Implement layer blend modes and info

examples/parse.js

@@ -4,6 +4,7 @@ psd = PSD.fromFile('./examples/images/example.psd');
 psd.parse();
 
 console.log(psd.header.export());
-psd.image.saveAsPng('./output.png').then(function () {
-  console.log("Finished!");
-});
\ No newline at end of file
+// psd.image.saveAsPng('./output.png').then(function () {
+//   console.log("Finished!");
+// });
+console.log(psd.layers.map(function (l) { return l.export(); }));
\ No newline at end of file

lib/psd.coffee

@@ -16,6 +16,9 @@ module.exports = class PSD
     @parsed = false
     @header = null
 
+    Object.defineProperty @, 'layers',
+      get: -> @layerMask.layers
+
   parse: ->
     return if @parsed
 

lib/psd/blend_mode.coffee

+{Module} = require 'coffeescript-module'
+
+module.exports = class BlendMode extends Module
+  @aliasProperty 'blendingMode', 'mode'
+
+  # All of the blend modes are stored in the PSD file with a specific key.
+  # This is the mapping of that key to its readable name.
+  BLEND_MODES = {
+    norm: 'normal',
+    dark: 'darken',
+    lite: 'lighten',
+    hue:  'hue',
+    sat:  'saturation',
+    colr: 'color',
+    lum:  'luminosity',
+    mul:  'multiply',
+    scrn: 'screen',
+    diss: 'dissolve',
+    over: 'overlay',
+    hLit: 'hard_light',
+    sLit: 'soft_light',
+    diff: 'difference',
+    smud: 'exclusion',
+    div:  'color_dodge',
+    idiv: 'color_burn',
+    lbrn: 'linear_burn',
+    lddg: 'linear_dodge',
+    vLit: 'vivid_light',
+    lLit: 'linear_light',
+    pLit: 'pin_light',
+    hMix: 'hard_mix',
+    pass: 'passthru',
+    dkCl: 'darker_color',
+    lgCl: 'lighter_color',
+    fsub: 'subtract',
+    fdiv: 'divide'
+  }
+
+  constructor: (@file) ->
+    @blendKey = null
+    @opacity = null
+    @clipping = null
+    @flags = null
+    @mode = null
+
+  parse: ->
+    @file.seek 4, true
+
+    @blendKey = @file.readString(4).trim()
+    @opacity = @file.readByte()
+    @clipping = @file.readByte()
+    @flags = @file.readByte()
+
+    @mode = BLEND_MODES[@blendKey]
+    @clipped = @clipping is 1
+
+    @visible = !((@flags & (0x01 << 1)) > 0)
+
+    @file.seek 1, true
+
+  opacityPercentage: -> @opacity * 100 / 255

lib/psd/file.coffee

@@ -38,10 +38,4 @@ module.exports = class File
   seek: (amt, rel = false) -> if rel then @pos += amt else @pos = amt
 
   readString: (length) -> @read(length).toString()
-  # readUInt: ->
-  #   @data.readUInt32(@pos)
-  #   @pos += 4
-
-  # readInt: ->
-  #   @data.readInt32(@pos)
-  #   @pos += 4
\ No newline at end of file
+  readByte: -> @read(1)[0]
\ No newline at end of file

lib/psd/layer.coffee

+{Module} = require 'coffeescript-module'
+
+module.exports = class Layer extends Module
+  @includes require('./layer/position_channels.coffee')
+  @includes require('./layer/blend_modes.coffee')
+  # @includes require('./layer/blending_ranges.coffee')
+  # @includes require('./layer/channel_image.coffee')
+
+  constructor: (@file, @header) ->
+    @mask = {}
+    @blendingRanges = {}
+    @adjustments = {}
+    @channelsInfo = []
+    @blendMode = {}
+    @groupLayer = null
+
+    @infoKeys = []
+
+  parse: ->
+    @parsePositionAndChannels()
+    @parseBlendModes()
+
+    extraLen = @file.readInt()
+    @layerEnd = @file.tell() + extraLen
+
+    @file.seek @layerEnd
+    return @
+
+  export: ->
+    top: @top
+    right: @right
+    bottom: @bottom
+    left: @left
+    width: @width
+    height: @height
+    opacity: @opacity
+    visible: @visible
+    clipped: @clipped
\ No newline at end of file

lib/psd/layer/blend_modes.coffee

+BlendMode = require '../blend_mode.coffee'
+
+module.exports =
+  parseBlendModes: ->
+    @blendMode = new BlendMode(@file)
+    @blendMode.parse()
+
+    @opacity = @blendMode.opacity
+    @visible = @blendMode.visible
+    @clipped = @blendMode.clipped
+
+  hidden: -> not @visible
+
+  # TODO: check section divider
+  blendingMode: ->
+    @blendMode.mode
\ No newline at end of file

lib/psd/layer/position_channels.coffee

+module.exports =
+  parsePositionAndChannels: ->
+    @top = @file.readInt()
+    @left = @file.readInt()
+    @bottom = @file.readInt()
+    @right = @file.readInt()
+    @channels = @file.readShort()
+
+    @rows = @height = @bottom - @top
+    @cols = @width = @right - @left
+
+    for i in [0...@channels]
+      id = @file.readShort()
+      length = @file.readInt()
+
+      @channelsInfo.push id: id, length: length

lib/psd/layer_mask.coffee

 Util = require('./util.coffee')
+Layer = require('./layer.coffee')
 
 module.exports = class LayerMask
   constructor: (@file, @header) ->
@@ -11,8 +12,6 @@ module.exports = class LayerMask
   parse: ->
     maskSize = @file.readInt()
     finish = maskSize + @file.tell()
-    @file.seek finish
-    return
 
     return if maskSize <= 0
 
@@ -25,3 +24,9 @@ module.exports = class LayerMask
         layerCount = Math.abs layerCount
         @mergedAlpha = true
 
+      for i in [0...layerCount]
+        @layers.push new Layer(@file, @header).parse()
+
+    @layers.reverse()
+
+    @file.seek finish