/*! \page qtboost Using the Qt Booster

Launcher makes it possible to start up various types of applications very
quickly. Launcher uses a different <em>booster</em> for each of the
application types. This section concentrates on launching Qt applications with the Qt booster.

\section intro Introduction

The launcher can start an application if the following pre-requisites are met:

\li The application is compiled and linked to a position independent binary
(executable or library) 

\li The application is started with the \c invoker command instead of executing the executable file.

\section howitworksforqt How the launcher can help Qt applications

There no cache (like MComponentCache) for Qt applications, but preloading Qt libraries make the launch faster. Using the launcher will also save memory.

\section source Modifying source code

The launcher needs to find the symbol \c main in the application binary
in order to start executing the application. However, unnecessary
symbols in the application binary cause unnecessary overhead, so the
recommended flags for compiling for the launcher hide symbols 
by default. When the flags are used, the main function must be
explicitly exported as follows:

\code
#include <QtCore/QtGlobal>

Q_DECL_EXPORT int main(int argc, char **argv)
{
...
}
\endcode

\section compilation Compiling and linking

To compile binaries that can be run with applauncherd, use
\c -fPIC option to produce position-independent code. To
produce a position-independent executable, \c -pie option and \c
-rdynamic options can be used in linking. This makes it possible to execute the result both 
traditionally and with the invoker.

To improve linking and load times of shared object libraries the size
of dynamic export table it is encouraged to hide the unnecessary
symbols from the resulting binary by using \c -fvisibility=hidden and
\c -fvisibility-inlines-hidden flags in compilation as well.

\subsection qmaketips Building with QMake

\subsubsection qmakepreferred Building in the preferred way

Once you have installed the \c applauncherd-dev package, simply use QMake configuration option \c qt-boostable:

\code
CONFIG += qt-boostable
\endcode

This tells qmake to use the \c qt-boostable feature, which
uses \c pkg-config for the flags. Unfortunately qmake does not complain
if you add the line but have not installed \c applauncherd-dev, so if the
QMake magic does not seem to work, double-check that the package is
indeed installed.

\subsubsection qmakeother Building with pkg-config

Use the \c pkg-config to get the correct flags:

\code
QMAKE_CXXFLAGS += `pkg-config --cflags qt-boostable`
QMAKE_LFLAGS += `pkg-config --libs qt-boostable`
\endcode

If \c applauncherd-dev is not installed, \c pkg-config 
complains when you run \c make.

\subsubsection qmakelastresort The last resort

Manually define the following variables in the .pro file:

\code
QMAKE_CXXFLAGS += -fPIC -fvisibility=hidden -fvisibility-inlines-hidden
QMAKE_LFLAGS += -pie -rdynamic
\endcode

It is then up to you to modify the .pro file if there are changes to the
required compiler and linker flags.

\subsection cmaketips Building with CMake

1. Use \c pkg-config in CMake by including \c FindPkgConfig in \c CMakeLists.txt:

\code
include(FindPkgConfig) 
\endcode

2. To obtain the compiler and linker flags, add the following lines:

\code
pkg_check_modules(QT_BOOSTABLE REQUIRED qt-boostable)
add_definitions(${QT_BOOSTABLE_CFLAGS})
link_libraries(${QT_BOOSTABLE_LDFLAGS})
\endcode  

If you do not want to use \c pkg-config for some reason, you can manually add the
compiler and linker flags as follows:

\code
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -fvisibility=hidden -fvisibility-inlines-hidden")
set(CMAKE_EXE_LINKER_FLAGS "-pie -rdynamic")
\endcode  

Again, you need to update the flags if something changes.

\subsection pkgconfig Obtaining flags with pkg-config

The package \c applauncherd-dev provides the necessary files for
\c pkg-config to get the appropriate compiler and linker flags.

1. To get the compiler flags, use the following:

\code
pkg-config --cflags qt-boostable
\endcode

2. To get the linker flags, use the following:

\code
pkg-config --libs qt-boostable
\endcode

\section running Running boosted application

Check that applauncherd package is installed and applancherd daemon is
running. You can now run your application as usual as
/usr/bin/application_binary, or use the qtboosted launching by running:

\code
invoker --type=q /usr/bin/application_binary
\endcode
*/