AS3 动态加载字体 ( AS3 Runtime Font Loading )
- 作者: 知明所以 • Milo
- 博客: http://www.cnblogs.com/jhzhu
- 邮箱: jhzhuustc@gmail.com
- 日期: 2013年5月23日
1. 为什么要动态加载字体
比如你需要让用户自定义 textField 的字体.
如果这些字体都 Embed 到项目中去的话, 就会大大增加项目Size.
并且, 每次您更改字体的时候都要重新编译.
2. 常用方法
第一步, 创建一个独立于项目之外的 font.swf. 这个swf即为字体文件. 内容如下:
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package { import flash.display.Sprite; public class FontLibrary extends Sprite { [Embed(systemFont='Bank Gothic', fontName='emBank Gothic', mimeType='application/x-font')] public static var BankGothicFont:Class; }} |
第二步, 在主项目中这样使用动态加载的字体
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var loader:Loader = new Loader();loader.contentLoaderInfo.addEventListener(Event.COMPLETE, completeHandler);loader.load(new URLRequest("fontlibrary.swf"));private function completeHandler(event:Event):void { var FontLibrary:Class = event.target.applicationDomain.getDefinition("FontLibrary") as Class; Font.registerFont(FontLibrary.BankGothicFont); var tf:TextField = new TextField(); tf.defaultTextFormat = new TextFormat("emBank Gothic", 12, 0); tf.embedFonts = true; tf.rotation = 15; // to demonstrate the embed worked tf.text = "blah blah blahnblah blah blahnblah blah blah "; addChild(tf);} |
3. 进阶方法
上面的做法, 即 把 “Embed 字体” 的操作从主项目嫁祸到辅助项目 font.swf 文件中去.
基本解决了我们动态加载字体的需求.
但是作为 程序员, 一件事情不弄舒坦是停不下来的. 上面的方法存在什么问题呢:
- 我们需要为每个字体文件单独生成一个 swf. 如果要有10个字体, 我就要处理10次. 这件事挺起来一点都不 Geek, 你能忍么? 反正我是不能忍
- 如果我们需要精简字体, 利用上一篇博文( Flash精简字体打包成SWF )中的方法打包成 精简的 swf. 为什么一个字体文件需要两个 swf 来浪费我的编译时间?
好了. 抱怨结束. 下面开始正文.
3.1 原理:
1. SWF文件是由一个文件头，以及一系列的标签组成的。标签类型有两种：定义型标签和控制型标签。( SWF文件格式解析请摸我 )
2. 咱们的字体在SWF中会对应一个定义型标签. 每个定义型标签有一个类型字段, 字体标签对应的类型为: 10 . ( SWF文件格式详解见官方文档: SWF File Format Specification )
官方文档中 DefineFont 标签的 简要信息
3. 理论上, 咱们加载完一个 SWF 文件之后, 只要挨家挨户找 Tag 类型为 10 的Tag. 就能把所有的 字体信息提取出来.
4. 但是提取出来之后, 我们还必须按照 SWF Player 可以识别的格式来组织起来, SWF Player 才能认识.
3.2 实现
上面的原理讲得头头是道, 第4步的重新组织是一个非常复杂精细并需要阅读大量文档的任务.
这方面, 咱们头顶上的俄国人比较突出. 下面就是一位 俄罗斯 Geeker 带来的 FontLoader. ( 请关注这位大拿的博客 )
优点:
- 能把 SWF 文件中的所有字体都提取出来, 为我所用.
