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# Installing Qt Jambi

Qt Jambi is available both in prebuilt and source packages for Linux, Mac OS X, and Windows. Java 1.5 or later is required to install Qt Jambi.

The procedure of installing is different depending on whether you have downloaded a source or prebuilt package. This installation guide has separate sections for each approach.

Enjoy !

- Installing from a Prebuilt Package

- Manually Launching Qt Jambi Applications

- Building Qt Jambi from a Source Package

- Configuring the System for Qt Jambi
- Building

- Building and Running the Jambi Generator
- Building C++ libraries and tools
- Generating Ui files
- Building the Java Source Files

- Running Qt Jambi Applications
- Trouble Shooting

- Common Problems
- Load Issues

- Platform Notes
- Running the Qt Designer
- Running the Qt Jambi Generator

## Installing from a Prebuilt Package

After extracting the package, you are ready to run the Launcher, which is an application that runs the examples and demos that come with Qt Jambi.

To run the examples and demo launcher on Windows run the

        qtjambi.exe

executable from the Qt Jambi directory. On Linux and Mac OS X run the

        qtjambi.sh

shell script from the Qt Jambi directory.

Running these files will verify the virtual machine version and set the correct environment for running Qt Jambi applications.

When you are ready to distribute your own applications, see the deployment document.

### Manually Launching Qt Jambi Applications

To manually run Qt Jambi, the `CLASSPATH` environment variable must include the `qtjambi.jar` file to get access to the library. To run the examples or launcher, the classpath must also include the Qt Jambi directory.

Qt Jambi must be enabled to find the native libraries. The Qt Jambi libraries is a set of class files contained in the qtjambi.jar file and a set of native libraries. Using the default package structure from the prebuilt package the native libraries will be automatically found by Qt Jambi, but it is also possible to change this structure and manually specify where to find libraries. This is done by specifying either the JVM system property `-Djava.library.path=[path_to_libraries]` or setting the following environment variable:

Platform | Comment
--- | ---
Windows | Set the `PATH` environment variable to include the bin directory in the Qt Jambi directory.
Linux | Set the `LD_LIBRARY_PATH` environment variable to include the lib directory in the Qt Jambi directory.
Mac OS X | Set the `DYLD_LIBRARY_PATH` environment variable to include the lib directory in the Qt Jambi directory.

Some of Qt's functionality is loaded via native plugins. This includes for instance support for jpeg images. In order for Qt Jambi to locate these plugins the QT_PLUGIN_PATH environment variable need to point to the location of $JAMBIDIR/plugins. It is also possible to deploy plugins as part of a .jar file rather than on the local filesystem by putting the contents of the $JAMBIDIR/plugins folder into a .jar file and starting java with the system property `-Dcom.trolltech.qt.pluginjars=[name_of_jarfile]`.

You are then ready to run Qt Jambi applications. For instance, the launcher can be run like this from the Qt Jambi directory (On Windows, replace the ':' with ';'):

        java -cp qtjambi.jar:. com.trolltech.launcher.Launcher

Note: When running a Qt Jambi application on Mac, it is necessary to pass the `-XstartOnFirstThread` argument to the Java executable.

## Building Qt Jambi from a Source Package

This section describes how to build Qt Jambi from source. We first explain how to configure your system, and then we go through the procedure of building Qt Jambi from the command line. Finally, we look at some common installation problems.

Note that a source package requires a Qt installation. On Mac OS X, Qt must be configured without frameworks (by running the `configure` script with the --no-framework option).

### Configuring the System for Qt Jambi

The Jambi source package requires Qt to be installed on the system. The java version must be at least 1.5.

The following table describes the environment variables necessary to install Qt Jambi. We assume that the JAMBI environment variable contains the path to the Qt Jambi directory. The QTDIR variable contains the Qt directory.

QTDIR | This variable must contain the path to the directory where Qt is installed.
JAVADIR | This variable must contain the path to the directory where Java is installed.
LD_LIBRARY_PATH on Linux DYLD_LIBRARY_PATH on Mac OS X PATH on Windows | This variable must include the directory JAMBI/lib and QTDIR/Lib
CLASSPATH | This variable should include the JAMBI directory.

### Building

We will now go through the procedure of building Qt Jambi step-by-step from the command line. We give shell transcripts for all commands necessary to successfully set up a working Qt Jambi environment. The transcripts are given from a Linux shell, but are essentially equal on all platforms; we will point out differences as we go along.

#### Building and Running the Jambi Generator

The Jambi Generator generates java source files that wrap the Qt C++ libraries. In order to build Jambi itself, we need the generator. So go into the directory in which it lives:

        cd $JAMBI/generator

Then run qmake and the make tool on your system (On windows the tool is usually `gmake` or `nmake`):

        qmake
        make

Then run the generator. Default settings are fine, so no command line arguments are necessary:

On Linux:

        ./generator

On Windows:

        release\generator

The generator will give several warnings while running. This is normal and does not present a problem.

