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While the point of a graphics device is usually to render the graphics, there
are a few situations where you are instead interested in only capturing the
instructions required to render the graphics. While all graphics devices can
be retrofitted for that using dev.control()
, they would still render to
their internal buffer even if you are only interested in the recorded
instructions, thus adding a performance penalty. agg_record()
is a device
that does no rendering whatsoever, but has recording turned on by default
making it a no-overhead solution for plot recording.
agg_record(
width = 480,
height = 480,
units = "px",
pointsize = 12,
background = "white",
res = 72,
scaling = 1,
snap_rect = TRUE,
bg
)
The dimensions of the device
The unit width
and height
is measured in, in either pixels
('px'
), inches ('in'
), millimeters ('mm'
), or centimeter ('cm'
).
The default pointsize of the device in pt. This will in general not have any effect on grid graphics (including ggplot2) as text size is always set explicitly there.
The background colour of the device
The resolution of the device. This setting will govern how device dimensions given in inches, centimeters, or millimeters will be converted to pixels. Further, it will be used to scale text sizes and linewidths
A scaling factor to apply to the rendered line width and text
size. Useful for getting the right dimensions at the resolution that you
need. If e.g. you need to render a plot at 4000x3000 pixels for it to fit
into a layout, but you find that the result appears to small, you can
increase the scaling
argument to make everything appear bigger at the
same resolution.
Should axis-aligned rectangles drawn with only fill snap to the pixel grid. This will prevent anti-aliasing artifacts when two rectangles are touching at their border.
Same as background
for compatibility with old graphic device APIs
# Capture drawing instructions
agg_record()
plot(1:10, 1:10)
rec <- recordPlot()
dev.off()
# Replay these on another device
file <- tempfile(fileext = '.png')
agg_png(file)
replayPlot(rec)
dev.off()
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