ECE497 Notes on Qt

Revision as of 11:02, 10 August 2011 by Yoder (Talk | contribs) (Qt Tutorials: Added suggested tutorials)

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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.


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 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-demos
$ opkg install linuxtag-ics
$ opkg install qt4-examples
$ opkg install qt4-x11-free qt4-x11-free-doc qt4-x11-free-dev
$ opkg install qmake2

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.

Qt Tutorials


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 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

./configure -opensource -confirm-license -prefix /opt/qt-arm -no-qt3support -x11 -little-endian -xplatform qws/linux-DM3730-g++ -qtlibinfix E

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


QWT is short for Qt Widgets for Technical Applications. It is a collection of widgets and support classes for creating technical applications such as those created using, for example, LabView or Test Point.

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

I'm trying to fix the include path with:

export CPLUS_INCLUDE_PATH=/usr/include/qt4/Qt