Starting to implement memon 1.0.0 saving

src/better_beats.cpp

@@ -0,0 +1,33 @@
+#include "better_beats.hpp"
+#include <boost/multiprecision/gmp.hpp>
+#include "json.hpp"
+
+bool is_expressible_as_240th(const Fraction& beat) {
+    return (
+        (
+            (240 * boost::multiprecision::numerator(beat))
+            % boost::multiprecision::denominator(beat)
+        ) == 0
+    );
+};
+
+nlohmann::ordered_json beat_to_best_form(const Fraction& beat) {
+    if (is_expressible_as_240th(beat)) {
+        return nlohmann::ordered_json(
+            (240 * boost::multiprecision::numerator(beat))
+            / boost::multiprecision::denominator(beat)
+        );
+    } else {
+        return beat_to_fraction_tuple(beat);
+    };
+};
+
+nlohmann::ordered_json beat_to_fraction_tuple(const Fraction& beat) {
+    const auto integer_part = static_cast<nlohmann::ordered_json::number_unsigned_t>(beat);
+    const auto remainder = beat % 1;
+    return {
+        integer_part,
+        static_cast<nlohmann::ordered_json::number_unsigned_t>(boost::multiprecision::numerator(remainder)),
+        static_cast<nlohmann::ordered_json::number_unsigned_t>(boost::multiprecision::denominator(remainder)),
+    };
+};

src/better_beats.hpp

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <json.hpp>
+
+#include "special_numeric_types.hpp"
+
+bool is_expressible_as_240th(const Fraction& beat);
+nlohmann::ordered_json beat_to_best_form(const Fraction& beat);
+nlohmann::ordered_json beat_to_fraction_tuple(const Fraction& beat);

src/better_chart.cpp

@@ -0,0 +1,16 @@
+#include "better_chart.hpp"
+
+#include <json.hpp>
+
+namespace better {
+    nlohmann::ordered_json Chart::dump_for_memon_1_0_0() const {
+        nlohmann::ordered_json json_chart;
+        if (level) {
+            json_chart["level"] = level->format("f");
+        }
+        if (timing) {
+            json_chart["timing"] = timing->dump_for_memon_1_0_0();
+        }
+        json_chart["notes"] = notes.dump_for_memon_1_0_0();
+    }
+}

src/better_chart.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <memory>
+#include <optional>
+#include <set>
+
+#include <json.hpp>
+
+#include "better_hakus.hpp"
+#include "better_notes.hpp"
+#include "better_timing.hpp"
+#include "special_numeric_types.hpp"
+
+namespace better {
+    struct Chart {
+        std::optional<Decimal> level;
+        std::optional<Timing> timing;
+        std::optional<Hakus> hakus;
+        Notes notes;
+
+        nlohmann::ordered_json dump_for_memon_1_0_0() const;
+    };
+}

src/better_hakus.cpp

@@ -0,0 +1,11 @@
+#include "better_hakus.hpp"
+
+#include "better_beats.hpp"
+
+nlohmann::ordered_json dump_hakus(const Hakus& hakus) {
+    auto j = nlohmann::ordered_json::array();
+    for (const auto& haku : hakus) {
+        j.push_back(beat_to_best_form(haku));
+    }
+    return j;
+}

src/better_hakus.hpp

@@ -0,0 +1,11 @@
+#pragma once
+
+#include <set>
+
+#include <json.hpp>
+
+#include "special_numeric_types.hpp"
+
+using Hakus = std::set<Fraction>;
+
+nlohmann::ordered_json dump_hakus(const Hakus& hakus);

src/better_metadata.hpp

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <string>
+
+#include "special_numeric_types.hpp"
+
+namespace better {
+    struct PreviewLoop {
+        Decimal start = 0;
+        Decimal duration = 0;
+    };
+
+    struct Metadata {
+        std::string title = "";
+        std::string artist = "";
+        std::string audio = "";
+        std::string jacket = "";
+        PreviewLoop preview_loop;
+        std::string preview_file = "";
+        bool use_preview_file = false;
+    };
+}

src/better_note.cpp

@@ -1,6 +1,9 @@
 #include "better_note.hpp"
+
 #include <variant>
 
+#include "better_beats.hpp"
+
 namespace better {
     Position::Position(unsigned int index) : x(index % 4), y (index / 4) {
         if (index > 15) {
@@ -47,6 +50,13 @@ namespace better {
         return position;
     };
 
+    nlohmann::ordered_json TapNote::dump_for_memon_1_0_0() const {
+        return {
+            {"n", position.index()},
+            {"t", beat_to_best_form(time)}
+        };
+    };
+
     LongNote::LongNote(Fraction time, Position position, Fraction duration, Position tail_tip)
     :
         time(time),
@@ -123,8 +133,24 @@ namespace better {
                 return 90;
             }
         }
-    }
+    };
 
