Class: JekyllImgFlow::Providers::Libvips

Inherits:
CliBase show all
Defined in:
lib/jekyll-imgflow/providers/libvips.rb

Overview

Libvips provider implementation using the standardized tag interface

Constant Summary

Constants inherited from BaseProvider

BaseProvider::COMPASS_TO_SHORT, BaseProvider::KNOWN_OPERATIONS, BaseProvider::SMARTCROP_POSITIONS

Instance Attribute Summary

Attributes inherited from BaseProvider

#config

Instance Method Summary collapse

Methods inherited from CliBase

#execute

Methods inherited from BaseProvider

#add_watermark, #alpha_byte_value, #alpha_opacity=, #check_http_service, #cli_available?, #compass_to_short, #convert_format, #crop, #crop_coords, #crop_geometry, #encode_file_url, #execute, #find_op, #format, #initialize, #input_format_ext, #op?, #opacity, #operations, #optimize, provider_name, #quality, #quality=, #relative_file_path, #reset_operations, #resize, #smartcrop_interestingness, #supports_operation?, supports_operation?, #temp_path, unsupported_operations, #watermark, #watermark_parts

Constructor Details

This class inherits a constructor from JekyllImgFlow::Providers::BaseProvider

Instance Method Details

#apply_watermark_alpha(base_path, input_path, commands) ⇒ Object 



92
93
94
95
96
97
98
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 92

def apply_watermark_alpha(base_path, input_path, commands)
  alpha_op = find_op(:alpha_opacity)
  return [base_path, commands] unless alpha_op

  alpha_temp = temp_path(input_path, "tmp_alpha.jpg")
  [alpha_temp, commands << build_alpha_command(base_path, alpha_temp)]
end

#available? ⇒ Boolean

Returns:

  • (Boolean) 


11
12
13
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 11

def available?
  cli_available?("vips")
end

#build_alpha_command(input_path, output_path) ⇒ Object 



161
162
163
164
165
166
167
168
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 161

def build_alpha_command(input_path, output_path)
  alpha_op = find_op(:alpha_opacity)
  alpha_value = alpha_op[:opacity].round(2)

  # vips linear multiplies alpha band: "1 1 1 alpha" scales alpha
  ["vips", "linear", input_path, output_path,
   "1 1 1 #{alpha_value}", "0"]
end

#build_alpha_pipeline(input_path, output_path, has_crop, has_resize) ⇒ Object 



67
68
69
70
71
72
73
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 67

def build_alpha_pipeline(input_path, output_path, has_crop, has_resize)
  temp = temp_path(input_path, "tmp_base.jpg")
  commands, base_path = build_base_pipeline(input_path, temp, has_crop, has_resize)
  commands << build_alpha_command(base_path, output_path)
  commands << [:cleanup, temp] unless base_path == input_path
  commands
end

#build_base_pipeline(input_path, temp_path, has_crop, has_resize) ⇒ Object 



84
85
86
87
88
89
90
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 84

def build_base_pipeline(input_path, temp_path, has_crop, has_resize)
  return [build_sequential_crop_resize(input_path, temp_path), temp_path] if has_crop && has_resize
  return [[build_resize_command(input_path, temp_path)], temp_path] if has_resize
  return [[build_crop_command(input_path, temp_path)], temp_path] if has_crop

  [[], input_path]
end

#build_commands(input_path, output_path) ⇒ Object 



15
16
17
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 15

def build_commands(input_path, output_path)
  build_vips_commands(input_path, output_path)
end

