Merge pull request #22 from javan/sbix

Parse bitmap data from sbix tables

lib/ttfunk.rb

@@ -106,7 +106,11 @@ def glyph_locations
     def glyph_outlines
       @glyph_outlines ||= TTFunk::Table::Glyf.new(self)
     end
-  end   
+
+    def sbix
+      @sbix ||= TTFunk::Table::Sbix.new(self)
+    end
+  end
 end
 
 require_relative "ttfunk/table/cmap"
@@ -120,3 +124,4 @@ def glyph_outlines
 require_relative "ttfunk/table/name"
 require_relative "ttfunk/table/os2"
 require_relative "ttfunk/table/post"
+require_relative "ttfunk/table/sbix"

lib/ttfunk/table/sbix.rb

@@ -0,0 +1,54 @@
+require_relative '../table'
+
+module TTFunk
+  class Table
+    class Sbix < Table
+      attr_reader :version
+      attr_reader :flags
+      attr_reader :num_strikes
+      attr_reader :strikes
+
+      BitmapData = Struct.new(:x, :y, :type, :data, :ppem, :resolution)
+
+      def bitmap_data_for(glyph_id, strike_index)
+        strike = strikes[strike_index]
+        return if strike.nil?
+
+        glyph_offset = strike[:glyph_data_offset][glyph_id]
+        next_glyph_offset = strike[:glyph_data_offset][glyph_id + 1]
+
+        if glyph_offset && next_glyph_offset
+          bytes = next_glyph_offset - glyph_offset
+          if bytes > 0
+            parse_from(offset + strike[:offset] + glyph_offset) do
+              x, y, type = read(8, "s2A4")
+              data = StringIO.new(io.read(bytes - 8))
+              BitmapData.new(x, y, type, data, strike[:ppem], strike[:resolution])
+            end
+          end
+        end
+      end
+
+      def all_bitmap_data_for(glyph_id)
+        strikes.each_index.map do |strike_index|
+          bitmap_data_for(glyph_id, strike_index)
+        end.compact
+      end
+
+      private
+
+        def parse!
+          @version, @flags, @num_strikes = read(8, "n2N")
+          strike_offsets = num_strikes.times.map { read(4, "N").first }
+
+          @strikes = strike_offsets.map do |strike_offset|
+            parse_from(offset + strike_offset) do
+              ppem, resolution = read(4, "n2")
+              data_offsets = (file.maximum_profile.num_glyphs + 1).times.map { read(4, "N").first }
+              { ppem: ppem, resolution: resolution, offset: strike_offset, glyph_data_offset: data_offsets }
+            end
+          end
+        end
+    end
+  end
+end

spec/integration/file_spec.rb

@@ -115,3 +115,33 @@
     it "should extract the correct value"
   end
 end
+
+describe TTFunk::File, "#sbix" do
+
+  context "with ColorTestSbix" do
+    # Thank you http://typophile.com/node/103268 for ColorTestSbix.ttf
+    let!(:file) { TTFunk::File.open(test_font("ColorTestSbix"))}
+
+    it "should should extract headers" do
+      expect(file.sbix.version).to eq(1)
+      expect(file.sbix.flags).to eq(1)
+      expect(file.sbix.num_strikes).to eq(1)
+    end
+
+    it "should extract bitmap data given a glyph id and strike index" do
+      bitmap = file.sbix.bitmap_data_for(4, 0)
+      expect(bitmap.x).to eq(0)
+      expect(bitmap.y).to eq(0)
+      expect(bitmap.type).to eq("png")
+      expect(bitmap.data.read).to match(/IHDR.*ImageReady.*IEND/m)
+      expect(bitmap.ppem).to eq(150)
+      expect(bitmap.resolution).to eq(72)
+    end
+
+    it "should extract an array of all bitmap data given a glyph id" do
+      all_bitmaps = file.sbix.all_bitmap_data_for(4)
+      expect(all_bitmaps.size).to eq(1)
+      expect(all_bitmaps[0].ppem).to eq(150)
+    end
+  end
+end