+    nlohmann::ordered_json LongNote::dump_for_memon_1_0_0() const {
+        return {
+            {"n", position.index()},
+            {"t", beat_to_best_form(time)},
+            {"l", beat_to_best_form(duration)},
+            {"p", tail_as_6_notation()}
+        };
+    };
+
+    int LongNote::tail_as_6_notation() const {
+        if (tail_tip.get_y() == position.get_y()) {
+            return tail_tip.get_x() - static_cast<int>(tail_tip.get_x() > position.get_x());
+        } else {
+            return 3 + tail_tip.get_y() - int(tail_tip.get_y() > position.get_y());
+        }
+    }
     
     auto _time_bounds = VariantVisitor {
         [](const TapNote& t) -> std::pair<Fraction, Fraction> { return {t.get_time(), t.get_time()}; },
@@ -146,5 +172,9 @@ namespace better {
     Fraction Note::get_end() const {
         return this->get_time_bounds().second;
     }
+
+    nlohmann::ordered_json Note::dump_for_memon_1_0_0() const {
+        return std::visit([](const auto& n){return n.dump_for_memon_1_0_0();}, this->note);
+    }
 }
 

src/better_note.hpp

@@ -6,6 +6,8 @@
 #include <utility>
 #include <variant>
 
+#include <json.hpp>
+
 #include "special_numeric_types.hpp"
 #include "variant_visitor.hpp"
 
@@ -46,6 +48,7 @@ namespace better {
 
         bool operator==(const TapNote&) const = default;
 
+        nlohmann::ordered_json dump_for_memon_1_0_0() const;
     private:
         Fraction time;
         Position position;
@@ -64,6 +67,9 @@ namespace better {
         unsigned int get_tail_angle() const;
 
         bool operator==(const LongNote&) const = default;
+
+        nlohmann::ordered_json dump_for_memon_1_0_0() const;
+        int tail_as_6_notation() const;
     private:
         Fraction time;
         Position position;
@@ -84,6 +90,8 @@ namespace better {
         auto visit(T& visitor) const {return std::visit(visitor, this->note);};
 
         bool operator==(const Note&) const = default;
+
+        nlohmann::ordered_json dump_for_memon_1_0_0() const;
     private:
         std::variant<TapNote, LongNote> note;
     };

src/better_notes.cpp

@@ -1,5 +1,9 @@
 #include "better_notes.hpp"
 
+#include <SFML/System/Time.hpp>
+#include <algorithm>
+#include "json.hpp"
+
 namespace better {
     std::pair<Notes::iterator, bool> Notes::insert(const Note& note) {
         auto conflicting_note = end();
@@ -56,4 +60,50 @@ namespace better {
         auto it = find(note);
         interval_tree::erase(it);
     };
+
+
+    bool Notes::is_colliding(const better::Note& note, const better::Timing& timing) {
+        const auto [start_beat, end_beat] = note.get_time_bounds();
+
+        /*
+        Two notes collide if they are within ~one second of each other :
+        Approach and burst animations of original jubeat markers last 16 frames
+        at (supposedly) 30 fps, which means a note needs (a bit more than) half
+        a second of leeway both before *and* after itself to properly display 
+        its marker animation, consequently, two consecutive notes on the same
+        button cannot be closer than ~one second from each other.
+
+        I don't really know why I shrink the collision zone down here ?
+        Shouldn't it be 32/30 seconds ? (~1066ms instead of 1000ms ?)
+
+        Reverse-engineering of the jubeat plus iOS app suggest the "official"
+        note collision zone size is 1030 ms, so actually I wasn't that far off
+        with 1000 ms !
+
+        TODO: Make the collision zone customizable
+        */
+        const auto collision_start = timing.beats_at(timing.time_at(start_beat) - sf::seconds(1));
+        const auto collision_end = timing.beats_at(timing.time_at(end_beat) + sf::seconds(1));
+
+        bool found_collision = false;
+        in(
+            {collision_start, collision_end},
+            [&](Notes::const_iterator it){
+                if (it->second.get_position() == note.get_position()) {
+                    if (it->second != note) {
+                        found_collision = true;
+                    }
+                }
+            }
+        );
+        return found_collision;
+    };
+
+    nlohmann::ordered_json Notes::dump_for_memon_1_0_0() const {
+        auto json_notes = nlohmann::ordered_json::array();
+        for (const auto& [_, note] : *this) {
+            json_notes.push_back(note.dump_for_memon_1_0_0());
+        }
+        return json_notes;
+    }
 }

src/better_notes.hpp

@@ -5,9 +5,12 @@
 #include <type_traits>
 #include <utility>
 
-#include "interval_tree.hpp"
+#include <interval_tree.hpp>
+#include <json.hpp>
 
 #include "better_note.hpp"
+#include "better_timing.hpp"
+#include "json.hpp"
 #include "special_numeric_types.hpp"
 
