= Building on GNU/Linux =

== Building QGIS with Qt 4.x ==

**Requires:** Ubuntu / Debian derived distro

These notes are for Ubuntu - other versions and Debian derived distros may
require slight variations in package names.

These notes are for if you want to build QGIS from source. One of the major
aims here is to show how this can be done using binary packages for ***all***
dependencies - building only the core QGIS stuff from source. I prefer this
approach because it means we can leave the business of managing system packages
to apt and only concern ourselves with coding QGIS! 

This document assumes you have made a fresh install and have a 'clean' system.
These instructions should work fine if this is a system that has already been
in use for a while, you may need to just skip those steps which are irrelevant
to you.

/!\ **Note:** Refer to the section ''Building Debian packages'' for building 
debian packages.  Unless you plan to develop on QGIS, that is probably the
easiest option to compile and install QGIS.

== Prepare apt ==

The packages qgis depends on to build are available in the "universe" component
of Ubuntu. This is not activated by default, so you need to activate it:

+ Edit your /etc/apt/sources.list file.  
+ Uncomment all the lines starting with "deb"

Also you will need to be running (K)Ubuntu 'edgy' or higher in order for 
all dependencies to be met.

Now update your local sources database:

``` 
sudo apt-get update 
```


== Install build dependencies ==

|| Distribution | install command for packages |
| precise | ``apt-get install bison cmake doxygen flex git graphviz grass-dev libexpat1-dev libfcgi-dev libgdal-dev libgeos-dev libgsl0-dev libopenscenegraph-dev libosgearth-dev libpq-dev libproj-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt5-qt4-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python python-dev python-qt4 python-qt4-dev python-sip python-sip-dev txt2tags xauth xfonts-100dpi xfonts-75dpi xfonts-base xfonts-scalable xvfb`` |
| quantal | ``apt-get install bison cmake doxygen flex git graphviz grass-dev libexpat1-dev libfcgi-dev libgdal1-dev libgeos-dev libgsl0-dev libopenscenegraph-dev libosgearth-dev libpq-dev libproj-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python python-dev python-qt4 python-qt4-dev python-sip python-sip-dev txt2tags xauth xfonts-100dpi xfonts-75dpi xfonts-base xfonts-scalable xvfb`` |
| raring | ``apt-get install bison cmake doxygen flex git graphviz grass-dev libexpat1-dev libfcgi-dev libgdal-dev libgeos-dev libgsl0-dev libopenscenegraph-dev libosgearth-dev libpq-dev libproj-dev libpython2.7-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt5-qt4-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python python-dev python-qt4 python-qt4-dev python-sip python-sip-dev txt2tags xauth xfonts-100dpi xfonts-75dpi xfonts-base xfonts-scalable xvfb`` |
| saucy | ``apt-get install bison cmake doxygen flex git graphviz grass-dev libexpat1-dev libfcgi-dev libgdal-dev libgeos-dev libgsl0-dev libopenscenegraph-dev libosgearth-dev libpq-dev libproj-dev libpython2.7-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt5-qt4-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python python-dev python-qt4 python-qt4-dev python-sip python-sip-dev txt2tags xauth xfonts-100dpi xfonts-75dpi xfonts-base xfonts-scalable xvfb`` |
| wheezy | ``apt-get install bison cmake doxygen flex git graphviz grass-dev libexpat1-dev libfcgi-dev libgdal1-dev libgeos-dev libgsl0-dev libopenscenegraph-dev libosgearth-dev libpq-dev libproj-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python python-dev python-qt4 python-qt4-dev python-sip python-sip-dev txt2tags xauth xfonts-100dpi xfonts-75dpi xfonts-base xfonts-scalable xvfb`` |
| jessie | ``apt-get install bison cmake flex grass-dev libexpat1-dev libfcgi-dev libgdal1-dev libgeos-dev libgsl0-dev libpq-dev libproj-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python python-dev python-qt4 python-qt4-dev python-sip python-sip-dev`` |
| sid | ``apt-get install bison cmake doxygen flex git graphviz grass-dev libexpat1-dev libfcgi-dev libgdal-dev libgeos-dev libgsl0-dev libopenscenegraph-dev libosgearth-dev libpq-dev libproj-dev libqt4-dev libqt4-opengl-dev libqtwebkit-dev libqwt-dev libspatialindex-dev libspatialite-dev libsqlite3-dev pkg-config pyqt4-dev-tools python-all python-all-dev python-qt4 python-qt4-dev python-sip python-sip-dev txt2tags xauth xfonts-100dpi xfonts-75dpi xfonts-base xfonts-scalable xvfb`` |

(extracted from the respective control files in ``debian/``)

/!\ **A Special Note:** If you are following this set of instructions on
a system where you already have Qt3 development tools installed, there will
be a conflict between Qt3 tools and Qt4 tools. For example, qmake will
point to the Qt3 version, not the Qt4. Ubuntu Qt4 and Qt3 packages are
designed to live alongside each other. This means that, for example, if you
have them both installed, you will have three qmake exe's:

``` 
/usr/bin/qmake -> /etc/alternatives/qmake 
/usr/bin/qmake-qt3
/usr/bin/qmake-qt4 
```

The same applies to all other Qt binaries. You will notice above that the
canonical 'qmake' is managed by apt alternatives, so before we start to
build QGIS, we need to make Qt4 the default. To return Qt3 to default later
you can use this same process.

