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# frozen_string_literal: true
# column_box.rb: Extends BoundingBox to allow for columns of text
#
# Author Paul Ostazeski.
#
# This is free software. Please see the LICENSE and COPYING files for details.
require_relative 'bounding_box'
module Prawn
class Document
# @group Experimental API
# A column box is a bounding box with the additional property that when
# text flows past the bottom, it will wrap first to another column on the
# same page, and only flow to the next page when all the columns are
# filled.
#
# column_box accepts the same parameters as bounding_box, as well as the
# number of :columns and a :spacer (in points) between columns. If resetting
# the top margin is desired on a new page (e.g. to allow for initial page
# wide column titles) the option :reflow_margins => true can be set.
#
# Defaults are :columns = 3, :spacer = font_size, and
# :reflow_margins => false
#
# Under PDF::Writer, "spacer" was known as "gutter"
#
def column_box(*args, &block)
init_column_box(block) do |parent_box|
map_to_absolute!(args[0])
@bounding_box = ColumnBox.new(self, parent_box, *args)
end
end
private
def init_column_box(user_block, options = {})
parent_box = @bounding_box
yield(parent_box)
self.y = @bounding_box.absolute_top
user_block.call
self.y = @bounding_box.absolute_bottom unless options[:hold_position]
@bounding_box = parent_box
end
# Implements the necessary functionality to allow Document#column_box to
# work.
#
class ColumnBox < BoundingBox
def initialize(document, parent, point, options = {}) #:nodoc:
super
@columns = options[:columns] || 3
@spacer = options[:spacer] || @document.font_size
@current_column = 0
@reflow_margins = options[:reflow_margins]
end
# The column width, not the width of the whole box,
# before left and/or right padding
def bare_column_width
(@width - @spacer * (@columns - 1)) / @columns
end
# The column width after padding.
# Used to calculate how long a line of text can be.
#
def width
bare_column_width - (@total_left_padding + @total_right_padding)
end
# Column width including the spacer.
#
def width_of_column
bare_column_width + @spacer
end
# x coordinate of the left edge of the current column
#
def left_side
absolute_left + (width_of_column * @current_column)
end
# Relative position of the left edge of the current column
#
def left
width_of_column * @current_column
end
# x co-orordinate of the right edge of the current column
#
def right_side
columns_from_right = @columns - (1 + @current_column)
absolute_right - (width_of_column * columns_from_right)
end
# Relative position of the right edge of the current column.
#
def right
left + width
end
# Moves to the next column or starts a new page if currently positioned at
# the rightmost column.
def move_past_bottom
@current_column = (@current_column + 1) % @columns
@document.y = @y
if @current_column.zero?
if @reflow_margins
@y = @parent.absolute_top
end
@document.start_new_page
end
end
# Override the padding functions so as not to split the padding amount
# between all columns on the page.
def add_left_padding(left_padding)
@total_left_padding += left_padding
@x += left_padding
end
def subtract_left_padding(left_padding)
@total_left_padding -= left_padding
@x -= left_padding
end
def add_right_padding(right_padding)
@total_right_padding += right_padding
end
def subtract_right_padding(right_padding)
@total_right_padding -= right_padding
end
end
end
end
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