resolves asciidoctor#353 add example with tests of extended converter…

… that supports image float

CHANGELOG.adoc

@@ -15,6 +15,11 @@ Enhancements::
 * rename `arrange_section` to `arrange_heading` to reflect proper terminology and purpose
 * add `index-column-gap` key to theme to control size of gap between columns
 * coerce `image-caption-max-width` to `fit-content` if `float` attribute is set on block image (#2150)
+* add support for text box with fixed height via `:height` option to `typeset_text` helper
+* configure `typeset_text` and `ink_prose` to return remaining fragments when `:height` option is specified
+* set `rendered-height`, `rendered-width`, and `caption-height` attributes on node of rendered block image to respective values
+* if `float` attribute is set on block image, set max width on caption to `fit-content` if max width not already set to a `fit-content` value
+* add example of extended converter that wraps text around preceding block image with `float` attribute (#353)
 
 Improvements::
 

docs/modules/extend/examples/pdf-converter-image-float.rb

@@ -0,0 +1,80 @@
+class PDFConverterImageFloat < (Asciidoctor::Converter.for 'pdf')
+  register_for 'pdf'
+
+  def convert_paragraph node
+    prev_sibling = (self_idx = (siblings = node.parent.blocks).index node) > 0 ? siblings[self_idx - 1] : nil
+    if (prev_sibling&.context == :image && (float_to = prev_sibling.attr 'float')) || (@float_box ||= nil)
+      start_cursor = cursor # start_cursor is always start of block below image
+      roles = node.roles
+      text_align = (resolve_text_align_from_role roles, query_theme: true, remove_predefined: true) || @base_text_align.to_sym
+      para_font_descender = para_font_size = nil
+      if roles.empty?
+        para_font_descender = font.descender
+        para_font_size = font_size
+        line_metrics = calc_line_metrics @base_line_height
+      else
+        line_metrics = theme_font_cascade (role_keys = roles.map {|role| %(role_#{role}).to_sym }) do
+          para_font_descender = font.descender
+          para_font_size = font_size
+          calc_line_metrics @base_line_height
+        end
+      end
+      if (float_box = @float_box)
+        @float_box = nil
+        float_box[:at][1] -= line_metrics.padding_top # typeset_text with box doesn't add line_metrics padding
+      else
+        float_gap_s, float_gap_b = ::Array === (float_gap = theme.image_float_gap) ? float_gap : [float_gap || 12, float_gap || 6]
+        float_w = (prev_sibling.attr 'rendered-width') + float_gap_s
+        float_h = (prev_sibling.attr 'rendered-height') + (prev_sibling.attr 'caption-height', 0) + float_gap_b
+        if (box_w = bounds.width - float_w) < para_font_size
+          prev_sibling.remove_attr 'float'
+          return convert_paragraph node
+        end
+        box_t = start_cursor + (float_h - float_gap_b) + theme.block_margin_bottom
+        box_l = float_to == 'right' ? 0 : float_w
+        box_t -= line_metrics.padding_top # typeset_text with box doesn't add line_metrics padding
+        # NOTE: allocate at least one whole empty line below image
+        line_height_length = line_metrics.height + line_metrics.leading + line_metrics.padding_top
+        float_box = { at: [box_l, box_t], width: box_w, height: [box_t, float_h + line_height_length].min }
+      end
+      float_box[:final_gap] = para_font_descender + line_metrics.padding_bottom
+      add_dest_for_block node if node.id
+      end_cursor = nil
+      prose_opts = float_box.merge align: text_align, hyphenate: true, margin_bottom: 0, draw_text_callback: (proc do |text, opts|
+        draw_text! text, opts
+        end_cursor = opts[:at][1]
+      end)
+      if role_keys
+        remaining = theme_font_cascade(role_keys) { ink_prose node.content, prose_opts }
+      else
+        remaining = ink_prose node.content, prose_opts
+      end
+      end_cursor = end_cursor ? end_cursor - float_box[:final_gap] : start_cursor
+      if remaining.empty?
+        if siblings[self_idx + 1]&.context == :paragraph
+          end_cursor -= theme.prose_margin_bottom
+          inked_height = float_box[:at][1] - end_cursor
+          if (float_box[:height] -= inked_height) > 0
+            float_box[:at][1] -= inked_height
+            float_box[:line_metrics] = line_metrics
+            @float_box = float_box
+          else
+            move_cursor_to end_cursor
+          end
+        else
+          move_cursor_to start_cursor
+        end
+      else
+        move_cursor_to end_cursor
+        if role_keys
+          theme_font_cascade(role_keys) { typeset_formatted_text remaining, line_metrics, align: text_align }
+        else
+          typeset_formatted_text remaining, line_metrics, align: text_align
+        end
+        theme_margin :prose, :bottom, (next_enclosed_block node)
+      end
+    else
+      super
+    end
+  end
+end

