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