Function main

examples/use_jpeg_buffer.cpp:56–109

Main procedure ----------------

// Main procedure
//----------------
int main() {

  // Create a jpeg memory buffer from the content of a jpeg file.
  // (this is for testing purposes only)
  const char *filename_input = "foo.jpg";
  std::fprintf(stderr," - Reading file '%s'\n",filename_input);
  std::FILE *file_input = std::fopen(filename_input,"rb");
  if (!file_input) { std::fprintf(stderr,"Input JPEG file not found !"); std::exit(0); }

  std::fprintf(stderr," - Construct input JPEG-coded buffer\n");
  unsigned buf_size = 500000; // Put the file size here !
  JOCTET *buffer_input = new JOCTET[buf_size];
  if (std::fread(buffer_input,sizeof(JOCTET),buf_size,file_input)) std::fclose(file_input);
  // -> 'buffer_input' is now a valid jpeg-coded memory buffer.

  // Create a CImg instance from the jpeg-coded buffer using the plug-in function.
  std::fprintf(stderr," - Create CImg instance from JPEG-coded buffer\n");
  CImg<unsigned char> img;
  img.load_jpeg_buffer(buffer_input, buf_size);
  delete[] buffer_input;

  // Do you image processing stuff here ....
  // Here, we just mirror the image and write "hello".
  std::fprintf(stderr," - Do simple processing\n");
  const unsigned char purple[] = { 255, 0, 0 };
  const unsigned char black[] = { 0, 0, 0 };
  img.mirror('y').draw_text(0,0,"   Hello!   ",purple,black,1,57);

  // Display image to see if everything's fine.
  img.display("Using 'jpeg_buffer.h' plugin");

  // Define a new JOCTET array where the processed image has to be saved
  // (we don't know its dimension before compressing it, therefore we have to allocate enough memory )
  std::fprintf(stderr," - Construct output JPEG-coded buffer\n");
  JOCTET *buffer_output = new JOCTET[2*buf_size];

  // Save processed image into this JOCTET buffer, compressed as jpeg.
  // This is done again by using the plug-in function.
  img.save_jpeg_buffer(buffer_output,buf_size,60);
  // Note that here, the variable 'buf_size' contains the length of the
  // data which have been written in the given output buffer.

  // Copy the content of the above array into a new file
  // (it should give you a valid JPEG file then !)
  const char *filename_output = "foo_output.jpg";
  std::fprintf(stderr," - Save output file '%s'\n",filename_output);
  std::FILE* file_output = std::fopen(filename_output,"wb");
  std::fwrite(buffer_output, sizeof(JOCTET), buf_size, file_output);
  std::fclose(file_output);
  delete[] buffer_output;

  std::fprintf(stderr," - All done !\n");
  return 0;
}