GNSS App: a Compass, with Places to be led back to and a level

Tab goes on from the Sky to a third view (issue #16): a rose that turns
with the device, the heading, where north came from and how long ago,
the sun on the rose, and a level. m marks where you stand as a Place,
t picks one as the target: an arrowhead on the rose, its distance and
bearing. The sensor's directions were checked by hand on the device.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162FokPdvY2KsS4NBfwyWPk

src/apps/gnss_app.h

@@ -1,35 +1,74 @@
 #pragma once
 
+#include <memory>
 #include <string>
+#include <vector>
 
 #include "app.h"
+#include "compass.h"
+#include "dialog_model.h"
+#include "line_editor.h"
+#include "list_model.h"
+#include "places.h"
 #include "services/gnss_service.h"
+#include "services/storage_service.h"
 #include "settings.h"
 
 namespace roro {
 
-// GNSS (see docs/milestones/M2.md, Q59): the Position view, and the Sky view with every satellite
-// in view placed by direction and elevation. Tab switches between them.
+// GNSS (see docs/milestones/M2.md, Q59): the Position view, the Sky view with every satellite in
+// view placed by direction and elevation, and the Compass (issue #16, docs/milestones/H1.md): a
+// rose that turns with the device, and the way to a Place the user marked. Tab goes round them.
 class GnssApp : public App {
    public:
-    GnssApp(GnssService& gnss, const Settings& settings) : gnss_(gnss), settings_(settings) {}
-    void onEnter() override { requestRedraw(); }
+    GnssApp(GnssService& gnss, const Settings& settings, StorageService& storage)
+        : gnss_(gnss), settings_(settings), storage_(storage) {}
+    void onEnter() override;
     bool onKey(const KeyEvent& e) override;
+    bool textEntryActive() const override { return mode_ == Mode::Name; }
     void update(uint32_t nowMs) override;
     void draw(Canvas& c) override;
     void help(std::vector<KeyHelp>& out) const override;
+    const char* helpTitle() const override;
     bool badge() const override { return gnss_.tracking(); }
 
    private:
+    enum class View { Position, Sky, Compass };
+    // Over the Compass: the list of Places, and the name of a new one.
+    enum class Mode { View, Places, Name };
+
     void drawPosition(Canvas& c);
     void drawSky(Canvas& c);
+    void drawCompass(Canvas& c);
+    void drawPlaces(Canvas& c);
+    bool compassKey(const KeyEvent& e);
+    bool placesKey(const KeyEvent& e);
+    void readImu();
+    void loadPlaces();
+    void savePlaces();
+    void mark();
+    void aimAtSun();
+    void say(const std::string& text);
 
     GnssService& gnss_;
     const Settings& settings_;
-    bool sky_ = false;
+    StorageService& storage_;
+    View view_ = View::Position;
+    Mode mode_ = Mode::View;
     uint32_t lastDrawMs_ = 0;
-    std::string refusal_;  // why a Track couldn't start, shown for a few seconds
+    std::string refusal_;  // why something couldn't be done, or that it was: shown for a few seconds
     uint32_t refusalMs_ = 0;
+
+    gnss::HeadingFilter heading_;
+    uint32_t imuUs_ = 0, imuMs_ = 0;
+    int courseSecond_ = -1;      // the Fix whose course was last given to the filter
+    float shownHeading_ = -1, shownTiltX_ = 0, shownTiltY_ = 0;
+    std::vector<gnss::Place> places_;
+    bool placesLoaded_ = false;
+    int target_ = -1;  // in places_; -1: none
+    ListModel list_{6};
+    LineEditor name_{gnss::kPlaceNameBytes};
+    std::unique_ptr<DialogModel> dialog_;
 };
 
 }  // namespace roro