From fd18ed2a65722cb962bef111af6a7f5f4b310d46 Mon Sep 17 00:00:00 2001
From: Dan Allen <dan.j.allen@gmail.com>
Date: Mon, 22 Jan 2024 17:43:55 +0200
Subject: [PATCH 1/2] Test case for wrong width of missing glyphs

---
 spec/prawn/font_spec.rb | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/spec/prawn/font_spec.rb b/spec/prawn/font_spec.rb
index a890c907e..ac9da98f4 100644
--- a/spec/prawn/font_spec.rb
+++ b/spec/prawn/font_spec.rb
@@ -670,4 +670,43 @@ def page_should_not_include_font(font)
     font_name = text.font_settings.first[:name].to_s.sub(/\w+\+/, 'subset+')
     expect(font_name).to eq 'subset+DustismoRoman'
   end
+
+  it 'does not change width of unknown glyph' do
+    text_with_string_widths =
+      Class.new(PDF::Inspector::Text) do
+        attr_reader :string_widths
+
+        def initialize(*)
+          super
+          @string_widths = []
+        end
+
+        def show_text(text, kerned = false)
+          super
+          @string_widths << ((@state.current_font.unpack text).reduce(0) do |width, code|
+            width + (@state.current_font.glyph_width code) * @font_settings[-1][:size] / 1000.0
+          end)
+        end
+      end
+
+    pdf =
+      Prawn::Document.new do
+        font_families.update(
+          'DejaVu Sans' => {
+            normal: "#{Prawn::DATADIR}/fonts/DejaVuSans.ttf",
+            bold: "#{Prawn::DATADIR}/fonts/DejaVuSans-Bold.ttf"
+          }
+        )
+
+        # changing option to subset: false fixes issue (albeit using different behavior)
+        font 'DejaVu Sans', subset: true do
+          text '日本語<b>end</b>', inline_format: true
+        end
+      end
+
+    rendered_pdf = pdf.render
+    analyzed_pdf = text_with_string_widths.analyze(rendered_pdf)
+    expect(analyzed_pdf.string_widths.length).to be 2
+    expect(analyzed_pdf.string_widths[0]).to be > 0.0
+  end
 end

From b5017b87b9c72433302e5cf1718f56b06e4ce0c8 Mon Sep 17 00:00:00 2001
From: Alexander Mankuta <alex@pointless.one>
Date: Mon, 22 Jan 2024 17:46:50 +0200
Subject: [PATCH 2/2] Fix missing glyph width.

Prawn correctly used width of missing glyphs to layout text but didn't
encode the widths correctly in subset fonts. The resulted in characters
with missing glyphs to have 0 width. And even though Prawn drawn
Replacement Character glyphs they were stacking on top of each other
because their widths were wrong.
---
 lib/prawn/fonts/ttf.rb    | 12 ++++++------
 spec/prawn_manual_spec.rb |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/prawn/fonts/ttf.rb b/lib/prawn/fonts/ttf.rb
index 5e55220f9..779234de8 100644
--- a/lib/prawn/fonts/ttf.rb
+++ b/lib/prawn/fonts/ttf.rb
@@ -393,18 +393,18 @@ def embed_simple_font(reference, font, unicode_mapping)
           XHeight: x_height
         )
 
-        first_char = font.cmap.tables.first.code_map.index { |gid| !gid.zero? }
-        last_char = font.cmap.tables.first.code_map.rindex { |gid| !gid.zero? }
+        first_char, last_char = unicode_mapping.keys.minmax
         hmtx = font.horizontal_metrics
         widths =
-          font.cmap.tables.first.code_map[first_char..last_char].map do |gid|
-            if gid.zero?
+          (first_char..last_char).map do |code|
+            if unicode_mapping.key?(code)
+              gid = font.cmap.tables.first.code_map[code]
+              Integer(hmtx.widths[gid] * scale_factor)
+            else
               # These characters are not in the document so we don't ever use
               # these values but we need to encode them so let's use as little
               # sapce as possible.
               0
-            else
-              Integer(hmtx.widths[gid] * scale_factor)
             end
           end
 
diff --git a/spec/prawn_manual_spec.rb b/spec/prawn_manual_spec.rb
index b92c55441..105016409 100644
--- a/spec/prawn_manual_spec.rb
+++ b/spec/prawn_manual_spec.rb
@@ -6,9 +6,9 @@
 MANUAL_HASH =
   case RUBY_ENGINE
   when 'ruby'
-    '8ace5f35f945e5994647cefc2cf7bc369d131e0646d91eb8aeb94e58f72de18d8e7bf82f58fc45406110c4adad239dcbe834059580d29fec2b2a039db67db04c'
+    '7991e4f72e944140840e1c26f0fff331029846eaab148de8483d06491c7808bc4963e8e7376a514e855037f1f1b4197877a31f2df44f511f4f7f5e0ce5df3170'
   when 'jruby'
-    'b77a740d3290192360c4c083018ca61ccc88d42e7c6a152c7bc394d751f5f08d85aec613549f6660713644b00518561cc0f9c947701f01e8c25632c9db81201a'
+    '29b8f8cb00910426805ce226fb47c59d6409683f35f0d2c056a6cf837ba086ca5c763ff89266cfc8e11b1d92af60c9974822b12ad761cdbdf520adb005a98750'
   end
 
 RSpec.describe Prawn do