#build_composite_commands(base_path, output_path) ⇒ Object 



105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 105

def build_composite_commands(base_path, output_path)
  wm_op = find_op(:watermark)
  parts = watermark_parts(wm_op)

  if parts[:opacity] && parts[:opacity] < 1.0
    wm_temp = temp_path(parts[:watermark_path], "tmp_wm.png")
    alpha_value = parts[:opacity]
    # Step 1: Apply alpha to watermark
    alpha_cmd = ["vips", "linear", parts[:watermark_path],
                 "#{wm_temp}[alpha]", "1 1 1 #{alpha_value}", "0"]
    # Step 2: Composite
    xy_args = position_to_vips_xy(parts[:position], base_path, parts[:watermark_path])
    composite_cmd = ["vips", "composite2", base_path, wm_temp,
                     build_format_spec(output_path), "over"] + xy_args
    # Step 3: Cleanup wm_temp
    [alpha_cmd, composite_cmd, [:cleanup, wm_temp]]
  else
    xy_args = position_to_vips_xy(parts[:position], base_path, parts[:watermark_path])
    [["vips", "composite2", base_path, parts[:watermark_path],
      build_format_spec(output_path), "over"] + xy_args]
  end
end

#build_copy_command(input_path, output_path) ⇒ Object 



247
248
249
250
251
252
253
254
255
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 247

def build_copy_command(input_path, output_path)
  format_spec = build_format_spec(output_path)
  # For SVGs, `vips copy` rasterizes at intrinsic size (potentially
  # huge). Use thumbnail with a large cap to bound the render safely.
  return ["vips", "thumbnail", input_path, format_spec, "2000"] if svg?(input_path)

  # vips copy input.jpg output.jpg[format]
  ["vips", "copy", input_path, format_spec]
end

#build_crop_command(input_path, output_path) ⇒ Object 



208
209
210
211
212
213
214
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 208

def build_crop_command(input_path, output_path)
  crop_op = find_op(:crop)
  geo = crop_geometry(crop_op)
  return build_smartcrop_command(geo, input_path, output_path) if geo[:smartcrop]

  build_extract_command(geo, input_path, output_path)
end

#build_extract_command(geo, input_path, output_path) ⇒ Object 



223
224
225
226
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 223

def build_extract_command(geo, input_path, output_path)
  ["vips", "extract_area", input_path, output_path,
   geo[:x].to_s, geo[:y].to_s, geo[:width].to_s, geo[:height].to_s]
end

#build_format_spec(output_path) ⇒ Object

Build vips output specification with format and quality. Returns a raw string — no shell quoting needed since commands are executed via Open3.capture3 array form (no shell).



260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 260

def build_format_spec(output_path)
  # Build vips output specification with format and quality
  format_op = find_op(:format)
  quality_op = find_op(:quality)

  # Simple case: no format/quality operations
  return output_path unless format_op || quality_op

  # Extract format from operation or output path
  ext = format_op ? format_op[:format] : File.extname(output_path).delete(".")
  base = output_path.gsub(/\.[^.]+$/, "")

  # Build format spec with quality if present
  if quality_op
    quality = quality_op[:quality]
    "#{base}.#{ext}[Q=#{quality}]"
  else
    "#{base}.#{ext}"
  end
end

#build_resize_command(input_path, output_path) ⇒ Object 



187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 187

def build_resize_command(input_path, output_path)
  resize_op = find_op(:resize)
  format_spec = build_format_spec(output_path)
  width = resize_op[:width]
  height = resize_op[:height]

  # Use `vips thumbnail` for all resize operations. thumbnail is the
  # recommended high-level resize API — it uses shrink-on-load for
  # JPEGs (efficient), handles SVGs safely by bounding render size
  # during load, and supports all image formats.
  # See https://www.libvips.org/API/current/func.thumbnail.html
  if width && height
    # Both dimensions: thumbnail to width, cap height, crop to fill
    ["vips", "thumbnail", input_path, format_spec,
     width.to_s, "--height=#{height}", "--crop=attention"]
  else
    # Only width: thumbnail maintains aspect ratio
    ["vips", "thumbnail", input_path, format_spec, width.to_s]
  end
end