 namespace better {
@@ -21,5 +24,14 @@ namespace better {
         const_iterator find(const Note& note) const;
         bool contains(const Note& note) const;
         void erase(const Note& note);
+
+        /*
+        Returns true if the given note (assumed to already be in the container)
+        is colliding with ANOTHER note. This means notes exactly equal to the
+        one passed as an argument are NOT taken into account.
+        */
+        bool is_colliding(const better::Note& note, const better::Timing& timing);
+
+        nlohmann::ordered_json dump_for_memon_1_0_0() const;
     };
 }

src/better_song.cpp

@@ -2,78 +2,67 @@
 
 #include <SFML/System/Time.hpp>
 
+#include "better_hakus.hpp"
+#include "json.hpp"
+#include "src/better_hakus.hpp"
 #include "std_optional_extras.hpp"
+#include "variant_visitor.hpp"
 
 namespace better {
-    std::optional<sf::Time> Chart::time_of_last_event() const {
-        if (notes.empty()) {
-            return {};
-        } else {
-            return timing.time_at(notes.crbegin()->second.get_end());
-        }
-    };
-
-    bool Chart::is_colliding(const better::Note& note) {
-        const auto [start_beat, end_beat] = note.get_time_bounds();
-
-        /*
-        Two notes collide if they are within ~one second of each other :
-        Approach and burst animations of original jubeat markers last 16 frames
-        at (supposedly) 30 fps, which means a note needs (a bit more than) half
-        a second of leeway both before *and* after itself, consequently, two
-        consecutive notes on the same button cannot be closer than ~one second
-        from each other.
-
-        I don't really know why I shrink the collision zone down here ?
-        Shouldn't it be 32/30 seconds ? (1.0666... seconds instead of 1 ?)
-
-        TODO: Make the collision zone customizable
-        */
-        const auto collision_start = timing.beats_at(timing.time_at(start_beat) - sf::seconds(1));
-        const auto collision_end = timing.beats_at(timing.time_at(end_beat) + sf::seconds(1));
-
-        bool found_collision = false;
-        notes.in(
-            {collision_start, collision_end},
-            [&](Notes::const_iterator it){
-                if (it->second.get_position() == note.get_position()) {
-                    if (it->second != note) {
-                        found_collision = true;
-                    }
-                }
-            }
-        );
-        return found_collision;
-    }
-
-    PreviewLoop::PreviewLoop(Decimal start, Decimal duration) :
-        start(start),
-        duration(duration)
-    {
-        if (start < 0) {
-            std::stringstream ss;
-            ss << "Attempted to create a PreviewLoop with negative start ";
-            ss << "position : " << start;
-            throw std::invalid_argument(ss.str());
-        }
-        
-        if (duration < 0) {
-            std::stringstream ss;
-            ss << "Attempted to create a PreviewLoop with negative ";
-            ss << "duration : " << duration;
-            throw std::invalid_argument(ss.str());
-        }
-    };
-
-    Decimal PreviewLoop::get_start() const {
-        return start;
-    };
-
-    Decimal PreviewLoop::get_duration() const {
-        return duration;
-    };
-
     std::string stringify_level(std::optional<Decimal> level) {
         return stringify_or(level, "(no level defined)");
     };
+
+    nlohmann::ordered_json Song::dump_as_memon_1_0_0() const {
+        nlohmann::ordered_json memon;
+        memon["version"] = "1.0.0";
+        auto json_metadata = dump_metadata_1_0_0();
+        if (not json_metadata.empty()) {
+            memon["metadata"] = json_metadata;
+        }
+        auto json_timing = nlohmann::ordered_json::object();
+        if (timing) {
+            json_timing.update(timing->dump_for_memon_1_0_0());
+        }
+        if (hakus) {
+            json_timing["hakus"] = dump_hakus(*hakus);
+        }
+        if (not json_timing.empty()) {
+            memon["timing"] = json_timing;
+        }
+        auto json_charts = nlohmann::ordered_json::object();
+        for (const auto& [name, chart] : charts) {
+            json_charts[name] = chart.dump_for_memon_1_0_0();
+        }
+        return memon;
+    }
+    
+    nlohmann::ordered_json Song::dump_metadata_1_0_0() const {
+        nlohmann::ordered_json json_metadata;
+        if (not metadata.title.empty()) {
+            json_metadata["title"] = metadata.title;
+        }
+        if (not metadata.artist.empty()) {
+            json_metadata["artist"] = metadata.artist;
+        }
+        if (not metadata.audio.empty()) {
+            json_metadata["audio"] = metadata.audio;
+        }
+        if (not metadata.jacket.empty()) {
+            json_metadata["jacket"] = metadata.jacket;
+        }
+        if (metadata.use_preview_file) {
+            if (not metadata.preview_file.empty()) {
+                json_metadata["preview"] = metadata.preview_file;
+            }
+        } else {
+            if (metadata.preview_loop.duration != 0) {
+                json_metadata["preview"] = {
+                    {"start", metadata.preview_loop.start.format("f")},
+                    {"duration", metadata.preview_loop.duration.format("f")}
+                };
+            }
+        }
+        return json_metadata;
+    };
 }

