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class="pilcrow">¶</a></div>A descriptor is a block of data that describes a complex data structure of some kind. It was added sometime around Photoshop 5.0 and it superceded a few legacy things such as layer names and type data. The benefit of the Descriptor is that it is self-contained, and allows us to dynamically define data of any size. It's always represented by an Object at the root. </td><td class="code"><div class="highlight"><pre>module.exports = class Descriptor</pre></div></td></tr><tr id="section-2"><td class="docs"><div class="pilwrap"><a href="#section-2" class="pilcrow">¶</a></div>Creates a new Descriptor. </td><td class="code"><div class="highlight"><pre> constructor: (@file) -></pre></div></td></tr><tr id="section-3"><td class="docs"><div class="pilwrap"><a href="#section-3" class="pilcrow">¶</a></div>The object that will store the resulting data. </td><td class="code"><div class="highlight"><pre> @data = {}</pre></div></td></tr><tr id="section-4"><td class="docs"><div class="pilwrap"><a href="#section-4" class="pilcrow">¶</a></div>Parses the Descriptor at the current location in the file. </td><td class="code"><div class="highlight"><pre> parse: -> @data.class = @parseClass()</pre></div></td></tr><tr id="section-5"><td class="docs"><div class="pilwrap"><a href="#section-5" class="pilcrow">¶</a></div>The descriptor defines the number of items it contains at the root. </td><td class="code"><div class="highlight"><pre> numItems = @file.readInt()</pre></div></td></tr><tr id="section-6"><td class="docs"><div class="pilwrap"><a href="#section-6" class="pilcrow">¶</a></div>Each item consists of a key/value combination, which is why our descriptor is stored as an object instead of an array at the root. </td><td class="code"><div class="highlight"><pre> for i in [0...numItems] [id, value] = @parseKeyItem() @data[id] = value @data</pre></div></td></tr><tr id="section-7"><td class="docs"><div class="pilwrap"><a href="#section-7" class="pilcrow">¶</a></div><h2 id="note">Note</h2> The rest of the methods in this class are considered private. You will never call any of them from outside this class. </td><td class="code"><div class="highlight"><pre></pre></div></td></tr><tr id="section-8"><td class="docs"><div class="pilwrap"><a href="#section-8" class="pilcrow">¶</a></div>Parses a class representation, which consists of a name and a unique ID. </td><td class="code"><div class="highlight"><pre> parseClass: -> name: @file.readUnicodeString() id: @parseId()</pre></div></td></tr><tr id="section-9"><td class="docs"><div class="pilwrap"><a href="#section-9" class="pilcrow">¶</a></div>Parses an ID, which is a unique String. </td><td class="code"><div class="highlight"><pre> parseId: -> len = @file.readInt() if len is 0 then @file.readString(4) else @file.readString(len)</pre></div></td></tr><tr id="section-10"><td class="docs"><div class="pilwrap"><a href="#section-10" class="pilcrow">¶</a></div>Parses a key/item value, which consists of an ID and an Item of any type. </td><td class="code"><div class="highlight"><pre> parseKeyItem: -> id = @parseId() value = @parseItem() return [id, value]</pre></div></td></tr><tr id="section-11"><td class="docs"><div class="pilwrap"><a href="#section-11" class="pilcrow">¶</a></div>Parses an Item, which can be one of many types of data, depending on the key. </td><td class="code"><div class="highlight"><pre> parseItem: (type = null) -> type = @file.readString(4) unless type? switch type when 'bool' then @parseBoolean() when 'type', 'GlbC' then @parseClass() when 'Objc', 'GlbO' then new Descriptor(@file).parse() when 'doub' then @parseDouble() when 'enum' then @parseEnum() when 'alis' then @parseAlias() when 'Pth' then @parseFilePath() when 'long' then @parseInteger() when 'comp' then @parseLargeInteger() when 'VlLs' then @parseList() when 'ObAr' then @parseObjectArray() when 'tdta' then @parseRawData() when 'obj ' then @parseReference() when 'TEXT' then @file.readUnicodeString() when 'UntF' then @parseUnitDouble() when 'UnFl' then @parseUnitFloat() parseBoolean: -> @file.readBoolean() parseDouble: -> @file.readDouble() parseInteger: -> @file.readInt() parseLargeInteger: -> @file.readLongLong() parseIdentifier: -> @file.readInt() parseIndex: -> @file.readInt() parseOffset: -> @file.readInt()</pre></div></td></tr><tr id="section-12"><td class="docs"><div class="pilwrap"><a href="#section-12" class="pilcrow">¶</a></div>Parses a Property, which consists of a class and a unique ID. </td><td class="code"><div class="highlight"><pre> parseProperty: -> class: @parseClass() id: @parseId()</pre></div></td></tr><tr