Module: ZPNG::ScanLine::Mixins::Interlaced

Defined in:

lib/zpng/scan_line/mixins.rb

Overview

scanline decoding

Instance Method Summary

• #prev_scanline_byte(x) ⇒ Object

Instance Method Details

#prev_scanline_byte(x) ⇒ Object

# File 'lib/zpng/scan_line/mixins.rb', line 8

def prev_scanline_byte x
  # When the image is interlaced, each pass of the interlace pattern is
  # treated as an independent image for filtering purposes
  image.adam7.pass_start?(@idx) ? 0 : image.scanlines[@idx-1].decoded_bytes.getbyte(x)
end