Class: AcroForge::ImageStamper

Inherits:
Object
  • Object
show all
Defined in:
lib/acroforge/image_stamper.rb

Overview

Stamps JPG/PNG files into AcroForm widget rectangles.

Constant Summary collapse

MAX_IMAGE_BYTES =

Caps a phone-camera passport photo from bloating the output PDF.

5 * 1024 * 1024
MAX_IMAGE_DIMENSION = 
4000
TARGET_PPI =

Auto-downsample images whose pixel resolution far exceeds this PPI at the widget’s rendered size. Requires ImageMagick on PATH.

200

Instance Method Summary collapse

Instance Method Details

#stamp!(doc, field, path) ⇒ Object 



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# File 'lib/acroforge/image_stamper.rb', line 16

def stamp!(doc, field, path)
  format, image_width, image_height = validate_image!(path)
  widget = field.each_widget.first
  return unless widget && widget[:Rect]

  page = doc.pages.find { |candidate_page| candidate_page[:Annots]&.include?(widget) }
  return unless page

  # Widget Rect is absolute page coords; canvas API is MediaBox-relative.
  media_box_x, media_box_y = page.box.value[0], page.box.value[1]
  rect_x_min, rect_y_min, rect_x_max, rect_y_max = widget[:Rect]
  slot_width = rect_x_max - rect_x_min
  slot_height = rect_y_max - rect_y_min
  slot_canvas_x = rect_x_min - media_box_x
  slot_canvas_y = rect_y_min - media_box_y

  stamp_path = prepare_image_for_slot(path, format, image_width, image_height,
    slot_width, slot_height) || path
  if stamp_path != path
    _, image_width, image_height = image_dimensions(stamp_path)
  end

  draw_width, draw_height = fit_inside(image_width, image_height, slot_width, slot_height)
  draw_x = slot_canvas_x + (slot_width - draw_width) / 2.0
  draw_y = slot_canvas_y + (slot_height - draw_height) / 2.0

  canvas = page.canvas(type: :overlay)
  canvas.fill_color(255, 255, 255)
  canvas.rectangle(slot_canvas_x, slot_canvas_y, slot_width, slot_height).fill
  canvas.image(stamp_path, at: [draw_x, draw_y], width: draw_width, height: draw_height)

  # Bake into the page so the widget's empty appearance doesn't repaint over the image.
  page[:Annots].delete(widget)
end

#validate_image!(path) ⇒ Object

Trust boundary in front of ImageMagick: any malformed-input path raises a single error class so worker retry policies can key on it.



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# File 'lib/acroforge/image_stamper.rb', line 53

def validate_image!(path)
  size = File.size(path)
  if size > MAX_IMAGE_BYTES
    raise ImageTooLargeError, "#{path}: #{size} bytes exceeds #{MAX_IMAGE_BYTES} byte cap"
  end
  format, width, height = image_dimensions(path)
  if width > MAX_IMAGE_DIMENSION || height > MAX_IMAGE_DIMENSION
    raise ImageTooLargeError,
      "#{path}: #{width}x#{height}px exceeds #{MAX_IMAGE_DIMENSION}px per side"
  end
  [format, width, height]
end