Class: RSyntaxTree::SVGGraph

Inherits:
BaseGraph show all
Defined in:
lib/rsyntaxtree/svg_graph.rb

Constant Summary collapse

REGION_DEFAULT_COLOR =

Default color for a region shade drawn with bare '%' (no color spec). An explicit '%@color:' is always honored, even in color-off mode, to stay consistent with how the @color: node-text color behaves.

"#888888"
REGION_FILL_OPACITY =

Fill opacity for region shades; low enough that nested/overlapping shades stack naturally without obscuring the tree underneath.

0.2
REGION_STROKE_OPACITY =

The border reuses the fill color but at a higher opacity, so it reads as a darker shade of the same color — keeping the region clearly bounded on a white page without a per-color "darker shade" lookup.

0.55
SHEAR_PLANE_FILL_OPACITY =

The plane a sheared figure lies on. Lighter than a region shade: a region marks part of a figure out from the rest, and the plane is behind all of it — at the region's own opacity the whole page darkens.

0.12

Constants inherited from BaseGraph

BaseGraph::LINK_ARROW_CLEARANCE, BaseGraph::TIDY_BASE_SPACING, BaseGraph::TIDY_CONVERGENCE, BaseGraph::TIDY_EXTRA_CAP, BaseGraph::TIDY_HEIGHT_BUDGET, BaseGraph::TIDY_LEVEL_BALANCE, BaseGraph::TIDY_MAX_ITERATIONS

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from BaseGraph

#ancestor_ids, #calculate_height, #calculate_indent, #calculate_level, #calculate_width, #child_spread, #connector_height_for, #contour_clearance, #derivation_row_extent, #derivation_rule_band, #draw_connector, #draw_elements, #effective_rect, #finalize_ltr, #flip_vertical, #get_leftmost, #get_rightmost, #layout_overlaps?, #layout_snapshot, #level_connector_heights, #level_derivation_rows, #link_connection_pairs, #make_balance, #middle_child_alignment, #mirror_layout, #node_centering, #normalize_horizontal, #parse_list, #prepare_ltr, #restore_layout, #restore_middle_child_alignment, #rule_name_room, #shift_subtree, #spread_linked_pairs, #subtree_height, #subtree_leaf_center_span, #subtree_leaf_span, #subtree_rects, #subtree_right, #tidy_compress, #tidy_gap, #triangle_asked_for?

Constructor Details

#initialize(element_list, params, global) ⇒ SVGGraph

Returns a new instance of SVGGraph.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 34

def initialize(element_list, params, global)
  super(element_list, params, global)
  @height = 0
  @width  = 0
  @extra_lines = []
  @region_shades = []
  @fontset = params[:fontset]
  @fontsize = params[:fontsize]
  @linewidth = params[:linewidth]
  @transparent = params[:transparent] == true
  @color = params[:color]
  @fontstyle = params[:fontstyle]
  @polyline = params[:polyline] == true
  @direction = params[:direction] || "ttb"
  # The angle arrives in degrees, positive leaning the top to the right.
  # What the transform wants is the x-shift per unit of y, and y grows
  # downward here, so the tangent changes sign on the way in.
  @shear_deg = (params[:shear] || 0).to_f
  @shear_k = (-Math.tan(@shear_deg * Math::PI / 180)).round(3)
  @shear_plane = params[:shear_plane] || "on"
  @line_styles = "<line style='fill: none; stroke:#{@col_line}; stroke-width:#{@global[:stroke_normal]}; stroke-linejoin:round; stroke-linecap:round;' x1='X1' y1='Y1' x2='X2' y2='Y2' />\n"
  @polyline_styles = "<polyline style='stroke:#{@col_line}; stroke-width:#{@global[:stroke_normal]}; fill:none; stroke-linejoin:round; stroke-linecap:round;'
                        points='CHIX CHIY MIDX1 MIDY1 MIDX2 MIDY2 PARX PARY' />\n"
  @polygon_styles = "<polygon style='fill: none; stroke: #{@col_connector}; stroke-width:#{@global[:stroke_normal]}; stroke-linejoin:round;stroke-linecap:round;' points='X1 Y1 X2 Y2 X3 Y3' />\n"
  @text_styles = "<text white-space='pre' alignment-baseline='text-top' style='fill: COLOR; stroke-width: 0; font-size: fontsize' x='X_VALUE' y='Y_VALUE'>CONTENT</text>\n"
  @tree_data = String.new
  @visited_x = {}
  @visited_y = {}
  @global = global
end

Instance Attribute Details

#height ⇒ Object

Returns the value of attribute height.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 32

def height
  @height
end

#width ⇒ Object

Returns the value of attribute width.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 32

def width
  @width
end

Instance Method Details

#along(from, to, distance) ⇒ Object

A point the given distance from from along the line towards to.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 346

def along(from, to, distance)
  dx = to[0] - from[0]
  dy = to[1] - from[1]
  length = Math.sqrt((dx * dx) + (dy * dy))
  return from.dup if length.zero?

  [from[0] + (dx / length * distance), from[1] + (dy / length * distance)]
end

#bothways_arrows(x1, y1, x2, y2, col, swidth) ⇒ Object

Two arrowheads back to back at the midpoint of a link, drawn as filled triangles sized to the link itself. The arrowBothways marker this replaces was one fixed size — three inter-node gaps wide — so on a short link between narrow-spaced boxes it spilled over both of them.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1052

def bothways_arrows(x1, y1, x2, y2, col, swidth)
  len = Math.hypot(x2 - x1, y2 - y1)
  return "" if len.zero?

  ux = (x2 - x1) / len
  uy = (y2 - y1) / len
  mx = (x1 + x2) / 2
  my = (y1 + y2) / 2

  # Same proportions the marker had — three inter-node gaps end to end,
  # one deep, two heads with a shaft's worth of daylight between them —
  # so a link long enough to hold it looks as it always did. What is new
  # is that a shorter link gets the same shape at a smaller size instead
  # of the one fixed size spilling over the boxes on either side.
  span = [@global[:h_gap_between_nodes] * 3, len * 0.8].min
  head = span / 3.0
  half = head / 2.0

  arrow = lambda do |dir|
    tip_x = mx + ux * (span / 2.0) * dir
    tip_y = my + uy * (span / 2.0) * dir
    base_x = mx + ux * half * dir
    base_y = my + uy * half * dir
    "<polygon points='#{tip_x},#{tip_y} " \
      "#{base_x - uy * half},#{base_y + ux * half} " \
      "#{base_x + uy * half},#{base_y - ux * half}' " \
      "style='fill:#{col}; stroke:none;' />"
  end

  arrow.call(1) + "\n" + arrow.call(-1)
end

#collect_region_shades ⇒ Object

Collect a background rectangle for every element flagged with '%'. Outer (shallower) regions are emitted first so deeper ones layer on top; with low opacity the overlap reads as a darker nesting.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 235

def collect_region_shades
  hctt = @global[:height_connector_to_text]
  pad = @global[:h_gap_between_nodes]  # generous padding for the non-parent-facing edges
  pad_parent = hctt / 2.0              # tighter margin on the parent-facing edge of the root
  radius = hctt / 2.0
  stroke_width = @global[:stroke_normal]
  half = stroke_width / 2.0
  @element_list.get_elements.each do |element|
    next unless element.region

    b = region_subtree_bounds(element.id)
    left = b[:left] - pad
    right = b[:right] + pad
    top = b[:top] - pad
    bottom = b[:bottom] + pad

    # The edge facing the parent is handled specially so the incoming
    # connector neither overlaps nor touches the plane. That edge is the
    # TOP in top-to-bottom layout and the LEFT in left-to-right layout; the
    # other edges keep the generous padding. For a non-root node the edge
    # is placed midway between the connector anchor and the content edge
    # (even gap on both sides); the tree root has no incoming connector, so
    # it just gets a tighter-but-consistent margin there.
    is_root = element.parent.zero?
    if @direction == "ltr"
      anchor = element.horizontal_indent - hctt
      left = if is_root
               b[:left] - pad_parent
             elsif anchor < b[:left]
               (b[:left] + anchor) / 2.0
             else
               left
             end
    else
      anchor = element.vertical_indent + hctt / 2.0
      top = if is_root
              b[:top] - pad_parent
            elsif anchor < b[:top]
              (b[:top] + anchor) / 2.0
            else
              top
            end
    end

    x = left
    y = top
    w = right - left
    h = bottom - top
    # An explicit shade color is always honored (consistent with the
    # @color: node-text color); bare '%' falls back to gray.
    color = element.region_color || REGION_DEFAULT_COLOR
    @region_shades << "<rect x='#{x}' y='#{y}' width='#{w}' height='#{h}' rx='#{radius}' ry='#{radius}' " \
                      "fill='#{color}' fill-opacity='#{REGION_FILL_OPACITY}' " \
                      "stroke='#{color}' stroke-opacity='#{REGION_STROKE_OPACITY}' stroke-width='#{stroke_width}' />\n"

