[Lazarus] TImage - Getting image properties in 'canvas space'
Hans-Peter Diettrich
DrDiettrich1 at aol.com
Wed Apr 18 09:58:56 CEST 2012
Reimar Grabowski schrieb:
> On Tue, 17 Apr 2012 22:19:45 +0200
> Sven Barth <pascaldragon at googlemail.com> wrote:
>
>> type
>> TMyHackImage = class(TImage)
>> public
>> function DestRect: TRect;
>> end;
>>
>> var
>> MyImage: TImage;
>> r: TRect;
>> begin
>> // let's suppose that MyImage contains a TImage instance
>> r := TMyHackImage(MyImage).DestRect
>> end;
> How should that work?
> What does the DestRec function look like?
You're right, above code should not work. The DestRect function has to
be omitted from above declaration, so that the DestRect of the base
class is used.
The elevation of visibility only works for *properties*, i.e.
public
property DestRect;
should work. But often (depending on the compiler) the mere declaration
of an empty derived class allows to access protected members of the base
class.
DoDi
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