grid.raster
Render a raster object
Render a raster object (bitmap image) at the given location, size, and orientation.
- Keywords
- dplot
Usage
grid.raster(image,
x = unit(0.5, "npc"), y = unit(0.5, "npc"),
width = NULL, height = NULL,
just = "centre", hjust = NULL, vjust = NULL,
interpolate = TRUE, default.units = "npc",
name = NULL, gp = gpar(), vp = NULL)rasterGrob(image,
x = unit(0.5, "npc"), y = unit(0.5, "npc"),
width = NULL, height = NULL,
just = "centre", hjust = NULL, vjust = NULL,
interpolate = TRUE, default.units = "npc",
name = NULL, gp = gpar(), vp = NULL)
Arguments
- image
Any R object that can be coerced to a raster object.
- x
A numeric vector or unit object specifying x-location.
- y
A numeric vector or unit object specifying y-location.
- width
A numeric vector or unit object specifying width.
- height
A numeric vector or unit object specifying height.
- just
The justification of the rectangle relative to its (x, y) location. If there are two values, the first value specifies horizontal justification and the second value specifies vertical justification. Possible string values are:
"left"
,"right"
,"centre"
,"center"
,"bottom"
, and"top"
. For numeric values, 0 means left alignment and 1 means right alignment.- hjust
A numeric vector specifying horizontal justification. If specified, overrides the
just
setting.- vjust
A numeric vector specifying vertical justification. If specified, overrides the
just
setting.- default.units
A string indicating the default units to use if
x
,y
,width
, orheight
are only given as numeric vectors.- name
A character identifier.
- gp
An object of class
gpar
, typically the output from a call to the functiongpar
. This is basically a list of graphical parameter settings.- vp
A Grid viewport object (or NULL).
- interpolate
A logical value indicating whether to linearly interpolate the image (the alternative is to use nearest-neighbour interpolation, which gives a more blocky result).
Details
Neither width
nor height
needs to be specified,
in which case, the aspect ratio of the image is preserved. If
both width
and height
are specified, it is likely
that the image will be distorted.
Not all graphics devices are capable of rendering raster images
and some may not be able to produce rotated images (i.e., if
a raster object is rendered within a rotated viewport). See also the
comments under rasterImage
.
All graphical parameter settings in gp
will be ignored,
including alpha
.
Value
A rastergrob grob.
See Also
dev.capabilities
to see if it is supported.
Examples
library(grid)
# NOT RUN {
redGradient <- matrix(hcl(0, 80, seq(50, 80, 10)),
nrow=4, ncol=5)
# interpolated
grid.newpage()
grid.raster(redGradient)
# blocky
grid.newpage()
grid.raster(redGradient, interpolate=FALSE)
# blocky and stretched
grid.newpage()
grid.raster(redGradient, interpolate=FALSE, height=unit(1, "npc"))
# The same raster drawn several times
grid.newpage()
grid.raster(0, x=1:3/4, y=1:3/4, w=.1, interp=FALSE)
# }