Work in progress to handle when the Windows 10 OSK shows/hides

FrameworkInputPaneHandler.pas

unit FrameworkInputPaneHandler;

interface

uses
  System.Win.ComObj,
  Winapi.Windows;

// https://github.com/tpn/winsdk-10/blob/master/Include/10.0.10240.0/um/ShObjIdl.idl
const
  CLSID_FrameworkInputPane: TGUID = '{D5120AA3-46BA-44C5-822D-CA8092C1FC72}';
  SID_IFrameworkInputPane = '{5752238B-24F0-495A-82F1-2FD593056796}';
  SID_IFrameworkInputPaneHandler = '{226C537B-1E76-4D9E-A760-33DB29922F18}';

type
  IFrameworkInputPaneHandler = interface(IUnknown)
    [SID_IFrameworkInputPaneHandler]
    function Hiding(var fEnsureFocusedElementInView: BOOL): HResult; stdcall;
    function Showing(var rcInputPaneScreenLocation: TRect; var fEnsureFocusedElementInView: BOOL): HResult; stdcall;
  end;

  IFrameworkInputPane = interface(IUnknown)
    [SID_IFrameworkInputPane]
    function Advise(var window: IUnknown; handler: IFrameworkInputPaneHandler; var dwCookie: DWORD): HResult; stdcall;
    function AdviseWithHWND(hwnd: HWND; handler: IFrameworkInputPaneHandler; var dwCookie: DWORD): HResult; stdcall;
    function Unadvise(dwCookie: DWORD): HResult; stdcall;
    function Location(var rcInputPaneScreenLocation: TRect): HResult; stdcall;
  end;

  TInputPaneHidingEvent = procedure(Sender: TObject; var EnsureFocusedElementInView: Boolean) of object;
  TInputPaneShowingEvent = procedure(Sender: TObject; const Rect: TRect; var EnsureFocusedElementInView: Boolean) of object;

  TFrameworkInputPaneHandler = class(TInterfacedObject, IFrameworkInputPaneHandler)
  private
    FAdviseCookie: DWORD;
    FInputPane: IFrameworkInputPane;
    FOnInputPaneHiding: TInputPaneHidingEvent;
    FOnInputPaneShowing: TInputPaneShowingEvent;
  protected
    { IFrameworkInputPaneHandler }
    function Hiding(var fEnsureFocusedElementInView: BOOL): HResult; stdcall;
    function Showing(var rcInputPaneScreenLocation: TRect; var fEnsureFocusedElementInView: BOOL): HResult; stdcall;
  public
    constructor Create(const AWnd: HWND);
    destructor Destroy; override;
    property OnInputPaneHiding: TInputPaneHidingEvent read FOnInputPaneHiding write FOnInputPaneHiding;
    property OnInputPaneShowing: TInputPaneShowingEvent read FOnInputPaneShowing write FOnInputPaneShowing;
  end;

implementation

uses
  Winapi.ActiveX;

{ TFrameworkInputPaneHandler }

constructor TFrameworkInputPaneHandler.Create(const AWnd: HWND);
begin
  // I am using the Handle property of the main form to pass as the AWnd parameter
  inherited Create;
  CoCreateInstance(CLSID_FrameworkInputPane, nil, CLSCTX_INPROC_SERVER, StringToGUID(SID_IFrameworkInputPane), FInputPane);
  FInputPane.AdviseWithHWND(AWnd, Self as IFrameworkInputPaneHandler, FAdviseCookie);
end;

destructor TFrameworkInputPaneHandler.Destroy;
begin
  FInputPane.Unadvise(FAdviseCookie);
  FInputPane := nil;
  inherited;
end;

function TFrameworkInputPaneHandler.Hiding(var fEnsureFocusedElementInView: BOOL): HResult;
begin
  // Intention here is to call the event handler
end;

function TFrameworkInputPaneHandler.Showing(var rcInputPaneScreenLocation: TRect; var fEnsureFocusedElementInView: BOOL): HResult;
begin
  // Intention here is to call the event handler
end;

end.

Thanks, @SSchiele! I've only just come across this..