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waitKey() function on Mac (version 10.12.2) but it didn't seem to work correctly. It always return 255 when no keys pressed as well as any key pressed! I'm wondering whether it's incorrectly installed or it's a bug in OpenCV itself. Any idea to fix it would be appreciated.Here the source code of my program:
#include "opencv2/highgui/highgui.hpp"
#include <iostream>
int main() {
int ch;
cv::namedWindow("Test waitKey()", cv::WINDOW_AUTOSIZE);
cv::Mat image = cv::Mat(100,100,CV_8U, cv::Scalar(0));
cv::imshow("Test waitKey()", image);
for (;;){
ch = cv::waitKey(1000);
std::cout << ch << std::endl; // always return 255
// and this if statement will never be executed!
if (ch == 'q') break;
}
return 0;
}
And here the output of cv::getBuildInformation() function:
General configuration for OpenCV 3.2.0
=====================================
Version control: unknown
Platform:
Timestamp: 2017-01-14T14:50:25Z
Host: Darwin 16.3.0 x86_64
CMake: 3.7.2
CMake generator: Unix Makefiles
CMake build tool: /usr/bin/make
Configuration: RELEASE
C/C++:
Built as dynamic libs?: YES
C++ Compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ (ver 8.0.0.8000042)
C++ flags (Release): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -fdiagnostics-show-option -Wno-long-long -Qunused-arguments -Wno-semicolon-before-method-body -fno-omit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -DNDEBUG
C++ flags (Debug): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -fdiagnostics-show-option -Wno-long-long -Qunused-arguments -Wno-semicolon-before-method-body -fno-omit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -fvisibility=hidden -fvisibility-inlines-hidden -g -O0 -DDEBUG -D_DEBUG
C Compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc
C flags (Release): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -fdiagnostics-show-option -Wno-long-long -Qunused-arguments -Wno-semicolon-before-method-body -fno-omit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -DNDEBUG
C flags (Debug): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-unnamed-type-template-args -Wno-comment -fdiagnostics-show-option -Wno-long-long -Qunused-arguments -Wno-semicolon-before-method-body -fno-omit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -fvisibility=hidden -fvisibility-inlines-hidden -g -O0 -DDEBUG -D_DEBUG
Linker flags (Release):
Linker flags (Debug):
ccache: NO
Precompiled headers: NO
Extra dependencies: -framework OpenCL -framework Cocoa -framework AVFoundation -framework CoreGraphics -framework CoreMedia -framework CoreVideo -framework QuartzCore -framework Accelerate
3rdparty dependencies: libjpeg libwebp libpng libtiff libjasper IlmImf zlib
OpenCV modules:
To be built: core flann imgproc ml photo video imgcodecs shape videoio highgui objdetect superres ts features2d calib3d stitching videostab python2
Disabled: world
Disabled by dependency: -
Unavailable: cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev java python3 viz
GUI:
QT: NO
Cocoa: YES
OpenGL support: NO
VTK support: NO
Media I/O:
ZLib: build (ver 1.2.8)
JPEG: build (ver 90)
WEBP: build (ver 0.3.1)
PNG: build (ver 1.6.24)
TIFF: build (ver 42 - 4.0.2)
JPEG 2000: build (ver 1.900.1)
OpenEXR: build (ver 1.7.1)
GDAL: NO
GDCM: NO
Video I/O:
DC1394 1.x: NO
DC1394 2.x: NO
FFMPEG: NO
avcodec: NO
avformat: NO
avutil: NO
swscale: NO
avresample: NO
GStreamer: NO
OpenNI: NO
OpenNI PrimeSensor Modules: NO
OpenNI2: NO
PvAPI: NO
GigEVisionSDK: NO
Aravis SDK: NO
AVFoundation: YES
V4L/V4L2: NO/NO
XIMEA: NO
gPhoto2: NO
Parallel framework: GCD
Other third-party libraries:
Use IPP: 9.0.1 [9.0.1]
at: /Users/ngoclinhng/opencv/release/3rdparty/ippicv/ippicv_osx
Use IPP Async: NO
Use VA: NO
Use Intel VA-API/OpenCL: NO
Use Lapack: YES (-framework Accelerate)
Use Eigen: NO
Use Cuda: NO
Use OpenCL: YES
Use OpenVX: NO
Use custom HAL: NO
OpenCL: <Link with OpenCL library>
Link libraries: -framework OpenCL
Use AMDFFT: NO
Use AMDBLAS: NO
Python 2:
Interpreter: /usr/bin/python2.7 (ver 2.7.10)
Libraries: /usr/lib/libpython2.7.dylib (ver 2.7.10)
numpy: /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/numpy/core/include (ver 1.8.0rc1)
packages path: lib/python2.7/site-packages
Python 3:
Interpreter: /Users/ngoclinhng/anaconda/bin/python3 (ver 3.5.2)
Python (for build): /usr/bin/python2.7
Java:
ant: NO
JNI: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/System/Library/Frameworks/JavaVM.framework/Headers /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/System/Library/Frameworks/JavaVM.framework/Headers /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/System/Library/Frameworks/JavaVM.framework/Headers
Java wrappers: NO
Java tests: NO
Matlab: Matlab not found or implicitly disabled
Documentation:
Doxygen: NO
Tests and samples:
Tests: YES
Performance tests: YES
C/C++ Examples: NO
Install path: /usr/local
cvconfig.h is in: /Users/ngoclinhng/opencv/release
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You should use cvWaitKey(n) instead~ After OpenCV 3.1, cv::waitKey(n) return value changed from -1 to 255 when no keydown during the n millis.
76
answered Jul 27 '26 01:07
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