scons_gd/scons/test/Docbook/basedir/htmlhelp/image/manual.xml
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<article>
<title>The SCons qt4 tool</title>
<articleinfo>
<author>
<surname>Dirk Baechle</surname>
</author>
<pubdate>2010-12-06</pubdate>
</articleinfo>
<section id="basics">
<title>Basics</title>
<para>This tool can be used to compile Qt projects, designed for versions
4.x.y and higher. It is not usable for Qt3 and older versions, since some
of the helper tools (<literal>moc</literal>, <literal>uic</literal>)
behave different.</para>
<section id="install">
<title>Install</title>
<para>Installing it, requires you to copy (or, even better: checkout)
the contents of the package's <literal>qt4</literal> folder to</para>
<orderedlist>
<listitem>
<para><quote><literal>/path_to_your_project/site_scons/site_tools/qt4</literal></quote>,
if you need the Qt4 Tool in one project only, or</para>
</listitem>
<listitem>
<para><quote><literal>~/.scons/site_scons/site_tools/qt4</literal></quote>,
for a system-wide installation under your current login.</para>
</listitem>
</orderedlist>
<para>For more infos about this, please refer to</para>
<itemizedlist>
<listitem>
<para>the SCons User's Guide, chap. 17.7 "Where to put your custom
Builders and Tools" and</para>
</listitem>
<listitem>
<para>the SCons Tools Wiki page at <ulink
url="https://github.com/SCons/scons/wiki/ToolsIndex">https://github.com/SCons/scons/wiki/ToolsIndex</ulink>.</para>
</listitem>
</itemizedlist>
</section>
<section id="activation">
<title>How to activate</title>
<para>For activating the tool "qt4", you have to add its name to the
Environment constructor, like this</para>
<screen>env = Environment(tools=['default','qt4'])
</screen>
<para>On its startup, the Qt4 tool tries to read the variable
<literal>QT4DIR</literal> from the current Environment and
<literal>os.environ</literal>. If it is not set, the value of
<literal>QTDIR</literal> (in Environment/<literal>os.environ</literal>)
is used as a fallback.</para>
<para>So, you either have to explicitly give the path of your Qt4
installation to the Environment with</para>
<screen>env['QT4DIR'] = '/usr/local/Trolltech/Qt-4.2.3'
</screen>
<para>or set the <literal>QT4DIR</literal> as environment variable in
your shell.</para>
</section>
<section id="requirements">
<title>Requirements</title>
<para>Under Linux, "qt4" uses the system tool
<literal>pkg-config</literal> for automatically setting the required
compile and link flags of the single Qt4 modules (like QtCore,
QtGui,...). This means that</para>
<orderedlist>
<listitem>
<para>you should have <literal>pkg-config</literal> installed,
and</para>
</listitem>
<listitem>
<para>you additionally have to set
<literal>PKG_CONFIG_PATH</literal> in your shell environment, such
that it points to $<literal>QT4DIR/lib/pkgconfig</literal> (or
$<literal>QT4DIR/lib</literal> for some older versions).</para>
</listitem>
</orderedlist>
<para>Based on these two environment variables
(<literal>QT4DIR</literal> and <literal>PKG_CONFIG_PATH</literal>), the
"qt4" tool initializes all <literal>QT4_*</literal> construction
variables listed in the Reference manual. This happens when the tool is
"detected" during Environment construction. As a consequence, the setup
of the tool gets a two-stage process, if you want to override the values
provided by your current shell settings:</para>
<screen># Stage 1: create plain environment
qtEnv = Environment()
# Set new vars
qtEnv['QT4DIR'] = '/usr/local/Trolltech/Qt-4.2.3
qtEnv['ENV']['PKG_CONFIG_PATH'] = '/usr/local/Trolltech/Qt-4.2.3/lib/pkgconfig'
# Stage 2: add qt4 tool
qtEnv.Tool('qt4')
</screen>
</section>
</section>
<section id="boilerplate">
<title>Suggested boilerplate</title>
<para>Based on the requirements above, we suggest a simple ready-to-go
setup as follows:</para>
<para>SConstruct</para>
<screen># Detect Qt version
qtdir = detectLatestQtDir()
# Create base environment
baseEnv = Environment()
#...further customization of base env
# Clone Qt environment
qtEnv = baseEnv.Clone()
# Set QT4DIR and PKG_CONFIG_PATH
qtEnv['ENV']['PKG_CONFIG_PATH'] = os.path.join(qtdir, 'lib/pkgconfig')
qtEnv['QT4DIR'] = qtdir
# Add qt4 tool
qtEnv.Tool('qt4')
#...further customization of qt env
# Export environments
Export('baseEnv qtEnv')
# Your other stuff...
# ...including the call to your SConscripts
</screen>
<para>In a SConscript</para>
<screen># Get the Qt4 environment
Import('qtEnv')
# Clone it
env = qtEnv.clone()
# Patch it
env.Append(CCFLAGS=['-m32']) # or whatever
# Use it
env.StaticLibrary('foo', Glob('*.cpp'))
</screen>
<para>The detection of the Qt directory could be as simple as directly
assigning a fixed path</para>
<screen>def detectLatestQtDir():
return "/usr/local/qt4.3.2"
</screen>
<para>or a little more sophisticated</para>
<screen># Tries to detect the path to the installation of Qt with
# the highest version number
def detectLatestQtDir():
if sys.platform.startswith("linux"):
# Simple check: inspect only '/usr/local/Trolltech'
paths = glob.glob('/usr/local/Trolltech/*')
if len(paths):
paths.sort()
return paths[-1]
else:
return ""
else:
# Simple check: inspect only 'C:\Qt'
paths = glob.glob('C:\\Qt\\*')
if len(paths):
paths.sort()
return paths[-1]
else:
return os.environ.get("QTDIR","")
</screen>
</section>
<section id="firstproject">
<title>A first project</title>
<para>The following SConscript is for a simple project with some cxx
files, using the QtCore, QtGui and QtNetwork modules:</para>
<screen>Import('qtEnv')
env = qtEnv.Clone()
env.EnableQt4Modules([
'QtGui',
'QtCore',
'QtNetwork'
])
