Backport code prawn to correctly render colspan table cells

Ports the following prs:
prawnpdf#712
prawnpdf#620

lib/prawn.rb

@@ -6,6 +6,7 @@
 #
 module Prawn #:nodoc:
   VERSION = "1.0.0.rc2"
+  FLOAT_PRECISION = 1.0e-9
 end
 
 require "prawn/utilities"

lib/prawn/table.rb

@@ -6,6 +6,7 @@
 #
 # This is free software. Please see the LICENSE and COPYING files for details.
 
+require 'prawn/table/column_width_calculator'
 require 'prawn/table/cells'
 require 'prawn/table/cell'
 require 'prawn/table/cell/in_table'
@@ -567,21 +568,7 @@ def assert_proper_table_data(data)
     # Returns an array of each column's natural (unconstrained) width.
     #
     def natural_column_widths
-      @natural_column_widths ||=
-        begin
-          widths_by_column = Hash.new(0)
-          cells.each do |cell|
-            next if cell.is_a?(Cell::SpanDummy)
-
-            # Split the width of colspanned cells evenly by columns
-            width_per_column = cell.width.to_f / cell.colspan
-            cell.colspan.times do |i|
-              widths_by_column[cell.column + i] =
-                [widths_by_column[cell.column + i], width_per_column].max
-            end
-          end
-          widths_by_column.sort_by { |col, _| col }.map { |_, w| w }
-        end
+      @natural_column_widths ||= ColumnWidthCalculator.new(cells).natural_widths
     end
 
     # Returns the "natural" (unconstrained) width of the table. This may be

lib/prawn/table/cells.rb

@@ -152,16 +152,7 @@ def style(options={}, &block)
       # Returns the total width of all columns in the selected set.
       #
       def width
-        widths = {}
-        each do |cell|
-          index = cell.column
-          per_cell_width = cell.width_ignoring_span.to_f / cell.colspan
-          cell.colspan.times do |n|
-            widths[cell.column+n] = [widths[cell.column+n], per_cell_width].
-              compact.max
-          end
-        end
-        widths.values.inject(0, &:+)
+        ColumnWidthCalculator.new(self).natural_widths.inject(0, &:+)
       end
 
       # Returns minimum width required to contain cells in the set.
@@ -228,48 +219,7 @@ def index_cells
       # each cell, grouped by +row_or_column+.
       #
       def aggregate_cell_values(row_or_column, meth, aggregate)
-        values = {}
-
-        #calculate values for all cells that do not span accross multiple cells
-        #this ensures that we don't have a problem if the first line includes
-        #a cell that spans across multiple cells
-        each do |cell|
-          #don't take spanned cells
-          if cell.colspan == 1 and cell.class != Prawn::Table::Cell::SpanDummy
-            index = cell.send(row_or_column)
-            values[index] = [values[index], cell.send(meth)].compact.send(aggregate)
-          end
-        end
-
-        each do |cell|
-          index = cell.send(row_or_column)          
-          if cell.colspan > 1
-            #calculate current (old) return value before we do anything
-            old_sum = 0
-            cell.colspan.times { |i|
-              old_sum += values[index+i] unless values[index+i].nil?
-            }
-
-            #calculate future return value 
-            new_sum = cell.send(meth) * cell.colspan
-
-            if new_sum >= old_sum
-              #not entirely sure why we need this line, but with it the tests pass
-              values[index] = [values[index], cell.send(meth)].compact.send(aggregate) 
-              #overwrite the old values with the new ones, but only if all entries existed
-              entries_exist = true
-              cell.colspan.times { |i| entries_exist = false if values[index+i].nil? }
-              cell.colspan.times { |i|
-                values[index+i] = cell.send(meth) if entries_exist
-              }
-            end
-          else
-            if cell.class == Prawn::Table::Cell::SpanDummy
-              values[index] = [values[index], cell.send(meth)].compact.send(aggregate) 
-            end
-          end
-        end
-        values.values.inject(0, &:+)
+        ColumnWidthCalculator.new(self).aggregate_cell_values(row_or_column, meth, aggregate)
       end
 
       # Transforms +spec+, a column / row specification, into an object that

spec/table_spec.rb

@@ -80,6 +80,34 @@
 
     end
 
+    it "illustrates issue #710", :issue => 710 do
+      partial_width = 40
+      pdf = Prawn::Document.new({page_size: "LETTER", page_layout: :portrait})
+      col_widths = [
+        50,
+        partial_width, partial_width, partial_width, partial_width
+      ]
+
+      day_header = [{
+          content: "Monday, August 5th, A.S. XLIX",
+          colspan: 5,
+      }]
+
+      times = [{
+        content: "Loc",
+        colspan: 1,
+      }, {
+        content: "8:00",
+        colspan: 4,
+      }]
+
+      data = [ day_header ] + [ times ]
+
+      #raised a Prawn::Errors::CannotFit:
+      #Table's width was set larger than its contents' maximum width (max width 210, requested 218.0)
+      table = Prawn::Table.new data, pdf, :column_widths => col_widths
+    end
+
     it "illustrate issue #533" do
       data = [['', '', '', '', '',''],
               ['',{:content => '', :colspan => 5}]]
@@ -91,15 +119,36 @@
       pdf = Prawn::Document.new
       first = {:content=>"Foooo fo foooooo",:width=>50,:align=>:center}
       second = {:content=>"Foooo",:colspan=>2,:width=>70,:align=>:center}
-      third = {:content=>"fooooooooooo, fooooooooooooo, fooo, foooooo fooooo",:width=>55,:align=>:center}
-      fourth = {:content=>"Bar",:width=>15,:align=>:center}
+      third = {:content=>"fooooooooooo, fooooooooooooo, fooo, foooooo fooooo",:width=>50,:align=>:center}
+      fourth = {:content=>"Bar",:width=>20,:align=>:center}
       table_content = [[
       first,
       [[second],[third,fourth]]
       ]]
       pdf.move_down(20)
+      table = Prawn::Table.new table_content, pdf
       pdf.table(table_content)
     end
+
+    #https://github.com/prawnpdf/prawn/issues/407#issuecomment-28556698
+    it "correctly computes column widths with empty cells + colspan" do
+      data = [['', ''],
+              [{:content => '', :colspan => 2}]
+              ]
+      pdf = Prawn::Document.new
+
+      table = Prawn::Table.new data, pdf, :column_widths => [50, 200]
+      table.column_widths.should == [50.0, 200.0]
+    end
+
+    it "illustrates a variant of problem in issue #407 - comment 28556698" do
+      pdf = Prawn::Document.new
+      table_data = [["a", "b", "c"], [{:content=>"d", :colspan=>3}]]
+      column_widths = [50, 60, 400]
+
+      # Before we fixed #407, this line incorrectly raise a CannotFit error
+      pdf.table(table_data, :column_widths => column_widths)
+    end
   end
 
   describe "#initialize" do