My task is:
- Using Ubuntu linux distribution with Olinuxino Lime,
- LCD with graphical GUI (which one ???)
- Develop a software with graphical interface (buttons, textboxes). What kind of tools can be used? Maybe it's worth consider build HTML jQuery application and pass data to local software (back end for logic)?
How is the best method to achieve the requirements??
I read about Qt but it's expensive for commercial usage.
from here: https://www.olimex.com/Products/OLinuXino/A10/A10-OLinuXino-LIME/open-source-hardware
"LCD connector compatible with with 4.3", 7.0", 10.1" LCD modules from Olimex"
See related products here: https://www.olimex.com/Products/OLinuXino/A13/
I would use Python Tkinter. With it you can develop the GUI on desktop Linux PC with any graphic environment ( LXDE,KDE,Gnome,Unity,XFCE) or even on Windows.
Qt could be licensed under commercial,GPL or LGPL.
What is you favorite programing lanuage? (the "language of choice"). There are lots of different toolkits, some are for only one language, another support multiple languages, scripted or compiled.
I made a GUI using the framebuffer library directfb. This means I don't have to use/include X in the final product. In fact; when development was more or less done, I started testing with buildroot and this works amazingly well. The final image is about 10 MB in size (mostly due to the images of the GUI).
In directfb I created 'text label' and 'button' elements (using C). Then I can programmatically build up a GUI. On top of that I listen to the touchscreen on /dev/input/event0. Directfb has some means to do that directly, but that didn't work out and with tslib, listening to the touch screen is very simple to do yourself.
I like the result because it is small, responsive and stable, but it is not as 'flashy' as some modern alternative could provide and there is almost no hardware acceleration. For our product it is ok though.
If you want something that does not need the XWindows, but you don't want just the framebuffer, you can use SDL. It can run on both (and can be ported easily even in MS Windows), so you can develop in the XWindows and deploy it on the framebuffer. And there are many libraries, some even with ready-to-use GUIs.
BTW, for frammebuffer, you don't need anything, you can just mmap it and write into it. But you must make all your drawing routines by yourself.