Question

我是使用CMake的新手。我正在尝试创建一个简单的CMakeList文件，并从QT5 5.7添加对QPrinter和QTextDocument的支持。从我发现的病情必须将以下库添加到我的CMakeList文件：

QT5Core
QT5PrintSupport
Qt5Gui
Qt5Widgets

这就是我现在所拥有的：

cmake_minimum_required(VERSION 2.8 FATAL_ERROR) 
PROJECT (photobooth)

find_package( Qt5Core )
find_package( Qt5PrintSupport )
find_package( Qt5Gui )
find_package( Qt5Widgets )

set( NAME_SRC
    src/main.cpp
    src/photobooth.cpp      
)

set( NAME_HEADERS 
    include/photobooth.h          

)

INCLUDE_DIRECTORIES( ${CMAKE_CURRENT_SOURCE_DIR}/include )
link_directories( ${CMAKE_BINARY_DIR}/bin)

set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/bin)

add_executable( photobooth ${NAME_SRC} ${NAME_HEADERS} )

target_link_libraries( photobooth Qt5::Widgets )
target_link_libraries( photobooth Qt5::Core )
target_link_libraries( photobooth Qt5::Qt5PrintSupport )
target_link_libraries( photobooth Qt5::Qt5Gui )

这是Cmake的输出：

Configuring done
CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5PrintSupport" but the target
  was not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5Gui" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5PrintSupport" but the target
  was not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5Gui" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5PrintSupport" but the target
  was not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5Gui" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5PrintSupport" but the target
  was not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5Gui" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) in CMakeLists.txt:
  Policy CMP0020 is not set: Automatically link Qt executables to qtmain
  target on Windows.  Run "cmake --help-policy CMP0020" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5PrintSupport" but the target
  was not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

CMake Warning (dev) at CMakeLists.txt:24 (add_executable):
  Policy CMP0028 is not set: Double colon in target name means ALIAS or
  IMPORTED target.  Run "cmake --help-policy CMP0028" for policy details.
  Use the cmake_policy command to set the policy and suppress this warning.

  Target "photobooth" links to target "Qt5::Qt5Gui" but the target was not
  found.  Perhaps a find_package() call is missing for an IMPORTED target, or
  an ALIAS target is missing?
This warning is for project developers.  Use -Wno-dev to suppress it.

Generating done

我的项目使用Visual Studio 14 2015 Win64作为我的构建生成。此外，当我在main.cpp中包含QTextDocument时，它会找到它而不是QPrinter。有什么我做错了吗？

Answer 1

一些提示：

find_package( Qt5Core )
find_package( Qt5PrintSupport )
find_package( Qt5Gui )
find_package( Qt5Widgets )

您可以在一个find_package中合并这些来电，寻找Qt5：

find_package(Qt5 REQUIRED
    Core
    PrintSupport
    Gui
    Widgets
)

请注意使用关键字REQUIRED，如果无法找到包，将导致CMake引发错误。查看错误日志，这可能是您的问题。你在某个地方设置了Qt5_DIR吗？

Core和Gui是可选的，因为Widgets取决于它们，因此它们会自动添加。

您应该将CMake所需的版本更改为2.8.11，以确保导入的目标嵌入包含目录。

您应该考虑target_include_directories而不是INCLUDE_DIRECTORIES以避免全局污染，并将参数附加到目标。这不是一个真正的观点，而是未来更大项目的良好实践。

您对link_directories的来电在这里毫无用处。如果您需要链接库，请选择target_link_libraries。

EXECUTABLE_OUTPUT_PATH是一个旧变量，由RUNTIME_OUTPUT_DIRECTORY取代，是一个目标属性。

清理后，您的CMake项目可能如下：

cmake_minimum_required(VERSION 2.8.11 FATAL_ERROR)
PROJECT (photobooth)

find_package(Qt5 REQUIRED
    Widgets
    PrintSupport
)

set( NAME_SRC
    src/main.cpp
    src/photobooth.cpp
)
set( NAME_HEADERS
    include/photobooth.h
)

add_executable( photobooth ${NAME_SRC} ${NAME_HEADERS} )

set_target_properties(photobooth PROPERTIES
    RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin
)

target_include_directories(photobooth PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include)

target_link_libraries( photobooth Qt5::Widgets Qt5::PrintSupport )

Answer 2

您需要＆＃34; 2.8＆＃34; CMake的版本，太低用于Qt的使用功能，如导入的目标和自动链接到Windows上的qtmain。这正是政策警告的内容。

改为使用

cmake_minimium_required(VERSION 2.8.11)

（此版本不再需要 FATAL_ERROR 选项。）

请注意，即使您拥有CMake 2.8.12，它也会模拟您在cmake_minimium_required命令中编写的完全版本。

将QT5库添加到CMake

2 个答案: