From c1359cf6f58cd58811bacd19ca13f659d2e62a85 Mon Sep 17 00:00:00 2001
From: 283375 <bilibili283375@163.com>
Date: Fri, 11 Aug 2023 23:19:54 +0800
Subject: [PATCH] feat: 283375/image-sift-database

---
 src/arcaea_offline_ocr/sift_db.py | 96 +++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 src/arcaea_offline_ocr/sift_db.py

diff --git a/src/arcaea_offline_ocr/sift_db.py b/src/arcaea_offline_ocr/sift_db.py
new file mode 100644
index 0000000..11be09f
--- /dev/null
+++ b/src/arcaea_offline_ocr/sift_db.py
@@ -0,0 +1,96 @@
+import io
+import sqlite3
+from gzip import GzipFile
+from typing import Tuple
+
+import cv2
+import numpy as np
+
+from .types import Mat
+
+
+class SIFTDatabase:
+    def __init__(self, db_path: str, load: bool = True):
+        self.__db_path = db_path
+        self.__tags = []
+        self.__descriptors = []
+        self.__size = None
+
+        if load:
+            self.load_db()
+
+    @property
+    def db_path(self):
+        return self.__db_path
+
+    @db_path.setter
+    def db_path(self, value):
+        self.__db_path = value
+
+    @property
+    def tags(self):
+        return self.__tags
+
+    @property
+    def descriptors(self):
+        return self.__descriptors
+
+    @property
+    def size(self):
+        return self.__size
+
+    @size.setter
+    def size(self, value: Tuple[int, int]):
+        self.__size = value
+
+    def load_db(self):
+        conn = sqlite3.connect(self.db_path)
+        with conn:
+            cursor = conn.cursor()
+
+            size_str = cursor.execute(
+                "SELECT value FROM properties WHERE id = 'size'"
+            ).fetchone()[0]
+            sizr_str_arr = size_str.split(", ")
+            self.size = tuple(int(s) for s in sizr_str_arr)
+            tag__descriptors_bytes = cursor.execute(
+                "SELECT tag, descriptors FROM sift"
+            ).fetchall()
+
+            gzipped = int(
+                cursor.execute(
+                    "SELECT value FROM properties WHERE id = 'gzip'"
+                ).fetchone()[0]
+            )
+            for tag, descriptor_bytes in tag__descriptors_bytes:
+                buffer = io.BytesIO(descriptor_bytes)
+                self.tags.append(tag)
+                if gzipped == 0:
+                    self.descriptors.append(np.load(buffer))
+                else:
+                    gzipped_buffer = GzipFile(None, "rb", fileobj=buffer)
+                    self.descriptors.append(np.load(gzipped_buffer))
+
+    def lookup_img(
+        self,
+        __img: Mat,
+        *,
+        sift=cv2.SIFT_create(),
+        bf: cv2.BFMatcher = cv2.BFMatcher(),
+    ) -> Tuple[str, float]:
+        img = __img.copy()
+        if self.size is not None:
+            img = cv2.resize(img, self.size)
+        _, descriptors = sift.detectAndCompute(img, None)
+
+        good_results = []
+        for des in self.descriptors:
+            matches = bf.knnMatch(descriptors, des, k=2)
+            good = sum(m.distance < 0.75 * n.distance for m, n in matches)
+            good_results.append(good)
+        best_match_index = max(enumerate(good_results), key=lambda i: i[1])[0]
+
+        return (
+            self.tags[best_match_index],
+            good_results[best_match_index] / len(descriptors),
+        )