What is the best way to adjust the line spacing for text added to an image using R?

Question

I'm currently working on a simple R script in RStudio that generates text-based images. I've almost completed the script and would like to share it with you. Here's my code so far...

# Check if required packages are installed, if not, install them
if (!requireNamespace("jpeg", quietly = TRUE)) install.packages("jpeg")
if (!requireNamespace("png", quietly = TRUE)) install.packages("png")
if (!requireNamespace("tools", quietly = TRUE)) install.packages("tools")
if (!requireNamespace("grid", quietly = TRUE)) install.packages("grid")
# Load the required packages
library(jpeg)
library(png)
library(tools)
library(grid)
# Set the directory path and quote file name
dir_path <- "/home/cake/Downloads/Archive"
quote_file <- "quotes.txt"
# Read the quotes
quotes <- readLines(file.path(dir_path, quote_file), warn = FALSE)
# Remove quotation marks and trim whitespace
quotes <- gsub('^"|"$', '', trimws(quotes))
quotes <- toupper(quotes)
# Function to wrap text
wrap_text <- function(text, width = 24) {
 paste(strwrap(text, width = width), collapse = "\n")
}
# Prepare wrapped quotes
wrapped_quotes <- sapply(quotes, wrap_text)
# Your website URL
website_url <- "GODSVERSE.ORG"
# Function to get dominant colors
get_dominant_colors <- function(img, n = 3) {
 colors <- rgb(img[,,1], img[,,2], img[,,3])
 col_freq <- table(colors)
 dominant <- names(sort(col_freq, decreasing = TRUE)[1:n])
 return(dominant)
}
calculate_text_width <- function(text, font_size) {
 # Split the text into lines
 lines <- strsplit(text, "\n")[[1]]
 # Calculate the width of each line
 line_widths <- sapply(lines, function(line) {
 strwidth(line, units = "inches", cex = font_size) # Assuming 12 pt is the base font size
 })
 # Return the maximum width
 print(lines)
 max(line_widths)
}
calculate_image_brightness <- function(img) {
 # Convert to grayscale if it's an RGB image
 if (dim(img)[3] == 3) {
 gray_img <- 0.2989 * img[,,1] + 0.5870 * img[,,2] + 0.1140 * img[,,3]
 } else {
 gray_img <- img
 }
 # Calculate average brightness
 mean(gray_img)
}
get_contrasting_color <- function(color) {
 rgb <- col2rgb(color)
 if ((rgb[1]*0.299 + rgb[2]*0.587 + rgb[3]*0.114) / 255 > 0.5) {
 return("black")
 } else {
 return("white")
 }
}
# Function to process a single image
process_image <- function(image_file, quote,
 overlay_height = 0.3,
 overlay_opacity = 0.8,
 quote_size = 1.2,
 quote_y_position = NULL,
 url_size = 0.8,
 url_x_position = 0.95,
 url_y_position = 0.02) {
 # Determine file type and read the image
 file_ext <- tolower(file_ext(image_file))
 if (file_ext == "jpg" || file_ext == "jpeg") {
 img <- readJPEG(file.path(dir_path, image_file))
 } else if (file_ext == "png") {
 img <- readPNG(file.path(dir_path, image_file))
 } else {
 stop("Unsupported file format")
 }
 # Get image dimensions
 height <- dim(img)[1]
 width <- dim(img)[2]
 # Get dominant colors
 dominant_colors <- get_dominant_colors(img)
 overlay_color <- col2rgb(dominant_colors[1]) / 255
 # Create overlay
 overlay <- rgb(overlay_color[1], overlay_color[2], overlay_color[3], alpha = overlay_opacity)
 # Create a new plot
 output_file <- file.path(dir_path, paste0("processed_", tools::file_path_sans_ext(image_file), ".png"))
 png(output_file, width = width, height = height, units = "px")
 par(mar = c(0, 0, 0, 0))
 plot(1, type = "n", xlim = c(0, 1), ylim = c(0, 1), axes = FALSE, xlab = "", ylab = "")
 # Add original image
 rasterImage(img, 0, 0, 1, 1)
 # cake <- calculate_text_width(quote, quote_size) * 96
 # print((lengths(regmatches(quote, gregexpr("\n", quote))) + 1))
 print(height)
 print(width)
 total_height <- (lengths(regmatches(quote, gregexpr("\n", quote))) + 1) * strheight("A", cex = quote_size) * 1.9
 total_height <- height / 700 * total_height
 print(total_height)
 brightness <- calculate_image_brightness(img)
 # Adjust overlay opacity based on brightness
 adjusted_opacity <- overlay_opacity + (brightness - 0.5) * 0.4
 adjusted_opacity <- max(0.6, min(0.95, adjusted_opacity)) # Keep opacity between 0.6 and 0.95
 # Get dominant colors
 dominant_colors <- get_dominant_colors(img)
 overlay_color <- col2rgb(dominant_colors[1]) / 255
 # Darken the overlay color for lighter images
 overlay_color <- overlay_color * (1 - brightness * 0.5)
 # Create overlay
 overlay <- rgb(overlay_color[1], overlay_color[2], overlay_color[3], alpha = adjusted_opacity)
 # Determine text color based on overlay color
 text_color <- get_contrasting_color(overlay)
 # Add overlay
 rect(0, 0, 1, total_height, col = overlay, border = NA)
 # Add quote
 if (is.null(quote_y_position)) {
 quote_y_position <- 0.35
 }

 text(x = 0.5, y = total_height - 0.02, labels = quote, col = "white", cex = c((quote_size * width / 466 * 1.1), (quote_size * height / 700)), adj = c(0.5, 1, 3), family = "Copperplate Gothic Std 29 BC")

 # Add website URL to the right
 # text(x = 0.5, y = url_y_position, labels = website_url, col = "white", cex = width / cake * url_size, adj = c(0.5, 1))
 dev.off()
 cat("Processed:", image_file, "with quote:", substr(quote, 1, 30), "...\n")
}
# Get all JPEG and PNG images in the directory
image_files <- list.files(dir_path, pattern = "\\.(jpe?g|png)$", ignore.case = TRUE)
# Process each image with a different quote
for (i in seq_along(image_files)) {
 quote_index <- (i - 1) %% length(wrapped_quotes) + 1
 current_image <- image_files[i]
 current_quote <- wrapped_quotes[quote_index]
 changed_quote <- paste0(current_quote, '\n', 'GODSVERSE.ORG')
 tryCatch({
 process_image(
 current_image,
 changed_quote,
 overlay_height = 0.5,
 overlay_opacity = 0.2,
 quote_size = 2.2,
 quote_y_position = 0.45,
 url_size = 2.4,
 url_x_position = 0.98,
 url_y_position = 0.05
 )
 }, error = function(e) {
 cat("Error processing", current_image, ":", conditionMessage(e), "\n")
 })
}
cat("All images processed.\n")

I'm looking to adjust the line spacing within the text, but the current code sets the opacity and adds new text lines from a file without allowing me to control the spacing between each line. Currently, I'm struggling to fine-tune the line spacing for each individual text line. Is there a way to specify line spacing in this context? I'd like to find a solution that enables me to customize the spacing between text lines.

• DavoOZ: Try changing the line spacing with: par(lheight=0.5) # default is 1
• Данил Коршунов: ggplot2 is much more convienient to control image and text.
• Karol: Thanks for your reply. But I think it can be fixed with a little changes.