Class: ZipKit::SizeEstimator

Inherits:
Object
  • Object
show all
Defined in:
lib/zip_kit/size_estimator.rb

Overview

Helps to estimate archive sizes

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.estimate(**kwargs_for_streamer_new) {|the| ... } ⇒ Integer

Performs the estimate using fake archiving. It needs to know the sizes of the entries upfront. Usage:

expected_zip_size = SizeEstimator.estimate do | estimator |
  estimator.add_stored_entry(filename: "file.doc", size: 898291)
  estimator.add_deflated_entry(filename: "family.tif",
          uncompressed_size: 89281911, compressed_size: 121908)
end

Yield Parameters:



28
29
30
31
32
33
 
# File 'lib/zip_kit/size_estimator.rb', line 28

def self.estimate(**kwargs_for_streamer_new)
  streamer = ZipKit::Streamer.new(ZipKit::NullWriter, **kwargs_for_streamer_new)
  estimator = new(streamer)
  yield(estimator)
  streamer.close # Returns the .tell of the contained IO
end

Instance Method Details

#add_deflated_entry(filename:, uncompressed_size:, compressed_size:, use_data_descriptor: false) ⇒ Object

Add a fake entry to the archive, to see how big it is going to be in the end.



62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/zip_kit/size_estimator.rb', line 62

def add_deflated_entry(filename:, uncompressed_size:, compressed_size:, use_data_descriptor: false)
  @streamer.add_deflated_entry(filename: filename,
    crc32: 0,
    compressed_size: compressed_size,
    uncompressed_size: uncompressed_size,
    use_data_descriptor: use_data_descriptor)

  @streamer.simulate_write(compressed_size)
  if use_data_descriptor
    @streamer.update_last_entry_and_write_data_descriptor(crc32: 0,
      compressed_size: compressed_size,
      uncompressed_size: uncompressed_size)
  end
  self
end

#add_empty_directory_entry(dirname:) ⇒ Object

Add an empty directory to the archive.



82
83
84
85
 
# File 'lib/zip_kit/size_estimator.rb', line 82

def add_empty_directory_entry(dirname:)
  @streamer.add_empty_directory(dirname: dirname)
  self
end

#add_stored_entry(filename:, size:, use_data_descriptor: false) ⇒ Object

Add a fake entry to the archive, to see how big it is going to be in the end.

data descriptor to specify size



42
43
44
45
46
47
48
49
50
51
52
 
# File 'lib/zip_kit/size_estimator.rb', line 42

def add_stored_entry(filename:, size:, use_data_descriptor: false)
  @streamer.add_stored_entry(filename: filename,
    crc32: 0,
    size: size,
    use_data_descriptor: use_data_descriptor)
  @streamer.simulate_write(size)
  if use_data_descriptor
    @streamer.update_last_entry_and_write_data_descriptor(crc32: 0, compressed_size: size, uncompressed_size: size)
  end
  self
end