class Prawn::Table

Next-generation table drawing for Prawn.

Data

Data, for a Prawn table, is a two-dimensional array of objects that can be converted to cells (“cellable” objects). Cellable objects can be:

String

Produces a text cell. This is the most common usage.

Prawn::Table::Cell

If you have already built a Cell or have a custom subclass of Cell you want to use in a table, you can pass through Cell objects.

Prawn::Table

Creates a subtable (a table within a cell). You can use Prawn::Document#make_table to create a table for use as a subtable without immediately drawing it. See examples/table/bill.rb for a somewhat complex use of subtables.

Array

Creates a simple subtable. Create a Table object using make_table (see above) if you need more control over the subtable's styling.

Options

Prawn/Layout provides many options to control style and layout of your table. These options are implemented with a uniform interface: the :foo option always sets the foo= accessor. See the accessor and method documentation for full details on the options you can pass. Some highlights:

cell_style

A hash of style options to style all cells. See the documentation on Prawn::Table::Cell for all cell style options.

header

If set to true, the first row will be repeated on every page. The header must be included as the first row of your data. Row numbering (for styling and other row-specific options) always indexes based on your data array. Whether or not you have a header, row(n) always refers to the nth element (starting from 0) of the data array.

column_widths

Sets widths for individual columns. Manually setting widths can give better results than letting Prawn guess at them, as Prawn's algorithm for defaulting widths is currently pretty boneheaded. If you experience problems like weird column widths or CannotFit errors, try manually setting widths on more columns.

position

Either :left (the default), :center, :right, or a number. Specifies the horizontal position of the table within its bounding box. If a number is provided, it specifies the distance in points from the left edge.

Initializer Block

If a block is passed to methods that initialize a table (Prawn::Table.new, Prawn::Document#table, Prawn::Document#make_table), it will be called after cell setup but before layout. This is a very flexible way to specify styling and layout constraints. This code sets up a table where the second through the fourth rows (1-3, indexed from 0) are each one inch (72 pt) wide:

pdf.table(data) do |table|
  table.rows(1..3).width = 72
end

As with Prawn::Document#initialize, if the block has no arguments, it will be evaluated in the context of the object itself. The above code could be rewritten as:

pdf.table(data) do
  rows(1..3).width = 72
end

Attributes

cells[R]

Returns a Prawn::Table::Cells object representing all of the cells in this table.

column_length[R]

Number of columns in the table.

header[W]

If true, designates the first row as a header row to be repeated on every page. Does not change row numbering – row numbers always index into the data array provided, with no modification.

position[W]

Position (:left, :right, :center, or a number indicating distance in points from the left edge) of the table within its parent bounds.

row_colors[W]

Accepts an Array of alternating row colors to stripe the table.

row_length[R]

Number of rows in the table.

width[W]

Manually set the width of the table.

Public Class Methods

new(data, document, options={}, &block) click to toggle source

Set up a table on the given document. Arguments:

data

A two-dimensional array of cell-like objects. See the “Data” section above for the types of objects that can be put in a table.

document

The Prawn::Document instance on which to draw the table.

options

A hash of attributes and values for the table. See the “Options” block above for details on available options.

# File lib/prawn/table.rb, line 125
def initialize(data, document, options={}, &block)
  @pdf = document
  @cells = make_cells(data)
  @header = false
  @epsilon = 1e-9
  options.each { |k, v| send("#{k}=", v) }

  if block
    block.arity < 1 ? instance_eval(&block) : block[self]
  end

  set_column_widths
  set_row_heights
  position_cells
end

Public Instance Methods

before_rendering_page(&block) click to toggle source

Specify a callback to be called before each page of cells is rendered. The block is passed a Cells object containing all cells to be rendered on that page. You can change styling of the cells in this block, but keep in mind that the cells have already been positioned and sized.

# File lib/prawn/table.rb, line 168
def before_rendering_page(&block)
  @before_rendering_page = block
end
cell_style=(style_hash) click to toggle source

Sets styles for all cells.

pdf.table(data, :cell_style => { :borders => [:left, :right] })
# File lib/prawn/table.rb, line 222
def cell_style=(style_hash)
  cells.style(style_hash)
end
column(col_spec)
Alias for: columns
column_widths() click to toggle source

Calculate and return the constrained column widths, taking into account each cell's min_width, max_width, and any user-specified constraints on the table or column size.

Because the natural widths can be silly, this does not always work so well at guessing a good size for columns that have vastly different content. If you see weird problems like CannotFit errors or shockingly bad column sizes, you should specify more column widths manually.