- 与主项目几乎无干扰
- 无需其他类, 总共就一个文件 FontLoader.as . 不会增加主项目大小
- 无需代码共享库
- … ( 非常 Geek, 非常 方便… )
用例:
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var url:String = 'aaaa.swf';var loader:FontLoader = new FontLoader( new URLRequest( url ) );loader.addEventListener( Event.COMPLETE, onFontLoaded );private static function onFontLoaded( e:Event ):void{ //字体已经注册成功, 做你其它的事情} |
更详细的用法请下载 FontLoader.as ( 点击下载 ) 查看源代码吧
想了想, 还是把源码贴上来吧. 更直观一些:
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/** * FontLoader 2.3 by Denis Kolyako. June 13, 2008. Last update: January 20, 2011. * Visit http://etcs.ru for documentation, updates and more free code. * * You may distribute this class freely, provided it is not modified in any way (including * removing this header or changing the package path). * * * Please contact etc[at]mail.ru prior to distributing modified versions of this class. *//** * The FontLoader class lets you load any swf movie (ver. 6 or later), which contains embedded fonts (CFF too) to use these fonts in your application. */package ru.etcs.utils { import flash.display.Loader; import flash.events.ErrorEvent; import flash.events.Event; import flash.events.EventDispatcher; import flash.events.HTTPStatusEvent; import flash.events.IOErrorEvent; import flash.events.ProgressEvent; import flash.events.SecurityErrorEvent; import flash.net.URLLoader; import flash.net.URLLoaderDataFormat; import flash.net.URLRequest; import flash.system.ApplicationDomain; import flash.system.LoaderContext; import flash.text.Font; import flash.utils.ByteArray; import flash.utils.Endian; [Event("complete", type="flash.events.Event")] [Event("open", type="flash.events.Event")] [Event("ioError", type="flash.events.IOErrorEvent")] [Event("verifyError", type="flash.events.IOErrorEvent")] [Event("httpStatus", type="flash.events.HTTPStatusEvent")] [Event("progress", type="flash.events.ProgressEvent")] [Event("securityError", type="flash.events.SecurityErrorEvent")] /** * FontLoader class * * @author etc * @version 2.3 * @playerversion Flash 9 * @langversion 3.0 */ public class FontLoader extends EventDispatcher { /** * @private */ private static const SWF_HEADER:ByteArray = new ByteArray(); /** * @private */ private static const CLASS_CODE:ByteArray = new ByteArray(); /** * @private */ private static const CLASS_NAME_PREFIX:String = 'Font$'; /** * @private */ private static const TAG_DO_ABC:uint = ((72 << 6) | 0x3F); /** * @private */ private static const TAG_SYMBOL_CLASS:uint = ((76 << 6) | 0x3f); /** * @private */ private static var _initialized:Boolean = false; /** * @private */ private static function init():void { if (FontLoader._initialized) return; var ba:SWFByteArray = new SWFByteArray(); ba.writeBytesFromString( '7800055F00000FA000000C01004411080000004302FFFFFFBF150B0000000100466F6E744C69620000' + 'BF1461020000010000000010002E00000000191272752E657463732E7574696C733A466F6E7400432F' + '55736572732F6574632F4465736B746F702F50726F6A656374732F466F6E744C6F616465724C69622F' + '7372633B72752F657463732F7574696C733B466F6E742E61731772752E657463732E7574696C733A46' + '6F6E742F466F6E74175B4F626A65637420466F6E7420666F6E744E616D653D2208666F6E744E616D65' + '0D2220666F6E745374796C653D2209666F6E745374796C650C2220666F6E74547970653D2208666F6E' + '745479706502225D1B72752E657463732E7574696C733A466F6E742F746F537472696E670653747269' + '6E6708746F537472696E67175F5F676F5F746F5F646566696E6974696F6E5F68656C700466696C6543' + '2F55736572732F6574632F4465736B746F702F50726F6A656374732F466F6E744C6F616465724C6962' + '2F7372632F72752F657463732F7574696C732F466F6E742E617303706F73033636380D72752E657463' + '732E7574696C7304466F6E740A666C6173682E74657874064F626A6563740335373006050116021614' + '161618010201030A07020607020807020A07020D07020E070315070415091501070217040000020000' + '00040000040C0000000200020F02101211130F02101211180106070905000101054100020100000001' + '030106440000010104000101040503D03047000001010105060EF103F018D030F019D04900F01A4700' + '00020201050620F103F01CD0302C05F01DD00401A02C07A0D00402A02C09A0D00403A02C0BA0480000' + '030201010421D030F103F0165D085D096609305D076607305D07660758001D1D6806F103F00B470000' ); // Magic