R/crop.R

In webmorphR: Reproducible Stimuli

#' Crop images and templates
#'
#' Remove or add margins to images and templates. 
#' 
#' @details 
#' Dimensions and offsets can be set in pixels or proportions. For width and height, values less than 2 will be interpreted as proportions, otherwise pixels. For x_off and y_off, values between -1 and 1 are interpreted as proportions, otherwise pixels. 
#' 
#' Cropping is anchored at the image center (or calculated template centroid if there is no image) unless x_off or y_off are set.
#'
#' @param stimuli list of stimuli
#' @param width,height dimensions of cropped image in pixels or proportion (<2)
#' @param x_off,y_off offset in pixels or proportion (<1) (NULL centers cropped image)
#' @param fill background color if cropping goes outside the original image, see [color_conv()]
#'
#' @return list of stimuli with cropped tems and/or images
#' @export
#' @family manipulators
#'
#' @examples
#' stimuli <- demo_stim()
#'
#' # crop to 60% width and 80% height (centered)
#' crop(stimuli, width = .60, height = .80)
#'
#' # crop to upper right quadrant
#' crop(stimuli, .5, .5, x_off = .5, y_off = 0)
#' 
#' \donttest{
#' # negative offset with fill
#' crop(stimuli, 260, 260, 
#'      x_off = -10, y_off = -10, 
#'      fill = c("red", "dodgerblue"))
#' }
crop <- function(stimuli,
                 width = 1.0, height = 1.0,
                 x_off = NULL, y_off = NULL,
                 fill = wm_opts("fill")) {
  stimuli <- as_stimlist(stimuli)

  fill <- sapply(fill, color_conv)
  suppressWarnings({
    l <- length(stimuli)
    width <- rep(width, length.out = l)
    height <- rep(height, length.out = l)
    x_off <- rep(x_off, length.out = l)
    y_off <- rep(y_off, length.out = l)
    fill <- rep(fill, length.out = l)
  })
  
  ## TODO: figure out the bug in this and move dim/offset calcs outside loop
  # origw <- width(stimuli)
  # w <- width %||% origw
  # w <- ifelse(w < 2, w * origw, w)
  # 
  # origh <- height(stimuli)
  # h <- height %||% origh
  # h <- ifelse(h < 2, h * origh, h)
  # 
  # # handle null or missing offsets by centering
  # x_off <- x_off %||% (origw - w)/2
  # y_off <- y_off %||% (origh - h)/2
  # x_off <- ifelse(is.na(x_off), (origw - w)/2, x_off)
  # y_off <- ifelse(is.na(y_off), (origh - h)/2, y_off)
  # 
  # # handle offsets < 1
  # x_off <- ifelse(x_off < 1, x_off * origw, x_off)
  # y_off <- ifelse(y_off < 1, y_off * origh, y_off)

  for (i in seq_along(stimuli)) {
    origw <- stimuli[[i]]$width
    origh <- stimuli[[i]]$height
    w <- width[i] %||% origw
    h <- height[i] %||% origh

    # handle percentages
    if (w < 2) w <- w * origw
    if (h < 2) h <- h * origh

    # handle percentage offsets
    if (!is.null(x_off[i]) && !is.na(x_off[i]) && abs(x_off[i]) < 1)
      x_off[i] <- x_off[i] * origw
    if (!is.null(y_off[i]) && !is.na(y_off[i]) && abs(y_off[i]) < 1)
      y_off[i] <- y_off[i] * origh

    # null offsets split the remainder between orig and new dimensions
    if (is.null(x_off[i]) || is.na(x_off[i])) x_off[i] <- (origw - w)/2
    if (is.null(y_off[i]) || is.na(y_off[i])) y_off[i] <- (origh - h)/2

    # update width and height in case no image
    # (gets updates from img below)
    stimuli[[i]]$width <- w
    stimuli[[i]]$height <- h

    if (!is.null(stimuli[[i]]$img) &&
        "magick-image" %in% class(stimuli[[i]]$img)) {
      # crop doesn't handle negative offsets well
      ga <- magick::geometry_area(
        width = min(w, origw),
        height = min(h, origh),
        x_off = max(0, x_off[i]),
        y_off = max(0, y_off[i])
      )

      newimg <- magick::image_crop(
        image = stimuli[[i]]$img,
        geometry = ga,
        gravity = "NorthWest"
      )

      # make background image with fill
      bg <- magick::image_blank(w, h, color = fill[i]) 
      offset <- magick::geometry_point(
        x = max(0, -x_off[i]),
        y = max(0, -y_off[i])
      )

      stimuli[[i]]$img <- magick::image_composite(
        image = bg,
        composite_image = newimg,
        operator = "Over",
        offset = offset
      )
      
      # get dim from magick in case of rounding differences
      info <- magick::image_info(stimuli[[i]]$img)
      stimuli[[i]]$width <- info$width[[1]]
      stimuli[[i]]$height <- info$height[[1]]
    }

    # crop template if present
    pts <- stimuli[[i]]$points
    if (!is.null(pts)) {
      # benchmarked 50x faster than apply (still trivial)
      stimuli[[i]]$points <- pts - c(x_off[i], y_off[i])
    }
  }

  stimuli
}

#' Pad images
#'
#' Add padding to sides of stimuli. This is a convenience function to calculate offsets for [crop()].
#' 
#' @details
#' The value for top is copied to bottom and right, and the value for right is copied to left, so setting only top produces a consistent border, while setting just top and right sets different borders for top-bottom and right-left. (This convention will be familiar if you use CSS.)
#' 
#' Padding size values are interpreted as a proportion of width or height if less than  1. 
#'
#' @param stimuli list of stimuli
#' @param top,right,bottom,left number of pixels or proportion (<1) to pad each side
#' @param ... additional arguments to pass to [crop()]
#'
#' @return list of stimuli
#' @export
#' @family manipulators
#'
#' @examples
#' stimuli <- demo_stim()
#' 
#' # default 10-pixel padding
#' pad(stimuli, fill = "dodgerblue")
#' 
#' \donttest{
#' # change pad width and set fill
#' pad(stimuli, 2, fill = "dodgerblue")
#' 
#' # set top border to 10% height
#' # different colour for each image
#' pad(stimuli, 0.1, 1, 1, 1,
#'     fill = c("hotpink", "dodgerblue"))
#' }
pad <- function(stimuli, top = 10, right = top, bottom = top, left = right, ...) {
  stimuli <- as_stimlist(stimuli)

  # convert if percents
  top    <- ifelse(abs(top) < 1,    top * height(stimuli),    top)
  bottom <- ifelse(abs(bottom) < 1, bottom * height(stimuli), bottom)
  left   <- ifelse(abs(left) < 1,   left * width(stimuli),    left)
  right  <- ifelse(abs(right) < 1,  right * width(stimuli),   right)

  stimuli |>
    crop(width = width(stimuli) + left + right,
         height = height(stimuli) + top + bottom,
         x_off = - left, y_off = - top, ...
    )
}


#' Crop to template boundaries and pad
#'
#' Calculate the maximum and minimum x and y coordinates across the stimuli (or for each stimulus) and crop all image to this plus padding.
#'
#' @param stimuli list of stimuli
#' @param top,right,bottom,left numeric; number of pixels or proportion (<1) to pad each side
#' @param each logical; Whether to calculate bounds for the full set (default) or each image separately
#' @param ... additional arguments to pass to [crop()]
#'
#' @return list of stimuli
#' @export
#' @family manipulators
#'
#' @examples
#' stimuli <- demo_stim()
#' ctem <- crop_tem(stimuli, each = TRUE)
#' draw_tem(ctem)
#' 
#' \donttest{
#' # demo with different templates
#' stimuli <- demo_tems()
#' 
#' # default 10 pixels around maximum template
#' crop_tem(stimuli) 
#' 
#' # crop specific to each image
#' crop_tem(stimuli, each = TRUE)
#' }
#' 
crop_tem <- function(stimuli, top = 10, right = top, bottom = top, left = right, each = FALSE, ...) {
  stimuli <- require_tems(stimuli)

  b <- bounds(stimuli, each = each)

  stimuli |>
    crop(width = ceiling(b$max_x - b$min_x + left + right),
         height = ceiling(b$max_y - b$min_y + top + bottom),
         x_off = floor(b$min_x - left),
         y_off = floor(b$min_y - top), ...
    )
}


#' Get template bounds
#'
#' @param stimuli A stimlist
#' @param each Whether to calculate max and min for the full set (default) or each image separately
#'
#' @return A list of min and max x and y values
#' @export
#'
#' @examples
#' demo_stim() |> bounds() |> str()
#'
#' demo_stim() |> bounds(each = TRUE)
bounds <- function(stimuli, each = FALSE) {
  stimuli <- require_tems(stimuli)

  if (isTRUE(each)) {
    # get separate bounds for each stimulus
    b <- lapply(stimuli, bounds) |> 
      do.call(what = rbind)
    return(b)
  }
  
  min_vals <- lapply(stimuli, `[[`, "points") |>
    sapply(apply, 1, min) |>
    apply(1, min)
    
  max_vals <- lapply(stimuli, `[[`, "points") |>
    sapply(apply, 1, max) |>
    apply(1, max)

  # only work if all tems are the same
  # A <- tems_to_array(stimuli)
  # x <- (A[, "X", ])
  # y <- (A[, "Y", ]) * -1

  data.frame(min_x = min_vals[["x"]],
             max_x = max_vals[["x"]],
             min_y = min_vals[["y"]],
             max_y = max_vals[["y"]])
}