You can use apt alternatives to correct this so that the Qt4 version of
applications is used in all cases:

``` 
sudo update-alternatives --config qmake
sudo update-alternatives --config uic 
sudo update-alternatives --config designer 
sudo update-alternatives --config assistant 
sudo update-alternatives --config qtconfig 
sudo update-alternatives --config moc 
sudo update-alternatives --config lupdate 
sudo update-alternatives --config lrelease 
sudo update-alternatives --config linguist 
```

Use the simple command line dialog that appears after running each of the
above commands to select the Qt4 version of the relevant applications.

/!\ Note: For python language bindings. If your distributions ships with older
versions of SIP or PyQt4 than specified in Section 2: Overview, you will need
to build and install those packages from source if you want to include support 
for python language bindings.


== Setup ccache (Optional) ==

You should also setup ccache to speed up compile times:

``` 
cd /usr/local/bin 
sudo ln -s /usr/bin/ccache gcc 
sudo ln -s /usr/bin/ccache g++ 
```

== Prepare your development environment ==

As a convention I do all my development work in $HOME/dev/<language>, so in
this case we will create a work environment for C++ development work like
this:

``` 
mkdir -p ${HOME}/dev/cpp 
cd ${HOME}/dev/cpp 
```

This directory path will be assumed for all instructions that follow.


== Check out the QGIS Source Code ==

There are two ways the source can be checked out. Use the anonymous method
if you do not have edit privileges for the QGIS source repository, or use
  the developer checkout if you have permissions to commit source code
  changes.

1. Anonymous Checkout

``` 
cd ${HOME}/dev/cpp 
git clone git://github.com/qgis/QGIS.git
```

2. Developer Checkout

``` 
cd ${HOME}/dev/cpp 
git clone git@github.com:qgis/QGIS.git
```

== Starting the compile ==

I compile my development version of QGIS into my ~/apps directory to avoid
conflicts with Ubuntu packages that may be under /usr. This way for example
you can use the binary packages of QGIS on your system along side with your
development version. I suggest you do something similar:

``` 
mkdir -p ${HOME}/apps 
```

Now we create a build directory and run ccmake:

```
cd QGIS
mkdir build-master
cd build-master
ccmake ..
```

When you run ccmake (note the .. is required!), a menu will appear where 
you can configure various aspects of the build. If you do not have root
access or do not want to overwrite existing QGIS installs (by your
packagemanager for example), set the CMAKE_INSTALL_PREFIX to somewhere you
have write access to (I usually use ${HOME}/apps). Now press
'c' to configure, 'e' to dismiss any error messages that may appear.
and 'g' to generate the make files. Note that sometimes 'c' needs to 
be pressed several times before the 'g' option becomes available.
After the 'g' generation is complete, press 'q' to exit the ccmake 
interactive dialog.

Now on with the build:

```
make
make install
```

It may take a little while to build depending on your platform.

After that you can try to run QGIS:

``` 
$HOME/apps/bin/qgis
```

If all has worked properly the QGIS application should start up and appear
on your screen.


== Building Debian packages ==

Instead of creating a personal installation as in the previous step you can
also create debian package.  This is done from the qgis root directory, where
you'll find a debian directory.

First you need to install the debian packaging tools once:

```
apt-get install build-essential
```

First you need to create an changelog entry for your distribution. For example for Ubuntu Lucid:

```
dch -l ~lucid  --force-distribution --distribution lucid "lucid build"
```

The QGIS packages will be created with:

```
dpkg-buildpackage -us -uc -b
```

/!\ **Note:** Install ``devscripts`` to get ``dch``.

/!\ **Note:** If ``dpkg-buildpackage`` complains about unmet build dependencies
you can install them using ``apt-get`` and re-run the command.

/!\ **Note:** If you have ``libqgis1-dev`` installed, you need to remove it first
using ``dpkg -r libqgis1-dev``.  Otherwise ``dpkg-buildpackage`` will complain about a
build conflict.

/!\ **Note:** By default tests are run in the process of building and their
results are uploaded to http://dash.orfeo-toolbox.org/index.php?project=QGIS.
You can turn the tests off using DEB_BUILD_OPTIONS=nocheck in front of the
build command. The upload of results can be avoided with DEB_TEST_TARGET=test.

The packages are created in the parent directory (ie. one level up).
Install them using dpkg.  E.g.:

```
sudo debi
```


== A practical case: Building QGIS and GRASS from source on Ubuntu with ECW and MrSID formats support ==

The following procedure has been tested on Ubuntu 8.04, 8.10 and 9.04 32bit. If
you want to use different versions of the software (gdal, grass, qgis), just
make the necessary adjustments to the following code. This guide assumes that
you don't have installed any previous version of gdal, grass and qgis.

