Parent

Namespace

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.

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

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.

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 119
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

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 197
def cell_style=(style_hash)
  cells.style(style_hash)
end
cells() click to toggle source

Returns a Cells object that can be used to select and style cells. See the Cells documentation for things you can do with cells.

# File lib/prawn/table/cells.rb, line 14
def cells
  @cell_proxy ||= Cells.new(@cells)
end
column(col_spec) click to toggle source
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 314
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, column(c).width
        (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 = column(c).width, 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 164
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 29
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 222
def draw
  # 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

  # 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
      Cell.draw_cells(cells_this_page)
      cells_this_page = []

      # start a new page or column
      @pdf.bounds.move_past_bottom
      draw_header unless cell.row == 0
      offset = @pdf.y - cell.y
      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)
      index = @header ? (cell.row - 1) : cell.row
      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
  Cell.draw_cells(cells_this_page)

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

Returns the height of the table in PDF points.

# File lib/prawn/table.rb, line 179
def height
  cells.height
end
row(row_spec) click to toggle source
Alias for: rows
row_heights() click to toggle source

Returns an array with the height of each row.

# File lib/prawn/table.rb, line 352
def row_heights
  @natural_row_heights ||= (0...row_length).map{ |r| row(r).height }
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 21
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 216
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 149
def width
  @width ||= [natural_width, @pdf.bounds.width].min
end

Protected Instance Methods

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 385
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
draw_header() click to toggle source

If the table has a header, draw it at the current position.

# File lib/prawn/table.rb, line 400
def draw_header
  if @header
    y = @pdf.cursor
    row(0).each do |cell|
      cell.y = y
      cell.draw
    end
    @pdf.move_cursor_to(y - row(0).height)
  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 362
def make_cells(data)
  assert_proper_table_data(data)

  cells = []
  
  @row_length = data.length
  @column_length = data.map{ |r| r.length }.max

  data.each_with_index do |row_cells, row_number|
    row_cells.each_with_index do |cell_data, column_number|
      cell = Cell.make(@pdf, cell_data)
      cell.extend(Cell::InTable)
      cell.row = row_number
      cell.column = column_number
      cells << cell
    end
  end
  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 413
def natural_column_widths
  @natural_column_widths ||= (0...column_length).map { |c| column(c).width }
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 422
def natural_width
  @natural_width ||= natural_column_widths.inject(0) { |sum, w| sum + w }
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 447
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 431
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 440
def set_row_heights
  row_heights.each_with_index { |h, row_num| row(row_num).height = h }
end

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