Split and refactor

lib/fastimage/fastimage_parsing/avif.rb

@@ -0,0 +1,12 @@
+module FastImageParsing
+  class Avif < ImageBase # :nodoc:  
+    def dimensions
+      bmff = IsoBmff.new(@stream)
+      [bmff.width, bmff.height]
+    end
+
+    def animated?
+      @stream.peek(12)[4..-1] == "ftypavis"
+    end
+  end
+end

lib/fastimage/fastimage_parsing/bmp.rb

@@ -0,0 +1,17 @@
+module FastImageParsing
+  class Bmp < ImageBase # :nodoc:
+    def dimensions
+      d = @stream.read(32)[14..28]
+      header = d.unpack("C")[0]
+
+      result = if header == 12
+                 d[4..8].unpack('SS')
+               else
+                 d[4..-1].unpack('l<l<')
+               end
+
+      # ImageHeight is expressed in pixels. The absolute value is necessary because ImageHeight can be negative
+      [result.first, result.last.abs]
+    end
+  end
+end

lib/fastimage/fastimage_parsing/exif.rb

@@ -0,0 +1,69 @@
+module FastImageParsing
+  class Exif # :nodoc:
+    attr_reader :width, :height, :orientation
+
+    def initialize(stream)
+      @stream = stream
+      @width, @height, @orientation = nil
+      parse_exif
+    end
+
+    def rotated?
+      @orientation >= 5
+    end
+
+    private
+
+    def get_exif_byte_order
+      byte_order = @stream.read(2)
+      case byte_order
+      when 'II'
+        @short, @long = 'v', 'V'
+      when 'MM'
+        @short, @long = 'n', 'N'
+      else
+        raise FastImage::CannotParseImage
+      end
+    end
+
+    def parse_exif_ifd
+      tag_count = @stream.read(2).unpack(@short)[0]
+      tag_count.downto(1) do
+        type = @stream.read(2).unpack(@short)[0]
+        @stream.read(6)
+        data = @stream.read(2).unpack(@short)[0]
+        case type
+        when 0x0100 # image width
+          @width = data
+        when 0x0101 # image height
+          @height = data
+        when 0x0112 # orientation
+          @orientation = data
+        end
+        if @width && @height && @orientation
+          return # no need to parse more
+        end
+        @stream.read(2)
+      end
+    end
+
+    def parse_exif
+      @start_byte = @stream.pos
+
+      get_exif_byte_order
+
+      @stream.read(2) # 42
+
+      offset = @stream.read(4).unpack(@long)[0]
+      if @stream.respond_to?(:skip)
+        @stream.skip(offset - 8)
+      else
+        @stream.read(offset - 8)
+      end
+
+      parse_exif_ifd
+
+      @orientation ||= 1
+    end
+  end
+end

lib/fastimage/fastimage_parsing/fiber_stream.rb

@@ -0,0 +1,58 @@
+module FastImageParsing
+  class FiberStream # :nodoc:
+    include StreamUtil
+    attr_reader :pos
+
+    # read_fiber should return nil if it no longer has anything to return when resumed
+    # so the result of the whole Fiber block should be set to be nil in case yield is no
+    # longer called
+    def initialize(read_fiber)
+      @read_fiber = read_fiber
+      @pos = 0
+      @strpos = 0
+      @str = ''
+    end
+
+    # Peeking beyond the end of the input will raise
+    def peek(n)
+      while @strpos + n > @str.size
+        unused_str = @str[@strpos..-1]
+
+        new_string = @read_fiber.resume
+        raise FastImage::CannotParseImage if !new_string
+        # we are dealing with bytes here, so force the encoding
+        new_string.force_encoding("ASCII-8BIT") if new_string.respond_to? :force_encoding
+
+        @str = unused_str + new_string
+        @strpos = 0
+      end
+
+      @str[@strpos, n]
+    end
+
+    def read(n)
+      result = peek(n)
+      @strpos += n
+      @pos += n
+      result
+    end
+
+    def skip(n)
+      discarded = 0
+      fetched = @str[@strpos..-1].size
+      while n > fetched
+        discarded += @str[@strpos..-1].size
+        new_string = @read_fiber.resume
+        raise FastImage::CannotParseImage if !new_string
+
+        new_string.force_encoding("ASCII-8BIT") if new_string.respond_to? :force_encoding
+
+        fetched += new_string.size
+        @str = new_string
+        @strpos = 0
+      end
+      @strpos = @strpos + n - discarded
+      @pos += n
+    end
+  end
+end

lib/fastimage/fastimage_parsing/gif.rb

@@ -0,0 +1,63 @@
+module FastImageParsing
+  class Gif < ImageBase # :nodoc:  
+    def dimensions
+      @stream.read(11)[6..10].unpack('SS')
+    end
+
+    # Checks for multiple frames
+    def animated?
+      frames = 0
+
+      # "GIF" + version (3) + width (2) + height (2)
+      @stream.skip(10)
+
+      # fields (1) + bg color (1) + pixel ratio (1)
+      fields = @stream.read(3).unpack("CCC")[0]
+      if fields & 0x80 != 0 # Global Color Table
+        # 2 * (depth + 1) colors, each occupying 3 bytes (RGB)
+        @stream.skip(3 * 2 ** ((fields & 0x7) + 1))
+      end
+
+      loop do
+        block_type = @stream.read(1).unpack("C")[0]
+
+        if block_type == 0x21 # Graphic Control Extension
+          # extension type (1) + size (1)
+          size = @stream.read(2).unpack("CC")[1]
+          @stream.skip(size)
+          skip_sub_blocks
+        elsif block_type == 0x2C # Image Descriptor
+          frames += 1
+          return true if frames > 1
+
+          # left position (2) + top position (2) + width (2) + height (2) + fields (1)
+          fields = @stream.read(9).unpack("SSSSC")[4]
+          if fields & 0x80 != 0 # Local Color Table
+            # 2 * (depth + 1) colors, each occupying 3 bytes (RGB)
+            @stream.skip(3 * 2 ** ((fields & 0x7) + 1))
+          end
+
+          @stream.skip(1) # LZW min code size (1)
+          skip_sub_blocks
+        else
+          break # unrecognized block
+        end
+      end
+
+      false
+    end
+
+    private
+
+    def skip_sub_blocks
+      loop do
+        size = @stream.read(1).unpack("C")[0]
+        if size == 0
+          break
+        else
+          @stream.skip(size)
+        end
+      end
+    end
+  end
+end

lib/fastimage/fastimage_parsing/heic.rb

@@ -0,0 +1,8 @@
+module FastImageParsing
+  class Heic < ImageBase # :nodoc:
+    def dimensions
+      bmff = IsoBmff.new(@stream)
+      [bmff.width, bmff.height]
+    end
+  end
+end

lib/fastimage/fastimage_parsing/ico.rb

@@ -0,0 +1,9 @@
+module FastImageParsing
+  class Ico < ImageBase
+    def dimensions
+      icons = @stream.read(6)[4..5].unpack('v').first
+      sizes = icons.times.map { @stream.read(16).unpack('C2').map { |x| x == 0 ? 256 : x } }.sort_by { |w,h| w * h }
+      sizes.last
+    end
+  end
+end

lib/fastimage/fastimage_parsing/image_base.rb

@@ -0,0 +1,17 @@
+module FastImageParsing
+  class ImageBase # :nodoc:
+    def initialize(stream)
+      @stream = stream
+    end
+
+    # Implement in subclasses
+    def dimensions
+      raise NotImplementedError
+    end
+
+    # Implement in subclasses if appropriate
+    def animated?
+      nil
+    end
+  end
+end