C++ libcurl 控制台进度条

Question

我希望在控制台窗口中下载文件时出现进度条。我的代码如下：Download file using libcurl in C/C++。

如何在libcurl中添加进度条？

- user197967

Answer 1

你的计量表。

#include <math.h>

int progress_func(void* ptr, double TotalToDownload, double NowDownloaded, 
                    double TotalToUpload, double NowUploaded)
{
    // ensure that the file to be downloaded is not empty
    // because that would cause a division by zero error later on
    if (TotalToDownload <= 0.0)) {
        return 0;
    }

    // how wide you want the progress meter to be
    int totaldotz=40;
    double fractiondownloaded = NowDownloaded / TotalToDownload;
    // part of the progressmeter that's already "full"
    int dotz = (int) round(fractiondownloaded * totaldotz);

    // create the "meter"
    int ii=0;
    printf("%3.0f%% [",fractiondownloaded*100);
    // part  that's full already
    for ( ; ii < dotz;ii++) {
        printf("=");
    }
    // remaining part (spaces)
    for ( ; ii < totaldotz;ii++) {
        printf(" ");
    }
    // and back to line begin - do not forget the fflush to avoid output buffering problems!
    printf("]\r");
    fflush(stdout);
    // if you don't return 0, the transfer will be aborted - see the documentation
    return 0; 
}

- fvu

---

非常感谢！我只需要包含 math.h 头文件，它就可以正常工作了。 - user197967

@fvu 你好，我在这里实现了你建议的方法，但是在 progress_func 函数中没有得到任何值。 - user1089679

很棒，我已经将它适配到了C语言，非常非常非常好用！ - workdreamer

@workdreamer 很高兴你喜欢它，但我有点困惑，上面的代码确实是 C ;) - fvu

@workdreamer 感谢您的编辑！如果您正在使用 PHP，请还要查看 phpclimate，以了解一种更简单的方法来制作一个更漂亮的进度条 :) - fvu

这个库很有趣。也许我以后会用到它。现在我正在使用你的代码 :) - workdreamer

Answer 2

来自curl文档

CURLOPT_PROGRESSFUNCTION

该函数指针应该匹配 curl_progress_callback 原型，如所示。在操作期间（大约每秒钟一次），无论是否正在传输数据，libcurl都会使用该函数代替其内部等效函数调用它。传递给回调的未知/未使用参数值将设置为零（例如，如果只下载数据，则上传大小将保持为0）。从此回调返回非零值将导致libcurl中止传输并返回 CURLE_ABORTED_BY_CALLBACK。

因此：

您提供一个看起来像这样的函数：

int progress_func(void* ptr, double TotalToDownload, double NowDownloaded, double TotalToUpload, double NowUploaded)
{
    // It's here you will write the code for the progress message or bar
}

在现有选项之后添加一些额外的选项

curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);  // already there
// Internal CURL progressmeter must be disabled if we provide our own callback
curl_easy_setopt(curl, CURLOPT_NOPROGRESS, FALSE);
// Install the callback function
curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_func); 

那就是需要完成的全部内容。

- fvu

---

我的问题是我无法为进度条编写出可工作的代码。 - user197967

如果我使用curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0);并安装回调函数curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, progress_func);，那么下载会失败。 - user1089679

@user1089679，请确保在你的回调函数中返回0。 - André Morujão

Answer 3

像apt进度条一样

#include <iostream>
#include <fstream>
#include <include/curl/curl.h>//Or #include <curl/curl.h>
#include <windows.h>
#include <math.h>

using namespace std;

int nb_bar;
double last_progress, progress_bar_adv;

HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);

int progress_bar (void *bar, double t, double d)
{
    if(last_progress != round(d/t*100))
    {
      nb_bar = 25;
      progress_bar_adv = round(d/t*nb_bar);

      cout<<"\r ";
      SetConsoleTextAttribute(hConsole, 160);
      cout<<" Progress : [ ";

      if(round(d/t*100) < 10)
      { cout<<"0"<<round(d/t*100)<<" %]"; }
      else
      { cout<<round(d/t*100)<<" %] "; }

      SetConsoleTextAttribute(hConsole, 15);
      cout<<" [";
      SetConsoleTextAttribute(hConsole, 10);
      for(int i = 0 ; i <= progress_bar_adv ; i++)
      { cout<<"#"; }
      SetConsoleTextAttribute(hConsole, 15);
      for(int i = 0 ; i < nb_bar - progress_bar_adv; i++)
      { cout<<"."; }

      cout<<"]";
      last_progress = round(d/t*100);
    }
  return 0;
}


int main()
{
  CURL *curl_download;
  FILE *fp;
  CURLcode res;
  string url = "http://www.gecif.net/articles/mathematiques/pi/pi_1_million.txt", output_file = "pi.txt";

  curl_download = curl_easy_init();

  if (curl_download)
  {
      //SetConsoleTextAttribute(hConsole, 11);
      fp = fopen(output_file.c_str(),"wb");

      curl_easy_setopt(curl_download, CURLOPT_URL, url.c_str());
      curl_easy_setopt(curl_download, CURLOPT_WRITEFUNCTION, NULL);
      curl_easy_setopt(curl_download, CURLOPT_WRITEDATA, fp);
      curl_easy_setopt(curl_download, CURLOPT_NOPROGRESS, FALSE);
      //progress_bar : the fonction for the progress bar
      curl_easy_setopt(curl_download, CURLOPT_PROGRESSFUNCTION, progress_bar);

      //Text color :   SetConsoleTextAttribute(hConsole, nb_color);
      SetConsoleTextAttribute(hConsole, 11);
      cout<<" Start download"<<endl<<endl;

      res = curl_easy_perform(curl_download);

      fclose(fp);
      if(res == CURLE_OK)
      {
        SetConsoleTextAttribute(hConsole, 10);
        cout<<endl<<endl<<" The file was download with succes"<<endl;
      }
      else
      {
        SetConsoleTextAttribute(hConsole, 4);
        cout<<endl<<endl<<" Error"<<endl;
      }
      curl_easy_cleanup(curl_download);
  }
  SetConsoleTextAttribute(hConsole, 11);
  return 0;
}

- Pmimo