===  Step 1: install base packages === 

First you need to install the necessary packages required to download the source 
code and compile it. Open the terminal and issue the following command:

``` 
sudo apt-get install build-essential g++ subversion
```

=== Step 2: compile and install the ecw libraries ===

Go to the ERDAS web site http://www.erdas.com/ and follow the links
"'''products --> ECW JPEG2000 Codec SDK --> downloads'''" 
then download the "'''Image Compression SDK Source Code 3.3'''" (you'll need to make a registration 
and accept a license).

Uncompress the archive in a proper location (this guide assumes 
that all the downloaded source code will be placed in the user home) 
and the enter the newly created folder

``` 
cd /libecwj2-3.3
```

Compile the code with the standard commands

``` 
./configure
```

then

``` 
make
```

then

``` 
sudo make install
```

leave the folder 

``` 
cd ..
```

=== Step 3: download the MrSID binaries ===

Go to the LIZARDTECH web site http://www.lizardtech.com/ and follow the links
"'''download --> Developer SDKs'''", 
then download the "'''GeoExpress SDK for Linux (x86) - gcc 4.1 32-bit'''"
(you'll need to make a registration and accept a license).

Uncompress the downloaded file. The resulting directory name should be similar to "Geo_DSDK-7.0.0.2167"

=== Step 4: compile and install the gdal libraries ===

Download the latest gdal source code

``` 
svn checkout https://svn.osgeo.org/gdal/trunk/gdal gdal
```

then copy a few files from the MrSID binaries folder to the folder with the gdal source code
('''replace "USERNAME" with your actual account username''')

``` 
cp /home/USERNAME/Geo_DSDK-7.0.0.2167/include/*.* /home/USERNAME/gdal/frmts/mrsid/
```

enter the gdal source code folder

``` 
cd /gdal
```

and run configure with a few specific parameters

``` 
./configure --without-grass --with-mrsid=../Geo_DSDK-7.0.0.2167 --without-jp2mrsid
``` 

at the end of the configuration process you should read something like

``` 
...
GRASS support:             no
...
...
...
ECW support:               yes
MrSID support              yes			
...
```

then compile normally

``` 
make
```

and

``` 
sudo make install
```

finish the process by creating the necessary links to the most recent shared libraries

``` 
sudo ldconfig
```

at this point you may want to check if gdal was compiled correctly with MrSID and ECW
support by issuing one (or both) of the following commands

``` 
gdalinfo --formats | grep 'ECW'
```

``` 
gdalinfo --formats | grep 'SID'
```

leave the folder 

``` 
cd ..
```

=== Step 5: compile and install GRASS ===

Before downloading and compile GRASS source code you need to install a few
other libraries and programs. We can do this through apt

``` 
sudo apt-get install flex bison libreadline5-dev libncurses5-dev lesstif2-dev \
debhelper dpatch libtiff4-dev tcl8.4-dev tk8.4-dev fftw-dev xlibmesa-gl-dev \
libfreetype6-dev autoconf2.13 autotools-dev libgdal1-dev proj libjpeg62-dev \
libpng12-dev libpq-dev unixodbc-dev doxygen fakeroot cmake python-dev \
python-qt4-common python-qt4-dev python-sip4 python2.5-dev sip4 libglew1.5-dev \
libxmu6 \ libqt4-dev libgsl0-dev python-qt4 swig python-wxversion \
python-wxgtk2.8 libwxgtk2.8-0 libwxbase2.8-0 tcl8.4-dev tk8.4-dev tk8.4 \
libfftw3-dev libfftw3-3
```

At this point we can get the GRASS source code: you may want to download it
through svn or maybe you want just to download the latest available source code
archive.  For example the GRASS 6.4rc4 is available at
http://grass.itc.it/grass64/source/grass-6.4.0RC4.tar.gz

Uncompress the archive, enter the newly created folder and run configure with a few specific parameters

``` 
CFLAGS="-fexceptions" ./configure \
--with-tcltk-includes=/usr/include/tcl8.4 \
--with-proj-share=/usr/share/proj \
--with-gdal=/usr/local/bin/gdal-config \
--with-python=/usr/bin/python2.5-config
```

The additional gcc option -fexceptions is necessary to enable exceptions
support in GRASS libraries. It is currently the only way to avoid QGIS crashes
if a fatal error happens in GRASS library. See also
http://trac.osgeo.org/grass/ticket/869

Then as usual (it will take a while)

``` 
make
```

and

``` 
sudo make install
```

leave the folder 

``` 
cd ..
```

you have now compiled and installed GRASS (also with the new wxpyhton interface) so you
may want to give it a try

``` 
grass64 -wxpython
```


=== Step 6: Compile and install QGIS ===

As for GRASS you can obtain the QGIS source code from different sources as described 
in section 2 above. Once you have the sources, create a build directory in them:

``` 
cd QGIS
mkdir build
cd build
```

then run ccmake

``` 
ccmake ..
```

Press the "c" key to do an initial configure.
Press the "c" again and the option "Press [g] to generate and exit" will appear.
Press the "g" key to generate and exit.

then as usual (it will take a while)

``` 
make
```

and

``` 
sudo make install
```

At the end of the process you should have QGIS and GRASS working with MrSID and ECW
raster format support.

To run QGIS just use this command 

``` 
qgis
```