source/graphics/imageloader.h

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