[Gambas-user] Drawing Areas, painting on them, and printing the results...

[Stephen]

   Attached is a sample project that dynamically instantiates 10 
business card sized DrawingAreas within a Panel on a forum. The form 
represents a North American letter-sized sheet of paper. Since the Draw 
event must be used to draw within each of the Drawing areas, and the the 
Drawing Areas are brought into existence at run-time, the question is 
how to draw something on them?

   The actual project uses a database to dynamically create (or 
re-create) QR or Barcode images.

Steve.

On 09/02/2014 07:05 PM, Stephen wrote:
> On 09/02/2014 06:22 PM, Jussi Lahtinen wrote:
>>> I guess it is the need to use the draw event in order to do anything
>>> with the drawing area that had me spun. I think in terms of methods,
>>> properties and events, but I do not think in terms of events being the
>>> very thing that actually does the work.
>>>
>> Draw event is called every time drawingarea needs to be drawn.
>      Yes, so we force the event by the refresh method. I'm slowly making
> progress... documenting things as I go. Thank you taking the time to help.
>
>> Thus it is
>> where you put the drawing commands.
>>
>> But you can change this behavior by setting Cached property to True.
>> Then you start painting by determining painting device (Gambas cannot know
>> where to draw, if you are not in specific drawing event)
>> Paint.Begin(hNameOfPaintingDevice) and end with Paint.End.
>> See the documentation.
>>
>>
>>
>>
>>> I'm thinking of it now in terms of Macros, using the Object.Call(me,
>>> $sFunctionName) treats the code in $sFunctionName like a Macro, (am I on
>>> the right track?) Flexible&   powerful yes. Intuitive in it's usage, not
>>> so much.
>>>
>> This only enables you to use string value to call a function. There are
>> many alternatives for this.
>>
>>
>>
>>
>>> One of the things that really confused me was the paint.reset command
>>> telling me it had no device.... ummm... no "device"? To me a device is a
>>> piece of hardware, a printer, a modem, a screen, keyboard, mouse,
>>> soundcard, NIC, Com port etc.
>> In Unix/Linux device has bit broader meaning, see example /dev/null or
>> /dev/random. Not all devices are physical devices.
>>
>>
>>
>>
>>> BTW, how does reset differ from clear?
>>>
>> http://gambaswiki.org/wiki/comp/gb.qt4/drawingarea/clear
>> http://gambaswiki.org/wiki/comp/gb.qt4/paint/reset
>>
>>
>>
>> Jussi
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>>
>

-- 
Kindest Regards
Stephen A. Bungay, Prop.
Smarts On Site Information Systems

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