R/nr-scale.R

In nara: Native Raster Image Tools

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#' Resize a native raster by specifying the output dimensions
#' 
#' @inheritParams nr_fill
#' @param algo 'nn' for nearest neighbor (the default), or 'bilinear' for 
#'        bilinear interpolation.
#' @param width,height dimensions for output image
#' @return New native raster image
#' @examples
#' stretched <- deer[[1]] |> 
#'     nr_copy() |> 
#'     nr_resize(100, 40, algo = 'nn')
#' plot(stretched)
#' @family resizing functions
#' @export
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
nr_resize <- function(nr, width, height, algo = 'nn') {
  if (algo == 'nn') {
    .Call(nr_resize_nn_, nr, width, height)
  } else {
    .Call(nr_resize_bilinear_, nr, width, height)
  }
}



#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#' Resize a native raster image using a scale factor
#' 
#' @inheritParams nr_resize
#' @param scale scale factor
#' 
#' @return New native raster image
#' @examples
#' big <- deer[[1]] |> nr_scale(2)
#' plot(big)
#' @family resizing functions
#' @export
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
nr_scale <- function(nr, scale, algo = 'nn') {
  nr_resize(nr, width = scale * ncol(nr), height = scale * nrow(nr), algo = algo)
}