Can disable auto-kerning

code-supply · Dec 11, 2024 · ecc8244 · ecc8244
1 parent fe858ea
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Showing 6 changed files with 61 additions and 15 deletions.
diff --git a/lib/mudbrick.ex b/lib/mudbrick.ex
@@ -47,19 +47,40 @@ defmodule Mudbrick do
       iex> import Mudbrick.TestHelper
       ...> import Mudbrick
       ...> new(fonts: %{bodoni: bodoni_bold()})
-      ...> |> page(size: {600, 200})
+      ...> |> page(size: {400, 100})
       ...> |> text(
-      ...>   [{"Warning\\n", underline: [width: 0.5]}, "MORE ", {"efficiency", underline: [width: 0.5]}],
+      ...>   [{"Warning\\n", underline: [width: 0.5]}],
       ...>   font: :bodoni,
       ...>   font_size: 70,
-      ...>   position: {7, 130}
+      ...>   position: {7, 30}
       ...> )
       ...> |> render()
       ...> |> then(&File.write("examples/auto_kerning.pdf", &1))
 
   Produces [this](examples/auto_kerning.pdf). Notice how the 'a' is underneath the 'W' in 'Warning'.
 
-  <object width="400" height="215" data="examples/auto_kerning.pdf?#navpanes=0" type="application/pdf"></object>
+  <object width="400" height="115" data="examples/auto_kerning.pdf?#navpanes=0" type="application/pdf"></object>
+
+  It's on by default, but we can turn it off:
+
+      iex> import Mudbrick.TestHelper
+      ...> import Mudbrick
+      ...> new(fonts: %{bodoni: bodoni_bold()})
+      ...> |> page(size: {400, 100})
+      ...> |> text(
+      ...>   [{"Warning\\n", underline: [width: 0.5]}],
+      ...>   font: :bodoni,
+      ...>   font_size: 70,
+      ...>   position: {7, 30},
+      ...>   auto_kern: false
+      ...> )
+      ...> |> render()
+      ...> |> then(&File.write("examples/auto_kerning_disabled.pdf", &1))
+
+  Produces [this](examples/auto_kerning_disabled.pdf).
+
+  <object width="400" height="115" data="examples/auto_kerning_disabled.pdf?#navpanes=0" type="application/pdf"></object>
+
   """
 
   alias Mudbrick.{

diff --git a/lib/mudbrick/content_stream/tj.ex b/lib/mudbrick/content_stream/tj.ex
@@ -1,6 +1,7 @@
 defmodule Mudbrick.ContentStream.TJ do
   @moduledoc false
-  defstruct font: nil,
+  defstruct auto_kern: true,
+            font: nil,
             text: nil
 
   defimpl Mudbrick.Object do
@@ -11,16 +12,23 @@ defmodule Mudbrick.ContentStream.TJ do
     def to_iodata(op) do
       [
         "[ ",
-        Mudbrick.Font.kerned(op.font, op.text)
-        |> Enum.map(fn
-          {glyph_id, kerning} ->
-            ["<", glyph_id, "> ", to_string(kerning), " "]
-
-          glyph_id ->
-            ["<", glyph_id, "> "]
-        end),
+        op.font
+        |> Mudbrick.Font.kerned(op.text)
+        |> Enum.map(&write_glyph(op, &1)),
         "] TJ"
       ]
     end
+
+    defp write_glyph(%{auto_kern: true} = op, {glyph_id, kerning}) do
+      write_glyph(op, glyph_id) ++ [to_string(kerning), " "]
+    end
+
+    defp write_glyph(op, {glyph_id, _kerning}) do
+      write_glyph(op, glyph_id)
+    end
+
+    defp write_glyph(_op, glyph_id) do
+      ["<", glyph_id, "> "]
+    end
   end
 end
diff --git a/lib/mudbrick/text_block.ex b/lib/mudbrick/text_block.ex
@@ -8,6 +8,7 @@ defmodule Mudbrick.TextBlock do
 
   @type option ::
           {:align, alignment()}
+          | {:auto_kern, boolean()}
           | {:colour, Mudbrick.colour()}
           | {:font, atom()}
           | {:font_size, number()}
@@ -43,6 +44,7 @@ defmodule Mudbrick.TextBlock do
         }
 
   defstruct align: :left,
+            auto_kern: true,
             colour: {0, 0, 0},
             font: nil,
             font_size: 12,
@@ -105,6 +107,7 @@ defmodule Mudbrick.TextBlock do
     line_texts = String.split(text, "\n")
 
     text_block_opts = [
+      auto_kern: tb.auto_kern,
       colour: tb.colour,
       font_size: tb.font_size,
       font: tb.font,

diff --git a/lib/mudbrick/text_block/line.ex b/lib/mudbrick/text_block/line.ex
@@ -8,12 +8,14 @@ defmodule Mudbrick.TextBlock.Line do
     @moduledoc false
 
     @enforce_keys [
+      :auto_kern,
       :colour,
       :font,
       :font_size,
       :text
     ]
-    defstruct colour: {0, 0, 0},
+    defstruct auto_kern: true,
+              colour: {0, 0, 0},
               font: nil,
               font_size: nil,
               left_offset: nil,

diff --git a/lib/mudbrick/text_block/output.ex b/lib/mudbrick/text_block/output.ex
@@ -49,7 +49,7 @@ defmodule Mudbrick.TextBlock.Output do
   defp add_part(output, part) do
     output
     |> with_font(
-      struct!(TJ, font: part.font, text: part.text),
+      struct!(TJ, auto_kern: part.auto_kern, font: part.font, text: part.text),
       part
     )
     |> colour(part.colour)

diff --git a/test/text_test.exs b/test/text_test.exs
@@ -207,6 +207,18 @@ defmodule Mudbrick.TextTest do
                |> Enum.take(-2)
     end
 
+    test "with auto-kerning disabled, doesn't write kerns" do
+      assert ["[ <0011> <0055> <0174> ] TJ", "ET"] =
+               new(fonts: %{bodoni: bodoni_regular()})
+               |> page()
+               |> text([{"\n", auto_kern: true}, {"CO₂", auto_kern: false}],
+                 font_size: 24,
+                 position: {0, 700}
+               )
+               |> operations()
+               |> Enum.take(-2)
+    end
+
     test "copes with trailing newlines" do
       assert new(fonts: %{bodoni: bodoni_regular()})
              |> page()