some fixes

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2023 TheIndustriousRabbit
+Copyright (c) 2023 John Bintz
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
 

README.md

@@ -1,3 +1,7 @@
 # png-to-ilbm
 
-Convert PNG images to IFF ILBM images using Ruby.
+Convert PNG images to IFF ILBM images using Ruby, preserving palette indexes.
+
+Copyright 2023 John Bintz. Learn more at https://theindustriousrabbit.com/
+
+Licensed under the MIT License.

png_to_ilbm_strict_palette.rb

@@ -10,24 +10,21 @@
 #
 # * http://etwright.org/lwsdk/docs/filefmts/ilbm.html
 
-# * [ ] AMOS and ADPro fail on an image that's less than 8 pixels wide?
-#   * DPaint can load it, other apps get weird
-
 require 'rmagick'
 
 class PixelColor
   attr_reader :r, :g, :b
-  
+
   def initialize(r:, g:, b:)
     @r = r
     @g = g
     @b = b
   end
-  
+
   def ==(other)
     r == other.r && g == other.g && b == other.b
   end
-  
+
   def to_cmap
     [
       r * 16 + r,
@@ -35,7 +32,7 @@ class PixelColor
       b * 16 + b
     ]
   end
-  
+
   def inspect
     "RGB: #{r.to_s(16)},#{g.to_s(16)},#{b.to_s(16)}"
   end
@@ -64,11 +61,11 @@ class Bitplane
   def initialize(bits:)
     @bits = bits
   end
-  
+
   def count
     @bits.count
   end
-  
+
   def [](idx)
     @bits[idx]
   end
@@ -84,38 +81,38 @@ class ImageComponentParser
     parser.parse!
     parser
   end
-  
+
   UnknownPaletteColor = Class.new(ArgumentError)
-  
+
   def initialize(image:, desired_palette:)
     @image = image
     @desired_palette = desired_palette
     @bitplanes = nil
   end
-  
+
   def bitplane_count
     Math.sqrt(@desired_palette.length).ceil
   end
-  
+
   def bitplanes
     return @bitplanes if @bitplanes
-    
+
     bits = []
     # get around duplicate objects
     bitplane_count.times { |i| bits << [] }
-    
+
     @bytes.each do |byte|
       mask = 1
       bitplane_count.times do |bit|
         bits[bit] << (((byte & mask) == mask) ? 1 : 0)
-        
+
         mask = mask << 1
       end
     end
-    
+
     @bitplanes = bits.map { |b| Bitplane.new(bits: b) }
   end
-  
+
   def parse!
     @bytes = []
     @image.each_pixel do |px|
@@ -125,12 +122,12 @@ class ImageComponentParser
         g: px.green >> 12,
         b: px.blue >> 12
       )
-    
+
       index = @desired_palette.find_index { |p| p == pixel_color }
       unless index
         raise UnknownPaletteColor, "Palette color not found! Check export: #{pixel_color}"  
       end
-      
+
       @bytes << index
     end
   end
@@ -141,20 +138,20 @@ module IFF
     def to_bytes
       data_bytes = to_data_bytes
       data_bytes_count = data_bytes.count
-      
+
       output = self.class.name.split("::").last.unpack("C*") +
-          [data_bytes_count].pack("N").unpack("C*") +
+        [data_bytes_count].pack("N").unpack("C*") +
-          data_bytes
+        data_bytes
-      
+
       # pad chunk
       output << 0 if data_bytes_count.odd?
-        
+
       output
     end
   end
-  
+
   # Construct an IFF ILBM image from the provided data.
-  class ILBMBuilder   
+  class ILBMBuilder
     def initialize(
       width:,
       height:,
@@ -170,28 +167,28 @@ module IFF
       @row_writer = row_writer
       @screen_format = screen_format
     end
-    
+
     def row_writer
       return UncompressedRowWriter
-      
+
       # here's no reason to use compression if the image is less 
       # than 24 pixels wide
       if @row_writer == CompressedRowWriter && @width < 24
         return UncompressedRowWriter
-      end      
+      end
-      
+
       @row_writer
     end
-    
+
     def build
       form = FORM.new
-      
+
       bmhd = BMHD.new
       bmhd.width = @width
       bmhd.height = @height
       bmhd.planes = Math.sqrt(@palette.length).ceil
       bmhd.compression = row_writer.bmhd_flag
-      
+
       cmap = CMAP.new(palette: @palette)
 
