How to prevent design-time interactions with TFrame registered as a component

Question

I created a new frame that I wanted to register as a component. I already knew about the RegisterSprigType from this question, so it saved me some hassle.

RegisterSprigType properly prevent the designer to select, accidently move or delete controls inside your frame, but only directly. The controls inside still accepts controls to be dropped.

In my situation, I have panels inside my frame. I can drop a button on said panel. If I delete the button, then the parent get selected (which happen to be the panel) and then I can delete the panel.

I tried removing csAcceptsControls from the frame's ControlStyle. It did prevent controls to be dropped directly on the frame, but the panel inside still accepted controls.

So, I ended up removing csAcceptsControls from all controls contained in my frame in the "Loaded" procedure.

If my frame was creating controls dynamically in response to property change, I presume I would also need to override the Notification procedure to strip csAcceptsControls from any added controls.

So, my question is, is there a better way to achieve the same result (Prevent the designer to add controls inside a frame registered as a component). A "register" telling the designer to ignore the frame class and its children as containers perhaps?

If this method is already the most optimal, did I miss anything?

Is there any "gotchas" I should be aware of with this approach? (Any side effects? both design and runtime.)

Livius · Answer 1 · 2016-04-28T11:16:49.837

I dig into but there is not good solution for your problem because all methods work in Frame context not its child components like DesignWndProc, WM_NCHITTEST ...

but i have solusion(not nice) look below but i do not know if it is better then your solution to remove csAcceptsControls.

You can create in design time only Panel(transparent) and remove only from it csAcceptsControls. In frame resize you can set this panel width and height to eat whole Frame. But you must put all controls in some top level panel(parent is Frame) with align alClient and every control will be on it. Then you create your design time panel (parent is Frame) and it will be second top level panel on your frame. And you can bring it to front only once after creation. This remove need to change every property which create new controls.

Something like this structure Frame{PanelTopLevel{any other controls}}{DesignPanel}:

object FrameTestDisableFrame: TFrameTestDisableFrame
  object PanelTopLevel: TPanel
    object Panel1: TPanel
      Left = 96
      Top = 56
      Width = 201
      Height = 105
      Caption = 'Panel1'
      TabOrder = 0
      object Button1: TButton
        Left = 48
        Top = 24
        Width = 75
        Height = 25
        Caption = 'Button1'
        TabOrder = 0
      end
    end
end

design panel code

TDesignPanel = class(TWinControl)
  protected
    procedure CreateParams(var Params: TCreateParams); override;
    procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
  public
    constructor Create(AOwner: TComponent); override;
  end;

implementation

{ TDesignPanel }

constructor TDesignPanel.Create(AOwner: TComponent);
begin
  inherited;
  ControlStyle:= ControlStyle - [csAcceptsControls];
  Color:= clBackground;
end;

procedure TDesignPanel.CreateParams(var Params: TCreateParams);
begin
  inherited;
  Params.ExStyle:= Params.ExStyle or WS_EX_TRANSPARENT;
end;

procedure TDesignPanel.WMEraseBkgnd(var Message: TWMEraseBkgnd);
begin
  Message.Result:= 1;
end;

and in your frame

private
    DesignPanel: TDesignPanel;

...

constructor TFrameTestDisableFrame.Create(AOwner: TComponent);
begin
  inherited;
  ControlStyle:= ControlStyle - [csAcceptsControls];
  if csDesigning in ComponentState then
    begin
      DesignPanel:= TDesignPanel.Create(Self);
      DesignPanel.Parent:= Self;
      DesignPanel.BringToFront;
    end;
end;



procedure TFrameTestDisableFrame.Resize;
begin
  inherited;
  DesignPanel.BringToFront;
  DesignPanel.SetBounds(0, 0, Width, Height);
end;

I tested this and work ok

Hint

In my situation, I have panels inside my frame. I can drop a button on said panel. If I delete the button, then the parent get selected (which happen to be the panel) and then I can delete the panel.

In delphi Seattle when i delete such button whole frame is selected not parent panel.

How to prevent design-time interactions with TFrame registered as a component

1 Answers1