TPanel

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TPanel is a component that creates a panel on a form. A TPanel is a descendant of TWinControl and is available under the Standard tab of the Component Palette. A TPanel can act as a visible container for other components.

Example

One way to use panels is when the control group is displayed and hidden. Instead of showing or hiding individual controls, you can hide and show the panel and all of its child controls with a single command. In this example, the following components are used: TButton, TShape

Create code

• Create a new blank GUI application with the form Form1
• Create the OnCreate event handler for the form, by clicking on your form, use the Object Inspector, the tab events, select the OnCreate event and click the button [...] or double click the button in the form.
• Add following code (Complete the missing parts):

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ExtCtrls, StdCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    aPanel:TPanel;
    procedure aButtonClick(Sender: TObject);
  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
var
  aButton:TButton;

  aShape1,aShape2:TShape;
begin
  Caption :='Panel demo';
  aButton:=TButton.Create(Self);
  aButton.Parent:=Self;
  aButton.Caption:= 'Show/Hide';
  aPanel:=TPanel.Create(Self);
  aPanel.Parent:=Self;
  aPanel.Caption:='';
  aShape1:=TShape.Create(aPanel);
  aShape1.Parent:=aPanel;
  aShape1.Shape:=stStar;
  aShape1.Top := 5;
  aShape2:=TShape.Create(aPanel);
  aShape2.Parent:=aPanel;
  aShape2.Shape:=stStar;
  aShape2.Top := 5;
  aShape2.Left:=aShape1.Width+10;
  aPanel.Height:=aShape1.Height+10;
  aButton.Top:=aPanel.Height+10;
  aButton.OnClick:=@aButtonClick;
  Height := aButton.Top+aButton.Height+10;
end;

procedure TForm1.aButtonClick(Sender: TObject);  //the event handler for the button
begin
  if (Sender is TButton)
    then begin
      if aPanel.Visible then aPanel.Visible := false else aPanel.Visible := true;
    end;
end;
end.

See also

• TPanel doc
• TBevel
• TFrame
• TFlowPanel