Add bin and edit workflow

bin/gems/pdf-reader-2.14.1/lib/pdf/reader/font_descriptor.rb

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+# coding: utf-8
+# typed: true
+# frozen_string_literal: true
+
+require 'ttfunk'
+
+class PDF::Reader
+
+  # Font descriptors are outlined in Section 9.8, PDF 32000-1:2008, pp 281-288
+  class FontDescriptor
+
+    attr_reader :font_name, :font_family, :font_stretch, :font_weight,
+                :font_bounding_box, :cap_height, :ascent, :descent, :leading,
+                :avg_width, :max_width, :missing_width, :italic_angle, :stem_v,
+                :x_height, :font_flags
+
+    def initialize(ohash, fd_hash)
+      # TODO change these to typed derefs
+      @ascent                = ohash.deref_number(fd_hash[:Ascent])    || 0
+      @descent               = ohash.deref_number(fd_hash[:Descent])   || 0
+      @missing_width         = ohash.deref_number(fd_hash[:MissingWidth]) || 0
+      @font_bounding_box     = ohash.deref_array_of_numbers(fd_hash[:FontBBox])  || [0,0,0,0]
+      @avg_width             = ohash.deref_number(fd_hash[:AvgWidth])  || 0
+      @cap_height            = ohash.deref_number(fd_hash[:CapHeight]) || 0
+      @font_flags            = ohash.deref_integer(fd_hash[:Flags])     || 0
+      @italic_angle          = ohash.deref_number(fd_hash[:ItalicAngle])
+      @font_name             = ohash.deref_name(fd_hash[:FontName]).to_s
+      @leading               = ohash.deref_number(fd_hash[:Leading])   || 0
+      @max_width             = ohash.deref_number(fd_hash[:MaxWidth])  || 0
+      @stem_v                = ohash.deref_number(fd_hash[:StemV])
+      @x_height              = ohash.deref_number(fd_hash[:XHeight])
+      @font_stretch          = ohash.deref_name(fd_hash[:FontStretch]) || :Normal
+      @font_weight           = ohash.deref_number(fd_hash[:FontWeight])  || 400
+      @font_family           = ohash.deref_string(fd_hash[:FontFamily])
+
+      # A FontDescriptor may have an embedded font program in FontFile
+      # (Type 1 Font Program), FontFile2 (TrueType font program), or
+      # FontFile3 (Other font program as defined by Subtype entry)
+      # Subtype entries:
+      # 1) Type1C:        Type 1 Font Program in Compact Font Format
+      # 2) CIDFontType0C: Type 0 Font Program in Compact Font Format
+      # 3) OpenType:      OpenType Font Program
+      # see Section 9.9, PDF 32000-1:2008, pp 288-292
+      @font_program_stream = ohash.deref_stream(fd_hash[:FontFile2])
+      #TODO handle FontFile and FontFile3
+
+      @is_ttf = true if @font_program_stream
+    end
+
+    def glyph_width(char_code)
+      if @is_ttf
+        if ttf_program_stream.cmap.unicode.length > 0
+          glyph_id = ttf_program_stream.cmap.unicode.first[char_code]
+        else
+          glyph_id = char_code
+        end
+        char_metric = ttf_program_stream.horizontal_metrics.metrics[glyph_id]
+        if char_metric
+          char_metric.advance_width
+        else
+          0
+        end
+      end
+    end
+
+    # PDF states that a glyph is 1000 units wide, true type doesn't enforce
+    # any behavior, but uses units/em to define how wide the 'M' is (the widest letter)
+    def glyph_to_pdf_scale_factor
+      if @is_ttf
+        @glyph_to_pdf_sf ||= (1.0 / ttf_program_stream.header.units_per_em) * 1000.0
+      else
+        @glyph_to_pdf_sf ||= 1.0
+      end
+      @glyph_to_pdf_sf
+    end
+
+    private
+
+    def ttf_program_stream
+      @ttf_program_stream ||= TTFunk::File.new(@font_program_stream.unfiltered_data)
+    end
+  end
+
+end