SM-26 synthesizer: initial implementation

Source/MenuSystem.h

@@ -0,0 +1,66 @@
+#pragma once
+
+#include <JuceHeader.h>
+#include "SynthParams.h"
+
+class MenuSystem;
+
+struct MenuItem
+{
+    enum Kind { Action, Value, Submenu, Separator };
+
+    juce::String label;
+    Kind kind = Action;
+    int paramId = -1;
+
+    std::function<void()> onEnter;
+    std::function<void(float delta)> onAdjust;
+    std::function<juce::String()> valueText;
+
+    MenuItem& action (std::function<void()> fn)   { onEnter = fn; return *this; }
+    MenuItem& param (int id, float lo, float hi)  { paramId = id; return *this; }
+    MenuItem& value (std::function<juce::String()> fn) { valueText = fn; kind = Value; return *this; }
+    MenuItem& submenu()                           { kind = Submenu; return *this; }
+    MenuItem& sep()                               { kind = Separator; return *this; }
+};
+
+struct MenuScreen
+{
+    juce::String title;
+    std::vector<MenuItem> items;
+    int selected = 0;
+};
+
+class MenuSystem
+{
+public:
+    MenuSystem();
+
+    void open();
+    void close();
+    bool isOpen() const { return ! stack.empty(); }
+
+    void up();
+    void down();
+    void left();
+    void right();
+    void enter();
+    void escape();
+
+    const MenuScreen& current() const;
+
+    void pushScreen (const MenuScreen& screen);
+
+    using ScreenBuilder = std::function<MenuScreen()>;
+
+    void setRootScreenBuilder (ScreenBuilder fn);
+
+    void refreshCurrent();
+
+private:
+    std::vector<MenuScreen> stack;
+    ScreenBuilder rootBuilder;
+    bool wasOpen = false;
+
+    void rebuildRoot();
+};