# Add your CCFLAGS and CPPPATHs to env here...
env.Program('foo', Glob('*.cpp'))
</screen>
</section>
<section id="mocup">
<title>MOC it up</title>
<para>For the basic support of automocing, nothing needs to be done by the
user. The tool usually detects the <literal>Q_OBJECT</literal> macro and
calls the <quote><literal>moc</literal></quote> executable
accordingly.</para>
<para>If you don't want this, you can switch off the automocing by
a</para>
<screen>env['QT4_AUTOSCAN'] = 0
</screen>
<para>in your SConscript file. Then, you have to moc your files
explicitly, using the Moc4 builder.</para>
<para>You can also switch to an extended automoc strategy with</para>
<screen>env['QT4_AUTOSCAN_STRATEGY'] = 1
</screen>
<para>Please read the description of the
<literal>QT4_AUTOSCAN_STRATEGY</literal> variable in the Reference manual
for details.</para>
<para>For debugging purposes, you can set the variable
<literal>QT4_DEBUG</literal> with</para>
<screen>env['QT4_DEBUG'] = 1
</screen>
<para>which outputs a lot of messages during automocing.</para>
</section>
<section id="forms">
<title>Forms (.ui)</title>
<para>The header files with setup code for your GUI classes, are not
compiled automatically from your <literal>.ui</literal> files. You always
have to call the Uic4 builder explicitly like</para>
<screen>env.Uic4(Glob('*.ui'))
env.Program('foo', Glob('*.cpp'))
</screen>
</section>
<section id="resources">
<title>Resource files (.qrc)</title>
<para>Resource files are not built automatically, you always have to add
the names of the <literal>.qrc</literal> files to the source list for your
program or library:</para>
<screen>env.Program('foo', Glob('*.cpp')+Glob('*.qrc'))
</screen>
<para>For each of the Resource input files, its prefix defines the name of
the resulting resource. An appropriate
<quote><literal>-name</literal></quote> option is added to the call of the
<literal>rcc</literal> executable by default.</para>
<para>You can also call the Qrc4 builder explicitly as</para>
<screen>qrccc = env.Qrc4('foo') # ['foo.qrc'] -&gt; ['qrc_foo.cc']
</screen>
<para>or (overriding the default suffix)</para>
<screen>qrccc = env.Qrc4('myprefix_foo.cxx','foo.qrc') # -&gt; ['qrc_myprefix_foo.cxx']
</screen>
<para>and then add the resulting cxx file to the sources of your
Program/Library:</para>
<screen>env.Program('foo', Glob('*.cpp') + qrccc)
</screen>
</section>
<section id="translation">
<title>Translation files</title>
<para>The update of the <literal>.ts</literal> files and the conversion to
binary <literal>.qm</literal> files is not done automatically. You have to
call the corresponding builders on your own.</para>
<para>Example for updating a translation file:</para>
<screen>env.Ts4('foo.ts','.') # -&gt; ['foo.ts']
</screen>
<para>By default, the <literal>.ts</literal> files are treated as
<emphasis>precious</emphasis> targets. This means that they are not
removed prior to a rebuild, but simply get updated. Additionally, they do
not get cleaned on a <quote><literal>scons -c</literal></quote>. If you
want to delete the translation files on the
<quote><literal>-c</literal></quote> SCons command, you can set the
variable <quote><literal>QT4_CLEAN_TS</literal></quote> like this</para>
<screen>env['QT4_CLEAN_TS']=1
</screen>
<para>Example for releasing a translation file, i.e. compiling it to a
<literal>.qm</literal> binary file:</para>
<screen>env.Qm4('foo') # ['foo.ts'] -&gt; ['foo.qm']
</screen>
<para>or (overriding the output prefix)</para>
<screen>env.Qm4('myprefix','foo') # ['foo.ts'] -&gt; ['myprefix.qm']
</screen>
<para>As an extension both, the Ts4() and Qm4 builder, support the
definition of multiple targets. So, calling</para>
<screen>env.Ts4(['app_en','app_de'], Glob('*.cpp'))
</screen>
<para>and</para>
<screen>env.Qm4(['app','copy'], Glob('*.ts'))
</screen>
<para>should work fine.</para>
<para>Finally, two short notes about the support of directories for the
Ts4() builder. You can pass an arbitrary mix of cxx files and subdirs to
it, as in</para>
<screen>env.Ts4('app_en',['sub1','appwindow.cpp','main.cpp']))
</screen>
<para>where <literal>sub1</literal> is a folder that gets scanned
recursively for cxx files by <literal>lupdate</literal>. But like this,
you lose all dependency information for the subdir, i.e. if a file inside
the folder changes, the .ts file is not updated automatically! In this
case you should tell SCons to always update the target:</para>
<screen>ts = env.Ts4('app_en',['sub1','appwindow.cpp','main.cpp'])
env.AlwaysBuild(ts)
</screen>
<para>Last note: specifying the current folder
<quote><literal>.</literal></quote> as input to Ts4() and storing the
resulting .ts file in the same directory, leads to a dependency cycle! You
then have to store the .ts and .qm files outside of the current folder, or
use <literal>Glob('*.cpp'))</literal> instead.</para>
</section>
</article>