Missing line width calculations

[Sharpie]

As reported by Baptiste Auguie:

A simple plot of several lines with various thicknesses using grid graphics:

require(grid)
require(tikzDevice)

tikz('line_width.tex', standAlone = TRUE)
plot.new()
segments(0,seq(-1,1,by=0.2),1,seq(-1,1,by=0.2),lwd=seq(0.2,by=0.2,length=11))
dev.off()

Produces output with far less variation in line thickness than the lwd parameter would suggest:

\draw[color=drawColor,line cap=round,line join=round,fill opacity=0.00,] ( 65.18,  2.61) -- (464.71,  2.61);

\draw[color=drawColor,line cap=round,line join=round,fill opacity=0.00,] ( 65.18, 75.85) -- (464.71, 75.85);

\draw[color=drawColor,line cap=round,line join=round,fill opacity=0.00,] ( 65.18,149.09) -- (464.71,149.09);

\draw[color=drawColor,line cap=round,line join=round,fill opacity=0.00,] ( 65.18,222.33) -- (464.71,222.33);

\draw[color=drawColor,line cap=round,line join=round,fill opacity=0.00,] ( 65.18,295.56) -- (464.71,295.56);

\draw[color=drawColor,line width= 0.8pt,line cap=round,line join=round,fill opacity=0.00,] ( 65.18,368.80) -- (464.71,368.80);

\draw[color=drawColor,line width= 0.8pt,line cap=round,line join=round,fill opacity=0.00,] ( 65.18,442.04) -- (464.71,442.04);

The parameter values passed to TikZ_Line in plotParams->lwd are:

1.0000
1.2000
1.4000
1.6000
1.8000
2.0000
2.2000

[Sharpie]

At the C level, R uses pGEcontext, a pointer to a structure, to store plot information. The line width is encoded in pGEcontext->lwd which is of type double. The code in the tikzDevice responsible for calculating and printing line widths was declaring lwd to be of type int. This resulted in calculations that were either incorrect or ignored.

[Sharpie]

Fixed in Sharpie/RTikZDevice@082cdf8c501bf69696bff6a57ddca6caa5b1f932