# File lib/RMagick.rb, line 1040
1040:         def initialize(img, x, y, width, height)
1041:             img.check_destroyed
1042:             if width <= 0 || height <= 0
1043:                 Kernel.raise ArgumentError, "invalid geometry (#{width}x#{height}+#{x}+#{y})"
1044:             end
1045:             if x < 0 || y < 0 || (x+width) > img.columns || (y+height) > img.rows
1046:                 Kernel.raise RangeError, "geometry (#{width}x#{height}+#{x}+#{y}) exceeds image boundary"
1047:             end
1048:             @view = img.get_pixels(x, y, width, height)
1049:             @img = img
1050:             @x = x
1051:             @y = y
1052:             @width = width
1053:             @height = height
1054:             @dirty = false
1055:         end

      # File lib/RMagick.rb, line 1057
1057:         def [](*args)
1058:             rows = Rows.new(@view, @width, @height, args)
1059:             rows.add_observer(self)
1060:             return rows
1061:         end

      # File lib/RMagick.rb, line 1064
1064:         def sync(force=false)
1065:             @img.store_pixels(x, y, width, height, @view) if (@dirty || force)
1066:             return (@dirty || force)
1067:         end

      # File lib/RMagick.rb, line 1071
1071:         def update(rows)
1072:             @dirty = true
1073:             rows.delete_observer(self)      # No need to tell us again.
1074:             nil
1075:         end