Add merged cells functionality

lib/spreadsheet/excel/internals.rb

@@ -216,6 +216,7 @@ module Internals
     :hlink        => 0x01b8, #    HLINK ➜ 6.52 (BIFF8 only)
     :label        => 0x0204, #    LABEL ➜ 6.59 (BIFF2-BIFF7)
     :labelsst     => 0x00fd, #    LABELSST ➜ 6.61 (BIFF8 only)
+    :mergedcells  => 0x00e5, # ○○ MERGEDCELLS	➜ 5.67 (BIFF8 only)
     :mulblank     => 0x00be, #    MULBLANK ➜ 6.64 (BIFF5-BIFF8)
     :mulrk        => 0x00bd, #    MULRK ➜ 6.65 (BIFF5-BIFF8)
     :number       => 0x0203, #    NUMBER ➜ 6.68

lib/spreadsheet/excel/reader.rb

@@ -761,6 +761,27 @@ def read_window2 worksheet, work, pos, len
     flags, _ = work.unpack 'v'
     worksheet.selected = flags & 0x0200 > 0
   end
+
+  def read_merged_cells worksheet, work, pos, len
+    # This record contains the addresses of merged cell ranges in the current sheet.
+    # Record MERGEDCELLS, BIFF8:
+    # Offset  Size  Contents
+    # 0	      var.	Cell range address list with merged ranges (➜ 2.5.15)
+    # If the record size exceeds the limit, it is not continued with a CONTINUE record,
+    # but another self-contained MERGEDCELLS record is started. The limit of 8224 bytes
+    # per record results in a maximum number of 1027 merged ranges.
+
+    worksheet.merged_cells.push *read_range_address_list(work, len)
+    #
+    # A cell range address list consists of a field with the number of ranges and the list
+    # of the range addresses.
+    # Cell range address list, BIFF2-BIFF8:
+    # Offset  Size          Contents
+    # 0       2             Number of following cell range addresses (nm)
+    # 2	      6∙nm or 8∙nm  List of nm cell range addresses (➜ 2.5.14)
+    #
+  end
+
   def read_workbook
     worksheet = nil
     previous_op = nil
@@ -843,6 +864,8 @@ def read_worksheet worksheet, offset
         read_hlink worksheet, work, pos, len
       when :window2
         read_window2 worksheet, work, pos, len
+      when :mergedcells # ○○ MERGEDCELLS	➜ 5.67
+        read_merged_cells worksheet, work, pos, len
       else
         if ROW_BLOCK_OPS.include?(op)
           set_missing_row_address worksheet, work, pos, len

lib/spreadsheet/excel/reader/biff5.rb

@@ -16,6 +16,26 @@ def read_string work, count_length=1
     length, = work.unpack fmt
     work[count_length, length]
   end
+
+  def read_range_address_list work, len
+    # Cell range address, BIFF2-BIFF5:
+    # Offset  Size  Contents
+    # 0       2     Index to first row
+    # 2       2     Index to last row
+    # 4       1     Index to first column
+    # 5       1     Index to last column
+    #
+    offset = 0, results = []
+    return results if len < 2
+    count = work[0..1].unpack('v').first
+    offset = 2
+    count.times do |i|
+      results << work[offset...offset+6].unpack('v2c2')
+      offset += 6
+    end
+    results
+  end
+
 end
     end
   end

lib/spreadsheet/excel/reader/biff8.rb

@@ -161,6 +161,27 @@ def read_string_header work, count_length=1, offset=0
     owing     = chars - have_chrs
     [chars, flagsize, wide, phonetic, richtext, avbl, owing, skip]
   end
+
+  def read_range_address_list work, len
+    # Cell range address, BIFF8:
+    # Offset  Size  Contents
+    # 0       2     Index to first row
+    # 2       2     Index to last row
+    # 4       2     Index to first column
+    # 6       2     Index to last column
+    # ! In several cases, BIFF8 still writes the BIFF2-BIFF5 format of a cell range address
+    # (using 8-bit values for the column indexes). This will be mentioned at the respective place.
+    #
+    offset = 0, results = []
+    return results if len < 2
+    count = work[0..1].unpack('v').first
+    offset = 2
+    count.times do |i|
+      results << work[offset...offset+8].unpack('v4')
+      offset += 8
+    end
+    results
+  end
   ##
   # Insert null-characters into a compressed UTF-16 string
   def wide string

lib/spreadsheet/excel/writer/worksheet.rb

@@ -488,6 +488,7 @@ def write_from_scratch
     # ○○ SELECTION ➜ 5.93
     # ○  STANDARDWIDTH ➜ 5.101
     # ○○ MERGEDCELLS ➜ 5.67
+    write_merged_cells
     # ○  LABELRANGES ➜ 5.64
     # ○  PHONETIC ➜ 5.77
     # ○  Conditional Formatting Table ➜ 4.12
@@ -837,6 +838,20 @@ def write_window2
     data = [ flags, 0, 0, 0, 0, 0 ].pack binfmt(:window2)
     write_op opcode(:window2), data
   end
+
+  def write_merged_cells
+    return unless @worksheet.merged_cells.any?
+    # FIXME standards say the record is limited by 1027 records at once
+    # And no CONTINUE is supported
+
+    merge_cells = @worksheet.merged_cells.dup
+    while (window = merge_cells.slice!(0...1027)).any?
+      count = window.size
+      data = ([count] + window.flatten).pack('v2v*')
+      write_op opcode(:mergedcells), data
+    end
+  end
+
   def write_wsbool
     bits = [
          #   Bit  Mask    Contents

lib/spreadsheet/worksheet.rb

@@ -27,7 +27,7 @@ class Worksheet
     include Spreadsheet::Encodings
     include Enumerable
     attr_accessor :name, :selected, :workbook
-    attr_reader :rows, :columns
+    attr_reader :rows, :columns, :merged_cells
     def initialize opts={}
       @default_format = nil
       @selected = opts[:selected]
@@ -37,6 +37,7 @@ def initialize opts={}
       @rows = []
       @columns = []
       @links = {}
+      @merged_cells = []
     end
     def active # :nodoc:
       warn "Worksheet#active is deprecated. Please use Worksheet#selected instead."
@@ -251,6 +252,12 @@ def [] row, column
     def []= row, column, value
       row(row)[column] = value
     end
+    ##
+    # Merges multiple cells into one.
+    def merge_cells start_row, start_col, end_row, end_col
+      # FIXME enlarge or dup check
+      @merged_cells.push [start_row, end_row, start_col, end_col]
+    end
     private
     def index_of_first ary # :nodoc:
       return unless ary