Module: SafeImage::Native

Defined in:
lib/safe_image/native.rb

Overview

The libvips fast path, implemented in pure Ruby on top of the VipsGlue Fiddle binding (formerly a compiled C extension; the function surface and messages are unchanged). Loaders are explicit per extension, every decode enforces the pixel cap from the header before pixel data is touched, and all images are released deterministically.

Constant Summary collapse

LOADERS = 
{
  "jpg" => "jpegload",
  "png" => "pngload",
  "webp" => "webpload",
  "gif" => "gifload",
  "heic" => "heifload",
  "avif" => "heifload",
  "jxl" => "jxlload"
}.freeze

Class Method Summary collapse

Class Method Details

.convert(input, output, format, quality, max_pixels) ⇒ Object 



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# File 'lib/safe_image/native.rb', line 112

def convert(input, output, format, quality, max_pixels)
  started = monotime
  quality = Integer(quality)
  validate_quality!(quality)
  out_format = output_format!(format)

  VipsGlue.with_images do |track|
    image, input_format = load_image(track, String(input))
    check_pixels!(image, max_pixels)
    rotated = track.call(VipsGlue.operation("autorot", { in: image }))

    # JPEG has no alpha; flatten onto white to match the ImageMagick
    # convert path (libvips composites onto black otherwise).
    final =
      if out_format == "jpg" && VipsGlue.alpha?(rotated)
        track.call(VipsGlue.operation("flatten", { in: rotated, background: [255.0, 255.0, 255.0] }))
      else
        rotated
      end
    save_image(final, String(output), out_format, quality)
    info(input_format, out_format, final, started)
  end
end

.crop_north(input, output, width, height, format, quality, max_pixels) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/safe_image/native.rb', line 87

def crop_north(input, output, width, height, format, quality, max_pixels)
  started = monotime
  width = Integer(width)
  height = Integer(height)
  quality = Integer(quality)
  raise ArgumentError, "width and height must be positive" if width <= 0 || height <= 0
  validate_quality!(quality)
  out_format = output_format!(format)

  VipsGlue.with_images do |track|
    image, input_format = load_image(track, String(input))
    check_pixels!(image, max_pixels)
    rotated = track.call(VipsGlue.operation("autorot", { in: image }))

    scale = [width.fdiv(VipsGlue.width(rotated)), height.fdiv(VipsGlue.height(rotated))].max * 1.0000001
    resized = track.call(VipsGlue.operation("resize", { in: rotated, scale: scale }))
    left = [(VipsGlue.width(resized) - width) / 2, 0].max
    cropped = track.call(
      VipsGlue.operation("extract_area", { input: resized, left: left, top: 0, width: width, height: height })
    )
    save_image(cropped, String(output), out_format, quality)
    info(input_format, out_format, cropped, started)
  end
end

.dominant_color(path, max_pixels) ⇒ Object

Alpha-weighted average colour as [r, g, b] integers. Premultiplying keeps parity with ImageMagick’s resize-based average; per-band means come from vips_stats (row b+1, column 4 of the stats matrix).



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# File 'lib/safe_image/native.rb', line 139

def dominant_color(path, max_pixels)
  VipsGlue.with_images do |track|
    image, = load_image(track, String(path))
    check_pixels!(image, max_pixels)

    srgb =
      if VipsGlue.colourspace_supported?(image)
        track.call(VipsGlue.operation("colourspace", { in: image, space: "srgb" }))
      else
        image
      end
    has_alpha = VipsGlue.alpha?(srgb)
    work = has_alpha ? track.call(VipsGlue.operation("premultiply", { in: srgb })) : srgb

    stats = track.call(VipsGlue.operation("stats", { in: work }))
    columns = VipsGlue.width(stats)
    matrix = VipsGlue.image_bytes(stats).unpack("d*")
    mean = ->(band) { matrix[(band + 1) * columns + 4] || 0.0 }

    bands = VipsGlue.bands(work)
    colour_bands = has_alpha ? bands - 1 : bands
    colour_bands = colour_bands.clamp(1, 3)
    raise InvalidImageError, "image has no colour bands" if colour_bands < 1

    alpha_mean = has_alpha ? mean.call(bands - 1) : 255.0
    (0...3).map do |band|
      value = mean.call([band, colour_bands - 1].min)
      value = alpha_mean.positive? ? value * 255.0 / alpha_mean : 0.0 if has_alpha
      value.round.clamp(0, 255)
    end
  end
end

.letter_avatar(output, size, red, green, blue, markup, font, fontfile) ⇒ Object

Renders a letter avatar: a Pango glyph mask blended in white at 80% opacity over a solid background via a single linear transform. The markup string is escaped by the Ruby caller; font and fontfile come from an allowlist.

Raises:

  • (ArgumentError) 


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# File 'lib/safe_image/native.rb', line 211

def letter_avatar(output, size, red, green, blue, markup, font, fontfile)
  size = Integer(size)
  markup = String(markup)
  font = String(font)
  fontfile = String(fontfile)
  channels = [Integer(red), Integer(green), Integer(blue)]
  raise ArgumentError, "size must be 1..4096" unless (1..4096).cover?(size)
  unless channels.all? { |value| (0..255).cover?(value) }
    raise ArgumentError, "background channels must be 0..255"
  end
  unless VipsGlue.type_find?("text")
    raise UnsupportedFormatError, "this libvips build has no text renderer (Pango support missing)"
  end

  VipsGlue.with_images do |track|
    mask =
      if markup.empty?
        # Blank letter: solid background only.
        track.call(VipsGlue.operation("black", { width: size, height: size }))
      else
        text_inputs = { text: markup, font: font, dpi: 72 }
        text_inputs[:fontfile] = fontfile unless fontfile.empty?
        text = track.call(VipsGlue.operation("text", text_inputs))