id="section-13"><td class="docs"><div class="pilwrap"><a href="#section-13" class="pilcrow">¶</a></div>Parses an enumerator, which consists of 2 IDs, one of which is the type, and the other is the value. </td><td class="code"><div class="highlight"><pre> parseEnum: -> type: @parseId() value: @parseId()</pre></div></td></tr><tr id="section-14"><td class="docs"><div class="pilwrap"><a href="#section-14" class="pilcrow">¶</a></div>Parses an enumerator reference, which consists of a class and 2 IDs: a type and value. </td><td class="code"><div class="highlight"><pre> parseEnumReference: -> class: @parseClass() type: @parseId() value: @parseId()</pre></div></td></tr><tr id="section-15"><td class="docs"><div class="pilwrap"><a href="#section-15" class="pilcrow">¶</a></div>Parses an Alias, which is a string of arbitrary length. </td><td class="code"><div class="highlight"><pre> parseAlias: -> len = @file.readInt() @file.readString(len)</pre></div></td></tr><tr id="section-16"><td class="docs"><div class="pilwrap"><a href="#section-16" class="pilcrow">¶</a></div>Parses a file path, which consists of a 4 character signature and a path. </td><td class="code"><div class="highlight"><pre> parseFilePath: -> len = @file.readInt() sig = @file.readString(4)</pre></div></td></tr><tr id="section-17"><td class="docs"><div class="pilwrap"><a href="#section-17" class="pilcrow">¶</a></div>Little endian. Who knows. </td><td class="code"><div class="highlight"><pre> pathSize = @file.read('<i') numChars = @file.read('<i') path = @file.readUnicodeString(numChars) sig: sig path: path</pre></div></td></tr><tr id="section-18"><td class="docs"><div class="pilwrap"><a href="#section-18" class="pilcrow">¶</a></div>Parses a list/array of Items. </td><td class="code"><div class="highlight"><pre> parseList: -> count = @file.readInt() items = [] for i in [0...count] items.push @parseItem() items</pre></div></td></tr><tr id="section-19"><td class="docs"><div class="pilwrap"><a href="#section-19" class="pilcrow">¶</a></div>Not documented anywhere and unsure of the data format. Luckily, this type is extremely rare. In fact, it's so rare, that I've never run into it among any of my PSDs. </td><td class="code"><div class="highlight"><pre> parseObjectArray: -> throw "Descriptor object array not implemented yet @ #{@file.tell()}"</pre></div></td></tr><tr id="section-20"><td class="docs"><div class="pilwrap"><a href="#section-20" class="pilcrow">¶</a></div>Parses raw byte data of arbitrary length. </td><td class="code"><div class="highlight"><pre> parseRawData: -> len = @file.readInt() @file.read(len)</pre></div></td></tr><tr id="section-21"><td class="docs"><div class="pilwrap"><a href="#section-21" class="pilcrow">¶</a></div>Parses a Reference, which is an array of items of multiple types. </td><td class="code"><div class="highlight"><pre> parseReference: -> numItems = @file.readInt() items = [] for i in [0...numItems] type = @file.readString(4) value = switch type when 'prop' then @parseProperty() when 'Clss' then @parseClass() when 'Enmr' then @parseEnumReference() when 'Idnt' then @parseIdentifier() when 'indx' then @parseIndex() when 'name' then @file.readUnicodeString() when 'rele' then @parseOffset() items.push type: type, value: value items</pre></div></td></tr><tr id="section-22"><td class="docs"><div class="pilwrap"><a href="#section-22" class="pilcrow">¶</a></div>Parses a double with a unit, such as angle, percent, pixels, etc. Returns an object with an ID, a unit, and a value. </td><td class="code"><div class="highlight"><pre> parseUnitDouble: -> unitId = @file.readString(4) unit = switch unitId when '#Ang' then 'Angle' when '#Rsl' then 'Density' when '#Rlt' then 'Distance' when '#Nne' then 'None' when '#Prc' then 'Percent' when '#Pxl' then 'Pixels' when '#Mlm' then 'Millimeters' when '#Pnt' then 'Points' value = @file.readDouble() id: unitId, unit: unit, value: value</pre></div></td></tr><tr id="section-23"><td class="docs"><div class="pilwrap"><a href="#section-23" class="pilcrow">¶</a></div>Parses a float with a unit, such as angle, percent, pixels, etc. Returns an object with an ID, a unit, and a value. </td><td class="code"><div class="highlight"><pre> parseUnitFloat: -> unitId = @file.readString(4) unit = switch unitId when '#Ang' then 'Angle' when '#Rsl' then 'Density' when '#Rlt' then 'Distance' when '#Nne' then 'None' when '#Prc' then 'Percent' when '#Pxl' then 'Pixels' when '#Mlm' then 'Millimeters' when '#Pnt' then 'Points' value = @file.readFloat() id: unitId, unit: unit, value: value </pre></div></td></tr></tbody></table><div id="generated">generated Tue May 12 2015 11:08:10 GMT-0400 (EDT) </div></div></body></html>