    # Track the union of region extents (the stroke straddles the edge, so
    # it reaches half a stroke-width outside the rect) for canvas growth.
    rb = (@region_bounds ||= { min_x: x - half, min_y: y - half, max_x: x + w + half, max_y: y + h + half })
    rb[:min_x] = x - half if x - half < rb[:min_x]
    rb[:min_y] = y - half if y - half < rb[:min_y]
    rb[:max_x] = x + w + half if x + w + half > rb[:max_x]
    rb[:max_y] = y + h + half if y + h + half > rb[:max_y]
  end
end

#connector_edges(child, parent) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1207

def connector_edges(child, parent)
  hctt = @global[:height_connector_to_text]
  child_above = child.vertical_indent <= parent.vertical_indent

  # Each endpoint decides for itself. A line through a chain of invisible
  # joints keeps one real label at most, and when the pair had to agree
  # on a geometry, the segments beside a joint fell back to the box
  # measure while their neighbours took the ink one — a row of leaves
  # under example 080's joints ended thirteen units apart.
  #
  # An element whose ink went unrecorded falls back to the measure the
  # boxes gave. Nothing reaches that now — every drawn label records its
  # ink — and it is kept as the answer for a label that somehow has none
  # rather than as a second geometry anyone can ask for.
  m = @global[:single_x_metrics].height * @global[:vmargin]

  child_y = if child.empty_label?
              child.vertical_indent + child.content_height / 2
            elsif child_above
              if m && child.ink_bottom
                ink_under(child) + m
              else
                child.vertical_indent + child.content_height + hctt
              end
            elsif m && child.ink_top
              ink_over(child) - m
            else
              child.vertical_indent + hctt / 2
            end

  parent_y = if parent.empty_label?
               parent.vertical_indent + parent.content_height / 2
             elsif child_above
               if m && parent.ink_top
                 ink_over(parent) - m
               else
                 parent.vertical_indent + hctt / 2
               end
             elsif m && parent.ink_bottom
               ink_under(parent) + m
             else
               parent.vertical_indent + parent.content_height + hctt
             end

  # A tight pitch can put the two endpoints past each other — the gap
  # between the inks smaller than the clearance on both sides — and a
  # crossed pair draws the stroke back up through a label. Both then
  # settle at the middle of the gap, which is the one point that is
  # clear of the ink on either side whenever the gap exists at all.
  if m
    upper_pt, lower_pt = child_above ? [child_y, parent_y] : [parent_y, child_y]
    if upper_pt > lower_pt
      mid = (upper_pt + lower_pt) / 2.0
      child_y = mid
      parent_y = mid
    end
  end

  [child_y, parent_y]
end

#draw_a_path(s_x, s_y, t_x, t_y, target_arrow = :none) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 430

def draw_a_path(s_x, s_y, t_x, t_y, target_arrow = :none)
  spacing = @global[:h_gap_between_nodes] * 1.25
  min_bulge = @global[:height_connector_to_text]
  # Small enough that the turn reads as an eased corner rather than as an
  # arc, and taken from a layout measure so it holds at every font size.
  corner_radius = min_bulge / 2.0

  # Centered offset for multiple lines at the same endpoint
  s_key = "#{s_x.round}"
  t_key = "#{t_x.round}"
  @visited_x[s_key] = (@visited_x[s_key] || 0) + 1
  @visited_x[t_key] = (@visited_x[t_key] || 0) + 1
  s_offset = ((@visited_x[s_key] - 1) - (@visited_x[s_key] - 1) / 2.0) * spacing
  t_offset = ((@visited_x[t_key] - 1) - (@visited_x[t_key] - 1) / 2.0) * spacing

  dashed = true if target_arrow == :none

  if @direction == "ltr"
    # LTR: route to the RIGHT of the tree (⊃ shape / reversed C)
    # Source → right → vertical → left → Target
    xmax = [s_x, t_x].max
    bulge = [min_bulge, (s_y - t_y).abs * 0.3 + min_bulge].min
    # Ensure paths don't overlap: extend beyond previous paths
    new_x = if xmax < @width
              @width + bulge
            else
              xmax + bulge
            end

    new_s_y = s_y + s_offset
    new_t_y = t_y + t_offset

    note_path_extent([[s_x, new_s_y], [new_x, new_s_y],
                      [new_x, new_t_y], [t_x, new_t_y]])
    @extra_lines << generate_path([[s_x, new_s_y], [new_x, new_s_y],
                                   [new_x, new_t_y], [t_x, new_t_y]],
                                  @col_path, dashed: dashed, radius: corner_radius,
                                  start_arrow: target_arrow == :double,
                                  end_arrow: target_arrow != :none)
    @width = new_x if new_x > @width
  else
    # TTB: route BELOW the tree (U shape)
    # Source → down → horizontal → up → Target
    ymax = [s_y, t_y].max
    # Proportional bulge: based on distance between endpoints,
    # not the full tree height
    bulge = [min_bulge, (s_x - t_x).abs * 0.3 + min_bulge].min
    new_y = ymax + bulge

    new_s_x = s_x - s_offset
    new_t_x = t_x - t_offset

    note_path_extent([[new_s_x, s_y], [new_s_x, new_y],
                      [new_t_x, new_y], [new_t_x, t_y]])
    @extra_lines << generate_path([[new_s_x, s_y], [new_s_x, new_y],
                                   [new_t_x, new_y], [new_t_x, t_y]],
                                  @col_path, dashed: dashed, radius: corner_radius,
                                  start_arrow: target_arrow == :double,
                                  end_arrow: target_arrow != :none)
    @height = new_y if new_y > @height
  end
end

#draw_bracket(x1, y1, width, height, col, bline = false) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 822

def draw_bracket(x1, y1, width, height, col, bline = false)
  swidth = bline ? @global[:stroke_bold] : @global[:stroke_normal]
  slwidth = @global[:h_gap_between_nodes] / 2
  @extra_lines << "<polyline style='stroke:#{col}; stroke-width:#{swidth}; fill:none; stroke-linejoin:round; stroke-linecap:round;'
                        points='#{x1 + slwidth},#{y1} #{x1},#{y1} #{x1},#{y1 + height} #{x1 + slwidth},#{y1 + height}' />\n"
  @extra_lines << "<polyline style='stroke:#{col}; stroke-width:#{swidth}; fill:none; stroke-linejoin:round; stroke-linecap:round;'
                        points='#{x1 + width - slwidth},#{y1} #{x1 + width},#{y1} #{x1 + width},#{y1 + height} #{x1 + width - slwidth},#{y1 + height}' />\n"
end

#draw_element(element) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 493

def draw_element(element)
  top = element.vertical_indent
  left = element.horizontal_indent
  right = left + element.content_width
  txt_pos = left + (right - left) / 2

  # Use element's custom color if specified, otherwise use default based on type
  col = if element.color
          element.color
        elsif element.type == ETYPE_LEAF
          @col_leaf
        else
          @col_node
        end

  text_data = @text_styles.sub(/COLOR/, col)
  text_data = text_data.sub(/fontsize/, @fontsize.to_s + "px;")
  # The node is laid out at the width of its label plus the room its own
  # enclosure needs, so the text starts that far inside the node's left
  # edge and the enclosure is drawn on the edge itself.
  enclosure_room = element.label_enclosure_room
  text_x = txt_pos - element.content_width / 2 + enclosure_room
  text_y = top + @global[:single_line_height] - @global[:height_connector_to_text]
  text_data  = text_data.sub(/X_VALUE/, text_x.to_s)
  text_data  = text_data.sub(/Y_VALUE/, text_y.to_s)
  new_text = +""
  this_x = 0
  this_y = 0
  prev_line_height = nil
  first_baseline = nil
  bc = { x: text_x - enclosure_room, y: top, width: element.content_width, height: nil }
  element.content.each_with_index do |l, idx|
    case l[:type]
    when :border, :bborder
      x1 = text_x
      if idx.zero?
        text_y -= l[:height]
      else
        text_y += l[:height]
      end
      y1 = text_y - @global[:single_line_height] / 8
      x2 = text_x + element.text_width
      y2 = y1
      case l[:type]
      when :border
        stroke_width = @global[:stroke_normal]
      when :bborder
        stroke_width = @global[:stroke_bold]
      end
      @extra_lines << "<line style=\"stroke:#{col}; fill:none; stroke-linecap:round; stroke-width:#{stroke_width}; \" x1=\"#{x1}\" y1=\"#{y1}\" x2=\"#{x2}\" y2=\"#{y2}\"></line>"
    else
      if @direction == "ltr" && element.type == ETYPE_LEAF
        # LTR leaves: left-align text at the node's left edge. A leaf
        # with its own enclosure starts one enclosure room inside, the
        # same as in TTB, or the bracket would sit on the glyphs.
        this_x = left + enclosure_room
      elsif element.enclosure == :brackets
        this_x = text_x
      else
        ewidth = 0
        l[:elements].each do |e|
          ewidth += e[:width]
        end
        this_x = txt_pos - (ewidth / 2)
      end
      # Advance by the height of the line just drawn, not of this one: a
      # row holding a nested matrix is as tall as the matrix, and the row
      # after it has to clear all of it.
      text_y += prev_line_height if idx != 0 && prev_line_height
      text_y += l[:top_room].to_f
      first_baseline ||= text_y
      prev_line_height = l[:elements].map { |e| e[:height] }.max