# File lib/prawn/table.rb, line 362
def column_widths
  @column_widths ||= begin
    if width - cells.min_width < -epsilon
      raise Errors::CannotFit,
        "Table's width was set too small to contain its contents " +
        "(min width #{cells.min_width}, requested #{width})"
    end

    if width - cells.max_width > epsilon
      raise Errors::CannotFit,
        "Table's width was set larger than its contents' maximum width " +
        "(max width #{cells.max_width}, requested #{width})"
    end

    if width - natural_width < -epsilon
      # Shrink the table to fit the requested width.
      f = (width - cells.min_width).to_f / (natural_width - cells.min_width)

      (0...column_length).map do |c|
        min, nat = column(c).min_width, natural_column_widths[c]
        (f * (nat - min)) + min
      end
    elsif width - natural_width > epsilon
      # Expand the table to fit the requested width.
      f = (width - cells.width).to_f / (cells.max_width - cells.width)

      (0...column_length).map do |c|
        nat, max = natural_column_widths[c], column(c).max_width
        (f * (max - nat)) + nat
      end
    else
      natural_column_widths
    end
  end
end
column_widths=(widths) click to toggle source

Sets column widths for the table. The argument can be one of the following types:

Array

[w0, w1, w2, ...] (specify a width for each column)

Hash

{0 => w0, 1 => w1, ...} (keys are column names, values are widths)

Numeric

72 (sets width for all columns)

# File lib/prawn/table.rb, line 189
def column_widths=(widths)
  case widths
  when Array
    widths.each_with_index { |w, i| column(i).width = w }
  when Hash
    widths.each { |i, w| column(i).width = w }
  when Numeric
    cells.width = widths
  else
    raise ArgumentError, "cannot interpret column widths"
  end
end
columns(col_spec) click to toggle source

Selects the given columns (0-based) for styling. Returns a Cells object – see the documentation on Cells for things you can do with cells.

# File lib/prawn/table/cells.rb, line 22
def columns(col_spec)
  cells.columns(col_spec)
end
Also aliased as: column
draw() click to toggle source

Draws the table onto the document at the document's current y-position.

# File lib/prawn/table.rb, line 247
def draw
  with_position do
    # The cell y-positions are based on an infinitely long canvas. The offset
    # keeps track of how much we have to add to the original, theoretical
    # y-position to get to the actual position on the current page.
    offset = @pdf.y

    # Reference bounds are the non-stretchy bounds used to decide when to
    # flow to a new column / page.
    ref_bounds = @pdf.reference_bounds

    last_y = @pdf.y

    # Determine whether we're at the top of the current bounds (margin box or
    # bounding box). If we're at the top, we couldn't gain any more room by
    # breaking to the next page -- this means, in particular, that if the
    # first row is taller than the margin box, we will only move to the next
    # page if we're below the top. Some floating-point tolerance is added to
    # the calculation.
    #
    # Note that we use the actual bounds, not the reference bounds. This is
    # because even if we are in a stretchy bounding box, flowing to the next
    # page will not buy us any space if we are at the top.
    if @pdf.y > @pdf.bounds.height + @pdf.bounds.absolute_bottom - 0.001
      # we're at the top of our bounds
      started_new_page_at_row = 0
    else
      started_new_page_at_row = -1

      # If there isn't enough room left on the page to fit the first data row
      # (excluding the header), start the table on the next page.
      needed_height = row(0).height
      needed_height += row(1).height if @header
      if needed_height > @pdf.y - ref_bounds.absolute_bottom
        @pdf.bounds.move_past_bottom
        offset = @pdf.y
        started_new_page_at_row = 0
      end
    end

    # Duplicate each cell of the header row into @header_row so it can be
    # modified in before_rendering_page callbacks.
    if @header
      @header_row = Cells.new
      row(0).each { |cell| @header_row[cell.row, cell.column] = cell.dup }
    end

    # Track cells to be drawn on this page. They will all be drawn when this
    # page is finished.
    cells_this_page = []

    @cells.each do |cell|
      if cell.height > (cell.y + offset) - ref_bounds.absolute_bottom &&
         cell.row > started_new_page_at_row
        # Ink all cells on the current page
        if @before_rendering_page
          c = Cells.new(cells_this_page.map { |c, _| c })
          @before_rendering_page.call(c)
        end
        Cell.draw_cells(cells_this_page)
        cells_this_page = []

