Beyond Linux From Scratch - Version 5.1-pre1

Part VIII. X + Window Managers

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X Libraries

This chapter does not contain libraries that are required to run X. It does contain libraries that enhance X. The enhancement is as simple as font support or as complex as libraries that sit between X and applications that run on X whose purpose is to standardize the look and feel and inter-process communications so that applications written by different programmers end up looking and acting similarly. They also assist programmers by supplying common elements.

Qt-3.3.2

Introduction to Qt

The Qt package contains a C++ GUI library. This is useful for creating graphical applications or executing graphical applications that are dynamically linked to the Qt library. One of the major users of Qt is KDE.

Package information

Qt dependencies

Required

Chapter 25, X Window Environment

Recommended

libjpeg-6b and libmng-1.0.7.

Optional

NAS-1.6, CUPS-1.1.20, MySQL-4.0.20, PostgreSQL-7.4.2, Firebird, and unixODBC.

Installation of Qt

There are several ways to install a complicated package such as Qt. The files are not completely position independent. Installation procedures execute the program pkg-config to determine the location of package executables, libraries, headers, and other files. For Qt, pkg-config will look for the file lib/pkgconfig/qt-mt.pc which must be modified if relocating the package. This file is set up correctly by the build process.

The default installation places the files in /usr/local/qt/. Many commercial distributions place the files in the system's /usr hierarchy. The package can also be installed in an arbitrary directory.

This section will demonstrate two different methods.

[Note]

Note

The build time for Qt is quite long. If you want to save some time and don't want the tutorials and examples, change the first make line to:

make sub-tools

Method 1 - Installing in the /usr hierarchy

The advantage of this method is that no updates to the /etc/ld.so.conf or /etc/man.conf files are required. The package files are distributed within several subdirectories of the /usr hierarchy. This is the method that most commercial distributions use. 

sed -i "s:cp -f:install:" mkspecs/linux-g++/qmake.conf &&
bash
export PATH=$PWD/bin:$PATH &&
export LD_LIBRARY_PATH=$PWD/lib:$LD_LIBRARY_PATH &&
./configure -prefix /usr -docdir /usr/share/doc/qt \
    -headerdir /usr/include/qt -plugindir /usr/lib/qt/plugins \
    -datadir /usr/share/qt -translationdir /usr/share/qt/translations \
    -sysconfdir /etc/qt -qt-gif -system-zlib \
    -no-exceptions -thread -plugin-imgfmt-png -system-libpng &&
find -type f -name Makefile | xargs sed -i "s@-Wl,-rpath,/usr/lib@@g" &&
make &&
make install &&
ln -sf libqt-mt.so /usr/lib/libqt.so &&
cp -r doc/man /usr/share &&
cp -r examples /usr/share/doc/qt &&
exit

Method 2 - Installing in /opt

This is the method recommended by the Qt developers. It has the advantage of keeping all the package files consolidated in a dedicated directory hierarchy. By using this method, an update can be made without overwriting a previous installation and users can easily back up to a previous version by changing one symbolic link.

The Qt developers use a default location of /usr/local/qt/, however this procedure puts the files in /opt/qt-3.3.2/ and then creates a symbolic link to /opt/qt/. 

bash
export QTDIR=$PWD &&
export LD_LIBRARY_PATH=$PWD/lib:$LD_LIBRARY_PATH &&
export PATH=$PWD/bin:$PATH &&
./configure -prefix /opt/qt-3.3.2 -qt-gif -system-libpng \
   -system-libmng -system-zlib -system-libjpeg -no-exceptions \
   -thread -plugin-imgfmt-png &&
make &&
make install &&
ln -sfn qt-3.3.2 /opt/qt &&
ln -s libqt-mt.so /opt/qt/lib/libqt.so &&
cp -r doc/man /opt/qt/doc &&
cp -r examples /opt/qt/doc
exit
Configuration

For Method 2 only, update the /etc/ld.so.conf and /etc/man.conf files. 

cat >> /etc/ld.so.conf << "EOF"
# Begin qt addition to /etc/ld.so.conf

/opt/qt/lib

# End qt addition
EOF
ldconfig

cat >> /etc/man.conf << "EOF"
# Begin qt addition to man.conf

MANPATH /opt/qt/doc/man

# End qt addition to man.conf
EOF

Also, QTDIR needs to be set when compiling packages that depend on Qt. Add the following so that it is available when compiling packages. 

export QTDIR=/opt/qt

Command explanations

sed -i "s:cp -f:install:" mkspecs/linux-g++/qmake.conf: install is safer than cp when libraries are in use.

bash: This command enters a sub-shell to isolate environment changes.

export QTDIR=$PWD: This command defines where the root of the Qt directory is located.

export LD_LIBRARY_PATH=$PWD/lib:$LD_LIBRARY_PATH: This command allows the not yet installed qt libraries to be used by the not yet installed qt programs.

export PATH=$PWD/bin:$PATH: This command allows the build process to find supporting executables.

-qt-gif: This switch adds support for gif files to the libraries.

-system-zlib -system-libpng: This switch forces the library to use the shared libraries that are on your system instead of recreating its own set of support libraries for these functions.

-no-exceptions: This switch disables the exceptions coding generated by the C++ compiler.

-thread: This switch adds support for multi-threading.

find -type f -name Makefile | xargs sed -i "s@-Wl,-rpath,/usr/lib@@g": This command removes hardcoded run-time path, else uic tries to run with system installed Qt libraries.

ln -s libqt-mt.so /usr/lib/libqt.so: This command allows configure scripts to find a working Qt installation.

cp -r doc/man /usr/share (or /opt/qt/doc): This command installs the man pages which are missed by make install.

cp -r examples /usr/share/doc/qt (or /opt/qt/doc): This command installs the examples which are missed by make install.

exit: This command returns to the parent shell and eliminates environment variables set earlier.

Configuring Qt

Configuration Information

As with most libraries, there is no configuration to do, save that the library directory i.e. /opt/lib or /usr/local/lib should appear in /etc/ld.so.conf so that ldd can find the shared libraries. After checking that this is the case, /sbin/ldconfig should be run while logged in as root.

Contents

The Qt/X11 library contains API's necessary to use programs based on Qt GUI toolkit.

The Qt package contains assistant, designer, linguist, lrelease, lupdate, moc, qm2ts, qmake, qtconfig, uic, and the libqt-mt and libqui libraries.

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