Class: Asciidoctor::BeautifyUri::PdfConverter

Inherits:
Object
  • Object
show all
Defined in:
lib/asciidoctor/beautify_uri/pdf_converter.rb

Overview

Draws the PDF card directly with Prawn — see pdf_card.rb for why this replaced an earlier version that composed the card as a real AsciiDoc table and let asciidoctor-pdf's own table converter render it. Every position here (thumbnail, title, subtitle, link line, frame) is one this method chooses explicitly, in the same coordinate space, rather than routed through a table cell's own layout — that's what fixes the thumbnail/title top-alignment (both start at the same y, full stop) and what makes rounding the thumbnail's corners a plain Prawn clip path instead of an SVG-wrapping detour with its own scale math to get wrong.

Vertical rhythm is anchored to real font metrics, not an arbitrary line pitch: each line of text is placed by its baseline (draw_text, not text_box — see the note below), lines are spaced a full font.height apart (ascender+descender+line gap — a font's own natural single-line height, not asciidoctor-pdf's tighter body-text pitch, which is tuned for paragraphs of running text, not a standalone few-line card) plus theme-configurable slack, the brand icon spans cap-height to baseline of the link line it sits next to, and the thumbnail spans the title's cap-height down to the link line's baseline — i.e. it lines up with the visible top and bottom of the text stack, not the extra headroom/footroom a font reserves for ascenders and descenders that never actually appear in this text.

Every visual knob (spacing, border, corner radii, font styles) reads from a uri_card theme namespace with a || DEFAULT fallback, the same convention asciidoctor-lists-extended uses for its own list-of keys — see doc/modules/ROOT/pages/pdf-theming.adoc for the full list. An unset theme behaves exactly as if these were still hardcoded constants. The one exception is a provider-mandated thumbnail corner radius (e.g. Spotify's design guidelines) — a real brand requirement, not a preference, so it overrides the theme key entirely; see pdf_card.rb and providers/spotify.rb.

Constant Summary collapse

DEFAULT_MARGIN_INNER_PT = 
8
DEFAULT_ICON_GAP_PT = 
4
DEFAULT_BORDER_COLOR = 
'B3B3B3'
DEFAULT_BORDER_WIDTH_PT = 
0.5
DEFAULT_BORDER_RADIUS_PT = 
6
DEFAULT_THUMBNAIL_BORDER_RADIUS_PT = 
4
DEFAULT_LINE_SPACING =

font.height (ascender+descender+line gap) is a font's own natural single-line pitch — already looser than asciidoctor-pdf's own tight body-text line height, but still reads as cramped for a card that's nothing but a few short stacked lines rather than running prose.

1.35
DEFAULT_TITLE_FONT_STYLE = 
:bold
DEFAULT_SUBTITLE_FONT_STYLE = 
:normal
:bold
ELLIPSIS = 
'…'

Instance Method Summary collapse

Instance Method Details

#convert_uri_card(node) ⇒ Object 



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# File 'lib/asciidoctor/beautify_uri/pdf_converter.rb', line 57

def convert_uri_card node
  add_dest_for_block node if node.id

  title = node.attr 'uri-card-title'
  subtitle = node.attr 'uri-card-subtitle'
  link_text = node.attr 'uri-card-link-text'
  target_url = node.attr 'uri-card-target-url'
  icon_path = node.attr 'uri-card-icon-path'
  thumb_url = node.attr 'uri-card-thumb-url'
  lines = subtitle ? 3 : 2

  margin_inner = theme_num 'margin_inner', DEFAULT_MARGIN_INNER_PT
  icon_gap = theme_num 'icon_gap', DEFAULT_ICON_GAP_PT
  title_style = theme_style 'title_font_style', DEFAULT_TITLE_FONT_STYLE
  subtitle_style = theme_style 'subtitle_font_style', DEFAULT_SUBTITLE_FONT_STYLE
  link_style = theme_style 'link_font_style', DEFAULT_LINK_FONT_STYLE

  line_h = font.height * (theme_num 'line_spacing', DEFAULT_LINE_SPACING)
  title_cap_h = nil
  with_style(title_style) { title_cap_h = cap_height_pt }
  link_cap_h = nil
  with_style(link_style) { link_cap_h = cap_height_pt }