src/better_song.hpp

@@ -8,51 +8,19 @@
 #include <string>
 #include <tuple>
 
+#include <json.hpp>
 #include <SFML/System/Time.hpp>
 
+#include "better_chart.hpp"
+#include "better_hakus.hpp"
+#include "better_metadata.hpp"
 #include "better_notes.hpp"
 #include "better_timing.hpp"
 #include "special_numeric_types.hpp"
 
 namespace better {
-    struct Chart {
-        std::optional<Decimal> level;
-        Timing timing;
-        std::optional<std::set<Fraction>> hakus;
-        Notes notes;
-
-        /*
-        Returns true if the given note (assumed to already be part of the
-        chart) is colliding with ANOTHER note in the chart. This means notes
-        exactly equal to the one passed as an argument are NOT taken into
-        account.
-        */
-        bool is_colliding(const better::Note& note);
-
-        std::optional<sf::Time> time_of_last_event() const;
-    };
-
     std::string stringify_level(std::optional<Decimal> level);
 
-    class PreviewLoop {
-    public:
-        PreviewLoop(Decimal start, Decimal duration);
-
-        Decimal get_start() const;
-        Decimal get_duration() const;
-    private:
-        Decimal start;
-        Decimal duration;
-    };
-
-    struct Metadata {
-        std::optional<std::string> title;
-        std::optional<std::string> artist;
-        std::optional<std::filesystem::path> audio;
-        std::optional<std::filesystem::path> jacket;
-        std::optional<std::variant<PreviewLoop, std::filesystem::path>> preview;
-    };
-
     const auto difficulty_name_comp_key = [](const std::string& s) {
         if (s == "BSC") {
             return std::make_tuple(1, std::string{});
@@ -76,6 +44,10 @@ namespace better {
             decltype(order_by_difficulty_name)
         > charts{order_by_difficulty_name};
         Metadata metadata;
-        Timing timing;
+        std::optional<Timing> timing;
+        std::optional<Hakus> hakus;
+
+        nlohmann::ordered_json dump_as_memon_1_0_0() const;
+        nlohmann::ordered_json dump_metadata_1_0_0() const;
     };
 }

src/better_timing.cpp

@@ -1,7 +1,12 @@
 #include "better_timing.hpp"
 
+#include <json.hpp>
+
+#include "better_beats.hpp"
+#include "src/better_beats.hpp"
+
 namespace better {
-    BPMAtBeat::BPMAtBeat(Fraction beats, Fraction bpm) : beats(beats), bpm(bpm) {
+    BPMAtBeat::BPMAtBeat(Fraction beats, Decimal bpm) : beats(beats), bpm(bpm) {
         if (bpm <= 0) {
             std::stringstream ss;
             ss << "Attempted to create a BPMAtBeat with negative BPM : ";
@@ -10,14 +15,23 @@ namespace better {
         }
     };
 
-    BPMEvent::BPMEvent(Fraction beats, Fraction seconds, Fraction bpm) :
+    BPMEvent::BPMEvent(Fraction beats, Fraction seconds, Decimal bpm) :
         BPMAtBeat(beats, bpm),
         seconds(seconds)
     {};
 
+    Fraction BPMAtBeat::get_beats() const {
+        return beats;
+    }
+
+    Decimal BPMAtBeat::get_bpm() const {
+        return bpm;
+    }
+
     Fraction BPMEvent::get_seconds() const {
         return seconds;
     };
+
     
     /*
     Create a Time Map from a list of BPM changes with times given in
@@ -75,7 +89,7 @@ namespace better {
             auto beats_since_last_event =
                 current->get_beats() - previous->get_beats();
             auto seconds_since_last_event = 
-                (60 * beats_since_last_event) / previous->get_bpm();
+                (60 * beats_since_last_event) / convert_to_fraction(previous->get_bpm());
             current_second += seconds_since_last_event;
             bpm_changes.emplace_back(
                 current->get_beats(),
@@ -125,7 +139,7 @@ namespace better {
         auto seconds_since_previous_event = (
             Fraction{60}
             * beats_since_previous_event
-            / bpm_change->get_bpm()
+            / convert_to_fraction(bpm_change->get_bpm())
         );
         return bpm_change->get_seconds() + seconds_since_previous_event;
     };
@@ -156,10 +170,27 @@ namespace better {
         }
         auto seconds_since_previous_event = fractional_seconds - bpm_change->get_seconds();
         auto beats_since_previous_event = (
-            bpm_change->get_bpm()
+            convert_to_fraction(bpm_change->get_bpm())
             * seconds_since_previous_event
             / Fraction{60}
         );
         return bpm_change->get_beats() + beats_since_previous_event;
     };
+
+    nlohmann::ordered_json Timing::dump_for_memon_1_0_0() const {
+        nlohmann::ordered_json j;
+        j["offset"] = convert_to_decimal(fractional_seconds_at(0), 5).format("f");
+        auto bpms = nlohmann::ordered_json::array();
+        for (const auto& bpm_change : events_by_beats) {
+            nlohmann::ordered_json bpm_event;
+            bpm_event["beat"] = beat_to_best_form(bpm_change.get_beats());
+            bpm_event["bpm"] = bpm_change.get_bpm().format("f");
+            bpms.push_back({
+                {"beat", beat_to_best_form(bpm_change.get_beats())},
+                {"bpm", bpm_change.get_bpm().format("f")}
+            });
+        }
+        j["bpms"] = bpms;
+        return j;
+    }
 }

