Changing component class at run-time on demand

This is easier as thought (thanks to Hallvard’s Blog – Hack#14: Changing the class of an object at run-time): procedure PatchInstanceClass(Instance: TObject; NewClass: TClass); type PClass = ^TClass; begin if Assigned(Instance) and Assigned(NewClass) and NewClass.InheritsFrom(Instance.ClassType) and (NewClass.InstanceSize = Instance.InstanceSize) then begin PClass(Instance)^ := NewClass; end; end; type TMyButton = class(TButton) public procedure Click; override; end; … Read more

How can I make AllocateHwnd threadsafe?

This problem can be solved like so: Obtain or implement a threadsafe version of AllocateHwnd and DeallocateHwnd. Replace the VCL’s unsafe versions of these functions. For item 1 I use Primo┼ż Gabrijelcic’s code, as described on his blog article on the subject. For item 2 I simply use the very well-known trick of patching the … Read more

How to kill a thread in delphi?

You have to check for Terminate in the thread for this to work. For instance: procedure TMyThread.Execute; begin while not Terminated do begin //Here you do a chunk of your work. //It’s important to have chunks small enough so that “while not Terminated” //gets checked often enough. end; //Here you finalize everything before thread terminates … Read more