/*!
\page qwtinstall Installing Qwt

\tableofcontents

\section DOWNLOAD Download

  Stable Qwt releases are available from the 
  Qwt <a href="https://sourceforge.net/projects/qwt/files/qwt">project page</a>.

  Qwt-6.3.0 consists of 3 files:

  - qwt-6.3.0.zip\n
    Zip file with the Qwt sources and the html documentation for Windows

  - qwt-6.3.0.tar.bz2\n
    Compressed tar file with the Qwt sources and the html documentation
    for UNIX systems ( Linux, Mac, ... )

  - qwt-6.3.0.qch\n
    Qwt documentation as Qt Compressed Help document, that can be loaded into
    the Qt Assistant or Creator. In the Qt Creator context sensitive help will be
    available like for Qt classes.

\section INSTALL Installing Qwt

  Beside headers, libraries and the html version of the class documentation a proper
  Qwt installation contains a Designer plugin and a Qwt features file for building 
  applications using Qwt.

  All files will be copied to an installation directory, that is configurable
  by editing qwtconfig.pri. Its default settings is:

  - Windows\n
    C:\\Qwt-6.3.0

  - Unix like systems\n
    /usr/local/qwt-6.3.0

  For the rest of the document this install path will be written as <i>${QWT_ROOT}</i> 
  and needs to be replaced by the real path in all commands below.

  It is not unlikely, to have more than one installation of Qwt 
  on the same system. F.e for using the Qwt Designer plugin in the Qt Creator 
  a version of Qwt is necessary with the same Qt and compiler combination, that had 
  been used for building the Qt Creator ( see "Help->About Qt Creator ..." ). 

  Installing Qwt is done in 3 steps, that are quite common on UNIX systems.

  -# Configuration\n
     In the configuration step all parameters are set to control how
     to build and install Qwt
  -# Build\n
     In the build step binaries are built from the source files.
  -# Installation\n
     The installation copies and rearranges all files that are necessary to build
     Qwt applications to a target directory. 

  The installation doesn't modify the system beside copying files to a
  directory in a proper way. After removing build and installation directories the
  system is in the same state as it was before.

\subsection CONFIGSUBSECTION Configuration

  Configuring Qwt has to be done by editing the Project files used for building:

  - qwtbuild.pri\n
    qwtbuild.pri contains settings for how to build Qwt. All settings
    of this file are only for building Qwt itself and doesn't have an impact
    on how an application using Qwt is built. Usually its default settings
    doesn't need to be modified.

  - qwtconfig.pri\n
    qwtconfig.pri defines what modules of Qwt will be built and where to
    install them. qwtconfig.pri gets installed together with the Qwt features
    file qwt.prf and all its settings are known to project files for building
    Qwt applications.

  In qwtconfig.pri the meaning of each option is explained in detail - it's worth
  reading it before running into problems later.

\subsection BUILDSUBSECTION Build and installation

  The Qt Creator is a graphical frontend for calling qmake/make and - technically -
  it could be used for building and installing Qwt. But as this way requires a lot
  more understanding of details the following step by step instructions are for 
  the easier way using the command line.

\subsubsection qwtinstall-unix Unix-like systems

  The first step before creating the Makefile is to check that the correct version
  of qmake is used. F.e. on older Linux distribution you often find a Qt3 qmake 
  and in the path.

  The default setting of qmake is to generate a makefile that builds Qwt for the 
  same environment where the version of qmake has been built for. 
  So creating a makefile usually means something like:

\code
  cd qwt-6.3.0
  /usr/local/Qt-5.0.1/bin/qmake qwt.pro
\endcode

  The generated Makefile includes all paths related to the chosen Qt version 
  and the next step is:

\code
  make
\endcode
  ( On multicore systems you can speed up building the Qwt libraries with running several 
  jobs simultaneously:  f.e. "make -j4" on a dual core. )


  Finally you have to install everything below the directories you have specified
  in qwtconfig.pri. Usually this is one of the system directories ( /usr/local, /opt, ... )
  where you don't have write permission and then the installation
  needs to be done as root:

\code
  sudo make install
\endcode
  ( On systems where sudo is not supported you can do the same with: su -c "make install" )

\subsubsection qwtinstall-windows Windows 

  Qt packages offer a command line interface, that can be found in the Qt application 
  menu: f.e "All Programs -> Qt -> Command Prompt".  It is not mandatory to use it, but 
  probably the easiest way as it offers an environment, where everything is 
  initialized for a version of Qt ( f.e qmake is in the PATH ).

  Creating a makefile usually means something like:

\code
  cd qwt-6.3.0
  qmake qwt.pro
\endcode

  The generated makefile includes all paths related to the chosen Qt version.

\paragraph qwtinstall-windows-mingw MinGW

  For MinGW builds the name of the make tool is "mingw32-make" 

\code
  mingw32-make
\endcode
  ( On multicore systems you can speed up building the Qwt libraries with running several 
  jobs simultaneously: "mingw32-make -j" )

  Finally you have to install everything below the directories you have specified
  in qwtconfig.pri. 

\code
  mingw32-make install
\endcode


\paragraph qwtinstall-windows-msvc MSVC

  For MSVC builds the name of the make tool is "nmake". Alternatively
  it is possible to use "jom" ( https://wiki.qt.io/Jom ),
  that is usually included in a Qt Creator package.

