让SDL_ttf支持中文
默认情况下、莪们可以使用TTF_RenderUTF8_Blended()函数来渲染UTF8文字到视频窗口中、但由于中文windows本地环境并非unicode编码而是gbk编码、这就涉及到多字节（双字节）转换成宽字节的问题了、因此还需要用一个小函数转化一下才能输出到SDL_tff中、注意其中使用到的函数要使用到windows.h头文件
char* localeToUTF8(char* src) { char* buf = NULL; int nRetLen = 0; wchar_t* unicode_buf = NULL; // *function: MultiByteToWideChar (Maps a character string to a UTF-16 (wide character) string.) // - UINT CodePage (Code page to use in performing the conversion. ) // CP_ACP: The system default Windows ANSI code page. // - DWORD dwFlags (Flags indicating the conversion type) // 0: // - LPCSTR lpMultiByteStr (Pointer to the character string to convert.) // src: the word that you want to conver // - int cbMultiByte (you want to process size of lpMultiByteStr) // -1: the function processes the entire input string, including the terminating null character. when the input string // not contains terminating null character, it will failure. // - LPWSTR lpWideCharStr (Pointer to a buffer that receives the converted string.) // NULL: no receives WideChar. // - int cchWideChar (size of lpWideCharStr) // 0: set the paramter for the function returns the required buffer size. // * return value : because of cchWideChar is 0, so returns the required buffer size of lpWideCharStr nRetLen = MultiByteToWideChar(CP_ACP, 0, src, -1, NULL, 0); // allocate space for unicode_buf unicode_buf = (wchar_t*)malloc((nRetLen+1) * sizeof(wchar_t)); // covert the src to utf-8, and store in unicode_buf MultiByteToWideChar(CP_ACP, 0, src, -1, unicode_buf, nRetLen); // *function: WideCharToMultiByte (Maps a UTF-16 (wide character) string to a new character string. ) // - UINT CodePage (Code page to use in performing the conversion. ) // CP_UTF8: With this value set, lpDefaultChar and lpUsedDefaultChar must be set to NULL. // - DWORD dwFlags (Flags indicating the conversion type. ) // 0 : // - LPCWSTR lpWideCharStr (Pointer to the Unicode string to convert.) // unicode_buf : the word that you want to conver // - int cchWideChar (you want to process size of lpWideCharStr) // -1: the function processes the entire input string, including the terminating null character. when the input string // not contains terminating null character, it will failure. // - LPSTR lpMultiByteStr (Pointer to a buffer that receives the converted string.) // NULL : no receives MultiByteStr. // - int cbMultiByte (size of lpMultiByteStr) // 0: set the paramter for the function returns the required buffer size. // - LPCSTR lpDefaultChar (Pointer to the character to use if a character cannot be represented in the specified code page. ) // NULL : For the CP_UTF7 and CP_UTF8 settings for CodePage, this parameter must be set to NULL. // - LPBOOL lpUsedDefaultChar (Pointer to a flag that indicates if the function has used a default character in the conversion.) // NULL : For the CP_UTF7 and CP_UTF8 settings for CodePage, this parameter must be set to NULL. nRetLen = WideCharToMultiByte(CP_UTF8, 0, unicode_buf, -1, NULL, 0, NULL, NULL); // allocate space for buf buf = (char*)malloc(nRetLen+1); WideCharToMultiByte(CP_UTF8, 0, unicode_buf, -1, buf, nRetLen, NULL, NULL); // release space of unicode_buf free(unicode_buf); return buf; }
在这个函数中、把字符串从多字节的ASCII编码转化成unicode的宽字节编码、又将unicode的宽字节转化成UTF8的多字节编码、因为SDL_ttf不支持宽字节编码的文字、所以中间就有了unicode作为两者的桥梁作用、转换完毕后、就可以把中间转化过程的unicode宽字节变量释放掉、这里、GBK汉字编码其实就是一种扩展的ASCII编码、
参考文章：
http://www.cnblogs.com/bombless/archive/2010/11/21/SDL-using-chinese-character.html
http://www.phpweblog.net/fuyongjie/archive/2009/03/11/6374.html
