Class: JekyllImgFlow::Providers::Libvips

Inherits:
BaseProvider 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::KNOWN_OPERATIONS, BaseProvider::SMARTCROP_POSITIONS

Instance Attribute Summary

Attributes inherited from BaseProvider

#config

Instance Method Summary collapse

Methods inherited from BaseProvider

#add_watermark, #alpha_opacity=, #check_http_service, #convert_format, #crop, #encode_file_url, #format, #initialize, #opacity, #operations, #optimize, provider_name, #quality, #quality=, #reset_operations, #resize, #supports_operation?, supports_operation?, unsupported_operations, #watermark

Constructor Details

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

Instance Method Details

#available? ⇒ Boolean

Returns:

  • (Boolean) 


11
12
13
14
15
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 11

def available?
  # Check if vips CLI is available
  _, _, status = Open3.capture3("which", "vips")
  status.success?
end

#build_alpha_command(input_path, output_path) ⇒ Object 



180
181
182
183
184
185
186
187
188
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 180

def build_alpha_command(input_path, output_path)
  alpha_op = @operations.find { |op| op[:type] == :alpha_opacity }
  opacity = alpha_op[:opacity]
  alpha_value = 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 



66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 66

def build_alpha_pipeline(input_path, output_path, has_crop, has_resize)
  commands = []
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_base.jpg")

  if has_crop && has_resize
    commands.concat(build_sequential_crop_resize(input_path, temp_path))
    base_path = temp_path
  elsif has_resize
    commands << build_resize_command(input_path, temp_path)
    base_path = temp_path
  elsif has_crop
    commands << build_crop_command(input_path, temp_path)
    base_path = temp_path
  else
    base_path = input_path
  end

  commands << build_alpha_command(base_path, output_path)
  commands << [:cleanup, temp_path] unless base_path == input_path
  commands
end

#build_composite_commands(base_path, output_path) ⇒ Object 



125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 125

def build_composite_commands(base_path, output_path)
  wm_op = @operations.find { |op| op[:type] == :watermark }
  watermark_path = wm_op[:watermark_path]
  position = wm_op[:options][:position]
  opacity = wm_op[:options][:opacity]

  if opacity && opacity < 1.0
    wm_temp = watermark_path.gsub(/\.[^.]+$/, ".tmp_wm.png")
    alpha_value = opacity
    # Step 1: Apply alpha to watermark
    alpha_cmd = ["vips", "linear", watermark_path,
                 "#{wm_temp}[alpha]", "1 1 1 #{alpha_value}", "0"]
    # Step 2: Composite
    xy_args = position_to_vips_xy(position, base_path, 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(position, base_path, watermark_path)
    [["vips", "composite2", base_path, watermark_path,
      build_format_spec(output_path), "over"] + xy_args]
  end
end

#build_copy_command(input_path, output_path) ⇒ Object 



281
282
283
284
285
286
287
288
289
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 281

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 



228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 228

def build_crop_command(input_path, output_path)
  crop_op = @operations.find { |op| op[:type] == :crop }
  opts = crop_op[:options] || {}
  params = crop_op[:params] || {}
  keep = opts[:keep] || params[:keep] || params[:position]

  if crop_op[:ratio] && keep && %w[attention entropy center
                                   centre].include?(keep.to_s)
    crop_width = opts[:calculated_width]
    crop_height = opts[:calculated_height]
    interestingness = case keep.to_s
                      when "entropy" then "entropy"
                      when "center", "centre" then "centre"
                      else "attention"
                      end
    ["vips", "smartcrop", input_path, output_path,
     crop_width.to_s, crop_height.to_s,
     "--interesting=#{interestingness}"]
  else
    crop_x = crop_op[:ratio] ? opts[:calculated_x] : (opts[:x] || 0)
    crop_y = crop_op[:ratio] ? opts[:calculated_y] : (opts[:y] || 0)
    crop_width = crop_op[:ratio] ? opts[:calculated_width] : opts[:width]
    crop_height = crop_op[:ratio] ? opts[:calculated_height] : opts[:height]
    ["vips", "extract_area", input_path, output_path,
     crop_x.to_s, crop_y.to_s, crop_width.to_s, crop_height.to_s]
  end
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).



