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Reference for unit 'Forms' (#lcl)

TCustomFrame

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

The base type for TFrame.

Declaration

Source position: forms.pp line 318

`type TCustomFrame = class(TCustomDesignControl)`
`protected`
`class procedure WSRegisterClass; override;`		Registers this component class with the current WidgetSet.
`procedure Notification(); override;`		Adds or removes an action list for the control.
`procedure SetColor(); override;`		Sets the value for the Color property.
`procedure SetParent(); override;`		Sets the value for the Parent property.
`procedure SetParentBackground(); override;`		Sets the value for the ParentBackground property.
`procedure CMParentColorChanged(); message;`		Handles the CM_PARENTCOLORCHANGED message for the control.
`procedure DefineProperties(); override;`		Defines non-published properties that are included in LCL component streaming.
`procedure CalculatePreferredSize(); override;`		Gets the preferred height and width for the control used during auto-sizing.
`procedure UpdateOpaque;`		Updates control style flags to reflect the transparency for the frame.
`public`
`constructor Create(); override;`		Constructor for the class instance.
`procedure GetChildren(); override;`		Invokes `Proc` for all Controls and also for all Components without a Parent.
`class function GetControlClassDefaultSize; override;`		Gets the default dimensions for a new instance of the class.
`property ParentBackground: Boolean;`		Indicates if the control uses the background from the parent.
`end;`

Inheritance

`TCustomFrame`		The base type for `TFrame`.
\|
`TCustomDesignControl`		Provides a designer surface for scaling and layout of its child controls.
\|
`TScrollingWinControl`		Implements a windowed control with scroll bars.
\|
`TCustomControl`		The base class for windowed controls which paint themselves.
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`TWinControl`		Implements a windowed control which can contain other child controls.
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`TControl`		The base class for visible controls.
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`TLCLComponent`		The base class for LCL components which have an associated widget.
\|
`TComponent,IUnknown,IInterfaceComponentReference`
\|
`TPersistent,IFPObserved`
\|
`TObject`

Description

TCustomFrame is a TCustomDesignControl descendant which implements the base class for TFrame. A Frame is a named container for related components. Groups of controls can be place on a frame, and re-used in your applications.

A Frame has behavior very similar to a Form. Their unique ability is that they can be embedded into forms or other frames in the designer. Like forms, they are stored in two separate files: the code is stored in a .pas unit file, and the design is stored in a .lfm file.

Frames can be created and designed in the Lazarus IDE by creating a new Frame module, and using the unit in your application. An existing frame can be added using the TFrame component on the Standard tab in the Lazarus IDE; you will be prompted for the TFrame class to use for the component.

Frames can also be created in code at run-time. They do not have to be installed in the Lazarus IDE. For example:

unit Unit1;

{$mode objfpc}{$H+}

interface

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

type

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    GroupBox1: TGroupBox;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { private declarations }
    Frame: TFrame;
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation
uses
  Unit2{TFrame1}, Unit3{TFrame2}, Unit4{TFrame3};

{$R *.lfm}

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  Frame := TFrame1.Create(GroupBox1);
  Frame.Parent := GroupBox1;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if not Assigned(Frame) then
  begin
    Frame := TFrame1.Create(GroupBox1);
    Frame.Parent := GroupBox1;
  end else if Frame is TFrame1 then begin
    Frame.Free;
    Frame := TFrame2.Create(GroupBox1);
    Frame.Parent := GroupBox1;
  end else if Frame is TFrame2 then begin
    Frame.Free;
    Frame := TFrame3.Create(GroupBox1);
    Frame.Parent := GroupBox1;
  end else begin
    FreeAndNil(Frame);
  end;
end;

end.

One drawback is that complex inheritance hierarchies for TFrame classes can be problematic; they do not propagate changes to all derived frames in a multi-level inheritance tree.

TFrame		Frames can be designed like Forms and used like custom controls, without much coding or installation in the IDE.
TCustomDesignControl		Provides a designer surface for scaling and layout of its child controls.

TCustomFrame

Declaration

Inheritance

Description

See also