cocos通過載入tiled 生成的tmx文件來生成遊戲地圖，本文主要分析cocos載入地圖模塊的源碼。
如圖所示，地圖載入模塊由以上幾個類組成。
對外的入口是類CCTMXTiledMap，在使用該類時，程序員不需要知道其底層的其他類便可解析tmx文件生成地圖。
那麼，我們首先分析類CCTMXTiledMap是如何調用其他類進行解析，該類的聲明如下：
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;
};通過查看函數實現，我們發現函數
/** creates a TMX Tiled Map with a TMX file.*/
static CCTMXTiledMap* create(const char*tmxFile);通過調用函數
/** initializes a TMX Tiled Mapwith a TMX file */
bool initWithTMXFile(const char *tmxFile);來實現文件的解析，並創建一個CCTMXTiledMap對象返回給使用者。
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;
}
通過看源碼，我們發現有2個重要的函數 CCTMXMapInfo::formatWithTMXFile(tmxFile)和buildWithMapInfo(mapInfo)，看名字應該能知道formatWithTMXFile是解析XML文件將其結構化，buildWithMapInfo是將結構化的數據變成CCNode從而顯示在遊戲界面上。
接下來，我們查看CCTMXMapInfo是如何組織數據以及如何解析XML文件的，首先我們還是查看CCTMXMapInfo的聲明
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;
};通過查看聲明 我們發現CCTMXMapInfo主要包括以下幾個數據：
- TMXLayerInfo的數組，用來存放地圖信息
- TMXTilesetInfo的數組，用來存放塊信息
- ObjectGroups的數組
另外，CCTMXMapInfo中有幾個重要的函數：
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);
這3個函數是libxml2中所需要解析xml的代理函數，分別表示標籤的開始，標籤的結束，標籤的內容
解析xml的標籤就在這幾個函數中。