bytes :-) ba.position = 0; ba.readBytes(FontLoader.SWF_HEADER); ba.length = 0; ba.writeBytesFromString( '392F55736572732F6574632F4465736B746F702F50726F6A656374732F466F6E744C6F616465724C69' + '622F7372633B3B466F6E743030302E61730568656C6C6F2B48656C6C6F2C20776F726C642120497320' + '616E79626F647920686572653F2057686F27732074686572653F0F466F6E743030302F466F6E743030' + '300D72752E657463732E7574696C7304466F6E74064F626A6563740A666C6173682E74657874175F5F' + '676F5F746F5F646566696E6974696F6E5F68656C700466696C65382F55736572732F6574632F446573' + '6B746F702F50726F6A656374732F466F6E744C6F616465724C69622F7372632F466F6E743030302E61' + '7303706F73023534060501160216071801160A00050702010703080702090705080300000200000006' + '0000000200010B020C0E0D0F0101020904000100000001020101440100010003000101050603D03047' + '0000010102060719F103F006D030EF01040008F007D049002C05F00885D5F009470000020201010527' + 'D030F103F00465005D036603305D046604305D026602305D02660258001D1D1D6801F103F002470000' ); // Another magic bytes :-) ba.position = 0; ba.readBytes(FontLoader.CLASS_CODE); ba.length = 0; FontLoader._initialized = true; } /** * Creates a new FontLoader object. If you pass a valid URLRequest object to the FontLoader constructor, * the constructor automatically calls the load() function. * If you do not pass a valid URLRequest object to the FontLoader constructor, * you must call the load() function or the stream will not load. * * @param request (default = null) — The URL that points to an external SWF file. * @param autoRegister — Register loaded fonts automatically. */ public function FontLoader(request:URLRequest = null, autoRegister:Boolean = true) { super(); FontLoader.init(); this._loader.dataFormat = URLLoaderDataFormat.BINARY; this._loader.addEventListener(Event.COMPLETE, this.handler_complete); this._loader.addEventListener(Event.OPEN, super.dispatchEvent); this._loader.addEventListener(HTTPStatusEvent.HTTP_STATUS, super.dispatchEvent); this._loader.addEventListener(IOErrorEvent.IO_ERROR, super.dispatchEvent); this._loader.addEventListener(ProgressEvent.PROGRESS, super.dispatchEvent); this._loader.addEventListener(SecurityErrorEvent.SECURITY_ERROR, super.dispatchEvent); if (request) this.load(request, autoRegister); } /** * @private */ private const _loader:URLLoader = new URLLoader(); /** * @private */ private var _bytes:ByteArray; /** * @private */ private var _libLoader:Loader; /** * @private */ private var _fontCount:uint; /** * @private */ private var _embeddedID:uint; /** * @private */ private var _autoRegister:Boolean = true; /** * Sets automatic font registration. */ public function set autoRegister(value:Boolean):void { if (this._autoRegister == value) return; this._autoRegister = value; if (value) this.registerFonts(); } public function get autoRegister():Boolean { return this._autoRegister; } public function get bytesLoaded():uint { return this._loader.bytesLoaded; } public function get bytesTotal():uint { return this._loader.bytesTotal; } /** * @private */ private const _fonts:Array = new Array(); /** * Returns an array of font classes, which you can use to register any extracted font. */ public function get fonts():Array { return this._fonts.concat(); } /** * Initiates loading of an external SWF file from the specified URL. You can load another swf file, when previous operation completed (or stream closed by user). * * @param request:URLRequest — A URLRequest object specifying the URL to download. If the value of this