Bump OpenCV to 4.12.0, add new constructor for FlannBasedMatcher (#370)

* add FlannIndexParams FlannSearchParams cv.FlannBasedMatcher.create

* add FlannAlgorithm

* more tests

Author: rainyl

.gitignore

@@ -33,6 +33,8 @@ publish/
 *.exe
 libdartcv*
 .DS_STORE
+.ccls-cache/
+example/
 
 # Files and directories created by pub
 .dart_tool/

packages/dartcv/lib/features2d.dart

@@ -6,3 +6,4 @@ library dartcv.features2d;
 
 export 'src/features2d/features2d.dart';
 export 'src/features2d/features2d_async.dart';
+export 'src/g/features2d.g.dart' show FlannIndexType, FlannAlgorithm, FlannDistance;