      l[:elements].each do |e|
        if e[:decoration].include?(:matrix)
          markup, this_x = render_matrix(e, this_x, text_y, element, col)
          new_text << markup
          next
        end

        markup, this_x = render_run(e, this_x, text_y, element, col)
        new_text << markup
      end
    end
    @height = text_y if text_y > @height
  end

  bc[:y] = bc[:y] + @global[:height_connector_to_text] * 3 / 4
  # text_y is the baseline of the last line. A line holding a nested matrix
  # reaches further down than a line of text, so the label has to be given
  # the rest of it.
  overhang = prev_line_height.to_f - @global[:single_x_metrics].height
  bc[:height] = text_y - bc[:y] + @global[:height_connector_to_text] + [overhang, 0].max
  case element.enclosure
  when :brackets
    draw_bracket(bc[:x], bc[:y], bc[:width], bc[:height], col)
  when :rectangle
    draw_rectangle(bc[:x], bc[:y], bc[:width], bc[:height], col)
  when :brectangle
    draw_rectangle(bc[:x], bc[:y], bc[:width], bc[:height], col, true)
  end

  element.content_height = bc[:height]

  # Where the label's ink is, for the symmetric clearances of vmargin.
  # A drawn shape — an enclosure, or a label that is one matrix — hands
  # over its own edges; a plain label hands over the font's band around
  # its first and last baselines, so the connectors of one level start
  # level with each other whatever letters happen to hang below.
  drawn_shape = element.enclosure != :none ||
                element.content.any? do |line|
                  line[:type] == :text &&
                    line[:elements].any? { |e| e[:decoration].include?(:matrix) }
                end
  if drawn_shape
    element.ink_top = bc[:y]
    element.ink_bottom = bc[:y] + bc[:height]
  elsif first_baseline
    # The label's own ink, not the font's whole band: measured from the
    # first and last lines of text as drawn. What the connectors then
    # keep clear of is the union of these across a row (see row_ink), so
    # the ends stay level within a row while a row of capitals pays no
    # tax for descenders nobody wrote.
    text_lines = element.content.select { |l| l[:type] == :text }
    first_text = text_lines.first[:elements].map { |e| e[:text].to_s }.join.gsub(WHITESPACE_BLOCK, " ")
    last_text = text_lines.last[:elements].map { |e| e[:text].to_s }.join.gsub(WHITESPACE_BLOCK, " ")
    f_m = FontMetrics.get_metrics(first_text.strip.empty? ? "X" : first_text,
                                  @fontset[:family], @fontsize.to_f, :normal, :normal)
    l_m = FontMetrics.get_metrics(last_text.strip.empty? ? "X" : last_text,
                                  @fontset[:family], @fontsize.to_f, :normal, :normal)
    element.ink_top = first_baseline - f_m.ink_above
    element.ink_bottom = text_y + (l_m.ink_height - l_m.ink_above)
  end
  @tree_data += text_data.sub(/CONTENT/, new_text)
end

#draw_paths ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 839

def draw_paths
  paths = []
  path_pool_target = {}
  path_pool_other = {}
  path_pool_source = {}
  path_flags = []

  line_pool = {}
  line_flags = []

  elist = @element_list.get_elements

  elist.each do |element|
    if @direction == "ltr"
      # LTR anchors: paths attach at left/right edges, vertically centered
      hctt = @global[:height_connector_to_text]
      y_center = element.vertical_indent + (element.content_height + hctt * 1.5) / 2
      x0 = element.horizontal_indent - hctt
      x1 = element.horizontal_indent + element.content_width + hctt
      x2 = element.horizontal_indent + element.content_width + hctt * 2
      y0 = y_center
      y1 = y_center
      # A line-type connection, though, wants the box's own geometry.
      # The path anchors sit a clearance off the box — right for a curve
      # leaving a node, but a straight link anchored there floats off
      # both boxes, or lands inside them when the gap is narrow.
      lgeom = {
        left: element.horizontal_indent,
        right: element.horizontal_indent + element.content_width,
        top: y_center - element.content_height / 2,
        bottom: y_center + element.content_height / 2,
        cx: element.horizontal_indent + element.content_width / 2,
        cy: y_center
      }
    else
      # x0/x2 are the box's own edges: a link between two nodes runs
      # between these plus a small margin. Anchoring a full h_gap
      # outside the box left links too short in wide gaps and pushed
      # them into the boxes in narrow ones. Only the line pool uses
      # x0/x2; movement paths read x1, which is unchanged.
      x0 = element.horizontal_indent
      x1 = element.horizontal_indent + element.content_width / 2
      x2 = element.horizontal_indent + element.content_width
      y0 = element.vertical_indent + @global[:height_connector_to_text] / 2
      y1 = element.vertical_indent + element.content_height + @global[:height_connector_to_text]
      lgeom = nil
    end
    et = element.path
    et.each do |tr|
      if /\A-(>|<)?(\d+)\z/ =~ tr
        arrow = $1
        tr = $2
        if line_pool[tr]
          line_pool[tr] << { x: { left: x0, center: x1, right: x2 }, y: { top: y0, center: y0 + (y1 - y0) / 2, bottom: y1 }, arrow: arrow, geom: lgeom }
        else
          line_pool[tr] = [{ x: { left: x0, center: x1, right: x2 }, y: { top: y0, center: y0 + (y1 - y0) / 2, bottom: y1 }, arrow: arrow, geom: lgeom }]
        end
        line_flags << tr
      elsif /\A(?:>|<)(\d+)\z/ =~ tr
        tr = $1
        if path_pool_target[tr]
          path_pool_target[tr] << [x1, y1]
        else
          path_pool_target[tr] = [[x1, y1]]
        end
        path_flags << tr
      elsif path_pool_source[tr]
        if path_pool_other[tr]
          path_pool_other[tr] << [x1, y1]
        else
          path_pool_other[tr] = [[x1, y1]]
        end
        path_flags << tr
      else
        path_pool_source[tr] = [x1, y1]
        path_flags << tr
      end
      raise RSTError.new(+"Error: input text contains a path having more than two ends:\n > #{tr}", code: :path_multiple_ends, hint: "A path or line takes exactly two ends; check the numbers.", retryable: true) if path_flags.tally.any? { |_k, v| v > 2 } || line_flags.tally.any? { |_k, v| v > 2 }
    end
  end

  path_flags.tally.each do |k, v|
    raise RSTError.new(+"Error: input text contains a path having only one end:\n > #{k}", code: :path_single_end, hint: "A path takes two ends: one '+N' on each of two nodes.", retryable: true) if v == 1
  end

  # A line-type connection is subject to the same rule as a path: it takes
  # two ends. Without this the drawing walked off a nil pool below.
  line_flags.tally.each do |k, v|
    raise RSTError.new(+"Error: input text contains a line having only one end:\n > #{k}", code: :path_single_end, hint: "A line connection takes two ends: '+-N' on each of two nodes.", retryable: true) if v == 1
  end

  path_pool_source.each do |k, v|
    path_flags.delete(k)
    if (targets = path_pool_target[k])
      targets.each do |t|
        paths << { x1: v[0], y1: v[1], x2: t[0], y2: t[1], arrow: :single }
      end
    elsif (others = path_pool_other[k])
      others.each do |t|
        paths << { x1: v[0], y1: v[1], x2: t[0], y2: t[1], arrow: :none }
      end
    end
  end

  path_flags.uniq.each do |k|
    targets = path_pool_target[k]
    next if targets.nil? || targets.empty?

