Support tracker to improve ALPR_OCR

modules/ANSLPR/ANSLPR_OCR.h

@@ -6,6 +6,7 @@
 #include <map>
 #include <string>
 #include <mutex>
+#include <unordered_map>
 #include <utility>
 #include <vector>
 
@@ -45,6 +46,66 @@ namespace ANSCENTER
 
         ALPRChecker     alprChecker;
 
+        // ----------------------------------------------------------------
+        //  Full-frame vs pipeline auto-detection (ported from ANSALPR_OD)
+        //
+        //  When the caller feeds ANSLPR_OCR pre-cropped vehicle ROIs (each
+        //  frame is a different small image), the tracker can't work — the
+        //  LP detector sees a totally new image every call so trackIds mean
+        //  nothing. In that "pipeline" mode we must skip the ALPRChecker
+        //  voting layer entirely and return raw OCR results.
+        //
+        //  When the caller feeds full-frame video (same resolution every
+        //  frame, plates moving through the scene), the tracker works
+        //  normally and we run plate text through ALPRChecker majority
+        //  voting + spatial dedup to stabilise readings.
+        //
+        //  Mode is auto-detected by watching whether consecutive frames
+        //  share the exact same (width, height) for at least
+        //  CONFIRM_THRESHOLD frames. Pipeline crops vary by a few pixels;
+        //  full-frame video is pixel-identical.
+        // ----------------------------------------------------------------
+        struct ImageSizeTracker {
+            cv::Size lastSize{ 0, 0 };
+            int      consistentCount = 0;
+            bool     detectedFullFrame = false;
+            static constexpr int CONFIRM_THRESHOLD   = 5;
+            static constexpr int MIN_FULLFRAME_WIDTH = 1000;
+        };
+        std::unordered_map<std::string, ImageSizeTracker> _imageSizeTrackers;
+
+        [[nodiscard]] bool shouldUseALPRChecker(const cv::Size& imageSize,
+                                                const std::string& cameraId);
+
+        // ----------------------------------------------------------------
+        //  Spatial plate identity persistence (ported from ANSALPR_OD)
+        //
+        //  Prevents the same plate string from appearing on two different
+        //  vehicles in the same frame. The LP tracker may briefly assign
+        //  the same trackId to two different plates when vehicles pass
+        //  each other, or two different trackIds to the same plate when
+        //  occlusion breaks a track. In either case, OCR can produce the
+        //  same text for two spatial locations for a frame or two — which
+        //  looks like "plate flicker" in the UI.
+        //
+        //  ensureUniquePlateText() resolves the ambiguity by accumulating
+        //  confidence per spatial location. When two detections share a
+        //  plate text, the one whose spatial history has the higher score
+        //  wins and the other has its className cleared.
+        // ----------------------------------------------------------------
+        struct SpatialPlateIdentity {
+            cv::Point2f center;                   // plate center in frame coords
+            std::string plateText;
+            float       accumulatedScore    = 0.0f;
+            int         framesSinceLastSeen = 0;
+        };
+        std::mutex _plateIdentitiesMutex;
+        std::unordered_map<std::string, std::vector<SpatialPlateIdentity>> _plateIdentities;
+        static constexpr float PLATE_SPATIAL_MATCH_THRESHOLD = 0.3f; // IoU threshold
+
+        void ensureUniquePlateText(std::vector<Object>& results,
+                                   const std::string& cameraId);
+
         // --- Original model zip path (reused for ANSONNXOCR initialization) ---
         std::string     _modelZipFilePath;