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image_size.h

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#ifndef image_size_h
#define image_size_h

#include <string>
#include <fstream>

// class for getting the geometry of an image
class ImageSize
{
public:
  
  enum Type
    {
      UNKNOWN  = -1,
      GIF      =  1,
      JPEG     =  2,
      PNG      =  3,
      BMP      =  4
    };

  enum Error
    {
      SUCCESS           =0, 
      INVALID_FILE      =1, 
      INVALID_FILE_NAME =2, 
      INVALID_FILE_TYPE =3, 
      BAD_HEADER        =4, 
      BAD_IMAGE         =5  
    };

private:
  bool valid;

  unsigned int width;
  unsigned int height;

  std::ifstream in;

  Type type;

  std::string file_name;

  Error error;

public:  
  ImageSize( std::string file_name );

  bool operator!() const { return !valid; }
  bool is_valid() const { return valid; }

  unsigned int get_width() const { return width; }
  unsigned int get_height() const { return height; }

  Type get_type() const { return type; } 

  Error get_error() const { return error; }

private:
  ImageSize(){}

  bool get_image_type();


  bool compare( std::string a, std::string b );

  bool get_1_byte( unsigned int& byte );

  bool get_le_2_bytes( unsigned int& bytes ); 
  bool get_be_2_bytes( unsigned int& bytes ); 
  
  bool get_le_4_bytes( unsigned int& bytes ); 
  bool get_be_4_bytes( unsigned int& bytes ); 

  bool jump_abs( unsigned int pos); 
  bool jump_rel( unsigned int n );  

  bool get_string( std::string& s, unsigned int n );

  // gif support
  void get_gif_geometry();
  bool check_gif_signature();

  // jpeg support
  void get_jpeg_geometry();
  bool check_jpeg_signature();
  bool jpeg_find_sof0_marker();

  // png support
  void get_png_geometry();
  bool check_png_signature();

  // bmp support
  void get_bmp_geometry();
  bool check_bmp_signature();

};

#endif

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