‍swf文件格式解析入门

‍swf文件格式解析入门（tag解析）

分类： Flash&Flex2012-11-28
13:15 275人阅读 评论(0) 收藏 举报

上文把文件头解析完成了，接下来就是解析标签

swf文件把所有的资源都打包在标签内部

如字体，位图，嵌入的2进制，代码等等

tag有两种类型，1种为短tag，1种为长tag

短tag的长度是小于63个字节的

短标签格式

RECORDHEADER (short)

Field Type Comment

TagCodeAndLength UI16 Upper 10 bits: tag type Lower 6 bits: tag length

高10位表示标签类型，低6位表示标签长度

长标签格式 长标签的TagCodeAndLength为0x3F (=63)

长标签使用Length来表示标签的长度

RECORDHEADER (long)

Field Type Comment

TagCodeAndLength UI16 Tag type and length of 0x3F Packed together as in short header

Length SI32 Length of tag

跟着标签头后面就是标签指定长度的数据

然后根据不同的标签类型来解析数据就可以了

每个tag读取结束后，后面的又重新字节对齐了，不用考虑剩余几个字节的问题

/**

* 读取tag类型，不移动position

* @param bytes

* @return

*/

private function readTagType(bytes:ByteArray):uint

{

var result:uint = bytes.readUnsignedShort();

result = result >> 6;



bytes.position -= 2;



return result;

}

/**

* 读取tag长度 不包括头本身占的长度

* @param bytes

* @return

*

*/

private function readTagLength(bytes:ByteArray):uint{

var tagLength:uint = (bytes.readUnsignedShort() & 0x3F);

if (tagLength == 0x3F){

tagLength = bytes.readUnsignedInt();

};

if (tagLength < 0){

throw (Error("SWFReader:无效的tag长度"));

};



return tagLength;

}

/**

* 读取tag列表

* @param bytes

*

*/

private function readTags(bytes:ByteArray):Array

{

var result:Array = [];



var tagType:uint;

var tagLength:uint;

var start:int;

var tag:Tag;

var cl:Class;



while(bytes.bytesAvailable > 0)

{

start = bytes.position;

tagType = readTagType(bytes);

tagLength = readTagLength(bytes);



cl = TagTypes.getTagClassByTagType(tagType);

if (cl == null)

{

trace("Tag Not Found, Type=" + tagType, tagLength);

bytes.position += tagLength;// 跳过长度

continue;

}

tag = new cl();

tag.tagType = tagType;

if( tagLength > 0)

bytes.readBytes(tag.data, 0, tagLength);



tag.data.endian = Endian.LITTLE_ENDIAN;

tag.data.position = 0;



// 调用解析方法

tag.parse();



result.push(tag);



if (tagType == TagTypes.TAG_END)

break;

}



return result;

}

// 所有的tag类型列表

package swf.file.tags

{

import com.the9.nbu.swf.file.tags.actions.*;

import com.the9.nbu.swf.file.tags.binary.*;

import com.the9.nbu.swf.file.tags.bitmaps.*;

import com.the9.nbu.swf.file.tags.buttons.*;

import com.the9.nbu.swf.file.tags.control.*;

import com.the9.nbu.swf.file.tags.displaylist.*;

import com.the9.nbu.swf.file.tags.font.*;

import com.the9.nbu.swf.file.tags.shapemorphing.*;

import com.the9.nbu.swf.file.tags.shapes.*;

import com.the9.nbu.swf.file.tags.sounds.*;

import com.the9.nbu.swf.file.tags.sprite.*;

import com.the9.nbu.swf.file.tags.text.*;

import com.the9.nbu.swf.file.tags.video.*;

import com.the9.nbu.swf.file.tags.unknown.*;



/**

* TagTypes

* @author 任冬

* $Id: TagTypes.as 499 2010-11-19 10:02:56Z rendong $

* @version 1.0

*/

public class TagTypes

{

// Flash 1 tags

public static const TAG_END:uint = 0;

public static const TAG_SHOWFRAME:uint = 1;

public static const TAG_DEFINESHAPE:uint = 2;

public static const TAG_FREECHARACTER:uint = 3;

public static const TAG_PLACEOBJECT:uint = 4;

public static const TAG_REMOVEOBJECT:uint = 5;

public static const TAG_DEFINEBITS:uint = 6;

public static const TAG_DEFINEBUTTON:uint = 7;

public static const TAG_JPEGTABLES:uint = 8;

public static const TAG_SETBACKGROUNDCOLOR:uint = 9;

public static const TAG_DEFINEFONT:uint = 10;

public static const TAG_DEFINETEXT:uint = 11;

public static const TAG_DOACTION:uint = 12;

public static const TAG_DEFINEFONTINFO:uint = 13;

public static const TAG_DEFINESOUND:uint = 14;

public static const TAG_STARTSOUND:uint = 15;

public static const TAG_STOPSOUND:uint = 16;

public static const TAG_DEFINEBUTTONSOUND:uint = 17;

public static const TAG_SOUNDSTREAMHEAD:uint = 18;

public static const TAG_SOUNDSTREAMBLOCK:uint = 19;

