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Qt5
Qt is a great framework for creating (not only) embedded applications with appealing GUIs. The apps are traditionally written in C++, but GUI design can be done in QML, a descriptive language. There is a rich library of platform independent C++ classes, somehow comparable to JAVA or .NET. Read more on the homepage https://www.qt.io/.
The rpi-av-image is already built with Qt5 support: LinuxFB (framebuffer) and EGLFS ( EGL) are configured as QPAs (Qt Platform Abstraction) and OpenGL ES 2.0 (OpenGL) is used for hardware accelerated drawing.
rpi-av-image comes with the cimematicExperience example prog. Before using Qt5, you have to specify the graphical backend (QT_QPA_PLATFORM=eglfs):
export QT_QPA_PLATFORM=eglfs
root@raspberrypi3:~# /usr/share/cinematicexperience-1.0/Qt5_CinematicExperience On the HDMI monitor, you should see a smooth rendering with 60 fps and, with htop, only a moderate CPU usage of some 20%.
http://www.jumpnowtek.com/rpi/Qt5-and-QML-Development-with-the-Raspberry-Pi.html has a small app qqtest which can be used for a first GUI test including a USB mouse for input.
Make sure that qtbase is configured with eglfs, gles2 and linuxfb. See https://github.com/jumpnow/meta-rpi/blob/rocko/recipes-qt/qt5/qtbase_git.bbappend. A nearby recipe https://github.com/jumpnow/meta-rpi/blob/rocko/recipes-qt/qt5-env/files/qt5-env.sh shows hot to automate path and environment settings.
After installing the image and booting the RasPi: compile a demo app on the RasPi.
root@raspberrypi3:~# wget http://quitcoding.com/download/Qt5_CinematicExperience_rpi_1.0.tgz
root@raspberrypi3:~# tar xvf Qt5_CinematicExperience_rpi_1.0.tgz
root@raspberrypi3:~# cd Qt5_CinematicExperience_rpi_1.0
### a patch needs to be applied, see http://wickwire2099.blogspot.de/2014/05/qt-530-qt5-cinematic-experience.html)
root@raspberrypi3:~/Qt5_CinematicExperience_rpi_1.0# sed -i 's/onText/textON/g' content/Switch.qml content/SettingsView.qml
root@raspberrypi3:~/Qt5_CinematicExperience_rpi_1.0# sed -i 's/offText/textOFF/g' content/Switch.qml content/SettingsView.qml
root@raspberrypi3:~/Qt5_CinematicExperience_rpi_1.0# qmake
root@raspberrypi3:~/Qt5_CinematicExperience_rpi_1.0# make
root@raspberrypi3:~/Qt5_CinematicExperience_rpi_1.0# ./Qt5_CinematicExperienceOutput on HDMI monitor. USB mouse recommended.
There is also a bitbake recipe for it: bitbake cinematicexperience would have build the demo on the build host.
Build (cross-compile) a test app on the build host.
From a bitbake shell:
frank@FrankBuntuSSD:~/raspi/build$ bitbake qt5-opengles2-testThe output package resides in one of the ${BUILDDIR}/tmp/deploy/ipk/* folders.
This time we don't use the package server, but a mere copy over the network (adjust IP address accordingly):
frank@FrankBuntuSSD:~/raspi/build$ scp ${BUILDDIR}/tmp/deploy/ipk/*/qt5-opengles2-test_1.0.4*.ipk [email protected]:/home/rootOn the RasPi install the package:
root@raspberrypi3:~# opkg install qt5-opengles2-test_1.0.4+gitr0+9383905070-r0_cortexa7hf-neon-vfpv4.ipk and start it:
root@raspberrypi3:~# qt5-opengles2-test Watch the output on an attached HDMI monitor. Its a quite simple test app only, but it demonstrates that all APIs needed are functional. I might be useful to study its recipe under sources/meta-qt5/recipes-qt/examples/qt5-opengles2-test_git.bb.