    fst = targets.shift
    next if fst.nil?

    targets.each do |t|
      paths << { x1: fst[0], y1: fst[1], x2: t[0], y2: t[1], arrow: :double }
    end
  end

  paths.each do |t|
    draw_a_path(t[:x1], t[:y1], t[:x2], t[:y2], t[:arrow])
  end

  line_pool.each do |_k, v|
    a = v[0]
    b = v[1]

    # A straight link stops a small margin short of each box. The margin
    # scales with the inter-node gap and is clamped so an endpoint can
    # never cross the facing edge.
    margin = @global[:h_gap_between_nodes] * 0.25
    inset = ->(gap) { [[margin, gap / 2 - 1].min, 0].max }

    if @direction == "ltr"
      # LTR: use x-position to determine depth relationship,
      # y-position for sibling relationship
      ga = a[:geom]
      gb = b[:geom]
      if ga[:left] > gb[:right]
        m = inset.call(ga[:left] - gb[:right])
        generate_connectors(ga[:left] - m, ga[:cy], gb[:right] + m, gb[:cy], @col_extra, false, a[:arrow], b[:arrow])
      elsif ga[:right] < gb[:left]
        m = inset.call(gb[:left] - ga[:right])
        generate_connectors(gb[:left] - m, gb[:cy], ga[:right] + m, ga[:cy], @col_extra, false, b[:arrow], a[:arrow])
      elsif ga[:cy] < gb[:cy]
        m = inset.call(gb[:top] - ga[:bottom])
        generate_connectors(ga[:cx], ga[:bottom] + m, ga[:cx], gb[:top] - m, @col_extra, false, a[:arrow], b[:arrow])
      else
        m = inset.call(ga[:top] - gb[:bottom])
        generate_connectors(gb[:cx], gb[:bottom] + m, gb[:cx], ga[:top] - m, @col_extra, false, b[:arrow], a[:arrow])
      end
    else
      # TTB: use y-position to determine depth relationship
      if a[:y][:top] > b[:y][:bottom]
        generate_connectors(a[:x][:center], a[:y][:top], b[:x][:center], b[:y][:bottom], @col_extra, false, a[:arrow], b[:arrow])
      elsif a[:y][:bottom] < b[:y][:top]
        generate_connectors(b[:x][:center], b[:y][:top], a[:x][:center], a[:y][:bottom], @col_extra, false, b[:arrow], a[:arrow])
      elsif a[:x][:center] < b[:x][:center]
        m = inset.call(b[:x][:left] - a[:x][:right])
        if a[:y][:top] == b[:y][:top]
          upper_y = a[:y][:center] < b[:y][:center] ? a[:y][:center] : b[:y][:center]
          generate_connectors(a[:x][:right] + m, upper_y, b[:x][:left] - m, upper_y, @col_extra, false, a[:arrow], b[:arrow])
        else
          generate_connectors(a[:x][:right] + m, a[:y][:center], b[:x][:left] - m, b[:y][:center], @col_extra, false, a[:arrow], b[:arrow])
        end
      elsif a[:y][:top] == b[:y][:top]
        upper_y = a[:y][:center] < b[:y][:center] ? a[:y][:center] : b[:y][:center]
        m = inset.call(a[:x][:left] - b[:x][:right])
        generate_connectors(b[:x][:right] + m, upper_y, a[:x][:left] - m, upper_y, @col_extra, false, b[:arrow], a[:arrow])
      else
        m = inset.call(a[:x][:left] - b[:x][:right])
        generate_connectors(b[:x][:right] + m, b[:y][:center], a[:x][:left] - m, a[:y][:center], @col_extra, false, b[:arrow], a[:arrow])
      end
    end
  end
  paths.size + line_pool.keys.size
end

#draw_rectangle(x1, y1, width, height, col, bline = false) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 816

def draw_rectangle(x1, y1, width, height, col, bline = false)
  swidth = bline ? @global[:stroke_bold] : @global[:stroke_normal]
  @extra_lines << "<polygon style='stroke:#{col}; stroke-width:#{swidth}; fill:none; stroke-linejoin:round; stroke-linecap:round;'
                        points='#{x1},#{y1} #{x1 + width},#{y1} #{x1 + width},#{y1 + height} #{x1},#{y1 + height}' />\n"
end

#draw_rule_name(parent, right, y) ⇒ Object

The name of the rule, set beside the end of its own line and smaller than the categories, which is where a derivation puts it and how it keeps the name from reading as part of either row.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1151

def draw_rule_name(parent, right, y)
  name = parent.rule_name
  return if name.nil? || name.empty?

  size = (@fontsize * 0.8).round(2)
  # Level with the rule, by the same reckoning an enclosure uses to sit
  # level with what it encloses.
  baseline = y + FontMetrics.visual_centre(@fontset[:family], size)
  x = right + @global[:width_half_x]
  # The name is the one thing drawn outside every element's own box, so the
  # canvas has to be told where it ends or the last step's name is cut off
  # at the edge of the image.
  edge = x + FontMetrics.get_metrics(name, @fontset[:family], size, :normal, :normal).width
  @rule_name_edge = edge if edge > @rule_name_edge.to_f
  @tree_data += @text_styles.sub(/COLOR/, @col_line)
                            .sub(/fontsize/, size.to_s + "px;")
                            .sub(/X_VALUE/, x.to_s)
                            .sub(/Y_VALUE/, baseline.round(2).to_s)
                            .sub(/CONTENT/) { CGI.escapeHTML(name) }
end

#element_visual_box(el) ⇒ Object

Visual bounding box of a single element as actually drawn: the label / enclosure box (which starts hctt*3/4 below vertical_indent, i.e. below the connector gap) widened to include any enclosure bracket/rectangle that is painted beyond the content width.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 304

def element_visual_box(el)
  hctt = @global[:height_connector_to_text]
  box_top = el.vertical_indent + hctt * 3 / 4 # bc[:y]: line-height / enclosure box top
  box_bottom = box_top + el.content_height
  left = el.horizontal_indent
  right = el.horizontal_indent + el.content_width
  if [:brackets, :rectangle, :brectangle].include?(el.enclosure)
    # The room the enclosure needs is already part of content_width; only
    # the stroke straddling the edge reaches beyond it.
    ext = @global[:stroke_bold]
    left -= ext
    right += ext
    sw = @global[:stroke_bold]
    top = box_top - sw
    bottom = box_bottom + sw
  else
    # No enclosure box is painted, so hug the actual glyphs rather than the
    # taller line-height box: the line box carries ~hctt*3/4 of leading both
    # above the cap top and below the baseline, which would otherwise leave
    # too much empty space above and below a plain label.
    top = el.vertical_indent + hctt * 3 / 2
    bottom = box_bottom - hctt * 3 / 4
  end
  { left: left, top: top, right: right, bottom: bottom }
end

#generate_connectors(x1, y1, x2, y2, col, dashed = false, s_arrow = false, t_arrow = false, bline = false) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1014

def generate_connectors(x1, y1, x2, y2, col, dashed = false, s_arrow = false, t_arrow = false, bline = false)
  string = if s_arrow && t_arrow
             "" # bothways arrowheads are drawn as chevrons below
           elsif s_arrow
             "marker-mid='url(#arrowForward)' "
           elsif t_arrow
             "marker-mid='url(#arrowBackward)' "
           else
             ""
           end
  dash = @fontsize / 4.0
  dasharray = dashed ? "stroke-dasharray='#{dash} #{dash}'" : ""
  swidth = bline ? @global[:stroke_bold] : @global[:stroke_normal]

  if s_arrow && t_arrow
    @extra_lines << "<line x1='#{x1}' y1='#{y1}' x2='#{x2}' y2='#{y2}' style='fill: none; stroke: #{col}; stroke-width:#{swidth}; stroke-linecap:round;' #{dasharray}/>"
    @extra_lines << bothways_arrows(x1, y1, x2, y2, col, swidth)
  elsif s_arrow || t_arrow
    x_mid = if x2 > x1
              x1 + (x2 - x1) / 2
            else
              x1 - (x1 - x2) / 2
            end
    y_mid = if y2 > y1
              y1 + (y2 - y1) / 2
            else
              y1 - (y1 - y2) / 2
            end
    @extra_lines << "<path d='M#{x1},#{y1} L#{x_mid},#{y_mid} L#{x2}, #{y2}' style='fill: none; stroke: #{col}; stroke-width:#{swidth}; stroke-linecap:round;' #{dasharray} #{string}/>"
  else
    @extra_lines << "<line x1='#{x1}' y1='#{y1}' x2='#{x2}' y2='#{y2}' style='fill: none; stroke: #{col}; stroke-width:#{swidth}; stroke-linecap:round;' #{dasharray} #{string}/>"
  end
end

