source/graphics/imageloader.h

   1 #ifndef MSP_GRAPHICS_IMAGELOADER_H_
   2 #define MSP_GRAPHICS_IMAGELOADER_H_
   3
   4 #include "image.h"
   5
   6 namespace Msp {
   7 namespace Graphics {
   8
   9 class unsupported_image_format: public std::runtime_error
  10 {
  11 public:
  12         unsupported_image_format(const std::string &w): std::runtime_error(w) { }
  13         virtual ~unsupported_image_format() throw() { }
  14 };
  15
  16 class bad_image_data: public std::runtime_error
  17 {
  18 public:
  19         bad_image_data(const std::string &w): std::runtime_error(w) { }
  20         virtual ~bad_image_data() throw() { }
  21 };
  22
  23
  24 class ImageLoader
  25 {
  26 public:
  27         enum State
  28         {
  29                 INITIAL,
  30                 HEADERS_LOADED,
  31                 FINISHED
  32         };
  33
  34 protected:
  35         class RegisterBase
  36         {
  37         protected:
  38                 RegisterBase() { }
  39         public:
  40                 virtual ~RegisterBase() { }
  41
  42                 virtual unsigned get_signature_size() const = 0;
  43                 virtual bool detect(const std::string &) const = 0;
  44                 virtual ImageLoader *create(IO::Seekable &) const = 0;
  45         };
  46
  47         template<typename T>
  48         class RegisteredLoader: public RegisterBase
  49         {
  50         public:
  51                 virtual unsigned get_signature_size() const { return T::get_signature_size(); }
  52                 virtual bool detect(const std::string &s) const { return T::detect(s); }
  53                 virtual ImageLoader *create(IO::Seekable &io) const { return new T(io); }
  54         };
  55
  56         struct Registry
  57         {
  58                 std::list<RegisterBase *> loaders;
  59                 bool changed;
  60
  61                 Registry();
  62                 ~Registry();
  63         };
  64
  65 private:
  66         IO::Base *source;
  67         State state;
  68
  69 protected:
  70         ImageLoader();
  71 public:
  72         virtual ~ImageLoader();
  73
  74         static bool detect_signature(const std::string &);
  75         static ImageLoader *open_file(const std::string &);
  76         static ImageLoader *open_io(IO::Seekable &);
  77
  78         virtual void load(Image::Data &);
  79         virtual void load_headers(Image::Data &);
  80 protected:
  81         virtual void load_headers_(Image::Data &) = 0;
  82         virtual void load_pixels_(Image::Data &) = 0;
  83
  84 public:
  85         State get_state() const { return state; }
  86
  87         template<typename T>
  88         static void register_loader();
  89 private:
  90         static Registry &get_registry();
  91
  92         static bool signature_size_compare(RegisterBase *, RegisterBase *);
  93 };
  94
  95 template<typename T>
  96 void ImageLoader::register_loader()
  97 {
  98         Registry &registry = get_registry();
  99         registry.loaders.push_back(new RegisteredLoader<T>);
 100         registry.changed = true;
 101 }
 102
 103 } // namespace Graphics
 104 } // namespace Msp
 105
 106 #endif