        # start a new page or column
        @pdf.bounds.move_past_bottom
        if cell.row > 0 && @header
          header_height = add_header(cells_this_page, @pdf.cursor, cell.row-1)
        else
          header_height = 0
        end
        offset = @pdf.y - cell.y - header_height
        started_new_page_at_row = cell.row
      end
   
      # Don't modify cell.x / cell.y here, as we want to reuse the original
      # values when re-inking the table. #draw should be able to be called
      # multiple times.
      x, y = cell.x, cell.y
      y += offset 

      # Translate coordinates to the bounds we are in, since drawing is 
      # relative to the cursor, not ref_bounds.
      x += @pdf.bounds.left_side - @pdf.bounds.absolute_left
      y -= @pdf.bounds.absolute_bottom

      # Set background color, if any.
      if @row_colors && (!@header || cell.row > 0)
        # Ensure coloring restarts on every page (to make sure the header
        # and first row of a page are not colored the same way).
        index = cell.row - [started_new_page_at_row, @header ? 1 : 0].max
        cell.background_color ||= @row_colors[index % @row_colors.length]
      end

      cells_this_page << [cell, [x, y]]
      last_y = y
    end
    # Draw the last page of cells
    if @before_rendering_page
      c = Cells.new(cells_this_page.map { |c, _| c })
      @before_rendering_page.call(c)
    end
    Cell.draw_cells(cells_this_page)

    @pdf.move_cursor_to(last_y - @cells.last.height)
  end
end
height() click to toggle source

Returns the height of the table in PDF points.

# File lib/prawn/table.rb, line 204
def height
  cells.height
end
row(row_spec)
Alias for: rows
row_heights() click to toggle source

Returns an array with the height of each row.

# File lib/prawn/table.rb, line 400
def row_heights
  @natural_row_heights ||=
    begin
      heights_by_row = Hash.new(0)
      cells.each do |cell|
        next if cell.is_a?(Cell::SpanDummy)

        # Split the height of row-spanned cells evenly by rows
        height_per_row = cell.height.to_f / cell.rowspan
        cell.rowspan.times do |i|
          heights_by_row[cell.row + i] =
            [heights_by_row[cell.row + i], height_per_row].max
        end
      end
      heights_by_row.sort_by { |row, _| row }.map { |_, h| h }
    end
end
rows(row_spec) click to toggle source

Selects the given rows (0-based) for styling. Returns a Cells object – see the documentation on Cells for things you can do with cells.

# File lib/prawn/table/cells.rb, line 14
def rows(row_spec)
  cells.rows(row_spec)
end
Also aliased as: row
style(stylable, style_hash={}, &block) click to toggle source

Allows generic stylable content. This is an alternate syntax that some prefer to the attribute-based syntax. This code using style:

pdf.table(data) do
  style(row(0), :background_color => 'ff00ff')
  style(column(0)) { |c| c.border_width += 1 }
end

is equivalent to:

pdf.table(data) do
  row(0).style :background_color => 'ff00ff'
  column(0).style { |c| c.border_width += 1 }
end
# File lib/prawn/table.rb, line 241
def style(stylable, style_hash={}, &block)
  stylable.style(style_hash, &block)
end
width() click to toggle source

Returns the width of the table in PDF points.

# File lib/prawn/table.rb, line 174
def width
  @width ||= [natural_width, @pdf.bounds.width].min
end

Protected Instance Methods

add_header(page_of_cells, y, row) click to toggle source

Add the header row to the given array of cells at the given y-position. Number the row with the given row index, so that the header appears (in any Cells built for this page) immediately prior to the first data row on this page.

Return the height of the header.

# File lib/prawn/table.rb, line 490
def add_header(page_of_cells, y, row)
  @header_row.each do |cell|
    cell.row = row
    page_of_cells << [cell, [cell.x, y]]
  end
  @header_row.height
end
assert_proper_table_data(data) click to toggle source

Raises an error if the data provided cannot be converted into a valid table.

# File lib/prawn/table.rb, line 501
def assert_proper_table_data(data)
  if data.nil? || data.empty?
    raise Prawn::Errors::EmptyTable,
      "data must be a non-empty, non-nil, two dimensional array " +
      "of cell-convertible objects"
  end

  unless data.all? { |e| Array === e }
    raise Prawn::Errors::InvalidTableData,
      "data must be a two dimensional array of cellable objects"
  end
end
make_cells(data) click to toggle source

Converts the array of cellable objects given into instances of Prawn::Table::Cell, and sets up their in-table properties so that they know their own position in the table.

