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Custom control size change notification?

Posted on 1998-07-10
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Last Modified: 2010-04-04
I am writing a descendant of TCustomControl and my control needs notification when it is resized (at design and run time), what is the easiest way of doing this?
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Question by:khenr29j
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Holger101497 earned 100 total points
ID: 1357672
You need to override SetBounds which is called when the size changes (also when assignments to Height, Width, Left, Top are made).
You can do whatever you want before calling the inherited method, even specify different behavior for design mode and runtime...


Here's an example from the Delphi FAQs that shows how to prevent a form from resizing. It should solve your problem as well...:

================ Delphi FAQ:
Preventing Components from Resizing

            Question:

            How can I prevent resizing of my component at design-time?

            Answer:

            Have your constructor  set the default size of the object.
            Override the SetBounds method, and then check the
            component state. If it is in design mode (csDesigning in
            ComponentState) simply pass the default values for width
            and heights to the inherited SetBounds, otherwise you
            pass the parameters unchanged.

            Example:

            procedure TVu.SetBounds(ALeft : integer;
                                    ATop : integer;
                                    AWidth : integer;
                                    AHeight : integer);
            begin
              if csdesigning in componentstate then begin
                AWidth := 50;
                AHeight := 50;
                inherited;
              end;

well, that's the whole sample code... My guess yould be there's an "end" missing after AHeight:=50; but it's also possible that you want to specify other non-standard behavior for runtime-resizing before calling the inherited function...
Good luck!
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