Trouble when creating custom TComboBox component

[darkdata]

Hi all,

I'm having trouble creating a TCustomComboBox component. I'm overriding Dropdown but it seems like the event never gets fired?

Code: [Select]

  TTDComboBox = class(TCustomComboBox)
  private
    { Private declarations }
  protected
    { Protected declarations }
    procedure DropDown; override;


Code: [Select]

procedure TTDComboBox.DropDown;
var
  i: Integer;
begin
//just a test
//SendMessage(Self.Handle, CB_SETDROPPEDWIDTH, ItemWidth, 0);
Self.Perform(CB_SETDROPPEDWIDTH, 100, 0);

What am I doing wrong here?

[skalogryz]

Perform() executes LCL code only. I presume you want so actually send the message to actual Windows control. Use Windows.SendMessage for that.

[darkdata]

I tried both. The SendMessage/Self.Perform pieces work fine with OnDropDown event of a TComboBox.

Here's a link to something similar I'm trying to achieve: http://www.delphicorner.f9.co.uk/articles/comps11.htm

[skalogryz]

are you saying it works with TComboBox but not working with TCustomComboBox?
Are there other changes made? because it works with for TCustomComboBox as well.

[darkdata]

Could you try making a TCustomComboBox package/component? That's where I seem to have the trouble.

[skalogryz]

i presume you didn't use SendMesssage after all.

Anyways. here's the package and a project that's using the package. Works as expected (on windows)

As soon as package is installed and Lazarus is rebuilt you'll see "dark data" tab where the dropdown resides.

[skalogryz]

I've just attached the package zip file. Not sure why didn't load the last time.

[darkdata]

Ok yours works. You can see that I did try to use SendMessage above though in my original post. When I created a component I did not get the extra file for the registration of the component like yours has. I'll have to dig to figure out how I missed this. Thanks.

[skalogryz]

When I created a component I did not get the extra file for the registration of the component like yours has.

I didn't get it too. I created one myself.