src/better_timing.hpp

@@ -9,6 +9,7 @@
 
 #include <SFML/System/Time.hpp>
 
+#include "json.hpp"
 #include "special_numeric_types.hpp"
 
 namespace better {
@@ -19,17 +20,17 @@ namespace better {
 
     class BPMAtBeat {
     public:
-        BPMAtBeat(Fraction beats, Fraction bpm);
+        BPMAtBeat(Fraction beats, Decimal bpm);
         Fraction get_beats() const;
-        Fraction get_bpm() const;
+        Decimal get_bpm() const;
     private:
         Fraction beats;
-        Fraction bpm;
+        Decimal bpm;
     };
 
     class BPMEvent : public BPMAtBeat {
     public:
-        BPMEvent(Fraction beats, Fraction seconds, Fraction bpm);
+        BPMEvent(Fraction beats, Fraction seconds, Decimal bpm);
         Fraction get_seconds() const;
     private:
         Fraction seconds;
@@ -53,6 +54,8 @@ namespace better {
         sf::Time time_between(Fraction beat_a, Fraction beat_b) const;
 
         Fraction beats_at(sf::Time time) const;
+
+        nlohmann::ordered_json dump_for_memon_1_0_0() const;
         
     private:
         std::set<BPMEvent, decltype(order_by_beats)> events_by_beats{order_by_beats};

src/editor_state.cpp

@@ -19,6 +19,7 @@
 #include "imgui_extras.hpp"
 #include "metadata_in_gui.hpp"
 #include "special_numeric_types.hpp"
+#include "src/better_song.hpp"
 #include "src/chart.hpp"
 #include "std_optional_extras.hpp"
 #include "variant_visitor.hpp"
@@ -32,7 +33,6 @@ EditorState::EditorState(
     playfield(assets_),
     linear_view(assets_),
     song(song_),
-    metadata_in_gui(song_.metadata),
     applicable_timing(song.timing),
     assets(assets_)
 {
@@ -241,12 +241,12 @@ void EditorState::display_properties() {
         }
         ImGui::EndChild();
 
-        ImGui::InputText("Title", &metadata_in_gui.title);
+        ImGui::InputText("Title", &song.metadata.title);
-        ImGui::InputText("Artist", &metadata_in_gui.artist);
+        ImGui::InputText("Artist", &song.metadata.artist);
 
         if (feis::InputTextColored(
             "Audio",
-            &metadata_in_gui.audio,
+            &song.metadata.audio,
             music_state.has_value(),
             "Invalid Audio Path"
         )) {
@@ -254,7 +254,7 @@ void EditorState::display_properties() {
         }
         if (feis::InputTextColored(
             "Jacket",
-            &metadata_in_gui.jacket,
+            &song.metadata.jacket,
             jacket.has_value(),
             "Invalid Jacket Path"
         )) {
@@ -264,45 +264,45 @@ void EditorState::display_properties() {
         ImGui::Separator();
         
