[Gambas-user] Gambas3: ScrollArea doesn't scroll

[Benoît Minisini]

Le 17/01/2012 08:48, Rolf-Werner Eilert a écrit :
> Am 12.01.2012 06:36, schrieb Benoît Minisini:
>> Le 10/01/2012 08:19, Rolf-Werner Eilert a écrit :
>>> Am 09.01.2012 13:39, schrieb Benoît Minisini:
>>>>>
>>>>> Ok, I think I understand: With the help of ScrollX and ScrollY I have to
>>>>> decide at which coordinate within my large drawing I start to draw to
>>>>> 1,1 on the DrawingArea?
>>>>>
>>>>> Rolf
>>>>>
>>>>
>>>> Yes. If you don't care with drawing everything at each draw event, it is
>>>> just a matter of translating the coordinate system with Draw.Translate().
>>>>
>>>
>>> Last evening I found that with Gambas3 under KDE nothing is shown in
>>> ScrollArea and DrawingArea, the areas just stay cleared, but no error
>>> occurs. When I switch them cached = TRUE it will crash with Sig #11
>>> after some drawings, but the IDE doesn't crash. Under LXDE everything
>>> works flawlessly.
>>>
>>> Rolf
>>>
>>
>> Which graphics system is configured for your Qt library: 'X11', 'Raster'
>> or 'OpenGL'?
>>
>
> Hi Benoit,
>
> I still don't know where to look for an answer to this. Frankly spoken,
> I do not even know what you mean: Gambas' Qt library, or system's Qt
> library?
>
> Have a nice Tuesday
>
> Rolf
>

The Qt graphics system defined how things are drawn on the screen by Qt:
- X11: by using X11 and XRender libraries.
- Raster: by doing everything in memory, and just blitting the result to 
X11.
- OpenGL: by using OpenGL.

KDE has a entry for that in the control center on my Ubuntu, named "Qt 
Graphics System".

It just modifies a shell script file named "qt-graphicssystem.sh" 
located in ~/.kde/env. That script just defined the value of the 
QT_GRAPHICSSYSTEM environment variable.

You can test your crashing application by defining this environmental 
variable directory from a shell console:

$ cd /path/to/my/project
$ QT_GRAPHICSSYSTEM=raster gbx3

The value of QT_GRAPHICSSYSTEM can be "raster", "x11" or "opengl" (in 
lower case).

Regards,

-- 
Benoît Minisini