[RQt-devel] par(xpd=NA) and the layout approach in qtpaint

[Yihui Xie]

Hi all,

I'm wondering if there are any approaches to completely show the
graphical elements on the boundaries under a layout containing several
layers. This is like the functionality par(xpd=NA) in base R graphics.
See the example below that the texts for the origin (0,0) on the axes
are partially hidden.

My another problem is, I don't really understand the layout approach,
although I've been reading the qtpaint vignette and digging the Nokia
Qt documentations. Specifically, how should we define the coordinate
system in each layer in a layout? (I experimented with mouse clicking
to get locations but got even more confused) With a single layer, I
can plot the data using its range to define the limits and everything
is fine. Besides, does anyone have a working demo to draw a simplest
plot with the layout approach? I struggled with
set(Column|Row)(Maximum|Minimum|Preferred)(Width|Height) and
set(Column|Row)StretchFactor, but they do not behave as we expect them
to, e.g. the stretch factor being 0 will not restrict the height/width
of a layer to be a fixed value -- they change as we resize the window.

Below is the R code:

# I need hints on how to split the root layer into several regions
# and what are their coordinate systems
library(qtpaint)
scene = qscene()
figLayer = qlayer(scene,limits=qrect(0,0,675,550))
titlePainter = function(item, painter) {
    qdrawText(painter, 'The Useless Title', 300, 0,'center','bottom')
    tmp=as.matrix(titleLayer$boundingRect())
    qdrawRect(painter, tmp[1,1],tmp[1,2],tmp[2,1],tmp[2,2])
}
yAxisPainter = function(item, painter) {
    qdrawText(painter, as.character(pretty(1:400)), 37.5, pretty(1:400))
}
plotPainter = function(item, painter) {
    qdrawPoint(painter, runif(1000, 0, 600), runif(1000, 0, 400))
    qdrawRect(painter, 1, 1, 600-1, 400-1)
}
xAxisPainter = function(item, painter) {
    qdrawText(painter, as.character(pretty(1:600)), pretty(1:600), 37.5)
}
mouseLocator = function(item, event){
    print(as.numeric(event$pos()))
}
titleLayer = qlayer(figLayer, titlePainter,
mousePressFun=mouseLocator, row=2,col=1)
yaxis = qlayer(figLayer, yAxisPainter,mousePressFun=mouseLocator,row = 1,col=0)
plotLayer = qlayer(figLayer, plotPainter,
mousePressFun=mouseLocator,row = 1, col = 1)
xaxis = qlayer(figLayer, xAxisPainter, mousePressFun=mouseLocator,row
= 0, col = 1)

layout = figLayer$gridLayout()

layout$setRowMaximumHeight(0, 75)
layout$setRowMinimumHeight(0, 60)
# main plot region: 400x600
layout$setRowPreferredHeight(1, 400)
layout$setRowMaximumHeight(2, 75)
layout$setRowMinimumHeight(2, 60)

layout$setColumnMaximumWidth(0, 75)
layout$setColumnMinimumWidth(0, 60)
layout$setColumnPreferredWidth(1, 600)
layout$setRowStretchFactor(0, 0)
layout$setRowStretchFactor(1, 1)
layout$setRowStretchFactor(2, 0)
layout$setColumnStretchFactor(0, 0)
layout$setColumnStretchFactor(1, 1)

print(view<-qplotView(scene = scene))


#################################################

> sessionInfo()
R version 2.11.1 (2010-05-31)
x86_64-pc-linux-gnu

locale:
[1] en_US.utf8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] qtpaint_0.7.9

loaded via a namespace (and not attached):
[1] qtbase_0.8-4 tools_2.11.1


Thanks a lot!

Regards,
Yihui
--
Yihui Xie <xieyihui at gmail.com>
Phone: 515-294-6609 Web: http://yihui.name
Department of Statistics, Iowa State University
3211 Snedecor Hall, Ames, IA