Create, destroy and count values inside dynamic controls in Delphi - delphi

Question

I have questions about how to create dynamic controls, how destroy and how get value inside newly created control.
Create and count edits create in form worked correctly, but where I create edits in panels with buttons to destroy chosen panel (Panel [Edit, button]), it's create correctly, but count doesnt work.
And I don't know how to destroy chosen by me panel with edit without error (I didn't make it yet in code below).
I have this code:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;
type
TfrmMain = class(TForm)
btnCreateNewObject: TButton;
btnCountValues: TButton;
btnCreateNewPanels: TButton;
btnAllEditsInPanels: TButton;
procedure btnCreateNewObjectClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure btnCountValuesClick(Sender: TObject);
procedure btnCreateNewPanelsClick(Sender: TObject);
procedure btnAllEditsInPanelsClick(Sender: TObject);
private
dynEdit: TEdit;
dynPanel: TPanel;
yposition: integer;
ypositionpanel: integer;
{ Private declarations }
public
{ Public declarations }
end;
var
frmMain: TfrmMain;
implementation
{$R *.dfm}
procedure TfrmMain.btnCountValuesClick(Sender: TObject);
var
i: integer;
res: integer;
begin
res := 0;
for i := 0 to Self.ControlCount - 1 do
begin
if Controls[i] is TEdit then
begin
res := res + StrToInt((Controls[i] as TEdit).Text);
end;
end;
ShowMessage(IntToStr(res));
end;
procedure TfrmMain.btnCreateNewObjectClick(Sender: TObject);
begin
dynEdit := TEdit.Create(Self);
with dynEdit do
begin
Parent := frmMain;
Width := 80;
Height := 25;
Top := yposition;
Left := 3;
end;
yposition := yposition + 26
end;
procedure TfrmMain.btnCreateNewPanelsClick(Sender: TObject);
begin
dynPanel := TPanel.Create(Self);
with dynPanel do
begin
Parent := frmMain;
Width := 100;
Height := 40;
Top := ypositionpanel;
Left := 120;
dynEdit := TEdit.Create(Self);
with dynEdit do
begin
Parent := dynPanel;
Width := 80;
Height := 25;
Top := 3;
Left := 3;
end;
end;
ypositionpanel := ypositionpanel + 41;
end;
procedure TfrmMain.btnAllEditsInPanelsClick(Sender: TObject);
var
i, j: integer;
res: integer;
begin
res := 0;
for i := 0 to Self.ControlCount - 1 do
begin
for j := 0 to dynPanel.ControlCount - 1 do
begin
if dynPanel.Controls[j] is TEdit then
begin
res := res + StrToInt( (Controls[j] as TEdit).Text );
end;
end;
end;
ShowMessage(IntToStr(res));
end;
procedure TfrmMain.FormCreate(Sender: TObject);
begin
yposition := 1;
ypositionpanel := 1;
end;
end.
object frmMain: TfrmMain
Left = 0
Top = 0
Caption = 'frmMain'
ClientHeight = 500
ClientWidth = 888
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
OnCreate = FormCreate
PixelsPerInch = 96
TextHeight = 13
object btnCreateNewObject: TButton
Left = 775
Top = 475
Width = 113
Height = 25
Caption = 'Create new edit'
TabOrder = 0
OnClick = btnCreateNewObjectClick
end
object btnCountValues: TButton
Left = 775
Top = 444
Width = 113
Height = 25
Caption = 'Count all edits'
TabOrder = 1
OnClick = btnCountValuesClick
end
object btnCreateNewPanels: TButton
Left = 648
Top = 475
Width = 121
Height = 25
Caption = 'Create new panels'
TabOrder = 2
OnClick = btnCreateNewPanelsClick
end
object btnAllEditsInPanels: TButton
Left = 648
Top = 444
Width = 121
Height = 25
Caption = 'Count all edits in panels'
TabOrder = 3
OnClick = btnAllEditsInPanelsClick
end
end

