lib/prawn/table/column_width_calculator.rb
# encoding: utf-8
module Prawn
class Table
# @private
class ColumnWidthCalculator
def initialize(cells)
@cells = cells
@widths_by_column = Hash.new(0)
@rows_with_a_span_dummy = Hash.new(false)
#calculate for each row if it includes a Cell:SpanDummy
@cells.each do |cell|
@rows_with_a_span_dummy[cell.row] = true if cell.is_a?(Cell::SpanDummy)
end
end
# does this row include a Cell:SpanDummy?
#
# @param row - the row that should be checked for Cell:SpanDummy elements
#
def has_a_span_dummy?(row)
@rows_with_a_span_dummy[row]
end
# helper method
# column widths are stored in the values array
# a cell may span cells whose value is only partly given
# this function handles this special case
#
# @param values - The columns widths calculated up until now
# @param cell - The current cell
# @param index - The current column
# @param meth - Meth (min/max); used to calculate values to be filled
#
def fill_values_if_needed(values, cell, index, meth)
#have all spanned indices been filled with a value?
#e.g. values[0], values[1] and values[2] don't return nil given a index of 0 and a colspan of 3
number_of_nil_values = 0
cell.colspan.times do |i|
number_of_nil_values += 1 if values[index+i].nil?
end
#nothing to do? because
#a) all values are filled
return values if number_of_nil_values == 0
#b) no values are filled
return values if number_of_nil_values == cell.colspan
#c) I am not sure why this line is needed FIXXME
#some test cases manage to this line even though there is no dummy cell in the row
#I'm not sure if this is a sign for a further underlying bug.
return values unless has_a_span_dummy?(cell.row)
#fill up the values array
#calculate the new sum
new_sum = cell.send(meth) * cell.colspan
#substract any calculated values
cell.colspan.times do |i|
new_sum -= values[index+i] unless values[index+i].nil?
end
#calculate value for the remaining - not yet filled - cells.
new_value = new_sum.to_f / number_of_nil_values
#fill the not yet filled cells
cell.colspan.times do |i|
values[index+i] = new_value if values[index+i].nil?
end
return values
end
def natural_widths
#calculate natural column width for all rows that do not include a span dummy
@cells.each do |cell|
unless has_a_span_dummy?(cell.row)
@widths_by_column[cell.column] =
[@widths_by_column[cell.column], cell.width.to_f].max
end
end
#integrate natural column widths for all rows that do include a span dummy
@cells.each do |cell|
next unless has_a_span_dummy?(cell.row)
#the width of a SpanDummy cell will be calculated by the "mother" cell
next if cell.is_a?(Cell::SpanDummy)
if cell.colspan == 1
@widths_by_column[cell.column] =
[@widths_by_column[cell.column], cell.width.to_f].max
else
#calculate the current with of all cells that will be spanned by the current cell
current_width_of_spanned_cells =
@widths_by_column.to_a[cell.column..(cell.column + cell.colspan - 1)]
.collect{|key, value| value}.inject(0, :+)
#update the Hash only if the new with is at least equal to the old one
#due to arithmetic errors we need to ignore a small difference in the new and the old sum
#the same had to be done in the column_widht_calculator#natural_width
update_hash = ((cell.width.to_f - current_width_of_spanned_cells) >
Prawn::FLOAT_PRECISION)
if update_hash
# Split the width of colspanned cells evenly by columns
width_per_column = cell.width.to_f / cell.colspan
# Update the Hash
cell.colspan.times do |i|
@widths_by_column[cell.column + i] = width_per_column
end
end
end
end
@widths_by_column.sort_by { |col, _| col }.map { |_, w| w }
end
# get column widths (either min or max depending on meth)
# used in cells.rb
#
# @param row_or_column - you may call this on either rows or columns
# @param meth - min/max
# @param aggregate - functions from cell.rb to be used to aggregate e.g. avg_spanned_min_width
#
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
@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
# if there are only colspanned or rowspanned cells in a table
spanned_width_needs_fixing = true
@cells.each do |cell|
index = cell.send(row_or_column)
if cell.colspan > 1
#special treatment if some but not all spanned indices in the values array have been calculated
#only applies to rows
values = fill_values_if_needed(values, cell, index, meth) if row_or_column == :column
#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
#due to float rounding errors we need to ignore a small difference in the new
#and the old sum the same had to be done in
#the column_width_calculator#natural_width
spanned_width_needs_fixing = ((new_sum - old_sum) > Prawn::FLOAT_PRECISION)
if spanned_width_needs_fixing
#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 spanned_width_needs_fixing && cell.class == Prawn::Table::Cell::SpanDummy
values[index] = [values[index], cell.send(meth)].compact.send(aggregate)
end
end
end
return values.values.inject(0, &:+)
end
end
end
end