#build_sequential_crop_resize(input_path, output_path) ⇒ Object 



170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 170

def build_sequential_crop_resize(input_path, output_path)
  if svg?(input_path)
    # SVG: use thumbnail with --crop to do crop+resize in one step
    resize_op = find_op(:resize)
    format_spec = build_format_spec(output_path)
    width = resize_op[:width]
    height = resize_op[:height]
    [["vips", "thumbnail", input_path, format_spec,
      width.to_s, "--height=#{height}", "--crop=attention"]]
  else
    temp = temp_path(input_path, "tmp_crop.jpg")
    [build_crop_command(input_path, temp),
     build_resize_command(temp, output_path),
     [:cleanup, temp]]
  end
end

#build_smartcrop_command(geo, input_path, output_path) ⇒ Object 



216
217
218
219
220
221
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 216

def build_smartcrop_command(geo, input_path, output_path)
  interestingness = smartcrop_interestingness(geo[:keep])
  ["vips", "smartcrop", input_path, output_path,
   geo[:width].to_s, geo[:height].to_s,
   "--interesting=#{interestingness}"]
end

#build_svg_crop_pipeline(input_path, output_path) ⇒ Object

SVG crop: use vips thumbnail with --crop to crop during thumbnailing. This avoids the coordinate mismatch that occurs when rasterizing at a different size than the SVG's viewBox (which caused "bad extract area"). thumbnail --crop uses smartcrop (attention/entropy/centre) to select the most interesting region — this is the correct behavior for SVGs since they have no fixed pixel dimensions.



234
235
236
237
238
239
240
241
242
243
244
245
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 234

def build_svg_crop_pipeline(input_path, output_path)
  crop_op = find_op(:crop)
  geo = crop_geometry(crop_op)
  crop_width = geo[:width] || 1000
  crop_height = geo[:height] || 1000
  format_spec = build_format_spec(output_path)
  interestingness = smartcrop_interestingness(geo[:keep])

  [["vips", "thumbnail", input_path, format_spec,
    crop_width.to_s, "--height=#{crop_height}",
    "--crop=#{interestingness}"]]
end

#build_vips_command(input_path, output_path) ⇒ Object

Convenience wrapper for backward compatibility with tests. Returns the commands joined as a debug string.



57
58
59
60
61
62
63
64
65
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 57

def build_vips_command(input_path, output_path)
  build_vips_commands(input_path, output_path).map do |cmd|
    if cmd.is_a?(Array) && cmd.first == :cleanup
      "rm -f #{cmd[1]}"
    else
      cmd.join(" ")
    end
  end.join(" && ")
end

#build_vips_commands(input_path, output_path) ⇒ Object

Build all vips commands as an array of command arrays. Each sub-array is passed directly to Open3.capture3 (no shell). Returns Array[Array[String]].



26
27
28
29
30
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 26

def build_vips_commands(input_path, output_path)
  flags = operation_flags
  operation_builder = select_operation_builder(flags)
  operation_builder.call(input_path, output_path)
end

#build_watermark_pipeline(input_path, output_path, has_crop, has_resize) ⇒ Object 



75
76
77
78
79
80
81
82
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 75

def build_watermark_pipeline(input_path, output_path, has_crop, has_resize)
  temp = temp_path(input_path, "tmp_base.jpg")
  commands, base_path = build_base_pipeline(input_path, temp, has_crop, has_resize)
  base_path, commands = apply_watermark_alpha(base_path, input_path, commands)
  commands.concat(build_composite_commands(base_path, output_path))
  cleanup_paths(commands, input_path, temp, base_path)
  commands
end

#cleanup_paths(commands, input_path, temp_path, base_path) ⇒ Object 



100
101
102
103
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 100

def cleanup_paths(commands, input_path, temp_path, base_path)
  temp_files = [temp_path, base_path == input_path ? nil : base_path].compact
  temp_files.each { |file| commands << [:cleanup, file] }
end

#crop_commands(input_path, output_path) ⇒ Object 



51
52
53
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 51

def crop_commands(input_path, output_path)
  svg?(input_path) ? build_svg_crop_pipeline(input_path, output_path) : [build_crop_command(input_path, output_path)]
end

#execute_command(command) ⇒ Object

Execute a command array via Open3.capture3 (no shell invocation).