         ImGui::Text("Preview");
-        ImGui::Checkbox("Use separate preview file", &metadata_in_gui.use_preview_file);
+        ImGui::Checkbox("Use separate preview file", &song.metadata.use_preview_file);
-        if (metadata_in_gui.use_preview_file) {
+        if (song.metadata.use_preview_file) {
             if (feis::InputTextColored(
                 "File",
-                &metadata_in_gui.preview_file,
+                &song.metadata.preview_file,
                 preview_audio.has_value(),
                 "Invalid Path"
             )) {
                 reload_preview_audio();
             }
         } else {
-            if (feis::InputDecimal("Start", &metadata_in_gui.preview_loop.start)) {
+            if (feis::InputDecimal("Start", &song.metadata.preview_loop.start)) {
-                metadata_in_gui.preview_loop.start = std::max(
+                song.metadata.preview_loop.start = std::max(
                     Decimal{0},
-                    metadata_in_gui.preview_loop.start
+                    song.metadata.preview_loop.start
                 );
                 if (music_state.has_value()) {
-                    metadata_in_gui.preview_loop.start = std::min(
+                    song.metadata.preview_loop.start = std::min(
                         Decimal{music_state->music.getDuration().asMicroseconds()} / 1000000,
-                        metadata_in_gui.preview_loop.start
+                        song.metadata.preview_loop.start
                     );
                 }
             }
-            if (feis::InputDecimal("Duration", &metadata_in_gui.preview_loop.duration)) {
+            if (feis::InputDecimal("Duration", &song.metadata.preview_loop.duration)) {
-                metadata_in_gui.preview_loop.duration = std::max(
+                song.metadata.preview_loop.duration = std::max(
                     Decimal{0},
-                    metadata_in_gui.preview_loop.duration
+                    song.metadata.preview_loop.duration
                 );
                 if (music_state.has_value()) {
-                    metadata_in_gui.preview_loop.start = std::min(
+                    song.metadata.preview_loop.start = std::min(
                         (
                             Decimal{
                                 music_state->music
                                 .getDuration()
                                 .asMicroseconds()
                             } / 1000000 
-                            - metadata_in_gui.preview_loop.start
+                            - song.metadata.preview_loop.start
                         ),
-                        metadata_in_gui.preview_loop.start
+                        song.metadata.preview_loop.start
                     );
                 }
             }
@@ -321,11 +321,11 @@ void EditorState::display_status() {
     ImGui::Begin("Status", &showStatus, ImGuiWindowFlags_AlwaysAutoResize);
     {
         if (not music_state) {
-            if (not metadata_in_gui.audio.empty()) {
+            if (not song.metadata.audio.empty()) {
                 ImGui::TextColored(
                     ImVec4(1, 0.42, 0.41, 1),
                     "Invalid music path : %s",
-                    metadata_in_gui.audio.c_str());
+                    song.metadata.audio.c_str());
             } else {
                 ImGui::TextColored(
                     ImVec4(1, 0.42, 0.41, 1),
@@ -334,11 +334,11 @@ void EditorState::display_status() {
         }
 
         if (not jacket) {
-            if (not metadata_in_gui.jacket.empty()) {
+            if (not song.metadata.jacket.empty()) {
                 ImGui::TextColored(
                     ImVec4(1, 0.42, 0.41, 1),
                     "Invalid jacket path : %s",
-                    metadata_in_gui.jacket.c_str());
+                    song.metadata.jacket.c_str());
             } else {
                 ImGui::TextColored(
                     ImVec4(1, 0.42, 0.41, 1),
@@ -636,13 +636,13 @@ void EditorState::reload_editable_range() {
  * of the song Resets the album cover state if anything fails
  */
 void EditorState::reload_jacket() {
-    if (not song_path.has_value() or not song.metadata.jacket.has_value()) {
+    if (not song_path.has_value() or song.metadata.jacket.empty()) {
         jacket.reset();
         return;
     }
 
     jacket.emplace();
-    auto jacket_path = song_path->parent_path() / metadata_in_gui.jacket;
+    auto jacket_path = song_path->parent_path() / song.metadata.jacket;
 
     if (
         not std::filesystem::exists(jacket_path)
@@ -658,12 +658,12 @@ void EditorState::reload_jacket() {
  * Updates playbackPosition and preview_end as well
  */
 void EditorState::reload_music() {
-    if (not song_path.has_value()) {
+    if (not song_path.has_value() or song.metadata.audio.empty()) {
         music_state.reset();
         return;
     }
 
-    const auto absolute_music_path = song_path->parent_path() / metadata_in_gui.audio;
+    const auto absolute_music_path = song_path->parent_path() / song.metadata.audio;
     try {
         music_state.emplace(absolute_music_path);
     } catch (const std::exception& e) {
@@ -680,35 +680,35 @@ void EditorState::reload_music() {
 };
 
 void EditorState::reload_preview_audio() {
-    if (not song_path.has_value()) {
+    if (not song_path.has_value() or song.metadata.preview_file.empty()) {
         preview_audio.reset();
         return;
     }
 
-    const auto path = song_path->parent_path() / metadata_in_gui.preview_file;
+    const auto path = song_path->parent_path() / song.metadata.preview_file;
     try {
-        preview_audio.emplace(path);
+        preview_audio.emplace(path.string());
     } catch (const std::exception& e) {
         preview_audio.reset();
     }
 };
 
-void reload_applicable_timing() {
+void EditorState::reload_applicable_timing() {
-    // TODO: implement
+    if (chart_state) {
+        applicable_timing = chart_state->chart.timing;
+    } else {
+        applicable_timing = song.timing;
+    }
 }
 