docs/modules/extend/pages/use-cases.adoc

@@ -165,6 +165,26 @@ image:
   indent: [0.5in, 0]
 ----
 
+== Float block image
+
+For the most part, Asciidoctor PDF stacks block elements vertically.
+The main exception is a table, which allows content to be arranged in a grid.
+By extending the converter and overriding the convert handler for a paragraph, you can arrange consecutive paragraphs that follow an image to fit into the empty space next to the image, then wrap around it.
+
+.Extended converter that wraps text around an image float
+[,ruby]
+----
+include::example$pdf-converter-image-float.rb[]
+----
+
+Using this extended converter, you can configure the gap between next to and below the image using the `image_float_gap` key.
+
+[,yaml]
+----
+image:
+  float_gap: [12, 6]
+----
+
 == Resources
 
 To find even more examples of how to override the behavior of the converter, refer to the extended converter in the {url-infoq-template}[InfoQ Mini-Book template^].

lib/asciidoctor/pdf/converter.rb

@@ -1588,7 +1588,7 @@ def convert_image node, opts = {}
         pinned = opts[:pinned]
 
         begin
-          rendered_w = nil
+          rendered_h = rendered_w = nil
           span_page_width_if align_to_page do
             if image_format == 'svg'
               if ::Base64 === image_path
@@ -1667,6 +1667,9 @@ def convert_image node, opts = {}
             end
           end
           ink_caption node, category: :image, end: :bottom, block_align: alignment, block_width: rendered_w, max_width: caption_max_width if caption_end == :bottom && node.title?
+          node.set_attr 'caption-height', (caption_h.round 5) if caption_h > 0
+          node.set_attr 'rendered-height', (rendered_h.round 5)
+          node.set_attr 'rendered-width', (rendered_w.round 5)
           theme_margin :block, :bottom, (next_enclosed_block node) unless pinned
         rescue => e
           raise if ::StopIteration === e
@@ -3063,12 +3066,13 @@ def ink_prose string, opts = {}
             text_decoration_width: (opts.delete :text_decoration_width),
           }.compact
         end
-        typeset_text string, (calc_line_metrics (opts.delete :line_height) || @base_line_height), {
+        result = typeset_text string, (calc_line_metrics (opts.delete :line_height) || @base_line_height), {
           color: @font_color,
           inline_format: [inline_format_opts],
           align: @base_text_align.to_sym,
         }.merge(opts)
         margin_bottom bot_margin
+        result
       end
 
       def generate_manname_section node
@@ -4180,9 +4184,10 @@ def rendered_width_of_char char, opts = {}
 
       # TODO: document me, esp the first line formatting functionality
       def typeset_text string, line_metrics, opts = {}
-        move_down line_metrics.padding_top
         opts = { leading: line_metrics.leading, final_gap: line_metrics.final_gap }.merge opts
         string = string.gsub CjkLineBreakRx, ZeroWidthSpace if @cjk_line_breaks
+        return text_box string, opts if opts[:height]
+        move_down line_metrics.padding_top
         if (hanging_indent = (opts.delete :hanging_indent) || 0) > 0
           indent hanging_indent do
             text string, (opts.merge indent_paragraphs: -hanging_indent)

spec/fixtures/lorem-ipsum.yml

@@ -5,6 +5,11 @@
 2-sentences-1-paragraph: |-
   Lorem ipsum dolor sit amet consectetur adipiscing elit conubia turpis, elementum porttitor sagittis pellentesque dictumst egestas ante praesent.
   Magna velit egestas quam sociis placerat facilisis felis mauris, primis ridiculus commodo scelerisque eleifend morbi non.
+4-sentences-1-paragraph: |-
+  Lorem ipsum dolor sit amet consectetur adipiscing elit conubia turpis, elementum porttitor sagittis pellentesque dictumst egestas ante praesent.
+  Magna velit egestas quam sociis placerat facilisis felis mauris, primis ridiculus commodo scelerisque eleifend morbi non.
+  Blandit nam porta arcu sociosqu eros libero cras morbi, enim tempus est elementum ut interdum accumsan, hendrerit ornare imperdiet proin vivamus inceptos fames mi, sociis leo odio donec mattis hac.
+  Condimentum egestas velit accumsan lobortis montes quisque mattis curae placerat magna, primis justo tristique elementum facilisis penatibus pretium in scelerisque est, euismod tempor luctus tincidunt sed potenti enim ac ut.
 2-sentences-2-paragraphs: |-
   Lorem ipsum dolor sit amet consectetur adipiscing elit conubia turpis, elementum porttitor sagittis pellentesque dictumst egestas ante praesent.