cocos通过加载tiled 生成的tmx文件来生成游戏地图。本文主要分析cocos加载地图模块的源代码。
如图所看到的，地图加载模块由以上几个类组成。
对外的入口是类CCTMXTiledMap，在使用该类时。程序猿不须要知道其底层的其它类便可解析tmx文件生成地图。
那么。我们首先分析类CCTMXTiledMap是怎样调用其它类进行解析，该类的声明例如以下：
class CC_DLL CCTMXTiledMap :public CCNode
{
/** the map's size property measured intiles */
CC_SYNTHESIZE_PASS_BY_REF(CCSize,m_tMapSize, MapSize);
/** the tiles's size property measured inpixels */
CC_SYNTHESIZE_PASS_BY_REF(CCSize,m_tTileSize, TileSize);
/** map orientation */
CC_SYNTHESIZE(int, m_nMapOrientation,MapOrientation);
/** object groups */
CC_PROPERTY(CCArray*, m_pObjectGroups,ObjectGroups);
/** properties */
CC_PROPERTY(CCDictionary*, m_pProperties,Properties);
public:
/**
* @js ctor
*/
CCTMXTiledMap();
/**
* @js NA
* @lua NA
*/
virtual ~CCTMXTiledMap();
/** creates a TMX Tiled Map with a TMXfile.*/
static CCTMXTiledMap* create(const char*tmxFile);
/** initializes a TMX Tiled Map with a TMXformatted XML string and a path to TMX resources */
static CCTMXTiledMap* createWithXML(constchar* tmxString, const char* resourcePath);
/** initializes a TMX Tiled Map with a TMXfile */
bool initWithTMXFile(const char *tmxFile);
/** initializes a TMX Tiled Map with a TMXformatted XML string and a path to TMX resources */
bool initWithXML(const char* tmxString,const char* resourcePath);
/** return the TMXLayer for the specificlayer
* @js getLayer
*/
CCTMXLayer* layerNamed(const char*layerName);
/** return the TMXObjectGroup for thespecific group
* @js getObjectGroup
*/
CCTMXObjectGroup* objectGroupNamed(constchar *groupName);
/** return the value for the specificproperty name
* @js getProperty
*/
CCString *propertyNamed(const char*propertyName);
/** return properties dictionary for tileGID */
CCDictionary* propertiesForGID(int GID);
private:
CCTMXLayer *parseLayer(CCTMXLayerInfo *layerInfo, CCTMXMapInfo *mapInfo);
CCTMXTilesetInfo *tilesetForLayer(CCTMXLayerInfo *layerInfo, CCTMXMapInfo *mapInfo);
void buildWithMapInfo(CCTMXMapInfo*mapInfo);
protected:
//! tile properties
CCDictionary* m_pTileProperties;
};通过查看函数实现，我们发现函数
/** creates a TMX Tiled Map with a TMX file.*/
static CCTMXTiledMap* create(const char*tmxFile);通过调用函数
/** initializes a TMX Tiled Mapwith a TMX file */
bool initWithTMXFile(const char *tmxFile);来实现文件的解析。并创建一个CCTMXTiledMap对象返回给使用者。
boolCCTMXTiledMap::initWithTMXFile(const char *tmxFile)
{
CCAssert(tmxFile != NULL &&strlen(tmxFile)>0, "TMXTiledMap: tmx file should not bi NULL");
setContentSize(CCSizeZero);
CCTMXMapInfo *mapInfo =CCTMXMapInfo::formatWithTMXFile(tmxFile);
if (! mapInfo)
{
return false;
}
CCAssert(mapInfo->getTilesets()->count() != 0, "TMXTiledMap: Map not found.Please check the filename.");
buildWithMapInfo(mapInfo);
return true;
}
通过看源代码。我们发现有2个重要的函数 CCTMXMapInfo::formatWithTMXFile(tmxFile)和buildWithMapInfo(mapInfo)，看名字应该能知道formatWithTMXFile是解析XML文件将其结构化。buildWithMapInfo是将结构化的数据变成CCNode从而显示在游戏界面上。
接下来，我们查看CCTMXMapInfo是怎样组织数据以及怎样解析XML文件的，首先我们还是查看CCTMXMapInfo的声明
class CC_DLL CCTMXMapInfo :public CCObject, public CCSAXDelegator
{
public:
/// map orientation
CC_SYNTHESIZE(int, m_nOrientation, Orientation);
/// map width & height
CC_SYNTHESIZE_PASS_BY_REF(CCSize,m_tMapSize, MapSize);
/// tiles width & height
CC_SYNTHESIZE_PASS_BY_REF(CCSize,m_tTileSize, TileSize);
/// Layers
CC_PROPERTY(CCArray*, m_pLayers, Layers);
/// tilesets
CC_PROPERTY(CCArray*, m_pTilesets,Tilesets);
/// ObjectGroups
CC_PROPERTY(CCArray*, m_pObjectGroups,ObjectGroups);
/// parent element
CC_SYNTHESIZE(int, m_nParentElement,ParentElement);
/// parent GID
CC_SYNTHESIZE(unsigned int, m_uParentGID,ParentGID);
/// layer attribs
CC_SYNTHESIZE(int, m_nLayerAttribs,LayerAttribs);
/// is storing characters?