  # No photographic thumbnail (thumbnail=false, or the provider simply
  # didn't resolve one): the provider's own brand mark fills that
  # column at full size instead of sitting small next to the link
  # text, so the card never has an empty thumbnail column with no
  # visual identity at all. The small link-line icon is then
  # redundant — the same mark already anchors the card much larger —
  # and dropped.
  has_photo = !thumb_url.nil?
  link_icon = has_photo ? (build_icon icon_path, link_cap_h) : nil
  link_icon_w = link_icon ? link_icon.document.sizing.output_width : 0

  # The visible span of the meta stack: the title's own cap-height
  # (its capital letters' true top) down to the link line's baseline —
  # not (lines * line_h), which would also count the title's ascender
  # headroom above cap-height and the link line's descender footroom
  # below its baseline, neither of which this stack actually uses.
  text_h = title_cap_h + (line_h * (lines - 1))
  logo_icon = has_photo ? nil : (build_icon icon_path, text_h)
  thumb_w = if has_photo
              thumbnail_width node, text_h
            elsif logo_icon
              logo_icon.document.sizing.output_width
            else
              0
            end

  # The printable area this card must never exceed — at a large
  # enough base font size (or an unusually long title/subtitle/link),
  # text sized only against its own natural width can run past the
  # page margin entirely rather than merely looking a little cramped.
  # Designed to comfortably fit a 25-character playlist/album name, an
  # 18-character artist name, and a 23-character track name (Spotify's
  # own typical metadata lengths) well within this budget at ordinary
  # font sizes; fit_text below is the actual backstop for whatever
  # exceeds it regardless of why.
  max_content_w = bounds.width - (margin_inner * 2)
  thumb_w = [thumb_w, max_content_w * 0.5].min if thumb_w.positive?
  max_text_w = thumb_w.positive? ? max_content_w - thumb_w - margin_inner : max_content_w
  max_link_text_w = [max_text_w - link_icon_w - icon_gap, 1].max

  title_w = nil
  with_style(title_style) { title = fit_text title, max_text_w; title_w = width_of title }
  link_w = nil
  with_style(link_style) { link_text = fit_text link_text, max_link_text_w; link_w = width_of link_text }
  # with_style (like Prawn's own font(name) { block }) returns the font
  # object, not the block's result — assign via an outer local instead
  # of the method's return value.
  subtitle_w = 0.0
  with_style(subtitle_style) { subtitle = fit_text subtitle, max_text_w; subtitle_w = width_of subtitle } if subtitle
  text_col_w = [title_w, link_w + link_icon_w + icon_gap, subtitle_w].max

  # One margin_inner value does double duty, matching how it reads
  # visually: the gap from the frame to the thumbnail (or to the text
  # column, without one) is the same gap as from the thumbnail to the
  # text column — a single consistent inner margin, not two knobs that
  # happen to usually agree.
  content_w = thumb_w.positive? ? thumb_w + margin_inner + text_col_w : text_col_w
  card_w = [content_w + (margin_inner * 2), bounds.width].min
  card_h = text_h + (margin_inner * 2)

  advance_page if card_h > cursor && !at_page_top?

  top = cursor
  left = bounds.left
  content_left = left + margin_inner
  # The line this card's own cap-height/thumbnail-top reference is
  # measured from — see text_h above.
  content_top = top - margin_inner

  draw_frame [left, top], card_w, card_h

  text_left = content_left
  if thumb_w.positive?
    if has_photo
      draw_thumbnail node, thumb_url, target_url, [content_left, content_top], thumb_w, text_h
    else
       logo_icon, target_url, [content_left, content_top], thumb_w, text_h
    end
    text_left += thumb_w + margin_inner
  end

  title_baseline = content_top - title_cap_h
  link_baseline = title_baseline - (line_h * (lines - 1))

  # draw_text (baseline-anchored), not text_box: text_box's own
  # line-fit check needs a touch more box height than a bare line
  # metric to accept a single line at all (confirmed empirically — a
  # box exactly one nominal line tall silently dropped the whole line
  # as unrendered "leftover" instead of drawing it), and every line
  # here is already sized (and, if need be, fit_text-truncated) to fit
  # within text_col_w, so there is nothing left for a box's
  # wrap/truncate machinery to do anyway.
  with_style(title_style) { draw_text title, at: [text_left, title_baseline] }
  with_style(subtitle_style) { draw_text subtitle, at: [text_left, title_baseline - line_h] } if subtitle
  draw_link_line link_icon, link_icon_w, icon_gap, link_text, link_style, target_url, text_left, link_baseline, text_col_w, link_cap_h

  move_cursor_to top - card_h
  theme_margin :block, :bottom, (next_enclosed_block node)
end