【发布时间】：2020-05-05 15:51:33
【问题描述】：
这个问题在 Stack Overflow 中被问了好几次。我在几次讨论中尝试了方法，但没有奏效。所以我用自定义Qt 构建的OpenCV 库无法正常工作：
import cv2
img = cv2.imread("IMAGE_PATH")
cv2.imshow("frame", img)
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: eglfs, minimal, minimalegl, offscreen, vnc, xcb.
Aborted (core dumped)
我尝试过的
- 我尝试设置
export QT_DEBUG_PLUGINS=1并执行 Python 脚本，让 OpenCV 绘制图像。错误信息：
QFactoryLoader::QFactoryLoader() checking directory path "/home/w/.conda/envs/py36/plugins/platforms" ...
QFactoryLoader::QFactoryLoader() looking at "/home/w/.conda/envs/py36/plugins/platforms/libqeglfs.so"
Found metadata in lib /home/w/.conda/envs/py36/plugins/platforms/libqeglfs.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"eglfs"
]
},
"className": "QEglFSIntegrationPlugin",
"debug": false,
"version": 329991
}
Got keys from plugin meta data ("eglfs")
QFactoryLoader::QFactoryLoader() looking at "/home/w/.conda/envs/py36/plugins/platforms/libqminimal.so"
Found metadata in lib /home/w/.conda/envs/py36/plugins/platforms/libqminimal.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"className": "QMinimalIntegrationPlugin",
"debug": false,
"version": 329991
}
Got keys from plugin meta data ("minimal")
QFactoryLoader::QFactoryLoader() looking at "/home/w/.conda/envs/py36/plugins/platforms/libqminimalegl.so"
Found metadata in lib /home/w/.conda/envs/py36/plugins/platforms/libqminimalegl.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimalegl"
]
},
"className": "QMinimalEglIntegrationPlugin",
"debug": false,
"version": 329991
}
Got keys from plugin meta data ("minimalegl")
QFactoryLoader::QFactoryLoader() looking at "/home/w/.conda/envs/py36/plugins/platforms/libqoffscreen.so"
Found metadata in lib /home/w/.conda/envs/py36/plugins/platforms/libqoffscreen.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"className": "QOffscreenIntegrationPlugin",
"debug": false,
"version": 329991
}
Got keys from plugin meta data ("offscreen")
QFactoryLoader::QFactoryLoader() looking at "/home/w/.conda/envs/py36/plugins/platforms/libqvnc.so"
Found metadata in lib /home/w/.conda/envs/py36/plugins/platforms/libqvnc.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"vnc"
]
},
"className": "QVncIntegrationPlugin",
"debug": false,
"version": 329991
}
Got keys from plugin meta data ("vnc")
QFactoryLoader::QFactoryLoader() looking at "/home/w/.conda/envs/py36/plugins/platforms/libqxcb.so"
Found metadata in lib /home/w/.conda/envs/py36/plugins/platforms/libqxcb.so, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"xcb"
]
},
"className": "QXcbIntegrationPlugin",
"debug": false,
"version": 329991
}
Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/home/w/.conda/envs/py36/bin/platforms" ...
Cannot load library /home/w/.conda/envs/py36/plugins/platforms/libqxcb.so: (/home/w/.conda/envs/py36/plugins/platforms/../../lib/libQt5XcbQpa.so.5: symbol _ZN11QFontEngine14bitmapForGlyphEj6QFixedRK10QTransform, version Qt_5_PRIVATE_API not defined in file libQt5Gui.so.5 with link time reference)
QLibraryPrivate::loadPlugin failed on "/home/w/.conda/envs/py36/plugins/platforms/libqxcb.so" : "Cannot load library /home/w/.conda/envs/py36/plugins/platforms/libqxcb.so: (/home/w/.conda/envs/py36/plugins/platforms/../../lib/libQt5XcbQpa.so.5: symbol _ZN11QFontEngine14bitmapForGlyphEj6QFixedRK10QTransform, version Qt_5_PRIVATE_API not defined in file libQt5Gui.so.5 with link time reference)"
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: eglfs, minimal, minimalegl, offscreen, vnc, xcb.
Aborted (core dumped)
- 我尝试在
~/.bashrc文件中设置export LD_LIBRARY_PATH=/opt/Qt5.14.0/5.14.0/gcc_64/lib:$LD_LIBRARY_PATH，但没有解决。 - 我尝试重新安装
Qt5，但没有成功。 - 正如人们所说，我尝试使用
ldd，但我不太确定应该查看哪些信息。
如果相关
- 首先，如果相关，我在 Ubuntu 16.04 上安装了 Anaconda，并创建了一个通用 Python 环境名称
py36，其中安装了多个库。我尝试运行conda list，以下是一些包：
...
pyqt 5.9.2 py36h05f1152_2
qt 5.9.7 h5867ecd_1
vtk 8.2.0 py36haa4764d_200
...
我真的不知道这些库是什么时候安装的（当我安装其他软件包时它们会自动安装。）
- 接下来，我下载了Qt offline installer并安装到
/opt/Qt-5.14.0。 - 接下来，我使用以下设置编译了 OpenCV 3.4.9。我进展顺利，没有任何错误。 （之后我在 conda 环境中设置符号链接
cv2.so指向在/opt中构建的OpenCV 库。）
cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D CMAKE_INSTALL_PREFIX=/opt/OpenCV/opencv-3.4.9 \
-D CMAKE_PREFIX_PATH="/opt/Qt5.14.0/5.14.0/gcc_64/lib/cmake;/opt/vtk-8.2.0/lib/cmake;/opt/g2o/lib/cmake" \
-D OPENCV_EXTRA_MODULES_PATH=/home/w/OpenCV/opencv-3.4.9/opencv_contrib-3.4.9/modules \
-D PYTHON3_EXECUTABLE=/home/w/.conda/envs/py36/bin/python3 \
-D WITH_OPENGL=ON \
-D WITH_V4L=ON \
-D WITH_LIBV4L=ON \
-D WITH_FFMPEG=ON \
-D WITH_VTK=ON \
-D WITH_QT=ON \
-D WITH_GTK=ON \
..
【问题讨论】：
标签： qt qt5 shared-libraries conda