#generate_line(x1, y1, x2, y2, col, dashed = false, arrow = false, bline = false) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1084

def generate_line(x1, y1, x2, y2, col, dashed = false, arrow = false, bline = false)
  string = if arrow
             "marker-end='url(#arrow)' "
           else
             ""
           end
  dash = @fontsize / 4.0
  dasharray = dashed ? "stroke-dasharray='#{dash} #{dash}'" : ""
  swidth = bline ? @global[:stroke_bold] : @global[:stroke_normal]

  "<line x1='#{x1}' y1='#{y1}' x2='#{x2}' y2='#{y2}' style='fill: none; stroke: #{col}; stroke-width:#{swidth}; stroke-linecap:round;' #{dasharray} #{string}/>"
end

#generate_path(points, col, dashed: false, radius: 0, start_arrow: false, end_arrow: false) ⇒ Object

One stroke rather than three lines meeting at right angles. Drawn this way the dash pattern runs round each turn instead of restarting at it, and an arrowhead is the end of the stroke rather than a marker on whichever line happens to finish last.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 385

def generate_path(points, col, dashed: false, radius: 0, start_arrow: false, end_arrow: false)
  # An arrowhead is drawn back along the run it ends, so the corner before
  # it has to leave that run its full length. Without this the shorter of
  # the two end runs — which is only as long as the path's bulge — lost half
  # of itself to the turn and the head came out sitting on the curve.
  arrow_length = @global[:h_gap_between_nodes]
  leg = ->(a, b) { Math.sqrt(((a[0] - b[0])**2) + ((a[1] - b[1])**2)) }
  radius = [radius, leg.call(points[0], points[1]) - arrow_length].min if start_arrow
  radius = [radius, leg.call(points[-2], points[-1]) - arrow_length].min if end_arrow
  radius = [radius, 0].max

  dash = @fontsize / 4.0
  dasharray = dashed ? "stroke-dasharray='#{dash} #{dash}' " : ""
  markers = +""
  markers << "marker-start='url(#arrowStart)' " if start_arrow
  markers << "marker-end='url(#arrow)' " if end_arrow

  # A round cap is half the stroke's width of ink past the point the stroke
  # ends at, and an arrowhead has its tip at exactly that point — so the
  # line came through the tip: 13% ink on the pixel beyond the head of a
  # path, and 81% beyond its tail, where the marker's apex sits on the
  # anchor rather than behind it. Squared off, the stroke stops where the
  # head begins. Only where there is a head: a path without one is the
  # dashed form, and every dash of it wants its round ends.
  linecap = start_arrow || end_arrow ? "butt" : "round"

  "<path d='#{rounded_polyline_d(points, radius)}' style='fill: none; stroke: #{col}; " \
    "stroke-width:#{@global[:stroke_normal]}; stroke-linecap:#{linecap}; stroke-linejoin:round;' " \
    "#{dasharray}#{markers}/>"
end

#ink_over(element) ⇒ Object

Where a connector clears an element on the vmargin geometry: the row's ink for a plain label, the drawn edge for an enclosed one.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1197

def ink_over(element)
  row = element.enclosure == :none && row_ink[element.vertical_indent.round(1)]
  row ? row[:top] : element.ink_top
end

#ink_under(element) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1202

def ink_under(element)
  row = element.enclosure == :none && row_ink[element.vertical_indent.round(1)]
  row ? row[:bottom] : element.ink_bottom
end

#line_to_parent(parent, child) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1268

def line_to_parent(parent, child)
  return if child.horizontal_indent.zero?

  if @direction == "ltr"
    # LTR: parent's right side → child's left side
    # Y center = midpoint between TTB top-connection and bottom-connection
    # top = vi + hctt/2, bottom = vi + content_height + hctt
    # midpoint = vi + (content_height + hctt * 1.5) / 2
    hctt = @global[:height_connector_to_text]
    y1 = child.vertical_indent + (child.content_height + hctt * 1.5) / 2
    y2 = parent.vertical_indent + (parent.content_height + hctt * 1.5) / 2
    x1 = child.empty_label? ? child.horizontal_indent + child.content_width / 2 : child.horizontal_indent - hctt
    x2 = parent.empty_label? ? parent.horizontal_indent + parent.content_width / 2 : parent.horizontal_indent + parent.content_width + hctt

    if @polyline
      mid_x1 = x2 + (x1 - x2) / 2
      mid_y1 = y1
      mid_x2 = mid_x1
      mid_y2 = y2
      @tree_data += @polyline_styles.sub(/CHIX/, x1.to_s)
                                    .sub(/CHIY/, y1.to_s)
                                    .sub(/MIDX1/, mid_x1.to_s)
                                    .sub(/MIDY1/, mid_y1.to_s)
                                    .sub(/MIDX2/, mid_x2.to_s)
                                    .sub(/MIDY2/, mid_y2.to_s)
                                    .sub(/PARX/, x2.to_s)
                                    .sub(/PARY/, y2.to_s)
    else
      line_data   = @line_styles.sub(/X1/, x1.to_s)
      line_data   = line_data.sub(/Y1/, y1.to_s)
      line_data   = line_data.sub(/X2/, x2.to_s)
      @tree_data += line_data.sub(/Y2/, y2.to_s)
    end
  else
    # TTB: parent's bottom → child's top
    if @polyline
      chi_x = child.horizontal_indent + child.content_width / 2
      par_x = parent.horizontal_indent + parent.content_width / 2
      chi_y, par_y = connector_edges(child, parent)

      mid_x1 = chi_x
      mid_y1 = par_y + (chi_y - par_y) / 2

      mid_x2 = par_x
      mid_y2 = mid_y1

      @tree_data += @polyline_styles.sub(/CHIX/, chi_x.to_s)
                                    .sub(/CHIY/, chi_y.to_s)
                                    .sub(/MIDX1/, mid_x1.to_s)
                                    .sub(/MIDY1/, mid_y1.to_s)
                                    .sub(/MIDX2/, mid_x2.to_s)
                                    .sub(/MIDY2/, mid_y2.to_s)
                                    .sub(/PARX/, par_x.to_s)
                                    .sub(/PARY/, par_y.to_s)
    else
      x1 = child.horizontal_indent + child.content_width / 2
      x2 = parent.horizontal_indent + parent.content_width / 2
      y1, y2 = connector_edges(child, parent)

      line_data   = @line_styles.sub(/X1/, x1.to_s)
      line_data   = line_data.sub(/Y1/, y1.to_s)
      line_data   = line_data.sub(/X2/, x2.to_s)
      @tree_data += line_data.sub(/Y2/, y2.to_s)
    end
  end
end

#note_path_extent(points) ⇒ Object

Where the movement paths have been, as a box. The canvas learns of a rail through @width and @height, which only say how far right and down anything got; the plane behind a sheared figure has to enclose the rail on every side, so the corners themselves are kept.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 420

def note_path_extent(points)
  xs = points.map(&:first)
  ys = points.map(&:last)
  b = (@path_bounds ||= { min_x: xs.min, min_y: ys.min, max_x: xs.max, max_y: ys.max })
  b[:min_x] = [b[:min_x], xs.min].min
  b[:min_y] = [b[:min_y], ys.min].min
  b[:max_x] = [b[:max_x], xs.max].max
  b[:max_y] = [b[:max_y], ys.max].max
end

#region_subtree_bounds(id) ⇒ Object

Union of element_visual_box over the subtree rooted at id, in final drawing coordinates. Used to size region shades so the whole subtree (labels, enclosures, brackets) sits inside the plane.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 333

def region_subtree_bounds(id)
  b = element_visual_box(@element_list.get_id(id))
  @element_list.get_id(id).children.each do |c|
    cb = region_subtree_bounds(c)
    b[:left] = cb[:left] if cb[:left] < b[:left]
    b[:right] = cb[:right] if cb[:right] > b[:right]
    b[:top] = cb[:top] if cb[:top] < b[:top]
    b[:bottom] = cb[:bottom] if cb[:bottom] > b[:bottom]
  end
  b
end

