, 1, width=1/4, height=1/4,
name="bar3"))
> grid.circle(name="testing")
> grid.text("123")
> upViewport()
>
> pushViewport(viewport(x = 1, 1, width=1/4, height=1/4,
name="bar4"))
> grid.circle(name="testing")
> grid.text("123")
> upViewport()
>
> upViewport()
> }
> }
>
> for (i in 1:10)
> {
>
> grid.gremove("testing")
>
> for (x in seq(0, 1, length=5))
> {
> for (y in seq(0, 1, length=5))
> {
> downViewport(paste("foo", x, y, sep=""))
>
> downViewport("bar1"); grid.circle(name="testing");
upViewport()
> downViewport("bar2"); grid.circle(name="testing");
upViewport()
> downViewport("bar3"); grid.circle(name="testing");
upViewport()
> downViewport("bar4"); grid.circle(name="testing");
upViewport()
>
> upViewport()
> }
> }
>
> }
>
> ###############################
>
> Once this is all set up, create a new arbitrary square on the device
>
> ###############################
> grid.rect(height=0.5, width=0.5, gp=gpar(lty = 2), name =
"lastShape")
> ###############################
>
> Now try to delete it
>
> ###############################
> grid.gremove("lastShape")
> ###############################
>
> Notice that when you run this last deletion command, all the small
> circles that I've been creating and deleting flicker slightly, even
> though I haven't touched them. This makes the entire graphic very
> distracting.
>
> The thing is, if I don't delete and re-create the original graphics so
> many times, this doesn't happen! So I figure I must be leaving a trail
> somewhere because of inefficient deleting.
>
> Any ideas how to prevent that?
>
> Thanks a million!
>
> ------------------------------------------------------
>
> Daniel Guetta
> PhD Candidate, Columbia University
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
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/