Add layer info parsing and unicode names

lib/psd/file.coffee

-{jspack} = require('jspack')
+{jspack} = require 'jspack'
+Util = require './util.coffee'
 
 module.exports = class File
   FORMATS =
@@ -38,4 +39,12 @@ module.exports = class File
   seek: (amt, rel = false) -> if rel then @pos += amt else @pos = amt
 
   readString: (length) -> @read(length).toString().replace /\u0000/g, ''
+  readUnicodeString: (length = null) ->
+    length or= @readInt()
+    @read(length * 2)
+      .toJSON()
+      .map((c) -> Util.getUnicodeCharacter(c))
+      .join('')
+      .replace(/\u0000/g, '')
+
   readByte: -> @read(1)[0]
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lib/psd/layer.coffee

@@ -6,6 +6,7 @@ module.exports = class Layer extends Module
   @includes require('./layer/mask.coffee')
   @includes require('./layer/blending_ranges.coffee')
   @includes require('./layer/name.coffee')
+  @includes require('./layer/info.coffee')
   # @includes require('./layer/channel_image.coffee')
 
   constructor: (@file, @header) ->
@@ -28,6 +29,7 @@ module.exports = class Layer extends Module
     @parseMaskData()
     @parseBlendingRanges()
     @parseLegacyLayerName()
+    @parseLayerInfo()
 
     @file.seek @layerEnd
     return @

lib/psd/layer/info.coffee

+LazyExecute = require '../lazy_execute.coffee'
+Util = require '../util.coffee'
+
+LAYER_INFO = {
+  name: require('../layer_info/unicode_name.coffee')
+}
+
+module.exports =
+  parseLayerInfo: ->
+    while @file.tell() < @layerEnd
+      @file.seek 4, true # sig
+
+      key = @file.readString(4)
+      length = Util.pad2 @file.readInt()
+      pos = @file.tell()
+
+      keyParseable = false
+      for own name, klass of LAYER_INFO
+        continue unless klass.shouldParse(key)
+
+        i = new klass(@, length)
+        @adjustments[name] = new LazyExecute(i, @file)
+          .now('skip')
+          .later('parse')
+          .get()
+
+        keyParseable = true
+        break
+
+      @file.seek length, true if not keyParseable
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lib/psd/layer_info.coffee

+module.exports = class LayerInfo
+  constructor: (@layer, @length) ->
+    @file = @layer.file
+    @section_end = @file.tell() + @length
+    @data = {}
+
+  skip: -> @file.seek @section_end
+  parse: -> @skip() # skip by default
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lib/psd/layer_info/unicode_name.coffee

+LayerInfo = require '../layer_info.coffee'
+
+module.exports = class UnicodeName extends LayerInfo
+  @shouldParse: (key) -> key is 'luni'
+
+  parse: ->
+    pos = @file.tell()
+    @data = @file.readUnicodeString()
+
+    @file.seek pos + @length
+    return @
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lib/psd/util.coffee

 module.exports = class Util
   @pad2: (i) -> (i + 1) & ~0x01
   @pad4: (i) -> ((i + 4) & ~0x03) - 1
+  @getUnicodeCharacter: (cp) ->
+    if cp >= 0 and cp <= 0xD7FF or cp >= 0xE000 and cp <= 0xFFFF
+      return String.fromCharCode(cp)
+    else if cp >= 0x10000 and cp <= 0x10FFFF
+      # we substract 0x10000 from cp to get a 20-bits number
+      # in the range 0..0xFFFF
+      cp -= 0x10000
+
+      # we add 0xD800 to the number formed by the first 10 bits
+      # to give the first byte
+      first = ((0xffc00 & cp) >> 10) + 0xD800
+
+      # we add 0xDC00 to the number formed by the low 10 bits
+      # to give the second byte
+      second = (0x3ff & cp) + 0xDC00
+
+      String.fromCharCode(first) + String.fromCharCode(second)
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