[RQt-devel] mosaiq

[Deepayan Sarkar]

Hi,

mosaiq is up and running again, more or less as it was back in DSC 2009.

I will keep working to improve it. The most distracting oddity at the
moment is that the space allocation for rows / columns in the
QGraphicsLayout seems to depend on the number of layers (or
something). E.g.,

tmp <- rlnorm(100)
df <- data.frame(x = runif(200),
                 y = c(tmp, 2 * tmp),
                 g = gl(2, 100))

## No axis on bottom row (OK without the 'alternating' argument)
library(mosaiq)
mosaiq.xyplot(x, y, margin = ~g, data = df, layout = c(1, 2),
              alternating = list(y = c(1, 0)))


I have been using QGridLayout::setRowStretchFactor() etc. to control
the spacing. Any suggestions for alternatives?


Another thing I find less than ideal is that there are way too many
calls to the paintFun. This is a problem when individual panels are
expensive to draw. A simple demo (using 'df' above):

mosaiq.xyplot(x, y+runif(length(y)), margin = ~g, data = df, layout =
c(1, 1, 2))

Switching between the tabs cause a repaint each time, which I think
should be avoided if possible. This is of course a silly example, but
see the last example in mosaiq/demo/maps.R for a real example where
redrawing is visibly slow.

Isn't it possible to set up a cache mode where such repaints are
redrawn from a pixmap rather than causing an R callback? On my (KDE)
system the redraw really seems to be triggered by a change in focus to
or from the view (even if the window is completely visible while that
happens), but not by expose events.

-Deepayan