Application disable resize over Dock

(macOS only)

On macOS it's often needed to disable app window's resize below OS Dock. But Lazarus forms always resize below it. How to disable this resize?

1) Create TForm.OnConstrainedResize handler for your form. Note, it was not "published" in LCL until LCL 1.7. Create it by hands:

  TfmMain = class(TForm)
    ... 
  private
    ...
    procedure FormConstrainedResize(Sender: TObject; var MinWidth, MinHeight,
      MaxWidth, MaxHeight: TConstraintSize);
    ...
  end;

procedure TfmMain.FormCreate(Sender: TObject);
begin
  ..
  Self.OnConstrainedResize:= @FormConstrainedResize; 
  ..
end;

2) Write code in handler to change MaxHeight, value must be workarea height minus current form's Top.

procedure TfmMain.FormConstrainedResize(Sender: TObject; var MinWidth, MinHeight,
  MaxWidth, MaxHeight: TConstraintSize);
const
  cMinHeight = 200;
var
  RWork: TRect;
begin
  {$ifndef darwin} exit; {$endif}
  RWork:= Screen.PrimaryMonitor.WorkareaRect;
  MaxHeight:= Max(cMinHeight, RWork.Bottom - RWork.Top - Top);
end;

3) Note: handler has side effect. On dragging window by its caption, handler is called too, so window will be resized on moving it too low, near the Dock.

See also

• Bounce Application Icon in Dock
• Hiding a macOS app from the Dock
• macOS Application Dock Menu
• Show Badge on Application Icon in Dock

From the Free Pascal wiki, page "Application disable resize over Dock", as it stood on 2021-12-15 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's Licensing page. If you have concerns about this material, message the admin.