Convert newlines to ' operator

Set leading to 120% of font size for now.

Author: camelpunch

lib/mudbrick.ex

@@ -74,13 +74,39 @@ defmodule Mudbrick do
         _ -> false
       end)
 
-    if latest_font_setting.font.descendant do
+    context =
       ContentStream.add(
         context,
-        ContentStream.Tj,
-        font: latest_font_setting.font,
-        text: text
+        ContentStream.TL,
+        leading: latest_font_setting.size * 1.2
       )
+
+    if latest_font_setting.font.descendant do
+      text_parts = String.split(text, "\n")
+
+      {_, context} =
+        for part <- text_parts, reduce: {true, context} do
+          {true, acc} ->
+            {false,
+             ContentStream.add(
+               acc,
+               ContentStream.Tj,
+               font: latest_font_setting.font,
+               text: part
+             )}
+
+          {false, acc} ->
+            {false,
+             ContentStream.add(
+               acc,
+               ContentStream.Tj,
+               font: latest_font_setting.font,
+               operator: "'",
+               text: part
+             )}
+        end
+
+      context
     else
       ContentStream.add(
         context,

lib/mudbrick/content_stream.ex

@@ -24,8 +24,20 @@ defmodule Mudbrick.ContentStream do
     end
   end
 
+  defmodule TL do
+    defstruct [:leading]
+
+    defimpl Mudbrick.Object do
+      def from(tl) do
+        [to_string(tl.leading), " TL"]
+      end
+    end
+  end
+
   defmodule Tj do
-    defstruct [:font, :text]
+    defstruct font: nil,
+              operator: "Tj",
+              text: nil
 
     defimpl Mudbrick.Object do
       def from(tj) do
@@ -42,9 +54,9 @@ defmodule Mudbrick.ContentStream do
               |> String.pad_leading(4, "0")
             end)
 
-          ["<", glyph_ids_hex, "> Tj"]
+          ["<", glyph_ids_hex, "> #{tj.operator}"]
         else
-          [Mudbrick.Object.from(tj.text), " Tj"]
+          [Mudbrick.Object.from(tj.text), " #{tj.operator}"]
         end
       end
     end

test/mudbrick/content_stream_test.exs

@@ -3,13 +3,35 @@ defmodule Mudbrick.ContentStreamTest do
 
   import Mudbrick
 
-  alias Mudbrick.ContentStream
+  alias Mudbrick.ContentStream.Tj
   alias Mudbrick.Font
   alias Mudbrick.Indirect
   alias Mudbrick.Object
 
   @font_data System.fetch_env!("FONT_LIBRE_BODONI_REGULAR") |> File.read!()
 
+  test "linebreaks are converted to the ' operator" do
+    {_doc, content_stream} =
+      new()
+      |> page(
+        size: :letter,
+        fonts: %{bodoni: [file: @font_data]}
+      )
+      |> contents()
+      |> font(:bodoni, size: 10)
+      |> text_position(0, 700)
+      |> text("""
+      a
+      b\
+      """)
+
+    [apostrophe, tj, leading | _] = content_stream.value.operations
+
+    assert Object.from(leading) |> to_string() == "12.0 TL"
+    assert Object.from(tj) |> to_string() == "<00A5> Tj"
+    assert Object.from(apostrophe) |> to_string() == "<00B4> '"
+  end
+
   test "font is assigned to the operator struct when font descendant present" do
     {_doc, content_stream} =
       new()
@@ -24,7 +46,7 @@ defmodule Mudbrick.ContentStreamTest do
 
     [show_text_operation | _] = content_stream.value.operations
 
-    assert %ContentStream.Tj{
+    assert %Tj{
              text: "CO₂",
              font: %Font{
                name: :"LibreBodoni-Regular",

test/mudbrick_test.exs

@@ -37,10 +37,10 @@ defmodule MudbrickTest do
              }
            )
            |> contents()
-           |> font(:helvetica, size: 24)
+           |> font(:helvetica, size: 100)
            |> text_position(300, 400)
            |> text("hello, world!")
-           |> font(:courier, size: 12)
+           |> font(:courier, size: 10)
            |> text_position(0, -24)
            |> text("a new line!")
            |> page(size: :a4)
@@ -86,15 +86,17 @@ defmodule MudbrickTest do
              >>
              endobj
              6 0 obj
-             <</Length 81
+             <</Length 99
              >>
              stream
              BT
-             /F2 24 Tf
+             /F2 100 Tf
              300 400 Td
+             120.0 TL
              (hello, world!) Tj
-             /F1 12 Tf
+             /F1 10 Tf
              0 -24 Td
+             12.0 TL
              (a new line!) Tj
              ET
              endstream
@@ -114,13 +116,13 @@ defmodule MudbrickTest do
              0000000241 00000 n 
              0000000345 00000 n 
              0000000490 00000 n 
-             0000000620 00000 n 
+             0000000638 00000 n 
              trailer
              <</Root 2 0 R
                /Size 8
              >>
              startxref
-             698
+             716
              %%EOF\
              """
   end