angle_extent <- function(dimension, extent = NULL, angle = 0){
## Adapted from rasterImageAdj in Ecfun by Spencer Graves
## https://CRAN.R-project.org/package=Ecfun
imagePixels <- dimension
if (is.null(extent)) extent <- c(0, dimension[1], 0, dimension[2])
xleft <- extent[1]
xright <- extent[2]
ybottom <- extent[3]
ytop <- extent[4]
##
## 2. x, y pixels per inch
##
imageUnits.x <- (xright-xleft)
imageUnits.y <- (ytop-ybottom)
# 2.2. plot units per inch (we should just use the scale of extent/dimension)
u <- par("usr")
xyinches <- c(u[2L] - u[1L], u[4L] - u[3L])/par("pin")
#print(xyinches)
#print(dimension / diff(extent)[c(1, 3)])
# 2.3. x, y pixels per inch in image region
pixelsPerInch.x <- (imagePixels[1]*xyinches[1] /
as.numeric(imageUnits.x))
pixelsPerInch.y <- (imagePixels[2]*xyinches[2] /
imageUnits.y)
##
## 3. Shrink imageUnits to max(PixelsPerInch)
##
maxPPI <- max(pixelsPerInch.x, pixelsPerInch.y)
imageUAdj.x <- (imagePixels[1] * xyinches[1] / maxPPI)
imageUAdj.y <- (imagePixels[2] * xyinches[2] / maxPPI)
##
## 4. (dX, dY) = imageUnitsAdj/2
## = half of the (width, height) in plotting units.
##
dX <- imageUAdj.x/2
dY <- imageUAdj.y/2
# lower left = 45 degrees from center
# Therefore, max deviation of a corner from the center: at 45 degrees
dX. <- dX*sqrt(2)
dY. <- dY*sqrt(2)
##
## 5. cntr = (xleft, ybottom) + imageUnits/2
##
cntr.x <- (xleft+(imageUnits.x/2))
cntr.y <- (ybottom+(imageUnits.y/2))
##
## 6. (x, y) location of the nominal lower left corner
## after rotation
##
adj.x <- sin((angle-45)*pi/180)*dX.
adj.y <- cos((angle-45)*pi/180)*dY.
xleft0 <- (cntr.x + adj.x)
xright0 <- (xleft0 + imageUAdj.x)
ybottom0 <- (cntr.y - adj.y)
ytop0 <- (ybottom0 + imageUAdj.y)
c(xleft0, xright0, ybottom0, ytop0)
}
library(png)
img <- readPNG(system.file("img", "Rlogo.png", package="png"), T)
imrot <- function(x, extent = c(0, ncol(x), 0, nrow(x)), interpolate = FALSE, add = FALSE, angle = 0, ...) {
if (!add) {
plot.new()
plot.window(xlim = extent[1:2], ylim = extent[3:4], asp = 1)
}
## use of par in here means plot must already be set up
extent <- angle_extent(dim(x), extent, angle = angle)
rasterImage(x, extent[1], extent[3], extent[2], extent[4], interpolate = interpolate, angle = angle, ...)
invisible(extent)
}
library(png)
img <- readPNG(system.file("img", "Rlogo.png", package="png"), T)
imrot(img)
imrot(img, angle = -90, add = TRUE)
should be able to unpick all the silly graphics device stuff and just use dimension and extent (and this possibly belongs in vaster not here)
should be able to unpick all the silly graphics device stuff and just use dimension and extent (and this possibly belongs in vaster not here)