Avoid q/Q bugs in e.g. Mac Preview

For now, just reset the font colour to black when we haven't been
explicit.

Author: camelpunch

lib/mudbrick.ex

@@ -69,37 +69,14 @@ defmodule Mudbrick do
     ContentStream.add(context, ContentStream.Td, tx: x, ty: y)
   end
 
-  defp latest_font_operation!(content_stream) do
-    Enum.find(
-      content_stream.value.operations,
-      &match?(%ContentStream.Tf{}, &1)
-    ) || raise Font.NotSet, "No font chosen"
-  end
-
-  def text({_doc, content_stream} = context, text, colour: {r, g, b}) do
+  def text(context, text, colour: {r, g, b}) do
     context
-    |> ContentStream.add(ContentStream.QPush, [])
     |> ContentStream.add(ContentStream.Rg, r: r, g: g, b: b)
-    |> text(text)
-    |> ContentStream.add(ContentStream.QPop, [])
-    |> ContentStream.add(latest_font_operation!(content_stream))
+    |> write_text(text)
   end
 
-  def text({_doc, content_stream} = context, text) do
-    import ContentStream
-
-    tf = latest_font_operation!(content_stream)
-
-    [first_part | parts] = String.split(text, "\n")
-
-    context
-    |> add(ContentStream.Tj, font: tf.font, text: first_part)
-    |> then(fn context ->
-      for part <- parts, reduce: context do
-        acc ->
-          add(acc, ContentStream.Apostrophe, font: tf.font, text: part)
-      end
-    end)
+  def text(context, text) do
+    text(context, text, colour: {0.0, 0.0, 0.0})
   end
 
   def render({doc, _page}) do
@@ -127,4 +104,28 @@ defmodule Mudbrick do
   def join(list, separator) do
     Enum.map_join(list, separator, &Mudbrick.Object.from/1)
   end
+
+  defp write_text({_doc, content_stream} = context, text) do
+    import ContentStream
+
+    tf = latest_font_operation!(content_stream)
+
+    [first_part | parts] = String.split(text, "\n")
+
+    context
+    |> add(ContentStream.Tj, font: tf.font, text: first_part)
+    |> then(fn context ->
+      for part <- parts, reduce: context do
+        acc ->
+          add(acc, ContentStream.Apostrophe, font: tf.font, text: part)
+      end
+    end)
+  end
+
+  defp latest_font_operation!(content_stream) do
+    Enum.find(
+      content_stream.value.operations,
+      &match?(%ContentStream.Tf{}, &1)
+    ) || raise Font.NotSet, "No font chosen"
+  end
 end

test/mudbrick/font_test.exs

@@ -36,13 +36,11 @@ defmodule Mudbrick.FontTest do
              BT
              /F1 10 Tf
              12.0 TL
+             0.0 0.0 0.0 rg
              (black and ) Tj
-             q
              1.0 0.0 0.0 rg
              (red) Tj
              (text) '
-             Q
-             /F1 10 Tf
              ET
              """
   end

test/mudbrick_test.exs

@@ -90,17 +90,19 @@ defmodule MudbrickTest do
              >>
              endobj
              6 0 obj
-             <</Length 99
+             <</Length 129
              >>
              stream
              BT
              /F2 100 Tf
              120.0 TL
              300 400 Td
+             0.0 0.0 0.0 rg
              (hello, world!) Tj
              /F1 10 Tf
              12.0 TL
              0 -24 Td
+             0.0 0.0 0.0 rg
              (a new line!) Tj
              ET
              endstream
@@ -120,13 +122,13 @@ defmodule MudbrickTest do
              0000000241 00000 n 
              0000000345 00000 n 
              0000000490 00000 n 
-             0000000638 00000 n 
+             0000000669 00000 n 
              trailer
              <</Root 2 0 R
                /Size 8
              >>
              startxref
-             716
+             747
              %%EOF\
              """
   end