        # vips_text returns the tight ink box; crop to the canvas when
        # the pointsize overflows it, then centre the ink optically.
        text_w = VipsGlue.width(text)
        text_h = VipsGlue.height(text)
        if text_w > size || text_h > size
          crop_w = [text_w, size].min
          crop_h = [text_h, size].min
          text = track.call(
            VipsGlue.operation(
              "extract_area",
              { input: text, left: (text_w - crop_w) / 2, top: (text_h - crop_h) / 2,
                width: crop_w, height: crop_h }
            )
          )
          text_w = crop_w
          text_h = crop_h
        end
        track.call(
          VipsGlue.operation(
            "embed",
            { in: text, x: (size - text_w) / 2, y: (size - text_h) / 2, width: size, height: size }
          )
        )
      end

    # blend = bg + (white - bg) * 0.8 * mask/255, one linear op.
    opacity = 204.0 / 255.0 # FFFFFFCC
    a = channels.map { |value| (255.0 - value) * opacity / 255.0 }
    blended = track.call(VipsGlue.operation("linear", { in: mask, a: a, b: channels.map(&:to_f) }))
    cast = track.call(VipsGlue.operation("cast", { in: blended, format: "uchar" }))
    srgb = track.call(VipsGlue.operation("copy", { in: cast, interpretation: "srgb" }))
    save_image(srgb, String(output), "png", 100)
  end
  true
end

.orientation(path, max_pixels) ⇒ Object 



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# File 'lib/safe_image/native.rb', line 180

def orientation(path, max_pixels)
  VipsGlue.with_images do |track|
    image, = load_image(track, String(path))
    check_pixels!(image, max_pixels)
    value = VipsGlue.orientation(image)
    (1..8).cover?(value) ? value : 1
  end
end

.pages(path, max_pixels) ⇒ Object 



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# File 'lib/safe_image/native.rb', line 172

def pages(path, max_pixels)
  VipsGlue.with_images do |track|
    image, = load_image(track, String(path))
    check_pixels!(image, max_pixels)
    VipsGlue.pages(image)
  end
end

.png_from_rgba(bytes, width, height, output) ⇒ Object

Encodes a raw RGBA buffer (top-down rows) as PNG. Used by the pure-Ruby ICO decoder.

Raises:

  • (ArgumentError) 


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# File 'lib/safe_image/native.rb', line 191

def png_from_rgba(bytes, width, height, output)
  bytes = String(bytes)
  width = Integer(width)
  height = Integer(height)
  raise ArgumentError, "width and height must be positive" if width <= 0 || height <= 0
  raise LimitError, "rgba buffer dimensions exceed 4096x4096" if width > 4096 || height > 4096
  raise ArgumentError, "rgba buffer must be width*height*4 bytes" if bytes.bytesize != width * height * 4

  VipsGlue.with_images do |track|
    image = track.call(VipsGlue.image_from_memory(bytes, width, height, 4, 0)) # 0 = uchar
    srgb = track.call(VipsGlue.operation("copy", { in: image, interpretation: "srgb" }))
    save_image(srgb, String(output), "png", 100)
  end
  true
end

.probe(path) ⇒ Object 



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# File 'lib/safe_image/native.rb', line 23

def probe(path)
  started = monotime
  VipsGlue.with_images do |track|
    image, format = load_image(track, String(path))
    {
      format: format,
      width: VipsGlue.width(image),
      height: VipsGlue.height(image),
      duration_ms: monotime - started
    }
  end
end

.resize(input, output, scale, format, quality, max_pixels) ⇒ Object 



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# File 'lib/safe_image/native.rb', line 67

def resize(input, output, scale, format, quality, max_pixels)
  started = monotime
  scale = Float(scale)
  quality = Integer(quality)
  unless scale.finite? && scale.positive? && scale <= 100.0
    raise ArgumentError, "scale must be finite and in 0..100"
  end
  validate_quality!(quality)
  out_format = output_format!(format)

  VipsGlue.with_images do |track|
    image, input_format = load_image(track, String(input))
    check_pixels!(image, max_pixels)
    rotated = track.call(VipsGlue.operation("autorot", { in: image }))
    resized = track.call(VipsGlue.operation("resize", { in: rotated, scale: scale }))
    save_image(resized, String(output), out_format, quality)
    info(input_format, out_format, resized, started)
  end
end

.thumbnail(input, output, width, height, format, quality, max_pixels) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/safe_image/native.rb', line 36

def thumbnail(input, output, width, height, format, quality, max_pixels)
  started = monotime
  input = String(input)
  output = String(output)
  width = Integer(width)
  height = Integer(height)
  quality = Integer(quality)
  raise ArgumentError, "width and height must be positive" if width <= 0 || height <= 0
  validate_quality!(quality)
  out_format = output_format!(format)

  VipsGlue.with_images do |track|
    # Header read through the explicit loader: validates the bytes and
    # enforces the pixel cap before any full decode.
    header, input_format = load_image(track, input)
    check_pixels!(header, max_pixels)

    # Thumbnail from the file so libvips can shrink on load (e.g.
    # libjpeg DCT downscaling); auto-rotates by default.
    thumb = track.call(
      VipsGlue.operation(
        "thumbnail",
        { filename: input, width: width, height: height,
          size: "both", crop: "centre", fail_on: "error" }
      )
    )
    save_image(thumb, output, out_format, quality)
    info(input_format, out_format, thumb, started)
  end
end