#render_matrix(e, this_x, text_y, element, col) ⇒ Object

Draws a matrix nested in a label: its own rows and columns, laid out from the sizes Element#measure_lines worked out, inside its own brackets.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 752

def render_matrix(e, this_x, text_y, element, col)
  out = +""
  advance = e[:width]
  # The room measured in front of the block, if it follows something in
  # the same cell. Taken off this_x here so the bracket starts after it,
  # and left in the advance so the row is as wide as it was measured.
  lead = e[:matrix_lead].to_f
  this_x += lead
  inner_x = this_x + @global[:width_half_x] * MATRIX_BRACKET_ROOM
  baseline = text_y
  prev_height = nil

  e[:matrix].each_with_index do |line, idx|
    # A rule across the matrix, the way one runs across a label: it takes
    # a row of its own and spans the width inside the brackets, so a
    # feature structure can separate its type from its features and a
    # tableau its header from its candidates.
    if %i[border bborder].include?(line[:type])
      # Placed from the baseline above it, the way a rule across a label
      # is: a third of a line under the row before, the rest of the gap
      # under the rule. Measuring from the row it is about to open
      # instead put the space on the wrong side — more above the rule
      # than below, where the ascenders of the next row need it.
      above = baseline
      baseline += prev_height if idx.positive? && prev_height
      prev_height = line[:height].to_f
      y = if idx.zero?
            above - prev_height - @global[:single_line_height] / 8
          else
            above + prev_height - @global[:single_line_height] / 8
          end
      inner_w = e[:width] - (inner_x - this_x) * 2
      stroke = line[:type] == :bborder ? @global[:stroke_bold] : @global[:stroke_normal]
      @extra_lines << "<line style=\"stroke:#{col}; fill:none; stroke-linecap:round; " \
                      "stroke-width:#{stroke}; \" x1=\"#{inner_x}\" y1=\"#{y}\" " \
                      "x2=\"#{inner_x + inner_w}\" y2=\"#{y}\"></line>"
      next
    end
    next unless line[:type] == :text

    baseline += prev_height if idx.positive? && prev_height
    baseline += line[:top_room].to_f
    prev_height = line[:elements].map { |x| x[:height] }.max
    pen = inner_x
    line[:elements].each do |cell|
      markup, pen = if cell[:decoration].include?(:matrix)
                      render_matrix(cell, pen, baseline, element, col)
                    else
                      render_run(cell, pen, baseline, element, col)
                    end
      out << markup
    end
  end

  # The bracket encloses the matrix and its own padding. The separation
  # from the rows either side is already in the baseline this was called
  # with, so taking it off here again would cancel it out and leave two
  # stacked blocks touching.
  padding = @global[:single_x_metrics].height * MATRIX_VERTICAL_ROOM
  top = text_y - @global[:single_x_metrics].height * 0.8 - padding
  draw_bracket(this_x, top, e[:width] - lead, e[:matrix_height] + padding * 2, col)
  [out, this_x + advance - lead]
end

#render_run(e, this_x, text_y, element, col) ⇒ Object

Draws one run of a label — a stretch of text with its decorations, or the box, circle or bar drawn around it — at the given pen position, and reports where the pen ends up. A nested matrix draws its own runs through here, so this could no longer live inside the drawing loop.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 633

def render_run(e, this_x, text_y, element, col)
  out = +""
  this_y = text_y
    escaped_text = e[:text].gsub('>', '&gt;').gsub('<', '&lt;');
    decorations = []
    decorations << "overline" if e[:decoration].include?(:overline)
    decorations << "underline" if e[:decoration].include?(:underline)
    decorations << "line-through" if e[:decoration].include?(:linethrough)
    decoration = "text-decoration=\"" + decorations.join(" ") + "\""

    style = "style=\""
    if e[:decoration].include?(:small)
      style += "font-size: #{(SUBSCRIPT_CONST.to_f * 100).to_i}%; "
      this_y = text_y - ((@global[:single_x_metrics].height - @global[:single_x_metrics].height * SUBSCRIPT_CONST) / 4) + @fontsize / 16.0
    elsif e[:decoration].include?(:superscript)
      style += "font-size: #{(SUBSCRIPT_CONST.to_f * 100).to_i}%; "
      this_y = text_y - (@global[:single_x_metrics].height / 4) + @fontsize / 32.0
    elsif e[:decoration].include?(:subscript)
      style += "font-size: #{(SUBSCRIPT_CONST.to_f * 100).to_i}%; "
      this_y = text_y + @fontsize / 8.0
    else
      this_y = text_y
    end

    style += "font-weight: bold; fill: #{@col_emph}; " if e[:decoration].include?(:bold) || e[:decoration].include?(:bolditalic)
    style += "font-style: italic; " if e[:decoration].include?(:italic) || e[:decoration].include?(:bolditalic)
    style += "\""

    fontstyle = FontFamily.for_svg(@fontstyle)

    if e[:decoration].include?(:box) || e[:decoration].include?(:circle) || e[:decoration].include?(:bar)
      # Measured around the enclosed marks in Element#setup; the line
      # height would draw the shape taller than what it encloses.
      enc_height = e[:enc_height] || e[:height]
      enc_y = this_y - (e[:enc_above] || e[:height] * 0.8)
      enc_width = e[:width]
      enc_x = this_x

      if e[:decoration].include?(:hatched)
        case element.type
        when ETYPE_LEAF
          fill = if @color
                   "url(#hatchForLeaf)"
                 else
                   "url(#hatchBlack)"
                 end
        when ETYPE_NODE
          fill = if @color
                   "url(#hatchForNode)"
                 else
                   "url(#hatchBlack)"
                 end
        end
      else
        fill = "none"
      end

      enc = nil

      stroke_width = if e[:decoration].include?(:bstroke)
                       @global[:stroke_bold]
                     else
                       @global[:stroke_normal]
                     end

      if e[:decoration].include?(:box)
        enc = "<rect style='stroke: #{col}; stroke-linejoin:round; stroke-width:#{stroke_width};'
                x='#{enc_x}' y='#{enc_y}'
                width='#{enc_width}' height='#{enc_height}'
                fill='#{fill}' />\n"
      elsif e[:decoration].include?(:circle)
        enc = "<rect style='stroke: #{col}; stroke-width:#{stroke_width};'
                x='#{enc_x}' y='#{enc_y}' rx='#{enc_height / 2}' ry='#{enc_height / 2}'
                width='#{enc_width}' height='#{enc_height}'
                fill='#{fill}' />\n"
      elsif e[:decoration].include?(:bar)
        x1 = enc_x
        y1 = enc_y + enc_height / 2
        x2 = enc_x + enc_width
        y2 = y1
        ar_hwidth = e[:width] / 4.0
        bar = "<line style='fill:none; stroke:#{col}; stroke-linejoin:round; stroke-linecap:round; stroke-width:#{stroke_width};' x1='#{x1 + stroke_width / 2}' y1='#{y1}' x2='#{x2 - stroke_width / 2}' y2='#{y2}'></line>\n"
        @extra_lines << bar

        if e[:decoration].include?(:arrow_to_l)
          l_arrowhead = "<polyline stroke-linejoin='round' stroke-linecap='round' fill='none' stroke='#{col}' stroke-width='#{stroke_width}' points='#{x1 + ar_hwidth},#{y1 + ar_hwidth / 2} #{x1 + stroke_width / 2},#{y1} #{x1 + ar_hwidth},#{y1 - ar_hwidth / 2}' />\n"
          @extra_lines << l_arrowhead
        end

        if e[:decoration].include?(:arrow_to_r)
          r_arrowhead = "<polyline stroke-linejoin='round' stroke-linecap='round' fill='none' stroke='#{col}' stroke-width='#{stroke_width}' points='#{x2 - ar_hwidth},#{y2 - ar_hwidth / 2} #{x2 - stroke_width / 2},#{y2} #{x2 - ar_hwidth},#{y2 + ar_hwidth / 2}' />\n"
          @extra_lines << r_arrowhead
        end
      end

      @extra_lines << enc if enc

      # Centre the marks in the shape. e[:width] is the shape's width,
      # e[:content_width] the marks' own, so half the difference is the
      # left inset — the line height used to stand in for the shape's
      # width here, which left the glyph off-centre once the shape was
      # measured from its content instead.
      inset = (e[:width] - e[:content_width]) / 2
      this_x += inset
      out << set_tspan(this_x, this_y, style, decoration, fontstyle, escaped_text)
      this_x += e[:content_width] + inset

    elsif e[:decoration].include?(:whitespace)
      return [out, this_x + e[:width]]
    else
      out << set_tspan(this_x, this_y, style, decoration, fontstyle, escaped_text)
      this_x += e[:width]
    end

  [out, this_x]
end

#rounded_polyline_d(points, radius) ⇒ Object

The d of a polyline whose corners are eased into quarter turns.