// Flash 2 tags

public static const TAG_DEFINEBITSLOSSLESS:uint = 20;

public static const TAG_DEFINEBITSJPEG2:uint = 21;

public static const TAG_DEFINESHAPE2:uint = 22;

public static const TAG_DEFINEBUTTONCXFORM:uint = 23;

public static const TAG_PROTECT:uint = 24;

public static const TAG_PATHSAREPOSTSCRIPT:uint = 25;

// Flash 3 tags

public static const TAG_PLACEOBJECT2:uint = 26;



public static const TAG_REMOVEOBJECT2:uint = 28;

public static const TAG_SYNCFRAME:uint = 29;



public static const TAG_FREEALL:uint = 31;

public static const TAG_DEFINESHAPE3:uint = 32;

public static const TAG_DEFINETEXT2:uint = 33;

public static const TAG_DEFINEBUTTON2:uint = 34;

public static const TAG_DEFINEBITSJPEG3:uint = 35;

public static const TAG_DEFINEBITSLOSSLESS2:uint = 36;

// Flash 4 tags

public static const TAG_DEFINEEDITTEXT:uint = 37;

public static const TAG_DEFINEVIDEO:uint = 38;

public static const TAG_DEFINESPRITE:uint = 39;

public static const TAG_NAMECHARACTER:uint = 40;

public static const TAG_PRODUCTINFO:uint = 41;

public static const TAG_DEFINETEXTFORMAT:uint = 42;

public static const TAG_FRAMELABEL:uint = 43;

// Flash 5 tags

public static const TAG_DEFINEBEH***IOR:uint = 44;

public static const TAG_SOUNDSTREAMHEAD2:uint = 45;

public static const TAG_DEFINEMORPHSHAPE:uint = 46;

public static const TAG_FRAMETAG:uint = 47;

public static const TAG_DEFINEFONT2:uint = 48;

public static const TAG_GENCOMMAND:uint = 49;

public static const TAG_DEFINECOMMANDOBJ:uint = 50;

public static const TAG_CHARACTERSET:uint = 51;

public static const TAG_FONTREF:uint = 52;

public static const TAG_DEFINEFUNCTION:uint = 53;

public static const TAG_PLACEFUNCTION:uint = 54;

public static const TAG_GENTAGOBJECT:uint = 55;

public static const TAG_EXPORTASSETS:uint = 56;

public static const TAG_IMPORTASSETS:uint = 57;

public static const TAG_ENABLEDEBUGGER:uint = 58;

// Flash 6 tags

public static const TAG_DOINITACTION:uint = 59;

public static const TAG_DEFINEVIDEOSTREAM:uint = 60;

public static const TAG_VIDEOFRAME:uint = 61;

public static const TAG_DEFINEFONTINFO2:uint = 62;

public static const TAG_DEBUGID:uint = 63;

public static const TAG_ENABLEDEBUGGER2:uint = 64;

public static const TAG_SCRIPTLIMITS:uint = 65;

// Flash 7 tags

public static const TAG_SETTABINDEX:uint = 66;

// Flash 8 tags





public static const TAG_FILEATTRIBUTES:uint = 69;

public static const TAG_PLACEOBJECT3:uint = 70;

public static const TAG_IMPORTASSETS2:uint = 71;

public static const TAG_DOABC:uint = 72;

public static const TAG_DEFINEFONTALIGNZONES:uint = 73;

public static const TAG_CSMTEXTSETTINGS:uint = 74;

public static const TAG_DEFINEFONT3:uint = 75;

public static const TAG_SYMBOLCLASS:uint = 76;

public static const TAG_METADATA:uint = 77;

public static const TAG_SCALINGGRID:uint = 78;







public static const TAG_DOABC2:uint = 82;

public static const TAG_DEFINESHAPE4:uint = 83;

public static const TAG_DEFINEMORPHSHAPE2:uint = 84;



// Flash 9 tags

public static const TAG_DEFINESCENEANDFRAMELABELDATA:uint = 86;

public static const TAG_DEFINEBINARYDATA:uint = 87;

public static const TAG_DEFINEFONTNAME:uint = 88;

public static const TAG_STARTSOUND2:uint = 89;

public static const TAG_DEFINEBITSJPEG4:uint = 90;

