Add a point on an image plotted with the function gimage (R package gWidgets)

I'm using the R package gWidgets. I want to add a point on a picture (.jpg).

My code is:

require(jpeg)
require(gWidgets)

options(guiToolkit="RGtk2")
w <- gwindow("test")
gimage("yourpath.jpg",dirname="", container = w,toolkit=guiToolkit("RGtk2"))
da <- w@widget@widget 
callbackID <- gSignalConnect(da,"button-release-event", function 
(w,e,...) { 
# allocation <- w$GetAllocation() 
addHandlerClicked(da, handler = function(h,...) {
})
xclick <- e$GetX() 
yclick <- e$GetY() 
print(xclick)
print(yclick)
points(xclick, yclick) 
pressed <<- FALSE 
return(TRUE) 
})

warning:

plot.new has not been called yet

Could someone help me? Thanks

Solution

warning:

plot.new has not been called yet

Well, that's true isn't it ? In the code above, nowhere is a plot created (using plot() or similar).

Also in your code I cannot see where you create "yourpath.jpg" -- presumably, it is the plot you're trying to draw.

In fact you are trying, it seems, to mix an image and a plot. If you want to include an R plot, what you need is a ggraphics.

Something like that should do what you seem to try and achieve:

library(gWidgets2)
options(guiToolkit="RGtk2")

# Generate some data
xdata<-rnorm(n=5)
ydata<-rnorm(n=5)

gTest<-function(){

#Plotting function
plotf<-function(...){
    plot(xdata,ydata)
}

# Function to add points
.addPoint<-function(h,...){
    points(h$x,h$y,col="red")
}

win <- gwindow("Test")
theplot<-ggraphics(cont=win)

addHandlerClicked(theplot,handler=.addPoint)

Sys.sleep(0.1) # Prevents error with "figure margins too large"

plotf()
}

gTest()

Note that as written, new points are plotted (with points()) but not actually saved. You would need to do, for instance

.addPoint<-function(h,...){
    points(h$x,h$y,col="red")
    xdata<<-c(xdata,h$x)
    ydata<<-c(ydata,h$y)
}

Here with a global assignment, that may or may not be what you need; mostly <<- and global variables are regarded as bad practice, but sometimes it's good enough!