# File lib/prawn/table.rb, line 424
def make_cells(data)
  assert_proper_table_data(data)

  cells = Cells.new
  
  row_number = 0
  data.each do |row_cells|
    column_number = 0
    row_cells.each do |cell_data|
      # If we landed on a spanned cell (from a rowspan above), continue
      # until we find an empty spot.
      column_number += 1 until cells[row_number, column_number].nil?

      # Build the cell and store it in the Cells collection.
      cell = Cell.make(@pdf, cell_data)
      cells[row_number, column_number] = cell

      # Add dummy cells for the rest of the cells in the span group. This
      # allows Prawn to keep track of the horizontal and vertical space
      # occupied in each column and row spanned by this cell, while still
      # leaving the master (top left) cell in the group responsible for
      # drawing. Dummy cells do not put ink on the page.
      cell.rowspan.times do |i|
        cell.colspan.times do |j|
          next if i == 0 && j == 0

          # It is an error to specify spans that overlap; catch this here
          if bad_cell = cells[row_number + i, column_number + j]
            raise Prawn::Errors::InvalidTableSpan,
              "Spans overlap at row #{row_number + i}, " +
              "column #{column_number + j}."
          end

          dummy = Cell::SpanDummy.new(@pdf, cell)
          cells[row_number + i, column_number + j] = dummy
          cell.dummy_cells << dummy
        end
      end

      column_number += cell.colspan
    end

    row_number += 1
  end

  # Calculate the number of rows and columns in the table, taking into
  # account that some cells may span past the end of the physical cells we
  # have.
  @row_length = cells.map do |cell|
    cell.row + cell.rowspan
  end.max

  @column_length = cells.map do |cell|
    cell.column + cell.colspan
  end.max

  cells
end
natural_column_widths() click to toggle source

Returns an array of each column's natural (unconstrained) width.

# File lib/prawn/table.rb, line 516
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
end
natural_width() click to toggle source

Returns the “natural” (unconstrained) width of the table. This may be extremely silly; for example, the unconstrained width of a paragraph of text is the width it would assume if it were not wrapped at all. Could be a mile long.

# File lib/prawn/table.rb, line 539
def natural_width
  @natural_width ||= natural_column_widths.inject(0, &:+)
end
position_cells() click to toggle source

Set each cell's position based on the widths and heights of cells preceding it.

# File lib/prawn/table.rb, line 564
def position_cells
  # Calculate x- and y-positions as running sums of widths / heights.
  x_positions = column_widths.inject([0]) { |ary, x| 
    ary << (ary.last + x); ary }[0..-2]
  x_positions.each_with_index { |x, i| column(i).x = x }

  # y-positions assume an infinitely long canvas starting at zero -- this
  # is corrected for in Table#draw, and page breaks are properly inserted.
  y_positions = row_heights.inject([0]) { |ary, y|
    ary << (ary.last - y); ary}[0..-2]
  y_positions.each_with_index { |y, i| row(i).y = y }
end
set_column_widths() click to toggle source

Assigns the calculated column widths to each cell. This ensures that each cell in a column is the same width. After this method is called, subsequent calls to #column_widths and width should return the finalized values that will be used to ink the table.

# File lib/prawn/table.rb, line 548
def set_column_widths
  column_widths.each_with_index do |w, col_num| 
    column(col_num).width = w
  end
end
set_row_heights() click to toggle source

Assigns the row heights to each cell. This ensures that every cell in a row is the same height.

# File lib/prawn/table.rb, line 557
def set_row_heights
  row_heights.each_with_index { |h, row_num| row(row_num).height = h }
end
with_position() { || ... } click to toggle source

Sets up a bounding box to position the table according to the specified :position option, and yields.

# File lib/prawn/table.rb, line 580
def with_position
  x = case @position || :left
      when :left   then return yield
      when :center then (@pdf.bounds.width - width) / 2.0
      when :right  then  @pdf.bounds.width - width
      when Numeric then  @position
      else raise ArgumentError, "unknown position #{@position.inspect}"
      end
  dy = @pdf.bounds.absolute_top - @pdf.y
  final_y = nil

  @pdf.bounding_box([x, @pdf.bounds.top], :width => width) do
    @pdf.move_down dy
    yield
    final_y = @pdf.y
  end

  @pdf.y = final_y
end

Private Instance Methods

epsilon() click to toggle source
# File lib/prawn/table.rb, line 602
def epsilon
  @epsilon
end