The radius is clamped to half of each of the two runs meeting at a corner, so a short leg can never be swallowed by its own turn and two adjacent corners can never overlap — which is the whole of the arithmetic that rounding a right angle needs, and why it can be a constant everywhere else.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 362

def rounded_polyline_d(points, radius)
  return +"" if points.size < 2

  at = ->(p) { "#{p[0].round(3)},#{p[1].round(3)}" }
  d = +"M#{at.call(points[0])}"
  points.each_cons(3) do |before, corner, after|
    r = [radius,
         Math.sqrt(((corner[0] - before[0])**2) + ((corner[1] - before[1])**2)) / 2.0,
         Math.sqrt(((after[0] - corner[0])**2) + ((after[1] - corner[1])**2)) / 2.0].min
    if r < 0.01
      d << " L#{at.call(corner)}"
    else
      d << " L#{at.call(along(corner, before, r))}" \
           " Q#{at.call(corner)} #{at.call(along(corner, after, r))}"
    end
  end
  d << " L#{at.call(points.last)}"
end

#row_ink ⇒ Object

Where a connector meets each box in a vertical layout: the underside of whichever sits higher and the top of whichever sits lower. Turned over, the parent is the lower of the two, and keeping the top-to-bottom edges sent the line back up through both labels. An empty label has no text to clear, so the line runs to its middle. The ink extents of a row: the union, across every plain label standing at one height, of where its type actually reaches. An endpoint measured from the label's own ink alone gives every label equal air but leaves the ends of a row's connectors ragged — a line reaches lower over on than over the; measured from the whole font's band the ends are level but a row of capitals pays for descenders nobody wrote. The row's own union keeps the ends level and charges only for what the row contains.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1184

def row_ink
  @row_ink ||= @element_list.get_elements.each_with_object({}) do |e, rows|
    next unless e.ink_top && e.ink_bottom
    next if e.enclosure != :none

    row = (rows[e.vertical_indent.round(1)] ||= { top: e.ink_top, bottom: e.ink_bottom })
    row[:top] = [row[:top], e.ink_top].min
    row[:bottom] = [row[:bottom], e.ink_bottom].max
  end
end

#rule_to_parent(parent, children) ⇒ Object

Draw a line between child/parent elements. An empty-label element (see Element#empty_label?) is a pass-through joint: the line runs to its center instead of stopping at its (invisible) text box, so the segments on both sides connect without a gap. One rule across all the premises, in place of a line to each. The rule runs the width of what it combines — the span from the leftmost child's left edge to the rightmost child's right edge — because that span is what the step applies to, and reading it off the children is what keeps it right when the layout moves.

Drawn at the parent's edge facing the children, so it sits between the material above it and the result below in a derivation, and between a node and its daughters in an ordinary tree.



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1110

def rule_to_parent(parent, children)
  return if children.empty?

  # The whole of what the step combines, not the labels of its premises:
  # a premise stands over a derivation of its own, and the rule is drawn
  # across all of it. Taken from the subtree extents, which is what the
  # layout already computes for the same purpose.
  left = children.map { |c| get_leftmost(c.id) }.min
  right = children.map { |c| get_rightmost(c.id) }.max
  # The parent may be wider than everything it combines, which happens when
  # a category is longer than the words under it. The rule covers both, so
  # that the label it belongs to is never wider than its own rule.
  left = [left, parent.horizontal_indent].min
  right = [right, parent.horizontal_indent + parent.content_width].max

  hctt = @global[:height_connector_to_text]
  above, below = derivation_rule_band(parent)
  y = if above
        (above + hctt + below) / 2.0
      else
        child_edge = children.map { |c| c.vertical_indent + c.content_height }.max
        parent_top = parent.vertical_indent
        if parent_top >= child_edge
          # The parent sits below: the rule goes between the two.
          (child_edge + hctt + parent_top) / 2.0
        else
          # The parent sits above (an ordinary top-to-bottom tree).
          (parent.vertical_indent + parent.content_height + hctt +
           children.map(&:vertical_indent).min) / 2.0
        end
      end

  @tree_data += @line_styles.sub(/X1/, left.to_s).sub(/Y1/, y.to_s)
                            .sub(/X2/, right.to_s).sub(/Y2/, y.to_s)

  draw_rule_name(parent, right, y)
end

#set_tspan(this_x, this_y, style, decoration, fontstyle, text) ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 831

def set_tspan(this_x, this_y, style, decoration, fontstyle, text)
  text.gsub!(/￭+/) do |x|
    num_spaces = x.size
    "<tspan style='fill:none;'>" + "￭" * num_spaces + "</tspan>"
  end
  "<tspan x='#{this_x}' y='#{this_y}' #{style} #{decoration} font-family=\"#{fontstyle}\">#{text}</tspan>\n"
end

#svg_data ⇒ Object 



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# File 'lib/rsyntaxtree/svg_graph.rb', line 65

def svg_data
  metrics = parse_list

  # Region shades depend on the final element positions and on the node
  # content_height that draw_element recomputes, so collect them only
  # after parse_list (which runs draw_elements) has completed.
  collect_region_shades

  @width = metrics[:width] + @global[:h_gap_between_nodes] * 2
  @height = metrics[:height] + @global[:height_connector_to_text] / 2

  x1 = 0 - @global[:h_gap_between_nodes]
  y1 = 0
  x2 = @width + @global[:h_gap_between_nodes]
  y2 = @height + @global[:height_connector_to_text] / 2

  # Grow the canvas so region shades that reach past the tree's own bounds
  # (e.g. a region on the root node, or one whose padded edge extends beyond
  # the deepest leaf) keep a margin instead of touching the image edge. A
  # margin is added around the region extents before unioning with the tree
  # bounds. x2/y2 are the viewBox width/height, so right = x1 + x2.
  if @region_bounds
    rb = @region_bounds
    m = @global[:h_gap_between_nodes]
    left = [x1, rb[:min_x] - m].min
    top = [y1, rb[:min_y] - m].min
    right = [x1 + x2, rb[:max_x] + m].max
    bottom = [y1 + y2, rb[:max_y] + m].max
    new_x2 = right - left
    new_y2 = bottom - top
    @width += new_x2 - x2
    @height += new_y2 - y2
    x1 = left
    y1 = top
    x2 = new_x2
    y2 = new_y2
  end

  # A sheared figure needs a canvas of its own shape. The plane is laid
  # out in the space the tree was drawn in — everything inside the shear
  # group shares it — so it is the union of all the ink there: the
  # elements, the region shades, the movement rails, and a rule's name
  # hanging past the last box. The canvas is that plane's four corners
  # after the shear, with the usual margin around them.
  unless @shear_k.zero?
    gap = @global[:h_gap_between_nodes]
    els = @element_list.get_elements
    ink_l = els.map(&:horizontal_indent).min
    ink_t = els.map(&:vertical_indent).min
    ink_r = els.map { |e| e.horizontal_indent + e.content_width }.max
    ink_b = els.map { |e| e.vertical_indent + e.content_height }.max
    ink_r = @rule_name_edge if @rule_name_edge.to_f > ink_r
    [@region_bounds, @path_bounds].compact.each do |b|
      ink_l = [ink_l, b[:min_x]].min
      ink_t = [ink_t, b[:min_y]].min
      ink_r = [ink_r, b[:max_x]].max
      ink_b = [ink_b, b[:max_y]].max
    end
    pad = gap * 1.5
    @plane_rect = { x: (ink_l - pad).round(3), y: (ink_t - pad).round(3),
                    w: (ink_r - ink_l + pad * 2).round(3), h: (ink_b - ink_t + pad * 2).round(3) }
    cx0 = @plane_rect[:x] - gap
    cx1 = @plane_rect[:x] + @plane_rect[:w] + gap
    cy0 = @plane_rect[:y] - gap
    cy1 = @plane_rect[:y] + @plane_rect[:h] + gap
    sheared = [cx0 + @shear_k * cy0, cx0 + @shear_k * cy1,
               cx1 + @shear_k * cy0, cx1 + @shear_k * cy1]
    x1 = sheared.min.round(3)
    x2 = (sheared.max - sheared.min).round(3)
    y1 = cy0.round(3)
    y2 = (cy1 - cy0).round(3)
    @width = x2
    @height = y2
  end

  extra_lines = @extra_lines.join("\n")

