Diagram Editor
lazarus / 31-LCL

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paulo_tavares · 2015-01-02 01:00

Hello There.

I want to create a diagram editor in lazarus mainly to create bpmn
diagrams (like yaoqiang http://sourceforge.net/projects/bpmn/) but to
be extended to other types of diagrams.

My question is about the architecture of such an application. I'm new
to lazarus or delphi and i need some advices.

Here is my first basic question (although vague) for someone who could
try and help me:

Should I use custom TShapes to draw the bpmn shapes ? (I'm having
troubles with transparency while overlapping shapes, even using
BGRABitmap)

Should I use a Custom Control with a BGRABitmap drawn in canvas and
all the bpmn shapes are drawn directly in BGRABitmap? (I think that in
this case i have to do all the drag an drop, click, mouse over, mouse
down and other events manually and the diagram whould have to be all
repainted every time... not just some parts)

Very kind for your help.

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Blaazen · 2015-01-02 01:26

I did similar component - my one is simplier, it does not implement
full UML.
It is TECScheme, it is part of my EC-Controls. There is also attached
demo.

Screenshot: http://s26.postimg.org/k5cwqv6o9/Scheme_Designer_Qt.png

For curiosity, the unit has ~2700 lines.

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jwdietrich · 2015-01-02 01:26

You might consider to use fpvectorial.

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janvb · 2015-01-02 02:31

Quote from: paulo_tavares on January 02, 2015, 02:00:26 am
Should I use a Custom Control with a BGRABitmap drawn in canvas and
all the bpmn shapes are drawn directly in BGRABitmap? (I think that in
this case i have to do all the drag an drop, click, mouse over, mouse
down and other events manually and the diagram whould have to be all
repainted every time... not just some parts)

Very kind for your help.
http://forum.lazarus.freepascal.org/index.php/topic,25296.0.html

have a look at that thread, it contains a few hints on the subject.

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paulo_tavares · 2015-01-05 13:50

Thank you all.

I think I will Try the BGRABitmap.

The fpvectorial I will use to expor the diagram to SVG or to odf.

Certainly I will continue posting for architectural issues.

Best Regards

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paulo_tavares · 2015-01-05 14:43

Quote from: Blaazen on January 02, 2015, 02:26:19 amI did similar
component - my one is simplier, it does not implement full UML.
It is TECScheme, it is part of my EC-Controls. There is also attached
demo.

Screenshot: http://s26.postimg.org/k5cwqv6o9/Scheme_Designer_Qt.png

For curiosity, the unit has ~2700 lines.

Thanks for the hint. I'll give a look.