Virtuelles Keyboard für ein bestimmtes Control deaktivieren

[Sir Rufo]

Ja, der Grund dafür ist, dass es sich um ein Singleton handelt und es von diesem Service nicht mehr als einen geben sollte.

Das Verschieben des Konstruktors ist daher Selbstschutz und Dokumentation für: Achtung, ein Singleton!

Allerdings habe ich festgestellt, dass ich das viel zu kompliziert angegangen bin und eine Umsetzung viel schonender erfolgen kann.

Delphi-Quellcode:

unit Common.FMX.VirtualKeyboardService;

interface

uses
  System.Classes,
  System.Generics.Collections,
  FMX.Types,
  FMX.VirtualKeyboard;

type
  TVirtualKeyboardService = class( TComponent, IFMXVirtualKeyboardService )
  private
    FObjects: TList<TFmxObject>;
    FOriginalService: IFMXVirtualKeyboardService;
    constructor Create( AOwner: TComponent );
    class constructor Create;
  protected
    function GetVirtualKeyboardState: TVirtualKeyboardStates;
    function HideVirtualKeyboard: Boolean;
    procedure SetTransientState( Value: Boolean );
    function ShowVirtualKeyboard( const AControl: TFmxObject ): Boolean;
    procedure Notification( AComponent: TComponent; Operation: TOperation ); override;
  public
    class function Current: TVirtualKeyboardService;
    destructor Destroy; override;

    procedure AddOverrideObject( AObject: TFmxObject );
    procedure RemoveOverrideObject( AObject: TFmxObject );
    function IsOverriddenObject( AObject: TFmxObject ): Boolean;
  private
    class var _current: TVirtualKeyboardService;
  end;

implementation

uses
  FMX.Forms,
  FMX.Platform,
  System.SysUtils;

{ TVirtualKeyboardService }

constructor TVirtualKeyboardService.Create( AOwner: TComponent );
begin
  inherited Create( AOwner );

  FObjects := TList<TFmxObject>.Create;

  if TPlatformServices.Current.SupportsPlatformService( IFMXVirtualKeyboardService, FOriginalService ) then
  begin
    TPlatformServices.Current.RemovePlatformService( IFMXVirtualKeyboardService );
    TPlatformServices.Current.AddPlatformService( IFMXVirtualKeyboardService, Self );
  end;
end;

procedure TVirtualKeyboardService.AddOverrideObject( AObject: TFmxObject );
begin
  if Supports( AObject, IVirtualKeyboardControl ) and not FObjects.Contains( AObject ) then
  begin
    FObjects.Add( AObject );
    Self.FreeNotification( AObject );
  end;
end;

class constructor TVirtualKeyboardService.Create;
begin
  TVirtualKeyboardService._current := TVirtualKeyboardService.Create( Application );
end;

class function TVirtualKeyboardService.Current: TVirtualKeyboardService;
begin
  Result := TVirtualKeyboardService._current;
end;

destructor TVirtualKeyboardService.Destroy;
begin
  if Assigned( FOriginalService ) then
  begin
    TPlatformServices.Current.RemovePlatformService( IFMXVirtualKeyboardService );
    TPlatformServices.Current.AddPlatformService( IFMXVirtualKeyboardService, FOriginalService );
  end;
  FObjects.Free;
  inherited;
end;

function TVirtualKeyboardService.GetVirtualKeyboardState: TVirtualKeyboardStates;
begin
  Result := FOriginalService.VirtualKeyboardState;
end;

function TVirtualKeyboardService.HideVirtualKeyboard: Boolean;
begin
  Result := FOriginalService.HideVirtualKeyboard;
end;

function TVirtualKeyboardService.IsOverriddenObject( AObject: TFmxObject ): Boolean;
begin
  Result := FObjects.Contains( AObject );
end;

procedure TVirtualKeyboardService.Notification( AComponent: TComponent; Operation: TOperation );
begin
  inherited;
  if ( Operation = opRemove ) and ( AComponent is TFmxObject ) then
  begin
    RemoveOverrideObject( AComponent as TFmxObject );
  end;
end;

procedure TVirtualKeyboardService.RemoveOverrideObject( AObject: TFmxObject );
begin
  if FObjects.Contains( AObject ) then
  begin
    FObjects.Remove( AObject );
    Self.RemoveFreeNotification( AObject );
  end;
end;

procedure TVirtualKeyboardService.SetTransientState( Value: Boolean );
begin
  FOriginalService.SetTransientState( Value );
end;

function TVirtualKeyboardService.ShowVirtualKeyboard( const AControl: TFmxObject ): Boolean;
begin
  if IsOverriddenObject( AControl ) then
  begin
    HideVirtualKeyboard;
    Result := False;
  end
  else
    Result := FOriginalService.ShowVirtualKeyboard( AControl );
end;

end.