  # Rounded like the stroke widths are: the arithmetic leaves float dust
  # (13.600000000000001) in an attribute of every figure, and the SVG is a
  # deliverable people open in editors.
  as2 = (@global[:h_gap_between_nodes] * 1.0).round(3)
  as4 = (as2 * 3).round(3)
  # The hatch density follows the type size the way the enclosure it
  # fills does: the cell is 10/32 of the font size, the line 4/32 —
  # the ratios the absolute 10 and 4 had at the default size.
  hatch_cell = @fontsize * 0.3125
  hatch_stroke = @fontsize * 0.125

  header = <<~HDR
    <?xml version="1.0" standalone="no"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
      <svg width="#{x2}" height="#{y2}" viewBox="#{x1}, #{y1}, #{x2}, #{y2}" version="1.1" xmlns="http://www.w3.org/2000/svg">
      <defs>
        <marker id="arrow" markerUnits="userSpaceOnUse" viewBox="0 0 10 10" refX="10" refY="5" markerWidth="#{as2}" markerHeight="#{as2}" orient="auto">
          <path d="M 0 0 L 10 5 L 0 10" fill="#{@col_extra}"/>
        </marker>
        <marker id="arrowStart" markerUnits="userSpaceOnUse" viewBox="0 0 10 10" refX="0" refY="5" markerWidth="#{as2}" markerHeight="#{as2}" orient="auto">
          <path d="M 10 0 L 0 5 L 10 10" fill="#{@col_extra}"/>
        </marker>
        <marker id="arrowBackward" markerUnits="userSpaceOnUse" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="#{as2}" markerHeight="#{as2}" orient="auto">
          <path d="M 0 0 L 10 5 L 0 10 z" fill="#{@col_extra}"/>
        </marker>
        <marker id="arrowForward" markerUnits="userSpaceOnUse" viewBox="0 0 10 10" refX="5" refY="5" markerWidth="#{as2}" markerHeight="#{as2}" orient="auto">
          <path d="M 10 0 L 0 5 L 10 10 z" fill="#{@col_extra}"/>
        </marker>
        <marker id="arrowBothways" markerUnits="userSpaceOnUse" viewBox="0 0 30 10" refX="15" refY="5" markerWidth="#{as4}" markerHeight="#{as2}" orient="auto">
          <path d="M 0 5 L 10 0 L 10 5 L 20 5 L 20 0 L 30 5 L 20 10 L 20 5 L 10 5 L 10 10 z" fill="#{@col_extra}"/>
        </marker>
        <pattern id="hatchBlack" x="10" y="10" width="#{hatch_cell}" height="#{hatch_cell}" patternUnits="userSpaceOnUse" patternTransform="rotate(45)">
          <line x1="0" y="0" x2="0" y2="#{hatch_cell}" stroke="black" stroke-width="#{hatch_stroke}"></line>
        </pattern>
        <pattern id="hatchForNode" x="10" y="10" width="#{hatch_cell}" height="#{hatch_cell}" patternUnits="userSpaceOnUse" patternTransform="rotate(45)">
          <line x1="0" y="0" x2="0" y2="#{hatch_cell}" stroke="#{@col_node}" stroke-width="#{hatch_stroke}"></line>
        </pattern>
        <pattern id="hatchForLeaf" x="10" y="10" width="#{hatch_cell}" height="#{hatch_cell}" patternUnits="userSpaceOnUse" patternTransform="rotate(45)">
          <line x1="0" y="0" x2="0" y2="#{hatch_cell}" stroke="#{@col_leaf}" stroke-width="#{hatch_stroke}"></line>
        </pattern>
      </defs>
  HDR

  rect = <<~RCT
    <rect x="#{x1}" y="#{y1}" width="#{x2}" height="#{y2}" stroke="none" fill="white" />
  RCT

  footer = "</svg>"

  # Region shades go at the very back: above the white background but
  # below tree connectors and labels.
  shades = @region_shades.join

  if @shear_k.zero?
    if @transparent
      header + shades + @tree_data + extra_lines + footer
    else
      header + rect + shades + @tree_data + extra_lines + footer
    end
  else
    # The whole picture shears as one: the plane, the shades, the tree
    # and the rails all live inside the group, so an affine map carries
    # every incidence with it — nothing can newly touch or cross. The
    # background stays outside, painted to the sheared canvas.
    # No plane on a transparent background: what a clear background is
    # for is laying the figure over something else, and an opaque sheet
    # under it is the one thing that would defeat that.
    plane = +""
    if @shear_plane != "off" && !@transparent
      color = @shear_plane == "on" ? REGION_DEFAULT_COLOR : @shear_plane
      radius = @global[:height_connector_to_text] / 2.0
      # Fill alone, no edge. A region shade is bounded because it marks
      # one part of a figure off from the rest; the plane is under all of
      # it, and a line around the whole drawing reads as a frame.
      plane = "<rect x=\"#{@plane_rect[:x]}\" y=\"#{@plane_rect[:y]}\" " \
              "width=\"#{@plane_rect[:w]}\" height=\"#{@plane_rect[:h]}\" " \
              "rx=\"#{radius}\" ry=\"#{radius}\" " \
              "fill=\"#{color}\" fill-opacity=\"#{SHEAR_PLANE_FILL_OPACITY}\" " \
              "stroke=\"none\" />\n"
    end
    body = "<g transform=\"matrix(1,0,#{@shear_k},1,0,0)\">\n" +
           plane + shades + @tree_data + extra_lines + "</g>\n"
    if @transparent
      header + body + footer
    else
      header + rect + body + footer
    end
  end
end

#triangle_to_parent(parent, child) ⇒ Object

Draw a triangle between child/parent elements



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# File 'lib/rsyntaxtree/svg_graph.rb', line 1336

def triangle_to_parent(parent, child)
  return if child.horizontal_indent.zero?

  if @direction == "ltr"
    # LTR: triangle opens vertically (top-bottom of child),
    # apex at parent's right side.
    # Use same vertical reference and dimensions as TTB uses horizontally.
    hctt = @global[:height_connector_to_text]
    child_y_center = child.vertical_indent + (child.content_height + hctt * 1.5) / 2
    parent_y_center = parent.vertical_indent + (parent.content_height + hctt * 1.5) / 2
    tri_half = @global[:single_x_metrics].height / 2
    x1 = child.horizontal_indent - @global[:height_connector_to_text] / 2
    y1 = child_y_center - tri_half
    x2 = child.horizontal_indent - @global[:height_connector_to_text] / 2
    y2 = child_y_center + tri_half
    x3 = parent.horizontal_indent + parent.content_width + @global[:height_connector_to_text]
    y3 = parent_y_center
  else
    # The triangle spans the child's text and points at the parent. Which
    # way it points is the question the connectors ask as `child_above`,
    # and the answer is not always the same: bottom-to-top turns the
    # finished layout over, so the child sits above the parent there and
    # the base and the apex trade sides. Drawn as though the child were
    # always below, a bottom-to-top triangle came out inside out — its
    # base struck through the leaf and its apex through the node — for as
    # long as the option has existed. No gallery figure carries one: the
    # bottom-to-top examples are derivations, which draw rules instead.
    x1 = child.horizontal_indent
    x2 = child.horizontal_indent + child.content_width
    x3 = parent.horizontal_indent + parent.content_width / 2
    child_above = child.vertical_indent <= parent.vertical_indent
    m = child.ink_top && parent.ink_bottom ? @global[:single_x_metrics].height * @global[:vmargin] : nil
    if child_above
      y1 = m ? ink_under(child) + m : child.vertical_indent + child.content_height + @global[:height_connector_to_text]
      y3 = m ? ink_over(parent) - m : parent.vertical_indent + @global[:height_connector_to_text] / 2
      # The apex must stay clear of the base, or the figure folds through
      # itself; where there is no room for both clearances they meet in
      # the middle of what room there is.
      if m && y3 < y1
        mid = (y1 + y3) / 2.0
        y1 = mid
        y3 = mid
      end
    else
      y1 = m ? ink_over(child) - m : child.vertical_indent + @global[:height_connector_to_text] / 2
      y3 = m ? ink_under(parent) + m : parent.vertical_indent + parent.content_height + @global[:height_connector_to_text]
      if m && y3 > y1
        mid = (y1 + y3) / 2.0
        y1 = mid
        y3 = mid
      end
    end
    y2 = y1
  end

  polygon_data = @polygon_styles.sub(/X1/, x1.to_s)
  polygon_data = polygon_data.sub(/Y1/, y1.to_s)
  polygon_data = polygon_data.sub(/X2/, x2.to_s)
  polygon_data = polygon_data.sub(/Y2/, y2.to_s)
  polygon_data = polygon_data.sub(/X3/, x3.to_s)
  @tree_data  += polygon_data.sub(/Y3/, y3.to_s)
end