-void EditorState::open_chart(better::Chart& chart) {
+void EditorState::open_chart(better::Chart& chart, const std::string& name) {
-    chart_state.emplace(chart, assets);
+    chart_state.emplace(chart, name, assets);
     reload_applicable_timing();
     reload_editable_range();
 };
 
-void ESHelper::save(EditorState& ed) {
+void EditorState::save(const std::filesystem::path& file) {
-    try {
+    const auto memon = song.dump_as_memon_1_0_0();
-        ed.song.autoSaveAsMemon();
-    } catch (const std::exception& e) {
-        tinyfd_messageBox("Error", e.what(), "ok", "error", 1);
-    }
 }
 
 void ESHelper::open(std::optional<EditorState>& ed, std::filesystem::path assets, std::filesystem::path settings) {

src/editor_state.hpp

@@ -108,11 +108,12 @@ public:
     void undo(NotificationsQueue& nq);
     void redo(NotificationsQueue& nq);
 
+    void save(const std::filesystem::path& file);
+
 private:
 
     better::Song song;
 
-    MetadataInGui metadata_in_gui;
     /*
     sf::Time bounds (in the audio file "coordinates") which are accessible
     (and maybe editable) from the editor, can extend before and after
@@ -127,15 +128,12 @@ private:
     better::Timing& applicable_timing;
     void reload_applicable_timing();
 
-
+    void open_chart(better::Chart& chart, const std::string& name);
-
-    void open_chart(better::Chart& chart);
 
     std::filesystem::path assets;
 };
 
 namespace ESHelper {
-    void save(EditorState& ed);
     void open(std::optional<EditorState>& ed, std::filesystem::path assets, std::filesystem::path settings);
     void openFromFile(
         std::optional<EditorState>& ed,

src/json_decimal_parser.cpp

@@ -0,0 +1,7 @@
+#include "json_decimal_parser.hpp"
+
+bool json_decimal_parser::number_float(number_float_t /*unused*/, const string_t& val) {
+    string_t copy = val;
+    string(copy);
+    return true;
+}

src/json_decimal_parser.hpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <json.hpp>
+/*
+This class allows parsing json files with nlohmann::json while losslessly
+recovering decimal number literals by storing their original string
+representation when parsing intead of their float or double conversion
+
+Usage :
+
+    nlohmann::json j;
+    json_decimal_parser sax{j};
+    nlohmann::json::sax_parse(..., &sax);
+
+*/
+
+using sax_parser = nlohmann::detail::json_sax_dom_parser<nlohmann::json>;
+
+class json_decimal_parser : public sax_parser {
+public:
+    /*
+    Inherit the constructor because life is too short to write constructors for
+    derived classes
+    */
+    using sax_parser::json_sax_dom_parser;
+
+    // override float parsing, divert it to parsing the original string
+    // as a json string literal
+    bool number_float(number_float_t /*unused*/, const string_t& val);
+};
+
+template<class InputType>
+nlohmann::json parse_decimal_json(InputType&& input) {
+    nlohmann::json j;
+    json_decimal_parser sax{j};
+    nlohmann::json::sax_parse(std::forward<InputType>(input), &sax);
+    return j;
+}

src/meson.build

@@ -1,4 +1,6 @@
 sources += files(
+    'better_chart.cpp',
+    'better_metadata.cpp',
     'better_note.cpp',
     'better_notes.cpp',
     'better_song.cpp',
@@ -9,6 +11,7 @@ sources += files(
     'fumen.cpp',
     'history_actions.cpp',
     'imgui_extras.cpp',
+    'json_decimal_parser.cpp',
     'ln_marker.cpp',
     'main.cpp',
     'marker.cpp',
@@ -21,7 +24,6 @@ sources += files(
     'precise_music.cpp',
     'preferences.cpp',
     'sound_effect.cpp',
-    'time_interval.cpp',
     'toolbox.cpp',
 )
 

src/metadata_in_gui.cpp

@@ -2,12 +2,13 @@
 
 #include <filesystem>
 #include <variant>
+#include "src/better_song.hpp"
 
 MetadataInGui::MetadataInGui(const better::Metadata& metadata) :
     title(metadata.title.value_or("")),
     artist(metadata.artist.value_or("")),
     audio(metadata.audio.value_or(std::filesystem::path{}).string()),
-    jacket(metadata.jacket.value_or(std::filesystem::path{}).string()),
+    jacket(metadata.jacket.value_or(std::filesystem::path{}).string())
 {
     if (metadata.preview.has_value()) {
         if (std::holds_alternative<better::PreviewLoop>(*metadata.preview)) {
@@ -19,4 +20,31 @@ MetadataInGui::MetadataInGui(const better::Metadata& metadata) :
             use_preview_file = true;
         }
     }
+}
+
+MetadataInGui::operator better::Metadata() const {
+    auto m = better::Metadata{};
+    if (not title.empty()) {
+        m.title = title;
+    }
+    if (not artist.empty()) {
+        m.artist = artist;
+    }
+    if (not audio.empty()) {
+        m.audio = audio;
+    }
+    if (not jacket.empty()) {
+        m.jacket = jacket;
+    }
+    if (use_preview_file) {
+        if (not preview_file.empty()) {
+            m.preview = std::filesystem::path(preview_file);
+        }
+    } else if (preview_loop.start != preview_loop.duration) {
+        m.preview = better::PreviewLoop{
+            preview_loop.start,
+            preview_loop.duration
+        };
+    }
+    return m;
 }

src/special_numeric_types.cpp

@@ -1,5 +1,7 @@
 #include "special_numeric_types.hpp"
 
