Scott Hollows – One Line At A Time

Get a list of all controls in your Delphi VCL form

Examples included a flat list and a hierarchical “tree” list

Related Posts – FireMonkey (FMX) version of this post

This will show three different ways to get a list of the controls in your form

1. Controls List
   This contains the first level controls on the form.
   For example, if a button is on a panel and the panel is on the form the panel will be included but the button will not
2. Components List
   All components on the form, from all levels.
   For example, if a button is on a panel and the panel is on the form – both the panel and the button will be included
   Does not include components within frames
3. Hierarchical “Tree” list
   This includes components from all levels.
   It includes components that are within frames

Flat Lists

The code for the first two flat lists is straight forward.
Simply loop through the forms controls and components lists.

Piece of cake

var
 i : integer;
begin
       // loop through all controls (first level only)
 memo1.lines.add ('*** Controls ***');
 for i := 0 to self.ControlCount - 1 do
      memo1.lines.add (self.controls[i].name);

       // loop through all components (all levels)
 memo1.lines.add ('*** Components ***');
 for i := 0 to self.ComponentCount- 1 do
     memo1.lines.add (self.components[i].name);
end;

Hierarchical List

The code for hierarchical list is more complex

The magic procedure

procedure TForm1.ProcessControl (
             aControl : TControl;
             aLevel   : integer = 0
             );
 // process the control including its child objects
 // aLevel is the level of the control
 //    0 for the form
 //    1 for controls directly owned by the form
 //    2 for a button that is on a panel on the form
 //    etc
var
 i : integer;
begin
 inc (aLevel);
        // do something with the control here
        // example: display indented control name
        // you will need LeftPadString from the download source
 memo1.lines.Add(
          LeftPadString ('', (aLevel -1) * 6, ' ') // indent
          + aControl.name
          );

      // process child objects such as a button on a panel
      // only TWinControls (such as TPanels and TFrame)
      // have child controls
 if aControl is TWinControl then
    for i := 0 to (aControl as TWinControl).ControlCount - 1 do
       ProcessControl(
                  (aControl as TWinControl).Controls[i]
                 ,aLevel);
end;

Call it like this

begin
           // self is the form.
           // you can also specify a container
           // such as a panel
  ProcessControl (self);
end;

You dont need to specify the value for aLevel as the procedure will track the level for you.

Controls vs Components List

This posts mentions Controls and Components.
Controls are visual, components can be visual or non visual
For example a DataSource that is owned by the form is a component, but it is not a control.

There are other difference between the two but I wont go into great detail about that here.

The key thing for this post is the controls list includes the first level only whereas the components list includes all levels.

For example, a button on a panel is included in the controls list, but  is not included in the components list

Disclaimers

I haven’t test this for all types of controls, but it should be good enough for most situations.

FMX Version

See this related post for a FireMonkey (FMX) version of this code

Download

Download full source code (Delphi 10.1) and pre-compiled demo

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About The Author

The Usual Suspect
– Scott Hollows –

• Oracle and Delphi software developer.
• Australian Delphi User Group – Western Australia Chief Cat Herder
• Australian Delphi User Group – President