Talking about the shadow build of Qmake (that is, separating the source path from the build path)

Shadow Build

What is Shadow build? is to separate the source path and build path (that is, the generated makefile files and other products are not put into the source path), so as to ensure the clean source path.

It's not Qmake's original thing, CMake used it long ago.

	CMake	Qmake	Note
In-source	CMake.	Qmake Project.pro	Execute under the source path
Out-of-source (Shadow-build)	mkdir Build CD Build CMake. /project	mkdir Build CD Build Qmake. /project/project.pro	Create directory, execute under other paths (parameters point to Source path)

• Attention:
• Qmake Shadow build is still very imperfect, and cmake is not the same
• Qmake Shadow build directory may not be a subdirectory of the source directory

Before

Before Shadow-build, in order to separate the generated and the source as much as possible, we would generally set a lot of qmake variables, such as:

DESTDIR = $ $PWD/bin	Destination file Drop Location
Dlldestdir = $$[Qt_install_bins]	Win under Copy dynamic library to qt installation path
Moc_dir = $ $PWD/temp	Where the product of the MOC is placed
Rcc_dir = $ $PWD/temp	Where the product of RCC is placed
Ui_dir = $ $PWD/temp	Where the products of UIC are placed
objects_dir = Pwd / te mp / TARGET	compiler-generated. O (. obj) file placement

In this way, we put the extended part of QT (MOC/RCC/UIC) and the intermediate product of the compiler into a temp subdirectory. The source is still relatively clean, but compared with out-of-source, or not very cool:

• The generated makefile is still under the source path
• If a set of source code to use msvc2008, msvc2008, MinGW separately compiled and not interfere with each other?

Create a build directory and then downgrade the directory with the appropriate qmake, and point to the project file under the source code to

Qmake. /project-sources/project.pro


An example of myself:


Suppose the project is stored under huang/called XXX


Shadow Directory and Huang are located at the same level called Huangbuild


We want to establish xxx-debug and xxx-release in Huangbuild to mark the Debug and release of XXX.


We need to enter the Huangbuild directory, if it is debug into the debug directory, this time qmake. /.. /huang/xxx.pro


Release is similar to this

Useful variables

As mentioned earlier, Qmake's Shadow-build function is not yet complete.

Pwd	The directory where the file (. Pro or. pri) of the variable is used, notice the comparison to the next
_pro_file_pwd_	The directory where the pro file is located (note: Even if it is used within a PRI file, it also refers to the directory where the pro file contains it)
_pro_file_	Full path to Pro file
Out_pwd	The path where the generated makefile file is located, and the_pro_file_pwd_corresponds

When built with shadow build, Out_pwd and_pro_file_pwd_are the same, so that we can determine what constructs are used, and then take different actions:

!contains(_PRO_FILE_PWD_, $${OUT_PWD}) {
#do something when using shadow build
}
#It's better to use equals directly, but manual doesn't explain it (so I don't know if your qmake supports it, at least it will be supported after qt4.5)
!equals(_PRO_FILE_PWD_, OUT_PWD) {
#do something when using shadow build
}

For example, when using Out-of-source build, we may need to copy some files from the source directory to the build directory, when using CMake, this is easy to do, but in Qmake, it seems that the lack of a common way, a simple demo is as follows:

• Note: All files to be copied can only be specified with a relative path (you can help to improve it, I did not find the appropriate function)

• This code needs to be placed in the pro file, or within the PRI file of the same directory

FILES_COPY_SRC = $$SOURCES /
                 dbzhang800.txt /
                 images/abc.png /
                 i18n/abcd.qm

win32{
    COPY = copy /y
    MKDIR = mkdir
}else{
    COPY = cp
    MKDIR = mkdir -p
}
!equals(_PRO_FILE_PWD_, OUT_PWD) {
    for(f, FILES_COPY_SRC){
        dist_file = $$OUT_PWD/$$f
        dist = $$dirname(dist_file)
        win32:dist = $$replace(dist, /, //)
        !exists($$dist):system($$MKDIR $$dist)
        !exists($$dist_file):system($$COPY $$f $$dist)
    }
}

Or write a little explanation, it may be helpful to everyone, but also to prevent their long time will forget.

• Under Windows, you must first replace the path separator with "/"
• The destination directory does not exist and the directory is created.
• The destination file does not exist, copy the file.

Some of my operations,

http://blog.csdn.net/ac_huang/article/details/23867443

Talking about the shadow build of Qmake (that is, separating the source path from the build path)