Map improv. (#3226)

firmware/application/ui/ui_geomap.hpp

@@ -30,13 +30,16 @@
 #include "bmpfile.hpp"
 #include "mathdef.hpp"
 
+#include <array>
+#include <cstdio>
+#include <inttypes.h>
 #include "portapack.hpp"
 
 namespace ui {
 
 #define MAX_MAP_ZOOM_IN 4000
-#define MAX_MAP_ZOOM_OUT 10
-#define MAP_ZOOM_RESOLUTION_LIMIT 5  // Max zoom-in to show map; rect height & width must divide into this evenly
+#define MAX_MAP_ZOOM_OUT 15
+#define MAP_ZOOM_RESOLUTION_LIMIT 10  // Max zoom-in to show map;
 
 #define INVALID_LAT_LON 200
 #define INVALID_ANGLE 400
@@ -74,6 +77,101 @@ struct GeoMarker {
     }
 };
 
+class BMPFileCache {
+   public:
+    static constexpr uint8_t SlotsCount = 9;
+
+    BMPFileCache() {
+    }
+
+    ~BMPFileCache() {
+        clear();
+    }
+
+    BMPFile* get(const int32_t z, const int32_t x, const int32_t y) {
+        // Cache hit.
+        for (auto& slot : slots_) {
+            if (slot.used && slot.x == x && slot.y == y && slot.z == z) {
+                slot.last_used = next_stamp();
+                return &slot.bmp;
+            }
+        }
+
+        // Select free slot first, otherwise LRU slot.
+        Slot* target = nullptr;
+        uint16_t oldest = 0xFFFFu;
+        for (auto& slot : slots_) {
+            if (!slot.used) {
+                target = &slot;
+                break;
+            }
+            if (slot.last_used < oldest) {
+                oldest = slot.last_used;
+                target = &slot;
+            }
+        }
+
+        if (!target) {
+            return nullptr;
+        }
+
+        if (target->used) {
+            target->bmp.close();
+            target->used = false;
+        }
+
+        // OSM tile path convention: <base>/<z>/<x>/<y>.bmp
+        char path_buffer[64];
+        snprintf(path_buffer, sizeof(path_buffer), "/OSM/%" PRId32 "/%" PRId32 "/%" PRId32 ".bmp", z, x, y);
+
+        if (!target->bmp.open(path_buffer, true)) {
+            target->bmp.close();
+            return nullptr;
+        }
+
+        target->x = x;
+        target->y = y;
+        target->z = z;
+        target->last_used = next_stamp();
+        target->used = true;
+        return &target->bmp;
+    }
+
+    void clear() {
+        for (auto& slot : slots_) {
+            if (slot.used) {
+                slot.bmp.close();
+                slot.used = false;
+            }
+        }
+    }
+
+   private:
+    struct Slot {
+        BMPFile bmp{};
+        int32_t x{};
+        int32_t y{};
+        int32_t z{};
+        uint16_t last_used{};
+        bool used{false};
+    };
+
+    uint16_t next_stamp() {
+        if (++stamp_ == 0) {
+            uint16_t v = 1;
+            for (auto& slot : slots_) {
+                if (slot.used) {
+                    slot.last_used = v++;
+                }
+            }
+            stamp_ = v;
+        }
+        return stamp_;
+    }
+    std::array<Slot, SlotsCount> slots_{};
+    uint16_t stamp_{0};
+};
+
 class GeoPos : public View {
    public:
     enum alt_unit {
@@ -276,6 +374,7 @@ class GeoMap : public Widget {
     bool hide_center_marker_{false};
     GeoMapMode mode_{};
     File map_file{};
+    BMPFileCache bmp_cache{};
     bool map_opened{};
     bool map_visible{};
     uint16_t map_width{}, map_height{};