QRCode

[niqt]

Why is not included the module to decode the QRCode? It's classic mobile thing

[nihui]

there is ncnn port here, and ncnn inference library is much faster than opencv on mobile
https://github.com/EdVince/QRCode-NCNN

[niqt]

Why if i enable -DBUILD_opencv_objdetect=ON this module is not built?

[sunmin89]

Why if i enable -DBUILD_opencv_objdetect=ON this module is not built?

One can refer to opencv-4.8.1/modules/objdetect/CMakeLists.txt

It says module opencv_objdetect depends on opencv_calib3d while opencv_calib3d itself depends on opencv_flann.

Besides, some objdetecting functions are introduced into opencv_dnn since opencv 4.5.x, you should enable opencv_dnn, if you need those dnn based objdetecting features.

opencv/opencv#22544

Some simple modifications should be enough to enable opencv_objdetect .

diff --git a/opencv4_cmake_options.txt b/opencv4_cmake_options.txt
index ec6783a..ec8beec 100644
--- a/opencv4_cmake_options.txt
+++ b/opencv4_cmake_options.txt
@@ -82,8 +82,8 @@
 -DBUILD_opencv_dnn=OFF
 -DBUILD_opencv_imgcodecs=OFF
 -DBUILD_opencv_videoio=OFF
--DBUILD_opencv_calib3d=OFF
--DBUILD_opencv_flann=OFF
--DBUILD_opencv_objdetect=OFF
+-DBUILD_opencv_calib3d=ON
+-DBUILD_opencv_flann=ON
+-DBUILD_opencv_objdetect=ON