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Mailing lists / fpc-pascal / 2007-06

fpcanvas and TFPEmptyXXX classes

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Graeme Geldenhuys

Hi,

What is the point/purpose of the TFPEmptyFont, TFPEmptyBrush, TFPEmptyXXX etc. classes?
They come in handy while I am implementing (converting) the fpGUI canvas class to descend from the TFPCanvas class, so I don't get abstract do they serve another purpose?

Regards,
- Graeme -

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Michael Van Canneyt
to Graeme Geldenhuys
Graeme Geldenhuys wrote 8 lines
Hi, What is the point/purpose of the TFPEmptyFont, TFPEmptyBrush, TFPEmptyXXX etc. classes? They come in handy while I am implementing (converting) the fpGUI canvas class to descend from the TFPCanvas class, so I don't get abstract errors at runtime. But do they serve another purpose?

No, they were used for the same reason as you. They can be used when you implement a system which needs not all available options: descend from them, and implement just what you need.

Michael.

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Graeme Geldenhuys
to Michael Van Canneyt
Michael Van Canneyt wrote 6 lines
No, they were used for the same reason as you. They can be used when you implement a system which needs not all available options: descend from them, and implement just what you need. Michael.

Thanks for the quick response Michael.
So far so good, but this conversion is going to take time, but I am sure it's going to be worth it. ;-)

PS:
I already have a few methods I think will be very handy to add to the base TFPCanvas class, but I will talk about those at a later date.

Graeme.

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Michael Van Canneyt
to Graeme Geldenhuys
Graeme Geldenhuys wrote 11 lines
On 29/06/07, Michael Van Canneyt wrote: > > No, they were used for the same reason as you. They can be used when > you implement a system which needs not all available options: descend > from them, and implement just what you need. > > Michael. Thanks for the quick response Michael. So far so good, but this conversion is going to take time, but I am sure it's going to be worth it. ;-)

Lazarus did it too, so...

PS: I already have a few methods I think will be very handy to add to the base TFPCanvas class, but I will talk about those at a later date.

Absolutely.

The design is not embedded in concrete, so any suggestions are most welcome.

Michael.

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