# File lib/RMagick.rb, line 965
965:         def initialize(img, x, y, width, height)
966:             if width <= 0 || height <= 0
967:                 Kernel.raise ArgumentError, "invalid geometry (#{width}x#{height}+#{x}+#{y})"
968:             end
969:             if x < 0 || y < 0 || (x+width) > img.columns || (y+height) > img.rows
970:                 Kernel.raise RangeError, "geometry (#{width}x#{height}+#{x}+#{y}) exceeds image boundary"
971:             end
972:             @view = img.get_pixels(x, y, width, height)
973:             @img = img
974:             @x = x
975:             @y = y
976:             @width = width
977:             @height = height
978:             @dirty = false
979:         end

     # File lib/RMagick.rb, line 981
981:         def [](*args)
982:             rows = Rows.new(@view, @width, @height, args)
983:             rows.add_observer(self)
984:             return rows
985:         end

     # File lib/RMagick.rb, line 988
988:         def sync(force=false)
989:             @img.store_pixels(x, y, width, height, @view) if (@dirty || force)
990:             return (@dirty || force)
991:         end

     # File lib/RMagick.rb, line 995
995:         def update(rows)
996:             @dirty = true
997:             rows.delete_observer(self)      # No need to tell us again.
998:             nil
999:         end