#### Building C++ libraries and tools

Go back to the JAMBI directory and run `qmake` to generate the necessary make file. Finally, build with `make`:

        cd ..
        qmake -r
        make

#### Generating Ui files

We now need to build the Ui files, i.e., create java files from UI created with the Qt Designer:

        ./bin/juic -cp .

#### Building the Java Source Files

The generator and juic have now created the Java source files for Qt Jambi. These are all listed in the file `java_files`. The Java compiler `javac` can take this file as an argument and will then compile all sources.

        javac -J-mx1024m @java_files

The VM option `-J-mx1024m` is on some systems necessary to prevent the VM from running out of heap space; you may need to choose a different heap size than 1024.

### Running Qt Jambi Applications

After building Jambi, you should add the JAMBI directory to the class path. Then Qt Jambi applications can be run, for instance the Launcher:

        java com.trolltech.launcher.Launcher

If Qt was built with debugging turned on, you need to use the Qt Jambi debug libraries. You can specify this with the `com.trolltech.qt.debug` system property.

Note: When running a Qt Jambi application on Mac, it is necessary to pass the `-XstartOnFirstThread` argument to the Java executable.

### Trouble Shooting

If you have trouble compiling and running Qt Jambi, we present problems that are commonly encountered in a table. This should be sufficient to solve most problems; failing that, try asking someone. The Jambi FAQ is a good place to start. In the Jambi Mailing List, active Jambi users and the Jambi development team can be helpful with installation problems; please run Qt Jambi with the `com.trolltech.qt.verbose-loading` system property and give stack traces if Qt Jambi fails to load native libraries.

#### Common Problems

In this section, we have tried to gather common problems encountered while building Qt Jambi. They are listed in a table with columns for the problem description and solution.

Problem | Solution
--- | ---
On Linux the `gcj` (GNU Java Compiler) is located in `/usr/bin`; the path to the correct java version must be before this in the PATH. This usually results in `java.lang.ClassFormatError` errors. | Make sure that it is the correct java executable in the PATH.
Environment variables are not set correctly. | Check with the Configuring the System for Qt Jambi section that your system is properly configured for Jambi.
Qt Jambi uses the Qt Header files to generate the mapping from c++ to java. Unless Qt was built with default settings, you may get link problems for bindings that are not in the native libraries. | Build Qt with default settings
`juic` does not update .jui files that are not modified, which can be a problem if Java sources are deleted. | Run juic with the `-a` option.
Qt Jambi expects that Qt was built with debugging turned off. If Qt was built with debugging, the libraries will not be found. | Run Qt Jambi with the `com.trolltech.qt.debug` system property.

#### Load Issues

If Jambi cannot find the native libraries, you will get `java.lang.UnsatisfiedLinkError`'s or other load issues. The search paths - in the order Jambi searches - for libraries are listed below.

- The com.trolltech.qt.library-path system property, which can be given `java` as command line argument.
- The classpath (including jar files).
- The subdirectory `lib` (Mac OS X and Linux) or `bin` (Windows) under the root of the Jambi package structure (i.e., the Qt Jambi directory).
- The java.library.path system property, which is set to LD_LIBRARY_PATH on Linux, PATH on Windows, and DYLD_LIBRARY_PATH on Mac OS X.

Jambi will tell which libraries fail if you run `java` with the `-Dcom.trolltech.qt.verbose-loading=true` command line argument. You can then check if the library is in one of Jambi's search paths. Note that Jambi will report on each attempt to load a library.

Jambi depends on a few common system libraries. Notably, Xinerama on Linux, which may be missing on older systems. Information about such missing libraries are not propagated from the operating system to Jambi; how missing libraries are reported may vary from system to system.

## Platform Notes

Platform | Comment
--- | ---
Mac OS X | When running a Qt Jambi application, it is necessary to pass the `-XstartOnFirstThread` argument to the Java executable. Also, if you have a source package, you have to build Qt with the --no-framework option.
Linux / 64 bit: | Install a 32 bit virtual machine, e.g., on Ubuntu, install the `ia32-sun-java5-bin` package and put `/usr/lib/jvm/ia32-java-1.5.0-sun-1.5.0.06/jre/bin` into the `PATH` environment variable.

## Running the Qt Designer

The Qt Designer is Trolltech's tool for designing and building user interfaces. If you have a prebuilt package, you can run it from the command line with the `qtdesigner.bat` or `qtdesigner.sh` scripts. The Eclipse integration handles the designer automatically.

You will find more information in the Qt Designer document.

## Running the Qt Jambi Generator

The generator is a Qt application which can be used to map C++ based Qt APIs onto equivalent Java APIs. The Qt Jambi package provides an example on how to use the Qt Jambi Generator, located in the `path/to/Qt Jambi/generator_example` directory.

To generate the example's Java library run the

        generator_example.bat

script on Windows. On Linux and Mac OS X run

        generator_example.sh

These scripts will generate and compile the Java source code, as well as compile the C++ side of the example. See the script files for details.

Warning: The Qt Jambi generator is written to handle Qt based source code, and is not intended for mapping C++ libraries in general.