added support for open type format 12

pixie.nimble

@@ -1,4 +1,4 @@
-version     = "5.0.6"
+version     = "5.0.7"
 author      = "Andre von Houck and Ryan Oldenburg"
 description = "Full-featured 2d graphics library for Nim."
 license     = "MIT"

src/pixie/fontformats/opentype.nim

@@ -455,6 +455,7 @@ proc parseCmapTable(buf: string, offset: int): CmapTable =
 
       let format = buf.readUint16(i + 0).swap()
       if format == 4:
+        # https://learn.microsoft.com/en-us/typography/opentype/spec/cmap#format-4-segment-mapping-to-delta-values
         type Format4 = object
           format: uint16
           length: uint16
@@ -518,8 +519,46 @@ proc parseCmapTable(buf: string, offset: int): CmapTable =
             if c != 65535:
               result.runeToGlyphId[Rune(c)] = glyphId.uint16
               result.glyphIdToRune[glyphId.uint16] = Rune(c)
+
+      elif format == 12:
+        # https://learn.microsoft.com/en-us/typography/opentype/spec/cmap#format-12-segmented-coverage
+        type Format12 = object
+          format: uint16
+          reserved: uint16
+          length: uint32
+          language: uint32
+          numGroups: uint32
+
+        buf.eofCheck(i + 16)
+
+        var subTable: Format12
+        subTable.format = format
+        subTable.reserved = buf.readUint16(i + 2).swap()
+        subTable.length = buf.readUint32(i + 4).swap()
+        subTable.language = buf.readUint32(i + 8).swap()
+        subTable.numGroups = buf.readUint32(i + 12).swap()
+        i += 16
+
+        buf.eofCheck(i + subTable.numGroups.int * 12)
+
+        for k in 0 ..< subTable.numGroups:
+          let startCharCode = buf.readUint32(i + 0).swap()
+          let endCharCode = buf.readUint32(i + 4).swap()
+          let startGlyphId = buf.readUint32(i + 8).swap()
+
+          for c in startCharCode .. endCharCode:
+            let glyphId = startGlyphId + (c - startCharCode)
+            if glyphId > uint16.high:
+              # TODO: currently only 16 bit glyph ids are supported
+              raise newException(PixieError, "Found glyph outside of uint16 range: " & $glyphId)
+
+            result.runeToGlyphId[Rune(c)] = uint16(glyphId)
+            result.glyphIdToRune[uint16(glyphId)] = Rune(c)
+
+          i += 12
+
       else:
-        # TODO implement other Windows encodingIDs
+        # TODO implement other windows formats
         discard
     else:
       # TODO implement other cmap platformIDs

tests/test_fonts.nim

@@ -4,6 +4,21 @@ proc wh(image: Image): Vec2 =
   ## Return with and height as a size vector.
   vec2(image.width.float32, image.height.float32)
 
+block:
+  var font = readFont("tests/fonts/NotoEmoji.otf")
+  font.size = 26
+  let image = newImage(800, 300)
+  image.fill(rgba(255, 255, 255, 255))
+  image.fillText(font, """
+🚑🐑👭🔉🚷🦣💆🔁💺🚵🕦🔦🗓🦟😶🦄⌛🍙😄🇽
+🐠💓🦗🎭🏛🔴🫕🧶🍖🦁🏋🌗🛬🕐💡👉🎯🕔🚏🚲
+🐵🎍💳🥬🟦🪘📠📊🎧🎦🎁🌌🪲🦩🤢☎🚺🚾👺🚃
+🐨🌆🥉💭🗳🦵🟪📆🥮⏯🩴💷🦲➗🌶🧜🖖⏰🛗🔻
+📁🧞😃🌴🚶󾠫🦙🔎⏲🔵🖐☦😪🌯🙆🇺😂🍅🇿🚟🤜
+📼👰🍁📽☪🔄🤝🔧🦸🏰🏳🔜🎥🚋🇫🦨🏜🆖🏤🪖⏏""")
+
+  image.xray("tests/fonts/masters/emoji.png")
+
 block:
   var font = readFont("tests/fonts/Roboto-Regular_1.ttf")
   font.size = 24