Cocos2d-x中libcurl库的使用(4)进度显示

概述libcurl中的进度显示类似于读取数据，需要设置回调函数和回调存储数据的指针到url中，CURLOPT_PROGRESSFUNCTION传入回调函数，CURLOPT_PROGRESSDATA传入存储数据的指针。 具体实例如下： #include <stdio.h>#include <curl/curl.h>#define STOP_DOWNLOAD_AFTER_THIS_MANY_BYTE

libcurl中的进度显示类似于读取数据，需要设置回调函数和回调存储数据的指针到url中，CURLOPT_PROGRESSFUNCTION传入回调函数，CURLOPT_PROGRESSDATA传入存储数据的指针。
具体实例如下：

#include <stdio.h>#include <curl/curl.h>#define Stop_DOWNLOAD_AFTER_THIS_MANY_BYTES         6000#define MINIMAL_PROGRESS_FUNCTIONAliTY_INTERVAL     3struct myprogress {  double lastruntime;  CURL *curl;};/* this is how the CURLOPT_XFERINFOFUNCTION callback works */static int xferinfo(voID *p,curl_off_t dltotal,curl_off_t dlNow,curl_off_t ultotal,curl_off_t ulNow){  struct myprogress *myp = (struct myprogress *)p;  CURL *curl = myp->curl;  double curtime = 0;  curl_easy_getinfo(curl,CURliNFO_TOTAL_TIME,&curtime);  /* under certain circumstances it may be desirable for certain functionality     to only run every N seconds,in order to do this the transaction time can     be used */  if((curtime - myp->lastruntime) >= MINIMAL_PROGRESS_FUNCTIONAliTY_INTERVAL) {    myp->lastruntime = curtime;    fprintf(stderr,"TOTAL TIME: %f \r\n",curtime);  }  fprintf(stderr,"UP: %" CURL_FORMAT_CURL_OFF_T " of %" CURL_FORMAT_CURL_OFF_T          "  DOWN: %" CURL_FORMAT_CURL_OFF_T " of %" CURL_FORMAT_CURL_OFF_T          "\r\n",ulNow,ultotal,dlNow,dltotal);  if(dlNow > Stop_DOWNLOAD_AFTER_THIS_MANY_BYTES)    return 1;  return 0;}//旧版本是参数类型double，新版本换成了curl_off_t/* for libcurl older than 7.32.0 (CURLOPT_PROGRESSFUNCTION) */static int older_progress(voID *p,double dltotal,double dlNow,double ultotal,double ulNow){  return xferinfo(p,(curl_off_t)dltotal,(curl_off_t)dlNow,(curl_off_t)ultotal,(curl_off_t)ulNow);}int main(voID){  CURL *curl;  CURLcode res = CURLE_OK;  struct myprogress prog;  curl = curl_easy_init();  if(curl) {    prog.lastruntime = 0;    prog.curl = curl;    curl_easy_setopt(curl,CURLOPT_URL,"http://example.com/");    curl_easy_setopt(curl,CURLOPT_PROGRESSFUNCTION,older_progress);//回调函数    /* pass the struct pointer into the progress function */    curl_easy_setopt(curl,CURLOPT_PROGRESSDATA,&prog);//存储数据结构体指针#if liBCURL_VERSION_NUM >= 0x072000    /* xferinfo was introduced in 7.32.0,no earlIEr libcurl versions will       compile as they won't have the symbols around.       If built with a newer libcurl,but running with an older libcurl:       curl_easy_setopt() will fail in run-time trying to set the new       callback,making the older callback get used.       New libcurls will prefer the new callback and instead use that one even       if both callbacks are set. */    curl_easy_setopt(curl,CURLOPT_XFERINFOFUNCTION,xferinfo);    /* pass the struct pointer into the xferinfo function,note that this is       an alias to CURLOPT_PROGRESSDATA */    curl_easy_setopt(curl,CURLOPT_XFERINFODATA,&prog);#endif    curl_easy_setopt(curl,CURLOPT_nopROGRESS,0L);    res = curl_easy_perform(curl);    if(res != CURLE_OK)      fprintf(stderr,"%s\n",curl_easy_strerror(res));    /* always cleanup */    curl_easy_cleanup(curl);  }  return (int)res;}

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