module ChunkyPNG::Canvas::StreamImporting

Methods to quickly load a canvas from a stream, encoded in RGB, RGBA, BGR or ABGR format.

Public Instance Methods

from_abgr_stream(width, height, stream) click to toggle source

Creates a canvas by reading pixels from an ARGB formatted stream with a provided with and height.

Every pixel should be represented by 4 bytes in the stream, in the correct ARGB order. This format is almost like the internal representation of a canvas object, so this kind of stream can be read extremely quickly.

@param [Integer] width The width of the new canvas. @param [Integer] height The height of the new canvas. @param [#read, String] stream The stream to read the pixel data from. @return [ChunkyPNG::Canvas] The newly constructed canvas instance.

   # File lib/chunky_png/canvas/stream_importing.rb
69 def from_abgr_stream(width, height, stream)
70   string = stream.respond_to?(:read) ? stream.read(4 * width * height) : stream.to_s[0, 4 * width * height]
71   new(width, height, string.unpack("V*"))
72 end
from_bgr_stream(width, height, stream) click to toggle source

Creates a canvas by reading pixels from an BGR formatted stream with a provided with and height.

Every pixel should be represented by 3 bytes in the stream, in the correct BGR order. This format closely resembles the internal representation of a canvas object, so this kind of stream can be read extremely quickly.

@param [Integer] width The width of the new canvas. @param [Integer] height The height of the new canvas. @param [#read, String] stream The stream to read the pixel data from. @return [ChunkyPNG::Canvas] The newly constructed canvas instance.

   # File lib/chunky_png/canvas/stream_importing.rb
51 def from_bgr_stream(width, height, stream)
52   string = ChunkyPNG::EXTRA_BYTE.dup # Add a first byte to the first BGR triple.
53   string << (stream.respond_to?(:read) ? stream.read(3 * width * height) : stream.to_s[0, 3 * width * height])
54   pixels = string.unpack("@1" << ("XV" * (width * height))).map { |color| color | 0x000000ff }
55   new(width, height, pixels)
56 end
from_rgb_stream(width, height, stream) click to toggle source

Creates a canvas by reading pixels from an RGB formatted stream with a provided with and height.

Every pixel should be represented by 3 bytes in the stream, in the correct RGB order. This format closely resembles the internal representation of a canvas object, so this kind of stream can be read extremely quickly.

@param [Integer] width The width of the new canvas. @param [Integer] height The height of the new canvas. @param [#read, String] stream The stream to read the pixel data from. @return [ChunkyPNG::Canvas] The newly constructed canvas instance.

   # File lib/chunky_png/canvas/stream_importing.rb
16 def from_rgb_stream(width, height, stream)
17   string = stream.respond_to?(:read) ? stream.read(3 * width * height) : stream.to_s[0, 3 * width * height]
18   string << ChunkyPNG::EXTRA_BYTE # Add a fourth byte to the last RGB triple.
19   unpacker = "NX" * (width * height)
20   pixels = string.unpack(unpacker).map { |color| color | 0x000000ff }
21   new(width, height, pixels)
22 end
from_rgba_stream(width, height, stream) click to toggle source

Creates a canvas by reading pixels from an RGBA formatted stream with a provided with and height.

Every pixel should be represented by 4 bytes in the stream, in the correct RGBA order. This format is exactly like the internal representation of a canvas object, so this kind of stream can be read extremely quickly.

@param [Integer] width The width of the new canvas. @param [Integer] height The height of the new canvas. @param [#read, String] stream The stream to read the pixel data from. @return [ChunkyPNG::Canvas] The newly constructed canvas instance.

   # File lib/chunky_png/canvas/stream_importing.rb
35 def from_rgba_stream(width, height, stream)
36   string = stream.respond_to?(:read) ? stream.read(4 * width * height) : stream.to_s[0, 4 * width * height]
37   new(width, height, string.unpack("N*"))
38 end