knit2docx: knit2docx

#' Plot rasters in ggplot with greyscale
#' @param x raster
#' @param layer layername
#' @param maxpixels Integer. Maximal number of pixels to sample
#' @param lowColor Character. Color for lowest value
#' @param highColor Character. Color for highest value
#' @param legendName Character. Layer name
#' @param ggObj Logical. Return a ggplot2 object (TRUE) or just the data.frame
#' 
#' @export 
ggRx <- function(x, layer = 1, maxpixels = 5000000, lowColor = "white", highColor = "black", legendName = "Legend", ggObj = TRUE) {    
	
	drast <- sampleRegular(x[[layer]], maxpixels, asRaster = TRUE)
	df <- data.frame(coordinates(drast), drast[])
	colnames(df) <- c("x", "y", names(x[[layer]]))
	layer <- colnames(df)[3]
	#  df <- melt(df, id.vars = c("x","y"))
	
	if(ggObj) {p <- ggplot(df) + geom_raster(aes_string(x = "x", y = "y", fill = layer)) +
				scale_fill_gradient(low = lowColor, high = highColor, na.value = NA, name = legendName) +
				coord_equal() 
	} else {
		p <- df
	}
	return(p)
}



#' Scalebar for ggplot
#'
#' @param ras Raster*
#' @param len Numeric. Length of scalebar (map units)
#' @param yoff y offset from lower left corner (in percent)
#' @param xoff x offset from lower left corner (in percent)
#' @param sdist Numeric. Length of ticks
#' @param tdist Numeric. Distance text from ticks.
#' @param size Numeric. Thickness of scalebar
#' @param tsize Numeric. Text size.
#' @param col Color of scalebar and text
#' @export 
SCALE <- function(ras = NULL, len = 10000, yoff = 0.6, xoff = 0.2, sdist = 800, tdist = 1000, size = 1, tsize = 3,col = "white"){
	if(is.null(ras)){
		ex <- new("Extent"
				, xmin = 579765
				, xmax = 668775
				, ymin = -522705
				, ymax = -477735
		)
	} else {
		ex <- extent(ras)
	}
	xoff <- xoff/100
	yoff <- yoff/100
	df <- data.frame(xf = ex@xmin*(1+xoff), xt = ex@xmin*(1+xoff) + len, y = ex@ymin * (1-yoff))
	df <- data.frame(x = rep(ex@xmin*(1+xoff),4) + c(0,0,len,len), y = rep(ex@ymin * (1-yoff),4) - c(sdist,0,0,sdist)) 
	
	dft <- data.frame(x = range(df$x), y = min(df$y) - tdist, lab = paste0(c("","    "), c(0, len/1000), c(""," km"))) 
	
	list(geom_line(data = df, aes(x=x, y=y), size = size, col = col),
			geom_text(data=dft, aes(x = x, y =y, label =lab),size = tsize, col = col) ) 
}




#' Theme for map plotting
#' @export 
MAPTHEME <- list(
		theme(
				axis.title.y = element_blank(),
				axis.title.x = element_blank(),
				axis.text.x  = element_text(size=9, colour="grey30"),
				axis.text.y  = element_text(angle=90, size=9, colour="grey30"),
				axis.ticks    = element_line(colour = "grey30"),
				axis.ticks.length = unit(0.06, "cm"),
				strip.text.x = element_text(size = 8),
				strip.text.y = element_text(size = 8, angle=270),
				plot.title   = element_text(size = 9, hjust  =  0),
				legend.title = element_text(size = 9),
				legend.text  = element_text(size = 8),
				plot.margin = unit(c(0,0,0,0),"lines")
		), 
		scale_x_continuous(expand = c(0,0)),
		scale_y_continuous(expand=c(0,0)) )