Parameters:

  • command (Array<String>) —

    Command and arguments as array



283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 283

def execute_command(command)
  if command.is_a?(Array) && command.first == :cleanup
    FileUtils.rm_f(command[1])
    return
  end

  Jekyll.logger.debug "LibVips command: #{command.join(' ')}"

  # Execute command array directly (no shell)
  # nosemgrep: ruby.lang.security.dangerous-exec.dangerous-exec -- command is an argument array; no shell is invoked.
  stdout, stderr, status = Open3.capture3(*command)
  output = "#{stdout}#{stderr}"
  success = status.success?

  unless success
    cmd_str = command.join(" ")
    # Filter out expected warnings and only log real errors
    raise "LibVips command failed: #{cmd_str}\nError: #{output}" unless output.include?("same file") || output.include?("VipsForeignSave")

    Jekyll.logger.warn "LibVips warning: #{output.strip}"
    return output.strip # Continue despite warnings

  end

  output.strip
end

#operation_flags ⇒ Object 



42
43
44
45
46
47
48
49
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 42

def operation_flags
  {
    crop: op?(:crop),
    resize: op?(:resize),
    watermark: op?(:watermark),
    alpha: op?(:alpha_opacity)
  }
end

#position_to_vips_xy(position, _base_path, watermark_path) ⇒ Object

Return x/y arguments as an array of strings (no shell substitution). Pre-computes image dimensions via vips header in Ruby.



130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 130

def position_to_vips_xy(position, _base_path, watermark_path)
  case position.to_s
  when "northeast", "top-right"
    width = vips_image_dimension(watermark_path, "width")
    ["--x", width.to_s, "--y", "0"]
  when "southwest", "bottom-left"
    height = vips_image_dimension(watermark_path, "height")
    ["--x", "0", "--y", height.to_s]
  when "southeast", "bottom-right"
    width = vips_image_dimension(watermark_path, "width")
    height = vips_image_dimension(watermark_path, "height")
    ["--x", width.to_s, "--y", height.to_s]
  else
    ["--x", "0", "--y", "0"] # northwest, top-left, center, centre, and default
  end
end

#run_command(cmd) ⇒ Object 



19
20
21
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 19

def run_command(cmd)
  execute_command(cmd)
end

#select_operation_builder(flags) ⇒ Object 



32
33
34
35
36
37
38
39
40
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 32

def select_operation_builder(flags)
  return ->(input, output) { build_watermark_pipeline(input, output, flags[:crop], flags[:resize]) } if flags[:watermark]
  return ->(input, output) { build_alpha_pipeline(input, output, flags[:crop], flags[:resize]) } if flags[:alpha]
  return ->(input, output) { build_sequential_crop_resize(input, output) } if flags[:crop] && flags[:resize]
  return ->(input, output) { [build_resize_command(input, output)] } if flags[:resize]
  return ->(input, output) { crop_commands(input, output) } if flags[:crop]

  ->(input, output) { [build_copy_command(input, output)] }
end

#vips_image_dimension(image_path, field) ⇒ Object

Get an image dimension (width or height) using vips header. Returns integer or 0 if vips is unavailable.



149
150
151
152
153
154
155
156
157
158
159
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 149

def vips_image_dimension(image_path, field)
  return 0 unless %w[width height].include?(field)

  # nosemgrep: ruby.lang.security.dangerous-exec.dangerous-exec -- Open3 receives an argument array and field is allowlisted.
  stdout, _, status = Open3.capture3("vips", "header", image_path, field)
  return 0 unless status.success?

  stdout.strip.to_i
rescue StandardError
  0
end