294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 294

def build_format_spec(output_path)
  # Build vips output specification with format and quality
  format_op = @operations.find { |op| op[:type] == :format }
  quality_op = @operations.find { |op| op[:type] == :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 



207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 207

def build_resize_command(input_path, output_path)
  resize_op = @operations.find { |op| op[:type] == :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 



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

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 = @operations.find { |op| op[:type] == :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_path = input_path.gsub(/\.[^.]+$/, ".tmp_crop.jpg")
    [build_crop_command(input_path, temp_path),
     build_resize_command(temp_path, output_path),
     [:cleanup, temp_path]]
  end
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.



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 262

def build_svg_crop_pipeline(input_path, output_path)
  crop_op = @operations.find { |op| op[:type] == :crop }
  opts = crop_op[:options] || {}
  crop_width = crop_op[:ratio] ? opts[:calculated_width] : (opts[:width] || 1000)
  crop_height = crop_op[:ratio] ? opts[:calculated_height] : (opts[:height] || 1000)
  format_spec = build_format_spec(output_path)

  keep = opts[:keep] || crop_op[:params]&.[](:keep) || crop_op[:params]&.[](:position)
  interestingness = case keep.to_s
                    when "entropy" then "entropy"
                    when "center", "centre" then "centre"
                    else "attention"
                    end

  [["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.



56
57
58
59
60
61
62
63
64
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 56

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]].



33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 33

def build_vips_commands(input_path, output_path)
  has_crop = @operations.any? { |op| op[:type] == :crop }
  has_resize = @operations.any? { |op| op[:type] == :resize }
  has_watermark = @operations.any? { |op| op[:type] == :watermark }
  has_alpha = @operations.any? { |op| op[:type] == :alpha_opacity }

  if has_watermark
    build_watermark_pipeline(input_path, output_path, has_crop, has_resize)
  elsif has_alpha
    build_alpha_pipeline(input_path, output_path, has_crop, has_resize)
  elsif has_crop && has_resize
    build_sequential_crop_resize(input_path, output_path)
  elsif has_resize
    [build_resize_command(input_path, output_path)]
  elsif has_crop
    svg?(input_path) ? build_svg_crop_pipeline(input_path, output_path) : [build_crop_command(input_path, output_path)]
  else
    [build_copy_command(input_path, output_path)]
  end
end

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



88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 88

def build_watermark_pipeline(input_path, output_path, has_crop, has_resize)
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_base.jpg")

  commands = []

  # Step 1: Process crop/resize/copy to produce base image
  if has_crop && has_resize
    commands.concat(build_sequential_crop_resize(input_path, temp_path))
    base_path = temp_path
  elsif has_resize
    commands << build_resize_command(input_path, temp_path)
    base_path = temp_path
  elsif has_crop
    commands << build_crop_command(input_path, temp_path)
    base_path = temp_path
  else
    base_path = input_path
  end

  # Step 2: Apply alpha opacity if present (before watermark)
  alpha_op = @operations.find { |op| op[:type] == :alpha_opacity }
  if alpha_op
    alpha_temp = input_path.gsub(/\.[^.]+$/, ".tmp_alpha.jpg")
    commands << build_alpha_command(base_path, alpha_temp)
    base_path = alpha_temp
  end

  # Step 3: Composite watermark over base
  commands.concat(build_composite_commands(base_path, output_path))

  # Step 4: Cleanup temp files
  temp_files = [temp_path, base_path == input_path ? nil : base_path].compact
  temp_files.each { |f| commands << [:cleanup, f] }

  commands
end

#execute(input_path, output_path) ⇒ Object 



17
18
19
20
21
22
23
24
25
26
27
28
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 17

def execute(input_path, output_path)
  return if @operations.empty?

  # Build and execute vips commands (array form, no shell).
  # Cleanup markers ([:cleanup, path]) are handled by execute_command.
  commands = build_vips_commands(input_path, output_path)
  commands.each { |cmd_array| execute_command(cmd_array) }

  output_path
ensure
  reset_operations
end

#execute_command(command) ⇒ Object

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

Parameters:

  • command (Array<String>) —

    Command and arguments as array



317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 317

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)
  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

#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.



152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 152

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

#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.



171
172
173
174
175
176
177
178
 
# File 'lib/jekyll-imgflow/providers/libvips.rb', line 171

def vips_image_dimension(image_path, field)
  stdout, _, status = Open3.capture3("vips", "header", image_path, field)
  return 0 unless status.success?

  stdout.strip.to_i
rescue StandardError
  0
end