Module: Morandi::CropUtils

Defined in:
lib/morandi/crop_utils.rb

Overview

Utility functions relating to cropping

Class Method Summary collapse

Class Method Details

.apply_crop(pixbuf, x_coord, y_coord, width, height, fill_col = 0xffffffff) ⇒ Object 



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# File 'lib/morandi/crop_utils.rb', line 44

def apply_crop(pixbuf, x_coord, y_coord, width, height, fill_col = 0xffffffff)
  if x_coord.negative? ||
     y_coord.negative? ||
     ((x_coord + width) > pixbuf.width) ||
     ((y_coord + height) > pixbuf.height)

    base_pixbuf = GdkPixbuf::Pixbuf.new(
      colorspace: GdkPixbuf::Colorspace::RGB,
      has_alpha: false,
      bits_per_sample: 8,
      width: width,
      height: height
    )
    base_pixbuf.fill!(fill_col)

    offset_x = [x_coord, 0].max
    offset_y = [y_coord, 0].max
    copy_w = [width, pixbuf.width - offset_x].min
    copy_h = [height, pixbuf.height - offset_y].min

    paste_x = [x_coord, 0].min * -1
    paste_y = [y_coord, 0].min * -1

    copy_w = base_pixbuf.width - paste_x if copy_w + paste_x > base_pixbuf.width
    copy_h = base_pixbuf.height - paste_y if copy_h + paste_y > base_pixbuf.height

    base_pixbuf.composite!(
      pixbuf,
      dest_x: paste_x,
      dest_y: paste_y,
      dest_width: copy_w,
      dest_height: copy_h,
      offset_x: paste_x - offset_x,
      offset_y: paste_y - offset_y,
      scale_x: 1,
      scale_y: 1,
      interpolation_type: :hyper,
      overall_alpha: 255
    )
    pixbuf = base_pixbuf
  else
    x_coord = x_coord.clamp(0, pixbuf.width)
    y_coord = y_coord.clamp(0, pixbuf.height)
    width = width.clamp(1, pixbuf.width - x_coord)
    height = height.clamp(1, pixbuf.height - y_coord)

    pixbuf = pixbuf.subpixbuf(x_coord, y_coord, width, height)
  end
  pixbuf
end

.apply_crop_vips(img, x_coord, y_coord, width, height) ⇒ Object 



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# File 'lib/morandi/crop_utils.rb', line 95

def apply_crop_vips(img, x_coord, y_coord, width, height)
  if x_coord.negative? ||
     y_coord.negative? ||
     ((x_coord + width) > img.width) ||
     ((y_coord + height) > img.height)

    extract_area_x = [0, x_coord].max
    extract_area_y = [0, y_coord].max
    area_to_copy = img.extract_area(extract_area_x, extract_area_y, img.width - extract_area_x,
                                    img.height - extract_area_y)

    fill_colour = [255, 255, 255]
    pixel = (Vips::Image.black(1, 1).colourspace(:srgb) + fill_colour).cast(img.format)
    canvas = pixel.embed 0, 0, width, height, extend: :copy

    cropped = canvas.composite(area_to_copy, :over, x: [-x_coord, 0].max,
                                                    y: [-y_coord, 0].max,
                                                    compositing_space: area_to_copy.interpretation)

    # Because image is drawn on an opaque white, alpha doesn't matter at this point anyway, so let's strip the
    # alpha channel from the output. According to #composite docs, the resulting image always has alpha channel,
    # but I added a guard to avoid regressions if that ever changes.
    cropped = cropped.extract_band(0, n: cropped.bands - 1) if cropped.has_alpha?
    cropped
  else
    x_coord = x_coord.clamp(0, img.width)
    y_coord = y_coord.clamp(0, img.height)
    width = width.clamp(1, img.width - x_coord)
    height = height.clamp(1, img.height - y_coord)

    img.crop(x_coord, y_coord, width, height)
  end
end

.autocrop_coords(pixbuf_width, pixbuf_height, target_width, target_height) ⇒ Object 



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# File 'lib/morandi/crop_utils.rb', line 10

def autocrop_coords(pixbuf_width, pixbuf_height, target_width, target_height)
  return nil unless target_width

  aspect = target_width.to_f / target_height
  pixbuf_aspect = pixbuf_width.to_f / pixbuf_height

  # TODO: this looks wrong - typically relative aspect ratios matter more
  # than whether this is portrait or landscape
  if pixbuf_height > pixbuf_width
    # Portrait image
    # Check whether the aspect ratio is greater or smaller
    # ie. where constraints will hit
    aspect = target_height.to_f / target_width
  end

  # Landscape
  if aspect > pixbuf_aspect
    # Width constraint - aspect-rect wider
    crop_width  = pixbuf_width
    crop_height = (crop_width / aspect).to_i
  else
    # Height constraint - aspect-rect wider
    crop_height = pixbuf_height
    crop_width  = (crop_height * aspect).to_i
  end

  [
    ((pixbuf_width - crop_width) >> 1),
    ((pixbuf_height - crop_height) >> 1),
    crop_width,
    crop_height
  ].map(&:to_i)
end