ECE497 Notes on Qt

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Revision as of 16:43, 11 August 2011 by Yoder (Talk | contribs) (Installing on the Beagle)

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Qt is one of the many UI frameworks that runs on the Beagle. It also runs on many other platforms such as Microsoft Windows, Mac OS X, and Linux, and it appears to be one of the more popular choices for the Beagle. It even runs on dumb cell phones. We'll be using it with X11, however there is an embedded version that doesn't need X.

Installation

Qt can be developed solely on the Beagle, but I suggest you install it on both your host and the Beagle. Compilations on the Beagle many only take 20 or 30 seconds, but run much faster on the host.


Installing v6

I'm running with v6 since it's an easy download on both the host and Beagle. You also get the sources for the examples this way.

Installing on the host

I think this is all I did on the host. This assumes you have oe installed.

$ source ~/.oe/environment-2008
$ bitbake qt4-x11-free-gles

Installing on the Beagle

Here's what I've installed on the Beagle

$ opkg update
$ opkg install qt4-x11-free     # 3 minutes
$ opkg install qmake2           # 1 minute
$ opkg install qt4-x11-free-dev # 4 minutes
$ opkg install qt4-x11-free-doc # 5 minutes

I had to hack a couple of things before running qmake.

$ cd /usr/bin
$ ln -s moc moc-qt4
$ ln -s uic uic-qt4
$ ln -s qmake-qt4 qmake

$ source /usr/share/qt4/environment-setup

Be sure to source the setup file before running qmake for the first time.

Check out the qt demos and documentation.

$ qtdemo
$ midori file:///usr/share/doc/qt4/html/index.html 

The following appears to load some qt examples with source code in /usr/share/ICS. You'll also find examples in /usr/bin/qt4/examples.

$ opkg install linuxtag-ics  # 1 minute

Installing v5

Version 5 is what you get when you use the package managers. I don't know how to get the source for the examples with this approach.

Installing on the host

Just run:

$ sudo apt-get update
$ sudo apt-get install libqwt-dev       # 1 minute
$ opkg intall libqwt-examples  # 1 minute


Installing on the Beagle

Just run:

$ opkg update
$ opkg intall libqwt-dev       # 1 minute
$ opkg intall libqwt-examples  # 1 minute

Qt Tutorials

Widgets

There are several nice Qt Tutorials here. I suggest you start with the Widgets Tutorial. Here's how you can run the examples on the Beagle.

  1. Go to the Creating a Window tutorial and download the main.cpp and toplevel.pro files. Put them in their own directory.
  2. Run qmake. (Be sure you have sourced the file noted above.) This will create a Makefile.
  3. Run make. This should compile the program. It takes about 30 seconds for the first make.
  4. Do an ls to see what files were created. You should see toplevel. Run it.
  5. Congratulations, you've just compiled and run your first Qt program.

Work through the rest of the widgets tutorials to learn about building at Qt from the bottom up. The Address Book tutorials look like they are also a good place to explore.

Qt Designer

It's possible to build a user interface from the command line, building a graphics user interface is more easily done with a graphical program. Qt Designer is Qt's tool for designing and building graphical user interfaces (GUIs) from Qt components. The Qt Designer Tutorial is a good overview of what Designer can do. Designer runs on the host and the Beagle. To install on the Beagle:

$ opkg update
$ opkg install qt4-designer

The Qt Designer tutorial ends rather quickly. I suggest you follow it up by looking at the Qt Designer Examples. Here you will learn different ways to take the *.ui file created by Designer and use it with your other Qt code.

Useful Links

Here are some usefule links I've found.

The Qt site
It's a bit overwhelming at first, but gives a good idea what Qt can do, how it can do it, and where it's doing it.
Qt Reference Documenation
This looks like a nice reference.
Building Qt to make use of the Beagle board’s SGX GPU
There is a version of Qt that uses the Beagle's SGC to render the 3D stuff. I'm not doing 3D right now, so I haven't looked into it.
Building Qt
This is TI's site.
Embedded Linux Qt
If you are thinking small, maybe you don't want X running on your Beagle. If so, look at Qt Embedded. It write straight to the frame buffer.
Setting Up Qt Development Environment for BeagleBoard-xM
This site has some nice instructions on getting QT going on the Beagle by recompiling everything. I don't think recompiling is really necessary. It's set up for using Qt embedded.

Qt Quick and Qt Creator

Qt Quick is another way of building a UI. Qt Quick is based on JavaScript, HTML and CSS. Qt Creator is a cross-platform integrated development environment (IDE) tailored to the needs of Qt developers; however it doesn't appear to run on the Beagle. I need to look into this some more.

I'm working through this example. I can't change mousearea1 to MouseArea to match the figure. I think something is missing in the instructions.

The Transitions section has some details missing:


   transitions: [
        Transition {
            from: "*"; to: "State1"
            NumberAnimation {
                properties: "x,y";
                duration: 1000
            }
        }
    ]

Real-time Plotting - QWT

QWT is short for Qt Widgets for Technical Applications. It is a collection of widgets and support classes for creating technical applications. I hope to use it to do real-time plotting on the Beagle.

Here is the main qwt site. Here is some info on QWT. I think it might be able to plot data as it comes in.

Here's how I think I installed it on the host.

$ svn co https://qwt.svn.sourceforge.net/svnroot/qwt/branches/qwt-6.0</code>.  # This is straight from the qwt site.
$ cd qwt-6.0
$ gedit qwtconfig.pri

Around line 108, uncomment QWT_CONFIG += QwtExamples. This will compile the examples too.

$ qmake-qt4
$ make

After a while it should be ready to run. Explore the examples folder. The Makefiles are setup to put all the binarys in examples/bin. Try running them.

On the Beagle

Here's what I did on the Beagle.

$ svn co https://qwt.svn.sourceforge.net/svnroot/qwt/branches/qwt-6.0
$ source /usr/share/qt4/environment-setup
$ cd qwt-6.0
$ qmake
$ make

The compile took about 20 minutes without the examples. The examples took an additional 17 minutes. The lib files don't get copied to /usr/lib (even with make install), so I copied them by hand.

$ cd lib
$ cp * /usr/lib

Now try an example.

$ cd ../examples/bode
$ qmake
$ make
$ ../bin/bode

You will now see a bode plot. They the Zoom and Export buttons.