       body = BODY.new(
@@ -199,62 +196,62 @@ module IFF
         width: @width,
         row_writer: row_writer
       )
-      
+
       ilbm = ILBM.new
       ilbm.bmhd = bmhd
       ilbm.cmap = cmap
       ilbm.body = body
       ilbm.camg = @screen_format
-      
+
       form << ilbm
-      
+
       form
     end
   end
-  
+
   # IFF wrapper
   class FORM
     include WithHeader
-    
+
     def initialize
       @chunks = []
     end
-    
+
     def <<(chunk)
       @chunks << chunk
     end
-    
+
     def to_data_bytes
       @chunks.flat_map(&:to_bytes)
     end
-    
+
     def to_s
       to_bytes.pack("C*")
     end
   end
-  
+
   # Image type header
   class ILBM
     attr_accessor :bmhd, :cmap, :body, :camg
-    
+
     def to_bytes
       "ILBM".unpack("C*") + 
-          bmhd.to_bytes +
+      bmhd.to_bytes +
-          cmap.to_bytes +
+      cmap.to_bytes +
-          camg.to_bytes +
+      camg.to_bytes +
-          # body is always last
+      # body is always last
-          body.to_bytes
+      body.to_bytes
     end
   end
-  
+
   # Image properties
   class BMHD
     include WithHeader
-    
+
     ASPECT_RATIO = 0x2C
-    
+
     attr_accessor :width, :height, :planes, :compression
-    
+
     def to_data_bytes
       [
         *word_to_bytes(width),
@@ -271,14 +268,14 @@ module IFF
         *word_to_bytes(height),
       ]
     end
-    
+
     private
-    
+
     def word_to_bytes(word)
       [ word >> 8, word & 0xff ]
     end
   end
-  
+
   # Color map
   class CMAP
     include WithHeader
@@ -286,12 +283,12 @@ module IFF
     def initialize(palette:)
       @palette = palette
     end
-    
+
     def to_data_bytes
       @palette.flat_map(&:to_cmap)
     end
   end
-  
+
   # Amiga-related display properties
   class CAMG
     include WithHeader
@@ -299,16 +296,16 @@ module IFF
     def self.PalLowRes
       new(0x00021000)
     end
-    
+
     def initialize(setting)
       @setting = setting
     end
-    
+
     def to_data_bytes
       [@setting].pack("N").unpack("C*")
     end
   end
-  
+
   module AsRowWriter
     def initialize
       @data = []
@@ -317,28 +314,28 @@ module IFF
     def <<(byte)
       @data << byte
     end
-    
+
     # Output pixel data is word padded
     def ensure_padded!
       @data << 0 if @data.length.odd?
     end
   end
-  
+
   # Write out uncompressed bitplane data
   class UncompressedRowWriter
     include AsRowWriter
-    
+
     def self.bmhd_flag
       0
     end
-    
+
     def to_bytes
       ensure_padded!
-      
+
       @data
     end
   end
-  
+
   # Write out compressed bitplane data using the
   # ByteRun1 run encoding algorithm.
   class CompressedRowWriter
@@ -347,12 +344,12 @@ module IFF
     def self.bmhd_flag
       1
     end
-      
+
     def to_bytes
       ensure_padded!
 
       runs = []
-      
+
       # discover initial runs
       # format is [byte, run count]
       @data.each do |byte|
@@ -377,11 +374,11 @@ module IFF
           if out.last&.first != :literal
             out << [:literal]
           end
-            
+
           out.last << byte
         end
       end
-      
+
       # write out compressed data
       runs.each_with_object([]) do |type, obj|
         case type.first
@@ -397,56 +394,56 @@ module IFF
       end
     end
   end
-  
+
   # Pixel data
   class BODY
     include WithHeader
-    
+
     def initialize(bitplanes:, width:, row_writer:)
       @bitplanes = bitplanes
       @width = width
       @row_writer = row_writer
     end
-    
+
     START_MASK = 1 << 7
-    
+
     def to_data_bytes
       rows = []
-      
+
       row_count = @bitplanes[0].count / @width
-      
+
       row_count.times do |y|
         # interleave the bitplanes
         pos = y * @width
-        
+
-        @bitplanes.each do |bitplane|         
+        @bitplanes.each do |bitplane|
           val = 0
           mask = START_MASK
-          
+
           # the row writer takes care of turning bitplane data into output
           current_row_writer = @row_writer.new
-          
+
           @width.times do |x|
             val = bitplane[pos + x] * mask | val
             mask >>= 1
-            
+
             # end of byte
             if mask == 0
               current_row_writer << val
-              
+
               val = 0
               mask = START_MASK
             end
           end
-          
+
           unless mask == START_MASK
             current_row_writer << val
           end
-          
+
           rows.concat(current_row_writer.to_bytes)
         end
       end
-      
+
       rows
     end
   end