\code
  nmake
\endcode

  Finally you have to install everything below the directories you have specified
  in qwtconfig.pri. 

\code
  nmake install
\endcode


\section INTEGRATION Qwt and the Qt tool chain

\subsection USEPLUGIN Designer plugin

  The Designer plugin and the corresponding Qwt library ( if the plugin has not 
  been built self containing ) have to be compatible with Qt version of the application 
  loading it ( usually the Qt Creator )  - what is often a different version of the 
  Qt libraries you want to build your application with. F.e on Windows the Qt Creator
  is usually built with a MSVC compiler - even if included in a MinGW package !

  To help Qt Designer/Creator with locating the Qwt Designer plugin 
  you have to set the environment variable QT_PLUGIN_PATH, modify qt.conf - 
  or install the plugin to one of the application default paths.

  The Qt documentation explains all options in detail:

  - https://doc.qt.io/qt-5/deployment-plugins.html
  - https://doc.qt.io/qtcreator/adding-plugins.html

  F.e. on a Linux system you could add the following lines to .bashrc:

\code
  QT_PLUGIN_PATH="${QWT_ROOT}/plugins:$QT_PLUGIN_PATH"
  export QT_PLUGIN_PATH
\endcode

  When the plugin has not been built including the Qwt library 
  ( see QwtDesignerSelfContained in qwtconfig.pri )
  the Qt Designer/Creator also needs to locate the Qwt libraries. On Unix systems the 
  path to the installed library is compiled into the plugin ( see rpath, ldd ), but on 
  Windows the Qt Creator needs to be configured ( ( \ref RUNAPP ) in the same way as for 
  any application using Qwt. 

  In case of problems the diagnostics of Qt Creator and Designer are very limited 
  ( usually none ), but setting the environment variable QT_DEBUG_PLUGINS might help. 
  In the Qt Creator it is possible to check which plugins were loaded 
  successfully and for certain problems it also lists those that were recognized
  but failed  ( <i>Tools > Form Editor > About Qt Designer Plugins</i> ).

\subsection USEHELP Online Help

  The Qwt class documentation can be loaded into the Qt Creator: 

  - open the settings dialog from the <i>Tools->Options</i> menu 
  - raise the tab "Help->Documentation". 
  - press the <i>Add</i> button and select qwt-6.3.0.qch.

  Now the context sensitive help ( <i>F1</i> ) works for Qwt classes.

  For browsing the documentation in the Qt Assistant:

  - open the settings dialog from the <i>Edit->Preferences</i> menu 
  - raise the tab <i>Documentation</i>. 
  - press the <i>Add</i> button and select qwt-6.3.0.qch.

\section COMPILEANDLINKAPP Building a Qwt application

All flags and settings that are necessary to compile and link an application using Qwt 
can be found in the file ${QWT_ROOT}/features/qwt.prf. 

When using qmake it can included from the application project file in 2 different ways:

  - Adding Qwt as qmake feature\n\n
    When using the qmake feature mechanism you can bind a special version
    of qmake to a special installation of Qwt without having to add
    this dependency to the application project.
    How to add Qwt as feature is documented in the 
    <a href="http://doc.qt.io/qt-5/qmake-advanced-usage.html#adding-new-configuration-features">qmake docs</a>.

    After adding Qwt as a feature f.e on Linux as a persistent property ....
@code
    qmake -set QMAKEFEATURES ${QWT_ROOT}/features
@endcode
    .. the following line can be added to the application project file:
\code
    CONFIG += qwt
\endcode 

  - Including qwt.prf in the application project file\n\n
    Instead of using qwt.prf as qmake feature it can be included from
    the application project file:\n\n
\code
include ( ${QWT_ROOT}/features/qwt.prf )
\endcode \n
    The advantage of using a direct include is, that all settings of qwt.prf 
    are known to the application project file ( qmake features are included after the
    application project file has been parsed ) and it can be implemented depending on - 
    f.e. settings made in qwtconfig.pri.

On Unix platforms it is possible to link a runtime path into the executable, so that the
location of the Qwt libraries can be found without having to configure a runtime environment:
  - <a href="/https://doc.qt.io/qt-5/qmake-variable-reference.html#qmake-lflags-rpath">QMAKE_LFLAGS_RPATH</a> 
  - <a href="/https://doc.qt.io/qt-5/qmake-variable-reference.html#qmake-rpath">QMAKE_RPATH</a> 
  - <a href="/https://doc.qt.io/qt-5/qmake-variable-reference.html#qmake-rpathdir">QMAKE_RPATHDIR</a> 


\section RUNAPP Running a Qwt application

  When using Qwt as shared library ( DLL ) the 
  <a href="http://en.wikipedia.org/wiki/Dynamic_linker">dynamic linker</a> has to find
  it according to the rules of the operating system.

\subsection RUNWINDOWS Windows

The only reasonable way to configure the runtime environment - without having to copy the
Qwt libraries around - is to modify the PATH variable. F.e. this could be done by adding
the following line to some batch file:

\code
set PATH=%PATH%;${QWT_ROOT}\lib
\endcode

\subsection RUNLINUX GNU/Linux

  Read the documentation about:

  - <i>ldconfig</i>
  - <i>/etc/ld.so.conf</i>
  - <i>LD_LIBRARY_PATH</i>

  Using the <i>ldd</i> command a configuration can be tested.
*/
