cairobasic
is a package which provides a fast canvas for drawing
operations.
This is a really demonstration package showing how cairocore may be made more palatable for programming within R.
This package currently only offers some basic drawing tools, but could easily be forked/expanded to suit different needs.
To get the most out of CairoGraphics at this stage, you would still need
to use cairocore
, but cairobasic
will accumulate features based upon
user feedback.
You can install from GitHub with:
# install.package('remotes')
remotes::install_github('coolbutuseless/cairobasic')
The cairobasic
package provides an
R6 class (CairoBasic
) which
keeps track of context information for rendering and the actual
rendering surface.
library(cairobasic)
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Create a new 'CairoBasic' object
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
width <- 800
height <- 400
cb <- CairoBasic$new(width = width, height = height)
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Add concentric circles
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
N <- 10
cb$add_circles(
x = rep(width/2, N),
y = 0,
r = seq(width, 0, length.out = N),
fill = '#80808020'
)
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Add Lines with rainbow colouring
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
N <- 500
cb$add_line_segments(
x1 = rep(width/2, N),
y1 = 0,
x2 = seq(1, width, length.out = N),
y2 = height,
colour = rainbow(N, alpha = 0.1)
)
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Add rectangles
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
N <- 10
xy <- expand.grid(x = seq(1, width/2, width/32), y = seq(1, height, width/32))
xy <- subset(xy, y < width/2 - x - width/16)
cb$add_rectangles(
x = xy$x,
y = xy$y,
width = width/32,
height = width/32,
fill = terrain.colors(nrow(xy)),
colour = '#20202020'
)
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Add polygons
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cx <- width * 0.85
cy <- height * 0.35
ang <- seq(0, 2*pi, pi/3)
x1 <- cx + 50 * sin(ang)
y1 <- cy + 50 * cos(ang)
x2 <- cx + 60 * sin(ang)
y2 <- cy + 60 * cos(ang)
x <- c(x1, x2)
y <- c(y1, y2)
idx <- as.integer(c(1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2))
cb$add_polygons(
x, y, idx, fill = NA,
linewidth = 5,
colour = c('red', 'blue'))
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Add Text
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cb$add_text("{cairobasic}", width*0.65 + 1, 10, fontsize = 50, colour = 'white')
cb$add_text("{cairobasic}", width*0.65 , 11, fontsize = 50, colour = '#606060a0')
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Show it
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cb$show(interpolate = TRUE)
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Save to PNG
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cb$write_png("output.png")
Read the cairocore README for more information
library(cairocore)
cairo_set_source_rgba(cb$cr, 1, 0, 0, 0.3)
cairo_set_line_width(cb$cr, 10)
cairo_set_dash(cb$cr, c(10, 15, 25), 3, 0)
cairo_rectangle(cb$cr, 100, 100, width-200, height-200)
cairo_stroke(cb$cr)
cb$show()
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- CRAN maintainers, for patiently shepherding packages onto CRAN and maintaining the repository