+#include <boost/math/special_functions/math_fwd.hpp>
+#include <boost/math/special_functions/pow.hpp>
 #include <boost/multiprecision/gmp.hpp>
 #include <boost/multiprecision/number.hpp>
 
@@ -36,4 +38,16 @@ Decimal convert_to_decimal(const Fraction& f, unsigned int precision) {
         Decimal{static_cast<long long>(boost::multiprecision::numerator(floored))}
         / Decimal{static_cast<long long>(boost::multiprecision::denominator(floored))}
     );
+}
+
+Fraction convert_to_fraction(const Decimal& d) {
+    const auto reduced = d.reduce();
+    const auto sign = reduced.sign();
+    const auto exponent = reduced.exponent();
+    const auto coefficient = reduced.coeff().u64();
+    if (exponent >= 0) {
+        return Fraction{sign > 0 ? 1 : -1} * Fraction{coefficient} * fast_pow(Fraction{10}, exponent);
+    } else {
+        return Fraction{sign > 0 ? 1 : -1} * Fraction{coefficient} / fast_pow(Fraction{10}, exponent);
+    }
 }

src/special_numeric_types.hpp

@@ -22,6 +22,7 @@ Fraction operator%(Fraction a, const Fraction& b);
 Fraction floor_fraction(const Fraction& f);
 Fraction round_fraction(const Fraction& f);
 Decimal convert_to_decimal(const Fraction& f, unsigned int precision);
+Fraction convert_to_fraction(const Decimal& d);
 
 // Rounds a given beat to the nearest given division (defaults to nearest 1/240th)
 const auto round_beats = [](Fraction beats, unsigned int denominator = 240) {
@@ -34,4 +35,20 @@ const auto floor_beats = [](Fraction beats, unsigned int denominator = 240) {
     beats *= denominator;
     const auto nearest = floor_fraction(beats);
     return nearest / Fraction{denominator};
-};
+};
+
+// Stolen from : https://github.com/progrock-libraries/kickstart/blob/d62c22efc92006dd76d455cf8f9d4f2a045e9126/source/library/kickstart/main_library/core/ns%E2%96%B8language/operations/intpow.hpp#L36
+// Essentially this is Horner's rule adapted to calculating a power, so that the
+// number of floating point multiplications is at worst O(log₂n).
+template<class Number>
+Number fast_pow( const Number base, const unsigned int exponent ) {
+    Number result = 1;
+    Number weight = base;
+    for (unsigned int n = exponent; n != 0; weight *= weight) {
+        if(n % 2 != 0) {
+           result *= weight;
+        }
+        n /= 2;
+    }
+    return result;
+}

tests/json_decimal.cpp

@@ -0,0 +1,30 @@
+#include <iostream>
+#include <map>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include <json.hpp>
+#include <libmpdec++/decimal.hh>
+
+class json_decimal_parser : public nlohmann::detail::json_sax_dom_parser<nlohmann::json> {
+public:
+    using nlohmann::detail::json_sax_dom_parser<nlohmann::json>::json_sax_dom_parser;
+    bool number_float(number_float_t /*unused*/, const string_t& val) {
+        string_t copy = val;
+        string(copy);
+        return true;
+    }
+};
+
+int main() {
+    nlohmann::json j{"blablabla"};
+    // json_decimal_parser sax{j};
+    // std::string json;
+    // std::getline(std::cin, json);
+    // nlohmann::json::sax_parse(json, &sax);
+    std::cout << "from const char * {} : " << nlohmann::json{"blablabla"} << std::endl;
+    std::cout << "from string {} : " << nlohmann::json{std::string{"blibloblu"}} << std::endl;
+    std::cout << "from const char * () : " << nlohmann::json("blablabla") << std::endl;
+    std::cout << "from string {} : " << nlohmann::json(std::string("blibloblu")) << std::endl;
+}

tests/meson.build

@@ -15,6 +15,13 @@ executable(
     include_directories: inc,
 )
 
+executable(
+    'json_decimal',
+    'json_decimal.cpp',
+    dependencies: deps,
+    include_directories: inc,
+)
+
 executable(
     'scrollwheel',
     'scrollwheel.cpp',