parameter or the URLRequest.url property of the URLRequest object passed are null, Flash Player throws a null pointer error. * @param autoRegister — Register loaded fonts automatically. * * @event complete:Event — Dispatched after data has loaded and parsed successfully. * @event httpStatus:HTTPStatusEvent — If access is by HTTP, and the current Flash Player environment supports obtaining status codes, you may receive these events in addition to any complete or error event. * @event ioError:IOErrorEvent — The load operation could not be completed. * @event verifyError:IOErrorEvent — Dispatched when a parse operation fails (data has incorrect format). * @event open:Event — Dispatched when a load operation starts. * @event securityError:SecurityErrorEvent — A load operation attempted to retrieve data from a server outside the caller's security sandbox. This may be worked around using a policy file on the server. */ public function load(request:URLRequest, autoRegister:Boolean = true):void { this.close(); this._fonts.length = 0; this._fontCount = 0; this._autoRegister = autoRegister; this._loader.load(request); } /** * Loads from binary data stored in a ByteArray object. * * @param bytes:URLRequest — A ByteArray object. The specified ByteArray must contain valid SWF file. * @param autoRegister — Register loaded fonts automatically. * * @event complete:Event — Dispatched after data has loaded and parsed successfully. * @event httpStatus:HTTPStatusEvent — If access is by HTTP, and the current Flash Player environment supports obtaining status codes, you may receive these events in addition to any complete or error event. * @event ioError:IOErrorEvent — The load operation could not be completed. * @event verifyError:IOErrorEvent — Dispatched when a parse operation fails (data has incorrect format). * @event open:Event — Dispatched when a load operation starts. * @event securityError:SecurityErrorEvent — A load operation attempted to retrieve data from a server outside the caller's security sandbox. This may be worked around using a policy file on the server. */ public function loadBytes(bytes:ByteArray, autoRegister:Boolean = true):void { this.close(); this._fonts.length = 0; this._fontCount = 0; this._autoRegister = autoRegister; this.analyze(bytes, true); } /** * Closes the stream, causing any download of data to cease. */ public function close():void { try { this._loader.close(); } catch (error:Error) {} if (this._libLoader) { this._libLoader.contentLoaderInfo.removeEventListener(Event.COMPLETE, this.handler_libComplete); try { this._libLoader.close(); } catch (error:Error) {} try { this._libLoader.unload(); } catch (error:Error) {} this._libLoader = null; } } /** * Registers all loaded fonts. */ public function registerFonts():void { for each (var font:Font in this._fonts) { Font.registerFont((font as Object).constructor); } } /** * @private */ private function analyze(bytes:ByteArray, delayed:Boolean = false):void { var o:Object; var stringID:String; var id:uint; var tempData:ByteArray; var fontSWF:ByteArray; var context:LoaderContext; var data:ByteArray; try { data = new SWFByteArray(bytes); } catch (error:Error) { if (delayed) { this._libLoader = new Loader(); this._libLoader.addEventListener(Event.ENTER_FRAME, this.handler_delayedVerifyError); } else { this.close(); super.dispatchEvent(new IOErrorEvent(IOErrorEvent.VERIFY_ERROR)); } return; } var fontData:Object = new Object(); var classCodeLength:uint = FontLoader.CLASS_CODE.length; this._embeddedID = 0; this.processSWF(data, fontData); tempData = new ByteArray(); tempData.endian = Endian.LITTLE_ENDIAN; tempData.writeBytes(FontLoader.SWF_HEADER); id = 0; for (o in fontData) { data = fontData[o] as ByteArray; if (data) { stringID = id.toString(); while (stringID.length < 3) stringID = '0' + stringID; stringID = FontLoader.CLASS_NAME_PREFIX + stringID; tempData.writeShort(FontLoader.TAG_DO_ABC); tempData.writeUnsignedInt(10 + stringID.length + classCodeLength); tempData.writeUnsignedInt(0x002E0010); tempData.writeUnsignedInt(0x10000000); tempData.writeByte(stringID.length); tempData.writeUTFBytes(stringID); tempData.writeByte(0); tempData.writeBytes(FontLoader.CLASS_CODE); tempData.writeBytes(data); tempData.writeShort(FontLoader.TAG_SYMBOL_CLASS); tempData.writeUnsignedInt(5 + stringID.length); tempData.writeShort(1); tempData.writeShort(o as uint); tempData.writeUTFBytes(stringID); tempData.writeByte(0); id++; } } this._fontCount = id; if (this._fontCount) { tempData.writeUnsignedInt(0x00000040); fontSWF = new ByteArray(); fontSWF.endian = Endian.LITTLE_ENDIAN; fontSWF.writeUTFBytes('FWS'); fontSWF.writeByte(9); fontSWF.writeUnsignedInt(tempData.length + 8); fontSWF.writeBytes(tempData); this._libLoader = new Loader(); this._libLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, this.handler_libComplete); context = new LoaderContext(); if ('allowLoadBytesCodeExecution' in context) { // AIR compatibility context['allowLoadBytesCodeExecution'] = true; } this._libLoader.loadBytes(fontSWF, context); } else { if (delayed) { this._libLoader = new Loader(); this._libLoader.addEventListener(Event.ENTER_FRAME, this.handler_delayedComplete); } else { this.close(); super.dispatchEvent(new Event(Event.COMPLETE)); } } } /** * @private */ private function processSWF(data:ByteArray, fontData:Object, startFontID:uint = 0):void { var fontID:uint; var id:uint; var tag:uint var length:uint; var pos:Number; var tempData:ByteArray; while (data.bytesAvailable) { tag = data.readUnsignedShort(); id = tag >> 6; length = ((tag & 0x3F) == 0x3F) ? data.readUnsignedInt() : (tag & 0x3F); pos = data.position; switch (id) { case 13: case 48: case 62: case 73: case 75: case 88: case 91: fontID = data.readUnsignedShort() + startFontID; tempData = fontData[fontID] as ByteArray; if (!tempData) { tempData = new ByteArray(); tempData.endian = Endian.LITTLE_ENDIAN; fontData[fontID] = tempData; } if ((tag & 0x3F) == 0x3F) { tempData.writeShort((id << 6) | 0x3F); tempData.writeUnsignedInt(length); } else { tempData.writeShort((id << 6) | (length & 0x3F)); } tempData.writeShort(fontID); tempData.writeBytes(data, data.position, length - 2); break; case 87: // DefineBinaryData tempData = new ByteArray(); tempData.endian = Endian.LITTLE_ENDIAN; data.readUnsignedShort(); // tag data.readUnsignedInt(); // reserved tempData.writeBytes(data, data.position, length - 6); tempData.position = 0; try { tempData = new SWFByteArray(tempData); this._embeddedID += 1; this.processSWF(tempData, fontData, startFontID + 2000 * this._embeddedID); } catch (error:ArgumentError) { // Not SWF. Do nothing. } break; } data.position = pos + length; } } /** * @private */ private function handler_delayedComplete(event:Event):void { this._libLoader.removeEventListener(Event.ENTER_FRAME, this.handler_delayedComplete); this._libLoader = null; this.close(); super.dispatchEvent(new Event(Event.COMPLETE)); } /** * @private */ private function handler_delayedVerifyError(event:Event):void { this._libLoader.removeEventListener(Event.ENTER_FRAME, this.handler_delayedVerifyError); this._libLoader = null; this.close(); super.dispatchEvent(new IOErrorEvent(IOErrorEvent.VERIFY_ERROR)); } /** * @private */ private function handler_complete(event:Event):void { this.analyze(this._loader.data as ByteArray); } /** * @private */ private function handler_libComplete(event:Event):void { var id:String; var i:uint; var fontClass:Class; var font:Font; var domain:ApplicationDomain = this._libLoader.contentLoaderInfo.applicationDomain; for (i = 0;i < this._fontCount;i++) { id = i.toString(); while (id.length < 3) id = '0' + id; id = FontLoader.CLASS_NAME_PREFIX + id; if (domain.hasDefinition(id)) { fontClass = domain.getDefinition(id) as Class; font = new fontClass() as Font; if (font && font.fontName) { // Skip static fonts this._fonts.push(font); if (this._autoRegister) Font.registerFont(fontClass); } } } this.close(); super.dispatchEvent(new Event(Event.COMPLETE)); } }}import flash.utils.ByteArray;import flash.utils.Endian;import flash.geom.Rectangle;internal class SWFByteArray extends ByteArray { /** * @private */ private static const TAG_SWF:String = 'FWS'; /** * @private */ private static const TAG_SWF_COMPRESSED:String = 'CWS'; public function SWFByteArray(data:ByteArray=null):void { super(); super.endian = Endian.LITTLE_ENDIAN; var endian:String; var tag:String; var position:uint; if (data) { endian = data.endian; position = data.position; data.endian = Endian.LITTLE_ENDIAN; data.position = 0; if (data.bytesAvailable > 26) { tag = data.readUTFBytes(3); if (tag == SWFByteArray.TAG_SWF || tag == SWFByteArray.TAG_SWF_COMPRESSED) { this._version = data.readUnsignedByte(); data.readUnsignedInt(); data.readBytes(this); if (tag == SWFByteArray.TAG_SWF_COMPRESSED) super.uncompress(); } else throw new ArgumentError('Error #2124: Loaded file is an unknown type.'); this.readHeader(); } else { throw new ArgumentError('Insufficient data.'); } data.endian = endian; data.position = position; } } /** * @private */ private var _bitIndex:uint; /** * @private */ private var _version:uint; public function get version():uint { return this._version; } /** * @private */ private var _frameRate:Number; public function get frameRate():Number { return this._frameRate; } /** * @private */ private var _rect:Rectangle; public function get rect():Rectangle { return this._rect; } public function writeBytesFromString(bytesHexString:String):void { var length:uint = bytesHexString.length; for (var i:uint = 0;i<length;i += 2) { var hexByte:String = bytesHexString.substr(i, 2); var byte:uint = parseInt(hexByte, 16); writeByte(byte); } } public function readRect():Rectangle { var pos:uint = super.position; var byte:uint = this[pos]; var bits:uint = byte >> 3; var xMin:Number = this.readBits(bits, 5) / 20; var xMax:Number = this.readBits(bits) / 20; var yMin:Number = this.readBits(bits) / 20; var yMax:Number = this.readBits(bits) / 20; super.position = pos + Math.ceil(((bits * 4) - 3) / 8) + 1; return new Rectangle(xMin, yMin, xMax - xMin, yMax - yMin); } public function readBits(length:uint, start:int = -1):Number { if (start < 0) start = this._bitIndex; this._bitIndex = start; var byte:uint = this[super.position]; var out:Number = 0; var shift:Number = 0; var currentByteBitsLeft:uint = 8 - start; var bitsLeft:Number = length - currentByteBitsLeft; if (bitsLeft > 0) { super.position++; out = this.readBits(bitsLeft, 0) | ((byte & ((1 << currentByteBitsLeft) - 1)) << (bitsLeft)); } else { out = (byte >> (8 - length - start)) & ((1 << length) - 1); this._bitIndex = (start + length) % 8; if (start + length > 7) super.position++; } return out; } public function traceArray(array:ByteArray):String { // for debug var out:String = ''; var pos:uint = array.position; var i:uint = 0; array.position = 0; while (array.bytesAvailable) { var str:String = array.readUnsignedByte().toString(16).toUpperCase(); str = str.length < 2 ? '0'+str : str; out += str+' '; } array.position = pos; return out; } /** * @private */ private function readFrameRate():void { if (this._version < 8) { this._frameRate = super.readUnsignedShort(); } else { var fixed:Number = super.readUnsignedByte() / 0xFF; this._frameRate = super.readUnsignedByte() + fixed; } } /** * @private */ private function readHeader():void { this._rect = this.readRect(); this.readFrameRate(); super.readShort(); // num of frames }} |