You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
137 lines
3.1 KiB
137 lines
3.1 KiB
\chapter Using Precompiled Headers
|
|
|
|
\target About
|
|
\section1 About Precompiled Headers
|
|
\index About Precompiled Headers
|
|
\index Using Precompiled Headers
|
|
\index Precompiled Headers
|
|
\index PCH
|
|
|
|
Precompiled headers are a performance feature supported by some
|
|
compilers to compile a stable body of code, and store the compiled
|
|
state of the code in a binary file. During subsequent compilations,
|
|
the compiler will load the stored state, and continue compiling the
|
|
specified file. Each subsequent compilation is faster because the
|
|
stable code does not need to be recompiled.
|
|
|
|
\e qmake supports the use of precompiled headers (PCH) on some
|
|
platforms and build environments, including:
|
|
\list
|
|
\i Windows
|
|
\list
|
|
\i nmake
|
|
\i Dsp projects (VC 6.0)
|
|
\i Vcproj projects (VC 7.0 \& 7.1)
|
|
\endlist
|
|
\i Mac OS X
|
|
\list
|
|
\i Makefile
|
|
\i Xcode
|
|
\i GCC 3.3 and up
|
|
\endlist
|
|
\i Unix
|
|
\list
|
|
\i GCC 3.4 and up
|
|
\endlist
|
|
\endlist
|
|
|
|
|
|
\target ADD_PCH
|
|
\section1 Adding PCH to your project
|
|
|
|
|
|
\target PCH_CONTENTS
|
|
\section2 Contents of the precompiled header file
|
|
|
|
The precompiled header must contain code which is \e stable
|
|
and \e static throughout your project. A typical PCH might look
|
|
like this:
|
|
\section3 stable.h
|
|
|
|
\code
|
|
/* Add C includes here */
|
|
|
|
#if defined __cplusplus
|
|
/* Add C++ includes here */
|
|
#include <stdlib>
|
|
#include <iostream>
|
|
#include <vector>
|
|
#include <qapplication.h> // Qt includes
|
|
#include <qpushbutton.h>
|
|
#include <qlabel.h>
|
|
#include "thirdparty/include/libmain.h"
|
|
#include "my_stable_class.h"
|
|
...
|
|
#endif
|
|
\endcode
|
|
|
|
Note that a precompiled header file needs to separate C includes from
|
|
CPP includes, since the precompiled header file for C files may not
|
|
contain C++ code.
|
|
|
|
|
|
\target PROJECT_OPTIONS
|
|
\section2 Project options
|
|
|
|
To make your project use PCH, the only thing you need to change in
|
|
your project settings (.pro), is to include the PRECOMPILED_HEADER option:
|
|
\code
|
|
PRECOMPILED_HEADER = stable.h
|
|
\endcode
|
|
\e qmake will handle the rest, to ensure the creation and use of the
|
|
precompiled header file. You do not need to include the precompiled
|
|
header file in HEADERS, as qmake will do this if the configuration
|
|
supports PCH.
|
|
|
|
All platforms that support precompiled headers have the configuration
|
|
option \Bold precompile_header set. Using this option, you may trigger
|
|
conditional blocks in your .pro file, to add settings when using PCH.
|
|
For example:
|
|
\code
|
|
precompile_header:!isEmpty(PRECOMPILED_HEADER) {
|
|
DEFINES += USING_PCH
|
|
}
|
|
|
|
\endcode
|
|
|
|
\target EXAMPLE_PROJECT
|
|
\section1 Example project
|
|
|
|
You can find the following source code in the
|
|
\e{qt/qmake/examples/precompile} directory:
|
|
|
|
\Bold mydialog.ui
|
|
\quotefile precompile/mydialog.ui
|
|
\skipto <!
|
|
\printuntil </UI>
|
|
|
|
\Bold stable.h
|
|
\quotefile precompile/stable.h
|
|
\skipto /*
|
|
\printuntil #endif
|
|
|
|
\Bold myobject.h
|
|
\quotefile precompile/myobject.h
|
|
\skipto #include
|
|
\printuntil }
|
|
|
|
\Bold myobject.cpp
|
|
\quotefile precompile/myobject.cpp
|
|
\skipto #include
|
|
\printuntil }
|
|
|
|
\Bold util.cpp
|
|
\quotefile precompile/util.cpp
|
|
\skipto void
|
|
\printuntil }
|
|
|
|
\Bold main.cpp
|
|
\quotefile precompile/main.cpp
|
|
\skipto #include
|
|
\printuntil }
|
|
|
|
\Bold precompile.pro
|
|
\quotefile precompile/precompile.pro
|
|
\skipto #
|
|
\printuntil .ui
|