Answer 1

You are iterating only through the Edit controls that are direct children of the Form itself, or of the last Panel created. You are not iterating through all of the Panels.
Use a TList or other suitable container to keep track of the Edits you create dynamically, then you can loop through that list/container when needed. And when you are ready to remove a Panel from the Form, simply Remove() its child TEdit from the list and then Free() the Panel, which will free the TEdit for you.
For example:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls,
System.Generics.Collections;
type
TfrmMain = class(TForm)
btnCreateNewObject: TButton;
btnCountValues: TButton;
btnCreateNewPanels: TButton;
btnAllEditsInPanels: TButton;
procedure btnCreateNewObjectClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure btnCountValuesClick(Sender: TObject);
procedure btnCreateNewPanelsClick(Sender: TObject);
procedure btnAllEditsInPanelsClick(Sender: TObject);
procedure DestroyPanel(Sender: TObject);
private
{ Private declarations }
AllEdits: TList<TEdit>;
yposition: integer;
ypositionpanel: integer;
public
{ Public declarations }
end;
var
frmMain: TfrmMain;
implementation
{$R *.dfm}
procedure TfrmMain.btnCountValuesClick(Sender: TObject);
var
i, res: integer;
dynEdit: TEdit;
begin
res := 0;
for i := 0 to AllEdits.Count - 1 do
begin
dynEdit := AllEdits[i];
if dynEdit.Parent = Self then
res := res + StrToInt(dynEdit.Text);
end;
ShowMessage(IntToStr(res));
end;
procedure TfrmMain.btnCreateNewObjectClick(Sender: TObject);
var
dynEdit: TEdit;
begin
dynEdit := TEdit.Create(Self);
try
with dynEdit do
begin
Parent := Self;
Width := 80;
Height := 25;
Top := yposition;
Left := 3;
end;
AllEdits.Add(dynEdit);
except
dynEdit.Free;
raise;
end;
yposition := yposition + 26
end;
procedure TfrmMain.btnCreateNewPanelsClick(Sender: TObject);
var
dynPanel: TPanel;
dynEdit: TEdit;
dynButton: TButton;
begin
dynPanel := TPanel.Create(Self);
try
with dynPanel do
begin
Parent := Self;
Width := 200;
Height := 40;
Top := ypositionpanel;
Left := 120;
end;
dynEdit := TEdit.Create(dynPanel);
with dynEdit do
begin
Parent := dynPanel;
Width := 80;
Height := 25;
Top := 3;
Left := 3;
end;
dynButton := TButton.Create(dynPanel);
with dynButton do
begin
Parent := dynPanel;
Width := 100;
Height := 25;
Top := 3;
Left := 100;
Caption := 'Destroy this pnl';
onClick := DestroyPanel;
end;
AllEdits.Add(dynEdit);
except
dynPanel.Free;
raise;
end;
ypositionpanel := ypositionpanel + 41;
end;
procedure TfrmMain.DestroyPanel(Sender: TObject);
var
dynPanel: TPanel;
dynEdit: TEdit;
begin
dynPanel := TPanel(TButton(Sender).Owner);
dynEdit := TEdit(dynPanel.Controls[0]);
AllEdits.Remove(dynEdit);
dynPanel.Free;
end;
procedure TfrmMain.btnAllEditsInPanelsClick(Sender: TObject);
var
i, res: integer;
dynEdit: TEdit;
begin
res := 0;
for i := 0 to AllEdits.Count - 1 do
begin
dynEdit := AllEdits[i];
if dynEdit.Parent <> Self then
res := res + StrToInt(dynEdit.Text);
end;
ShowMessage(IntToStr(res));
end;
procedure TfrmMain.FormCreate(Sender: TObject);
begin
yposition := 1;
ypositionpanel := 1;
AllEdits := TList<TEdit>.Create;
end;
procedure TfrmMain.FormDestroy(Sender: TObject);
begin
AllEdits.Free;
end;
end.