相关代码:

  zip_stat_t filestat;
  uint64_t filetotal = 0;
  SDL_RWops* rwop = SDL_AllocRW();

//bunch of code that's not relevant to the matter goes here

  std::vector<char> rwbuffer(filestat.size);
  rwop = SDL_RWFromMem(rwbuffer.data(), filestat.size);
  while(filetotal < filestat.size)
  {
    char buffer[256];
    int64_t length;
    //read the file into the buffer
    length = zip_fread(file, buffer, 256);
    if (length == -1)
    {
      u_error(std::cerr, CC_ERROR_ZIP, "zip_fread");
      zip_fclose(file);
      SDL_FreeRW(rwop);
      return false;
    }
    //write the buffer into the rwop stream
    if ( (uint16_t)length != SDL_RWwrite(rwop, buffer, 1, (size_t)length) )
    {
      u_error(std::cerr, CC_ERROR_SDL, "SDL_RWwrite");
      zip_fclose(file);
      SDL_FreeRW(rwop);
      return false;
    }
    //Increment the count so that the loop ends
    filetotal += length;
  }
  zip_fclose(file);
  //Put it onto a surface
  SDL_Surface* surf_load = IMG_Load_RW(rwop, 0);
  if(surf_load == NULL)
  {
    u_error(std::cerr, CC_ERROR_IMAGE, "IMG_Load_RW");
    SDL_FreeRW(rwop);
    u_cleanup(surf_load);
    return false;
  }

//...

我已经用调试器转储了 vector rwbuffer的内容,它是有效的png,但是IMG_Load_RW仍然给我一个错误“不支持的图像格式”。我已经安装了libpng,并且IMG_Init似乎可以正常工作,因此SDL_image库必须可以正常工作。显然libzip给我正确的数据。我对为什么会出错感到非常困惑。

最佳答案

我想到了。在数据读取的while循环结束时,RWops流的查找值位于文件的末尾,而IMG_LoadPNG_RW不会将其重置,因此我必须手动SDL_RWseek(rwop,0,RW_SEEK_SET);在while循环完成之后,为了读取png数据。

  //Return the seek pointer of the RWop to the beginning so that the file can be read
  SDL_RWseek(rwop,0,RW_SEEK_SET);
  //Put it onto a surface
  SDL_Surface* surf_load = IMG_Load_RW(rwop, 0);
  if(surf_load == NULL)
  {
    u_error(std::cerr, CC_ERROR_IMAGE, "IMG_Load_RW");
    SDL_FreeRW(rwop);
    u_cleanup(surf_load);
    return false;
  }

关于c++ - 在LibZip中使用SDL_image和SDL_RWops将zip中的png加载到表面上,但无法识别png,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/61067536/

10-15 16:23