Create screenshot in SDL2

sdl2_screenshot.cpp

// Save screenshot
// file: Filename for created screenshot
// renderer: pointer to SDL_Renderer
bool saveScreenshot(const std::string &file, SDL_Renderer *renderer ) {
  // Used temporary variables
  SDL_Rect _viewport;
  SDL_Surface *_surface = NULL;
  
  // Get viewport size
  SDL_RenderGetViewport( renderer, &_viewport);
  
  // Create SDL_Surface with depth of 32 bits
  _surface = SDL_CreateRGBSurface( 0, _viewport.w, _viewport.h, 32, 0, 0, 0, 0 );
  
  // Check if the surface is created properly
  if ( _surface == NULL ) {
    std::cout << "Cannot create SDL_Surface: " << SDL_GetError() << std::endl;
    return false;
   }
  
  // Get data from SDL_Renderer and save them into surface
  if ( SDL_RenderReadPixels( renderer, NULL, _surface->format->format, _surface->pixels, _surface->pitch ) != 0 ) {
    std::cout << "Cannot read data from SDL_Renderer: " << SDL_GetError() << std::endl;
    
    // Don't forget to free memory
    SDL_FreeSurface(_surface);
    return false;
  }
  
  // Save screenshot as PNG file
  if ( IMG_SavePNG( _surface, file.c_str() ) != 0 ) {
    std::cout << "Cannot save PNG file: " << SDL_GetError() << std::endl;
    
    // Free memory
    SDL_FreeSurface(_surface);
    return false;
  }
  
  // Free memory
  SDL_FreeSurface(_surface);
  return true;
}

Maybe

_surface-->pitch

should be

_surface->pitch

@fccm Thank you for pointing that out. ;) Corrected.

I get
dyld: Symbol not found: _SDL_RWwrite Referenced from: /Library/Frameworks/SDL2_image.framework/Versions/A/SDL2_image Expected in: /Library/Frameworks/SDL2.framework/Versions/A/SDL2
as an ouput

@HugoAndre276

Symbol not found: _SDL_RWwrite

I think it has something to do with a recent change in SDL library. They changed SDL_RW* macros to functions. All I have found is that now you have to link SDL2 library to your project.

Make sure you are using latest version of SDL2 and SDL_Image as well.

But I am not sure how to solve your problem, since I don't own mac or Xcode. Try contacting official forum. They might help you.

Any ready project's? For example with rect's and transparency?
It's .zip file.

@malja