// Flash 10 tags

public static const TAG_DEFINEFONT4:uint = 91;



/**

* tagType => tag 名称

*/

private static const TAG_NAMES:Array =["End","ShowFrame","DefineShape","FreeCharacter","PlaceObject","RemoveObject","DefineBits","DefineButton","JPEGTables","SetBackgroundColor","DefineFont","DefineText","DoAction","DefineFontInfo","DefineSound","StartSound","StopSound","DefineButtonSound","SoundStreamHead","SoundStreamBlock","DefineBitsLossless","DefineBitsJPEG2","DefineShape2","DefineButtonCxform","Protect","PathsArePostScript","PlaceObject2","27
(invalid)","RemoveObject2","SyncFrame","30 (invalid)","FreeAll","DefineShape3","DefineText2","DefineButton2","DefineBitsJPEG3","DefineBitsLossless2","DefineEditText","DefineVideo","DefineSprite","NameCharacter","ProductInfo","DefineTextFormat","FrameLabel","DefineBehavior","SoundStreamHead2","DefineMorphShape","FrameTag","DefineFont2","GenCommand","DefineCommandObj","CharacterSet","FontRef","DefineFunction","PlaceFunction","GenTagObject","ExportAssets","ImportAssets","EnableDebugger","DoInitAction","DefineVideoStream","VideoFrame","DefineFontInfo2","DebugID","EnableDebugger2","ScriptLimits","SetTabIndex","67
(invalid)","68 (invalid)","FileAttributes","PlaceObject3","ImportAssets2","DoABC","DefineFontAlignZones","CSMTextSettings","DefineFont3","SymbolClass","Metadata","ScalingGrid","79 (invalid)","80 (invalid)","81 (invalid)","DoABC2","DefineShape4","DefineMorphShape2","85
(invalid)","DefineSceneAndFrameLabelData","DefineBinaryData","DefineFontName","StartSound2","DefineBitsJPEG4","DefineFont4"];

/**

* tagType => tag class

*/

private static const TAG_CLASS:Array = [EndTag,ShowFrameTag,DefineShapeTag,FreeCharacterTag,PlaceObjectTag,RemoveObjectTag,DefineBitsTag,DefineButtonTag,JPEGTablesTag,SetBackgroundColorTag,DefineFontTag,DefineTextTag,DoActionTag,DefineFontInfoTag,DefineSoundTag,StartSoundTag,StopSoundTag,DefineButtonSoundTag,SoundStreamHeadTag,SoundStreamBlockTag,DefineBitsLosslessTag,DefineBitsJPEG2Tag,DefineShape2Tag,DefineButtonCxformTag,ProtectTag,PathsArePostScriptTag,PlaceObject2Tag,null,RemoveObject2Tag,SyncFrameTag,null,FreeAllTag,DefineShape3Tag,DefineText2Tag,DefineButton2Tag,DefineBitsJPEG3Tag,DefineBitsLossless2Tag,DefineEditTextTag,DefineVideoTag,DefineSpriteTag,NameCharacterTag,ProductInfoTag,DefineTextFormatTag,FrameLabelTag,DefineBehaviorTag,SoundStreamHead2Tag,DefineMorphShapeTag,FrameTagTag,DefineFont2Tag,GenCommandTag,DefineCommandObjTag,CharacterSetTag,FontRefTag,DefineFunctionTag,PlaceFunctionTag,GenTagObjectTag,ExportAssetsTag,ImportAssetsTag,EnableDebuggerTag,DoInitActionTag,DefineVideoStreamTag,VideoFrameTag,DefineFontInfo2Tag,DebugIDTag,EnableDebugger2Tag,ScriptLimitsTag,SetTabIndexTag,null,null,FileAttributesTag,PlaceObject3Tag,ImportAssets2Tag,DoABCTag,DefineFontAlignZonesTag,CSMTextSettingsTag,DefineFont3Tag,SymbolClassTag,MetadataTag,ScalingGridTag,null,null,null,DoABCTag,DefineShape4Tag,DefineMorphShape2Tag,null,DefineSceneAndFrameLabelDataTag,DefineBinaryDataTag,DefineFontNameTag,StartSound2Tag,DefineBitsJPEG4Tag,DefineFont4Tag];





/**

* 根据编号获取tag名称

* @param tagType

* @return

*

*/

public static function getTagNameByTagType(tagType:int):String

{

return TAG_NAMES[tagType] || null;

}



/**

* 根据变化获取tag class

* @param tagType

* @return

*

*/

public static function getTagClassByTagType(tagType:int):Class

{

return TAG_CLASS[tagType] || null;

}

}

}