CC_SYNTHESIZE(bool, m_bStoringCharacters,StoringCharacters);
/// properties
CC_PROPERTY(CCDictionary*, m_pProperties,Properties);
public:
/**
* @js ctor
* @lua NA
*/
CCTMXMapInfo();
/**
* @js NA
* @lua NA
*/
virtual ~CCTMXMapInfo();
/** creates a TMX Format with a tmx file */
static CCTMXMapInfo *formatWithTMXFile(const char *tmxFile);
/** creates a TMX Format with an XML stringand a TMX resource path */
static CCTMXMapInfo * formatWithXML(constchar* tmxString, const char* resourcePath);
/** initializes a TMX format with a tmx file
* @lua NA
*/
bool initWithTMXFile(const char *tmxFile);
/** initializes a TMX format with an XMLstring and a TMX resource path
* @lua NA
*/
bool initWithXML(const char* tmxString,const char* resourcePath);
/** initializes parsing of an XML file,either a tmx (Map) file or tsx (Tileset) file */
bool parseXMLFile(const char *xmlFilename);
/* initializes parsing of an XML string,either a tmx (Map) string or tsx (Tileset) string */
bool parseXMLString(const char *xmlString);
CCDictionary* getTileProperties();
void setTileProperties(CCDictionary*tileProperties);
/** implement pure virtual methods ofCCSAXDelegator
* @js NA
*/
void startElement(void *ctx, const char*name, const char **atts);
/**
* @js NA
*/
void endElement(void *ctx, const char*name);
/**
* @js NA
*/
void textHandler(void *ctx, const char *ch,int len);
inline const char* getCurrentString(){return m_sCurrentString.c_str(); }
inline void setCurrentString(const char*currentString){ m_sCurrentString = currentString; }
inline const char* getTMXFileName(){ returnm_sTMXFileName.c_str(); }
inline void setTMXFileName(const char*fileName){ m_sTMXFileName = fileName; }
private:
void internalInit(const char* tmxFileName,const char* resourcePath);
protected:
//! tmx filename
std::string m_sTMXFileName;
// tmx resource path
std::string m_sResources;
//! current string
std::string m_sCurrentString;
//! tile properties
CCDictionary* m_pTileProperties;
unsigned int m_uCurrentFirstGID;
};通过查看声明 我们发现CCTMXMapInfo主要包含下面几个数据：
- TMXLayerInfo的数组，用来存放地图信息
- TMXTilesetInfo的数组，用来存放块信息
- ObjectGroups的数组
另外。CCTMXMapInfo中有几个重要的函数：
bool initWithXML(const char* tmxString, constchar* resourcePath);
/** initializes parsing of an XML file,either a tmx (Map) file or tsx (Tileset) file */
bool parseXMLFile(const char *xmlFilename);
/* initializes parsing of an XML string, eithera tmx (Map) string or tsx (Tileset) string */
bool parseXMLString(const char *xmlString);
这3个函数是libxml2中所须要解析xml的代理函数，分别表示标签的開始，标签的结束，标签的内容
解析xml的标签就在这几个函数中。