Initial ICO parsing

lib/ico.rb

@@ -0,0 +1,90 @@
+require "stringio"
+
+class W3DHub
+  class ICO
+    IconDirectory = Struct.new(:reserved, :type, :image_count)
+
+    IconDirectoryEntity = Struct.new(
+      :width,
+      :height,
+      :palette_size,
+      :reserved,
+      :color_planes,
+      :bit_depth,
+      :image_size,
+      :image_offset
+    )
+
+
+    def initialize(file:)
+      @file = StringIO.new(File.binread(file))
+
+      @images = []
+
+      parse
+    end
+
+    def directory
+      @icon_directory
+    end
+
+    def images
+      @images
+    end
+
+    # SEE: https://en.wikipedia.org/wiki/ICO_(file_format)
+    def parse
+      # Parse IconDirectory
+      @icon_directory = IconDirectory.new(
+        read_u16, read_u16, read_u16
+      )
+
+      @icon_directory.image_count.times do
+        @images << IconDirectoryEntity.new(
+          read_u8,
+          read_u8,
+          read_u8,
+          read_u8,
+          read_u16,
+          read_u16,
+          read_u32,
+          read_u32
+        )
+      end
+    end
+
+    def read_u8
+      @file.read(1).unpack1("C")
+    end
+
+    def read_u16
+      @file.read(2).unpack1("v")
+    end
+
+    def read_u32
+      @file.read(4).unpack1("V")
+    end
+
+    def to_rgba32_blob(image)
+      @file.pos = image.image_offset
+      buf = @file.read(image.image_size)
+
+      File.write("TEMP.bmp", buf)
+    end
+
+    def select_pngs
+      @images.select do |image|
+        @file.pos = image.image_offset
+        buf = @file.read(8).unpack1("a*")
+        buf == "\211PNG\r\n\032\n".force_encoding("ASCII-8BIT")
+      end
+    end
+
+    def select_bmps
+    end
+  end
+end
+
+data = W3DHub::ICO.new(file: "/home/cyberarm/Downloads/icos/ar.ico")
+pp data.select_pngs.size, data.images.size
+# data.to_rgba32_blob(data.images.first)