Methods to quickly load a canvas from a stream, encoded in RGB, RGBA, BGR or ABGR format.
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, line 71 def from_abgr_stream(width, height, stream) string = stream.respond_to?(:read) ? stream.read(4 * width * height) : stream.to_s[0, 4 * width * height] self.new(width, height, string.unpack("V*")) end
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, line 53 def from_bgr_stream(width, height, stream) string = ChunkyPNG::EXTRA_BYTE # Add a first byte to the first BGR triple. string << stream.respond_to?(:read) ? stream.read(3 * width * height) : stream.to_s[0, 3 * width * height] pixels = string.unpack("@1" << ('XV' * (width * height))).map { |color| color | 0x000000ff } self.new(width, height, pixels) end
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, line 18 def from_rgb_stream(width, height, stream) string = stream.respond_to?(:read) ? stream.read(3 * width * height) : stream.to_s[0, 3 * width * height] string << ChunkyPNG::EXTRA_BYTE # Add a fourth byte to the last RGB triple. unpacker = 'NX' * (width * height) pixels = string.unpack(unpacker).map { |color| color | 0x000000ff } self.new(width, height, pixels) end
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, line 37 def from_rgba_stream(width, height, stream) string = stream.respond_to?(:read) ? stream.read(4 * width * height) : stream.to_s[0, 4 * width * height] self.new(width, height, string.unpack("N*")) end
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