class ChunkyPNG::Chunk::Physical
The Physical
(pHYs) chunk specifies the intended pixel size or aspect ratio for display of the image.
Constants
- INCHES_PER_METER
Attributes
ppux[RW]
ppuy[RW]
unit[RW]
Public Class Methods
new(ppux, ppuy, unit = :unknown)
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Calls superclass method
ChunkyPNG::Chunk::Base::new
# File lib/chunky_png/chunk.rb 338 def initialize(ppux, ppuy, unit = :unknown) 339 raise ArgumentError, "unit must be either :meters or :unknown" unless [:meters, :unknown].member?(unit) 340 super("pHYs") 341 @ppux, @ppuy, @unit = ppux, ppuy, unit 342 end
read(type, content)
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# File lib/chunky_png/chunk.rb 354 def self.read(type, content) 355 ppux, ppuy, unit = content.unpack("NNC") 356 unit = unit == 1 ? :meters : :unknown 357 new(ppux, ppuy, unit) 358 end
Public Instance Methods
content()
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Assembles the content to write to the stream for this chunk. @return [String] The binary content that should be written to the datastream.
# File lib/chunky_png/chunk.rb 362 def content 363 [ppux, ppuy, unit == :meters ? 1 : 0].pack("NNC") 364 end
dpix()
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# File lib/chunky_png/chunk.rb 344 def dpix 345 raise ChunkyPNG::UnitsUnknown, "the PNG specifies its physical aspect ratio, but does not specify the units of its pixels' physical dimensions" unless unit == :meters 346 ppux * INCHES_PER_METER 347 end
dpiy()
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# File lib/chunky_png/chunk.rb 349 def dpiy 350 raise ChunkyPNG::UnitsUnknown, "the PNG specifies its physical aspect ratio, but does not specify the units of its pixels' physical dimensions" unless unit == :meters 351 ppuy * INCHES_PER_METER 352 end