【QT】找不到qwt

【QT】找不到qwt_plot.h

系统环境：
linux 20.04
qt 6.7.2
cmake 3.22

原因：

Qwt没有正式的FindQwt.cmake，Qwt也没有提供QwtConfig.cmake。而且cmake不支持qmake的配置特性，也不支持读取mkspecs (.prf)文件。也就是说cmake构建的qt项目不可用qwt。

解决步骤：

1. 添加qwt模块

在CmakelLists.txt中添加如下代码

find_package(Qwt REQUIRED)

如果提示找不到FindQwt.cmake，执行步骤 2。

2. 添加FindQwt.cmake

在/usr/share/cmake-3.22/Modules（替换自己的cmake版本）路径下自行创建FindQwt.cmake ，内容如下：[cmake参考链接]https://gitlab.kitware.com/cmake/community/-/wikis/contrib/modules/FindQwt)

# Qt Widgets for Technical Applications
# available at http://www.http://qwt.sourceforge.net/
#
# The module defines the following variables:
#  Qwt_FOUND - the system has Qwt
#  QWT_INCLUDE_DIR - where to find qwt_plot.h
#  QWT_INCLUDE_DIRS - qwt includes
#  QWT_LIBRARY - where to find the Qwt library
#  QWT_LIBRARIES - aditional libraries
#  QWT_VERSION_STRING - version (ex. 5.2.1)
#
# It also defines this imported target:
#  Qwt::Qwt#=============================================================================
# Copyright 2010-2013, Julien Schueller
# Copyright 2018-2020, Rolf Eike Beer
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met: 
# 
# 1. Redistributions of source code must retain the above copyright notice, this
#    list of conditions and the following disclaimer. 
# 2. Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution. 
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.# The views and conclusions contained in the software and documentation are those
# of the authors and should not be interpreted as representing official policies, 
# either expressed or implied, of the FreeBSD Project.
#=============================================================================if (Qt5Gui_FOUND)get_target_property(QT_INCLUDE_DIR Qt5::Gui INTERFACE_INCLUDE_DIRECTORIES)
endif ()find_path ( QWT_INCLUDE_DIRNAMES qwt_plot.hHINTS ${QT_INCLUDE_DIR}PATH_SUFFIXES qwt qwt-qt5 qwt6
)set ( QWT_INCLUDE_DIRS ${QWT_INCLUDE_DIR} )# version
set ( _VERSION_FILE ${QWT_INCLUDE_DIR}/qwt_global.h )
if ( EXISTS ${_VERSION_FILE} )file ( STRINGS ${_VERSION_FILE} _VERSION_LINE REGEX "define[ ]+QWT_VERSION_STR" )if ( _VERSION_LINE )string ( REGEX REPLACE ".*define[ ]+QWT_VERSION_STR[ ]+\"([^\"]*)\".*" "\\1" QWT_VERSION_STRING "${_VERSION_LINE}" )endif ()
endif ()
unset ( _VERSION_FILE )find_library ( QWT_LIBRARYNAMES qwt qwt-qt5HINTS ${QT_LIBRARY_DIR}
)set ( QWT_LIBRARIES ${QWT_LIBRARY} )include ( FindPackageHandleStandardArgs )
find_package_handle_standard_args( Qwt REQUIRED_VARS QWT_LIBRARY QWT_INCLUDE_DIR VERSION_VAR QWT_VERSION_STRING )if (Qwt_FOUND AND NOT TARGET Qwt::Qwt)add_library(Qwt::Qwt UNKNOWN IMPORTED)set_target_properties(Qwt::Qwt PROPERTIESINTERFACE_INCLUDE_DIRECTORIES "${QWT_INCLUDE_DIRS}"IMPORTED_LOCATION "${QWT_LIBRARIES}")
endif ()mark_as_advanced (QWT_LIBRARYQWT_INCLUDE_DIR
)