Next-generation table drawing for Prawn.
Data, for a Prawn table, is a two-dimensional array of objects that can be converted to cells (“cellable” objects). Cellable objects can be:
Produces a text cell. This is the most common usage.
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.
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.
Creates a simple subtable. Create a Table object using make_table (see above) if you need more control over the subtable's styling.
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.
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
Returns a Prawn::Table::Cells object representing all of the cells in this table.
Number of columns in the table.
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 (:left, :right, :center, or a number indicating distance in points from the left edge) of the table within its parent bounds.
Accepts an Array of alternating row colors to stripe the table.
Number of rows in the table.
Manually set the width of the table.
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
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
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
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
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
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
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
Returns the height of the table in PDF points.
# File lib/prawn/table.rb, line 204 def height cells.height end
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
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
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
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
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
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
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
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
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
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
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
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
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
# File lib/prawn/table.rb, line 602 def epsilon @epsilon end