Question

In Delphi XE2, how can I detect if the user clicked a popup menu item with the left or with the right mouse button?

Answer 1

Use this unit, install it as a component and replace the standard TPopupMenu which adds an OnMenuRightClick event.

unit RCPopupMenu;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Menus;

type
  TMenuRightClickEvent = procedure (Sender: TObject; Item: TMenuItem) of object;

  TRCPopupList = class(TPopupList)
  protected
    procedure WndProc(var Message: TMessage); override;
  end;

  TRCPopupMenu = class(TPopupMenu)
  private
    FOnMenuRightClick: TMenuRightClickEvent;
  protected
    function DispatchRC(aHandle: HMENU; aPosition: Integer): Boolean;
    procedure RClick(aItem: TMenuItem);
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    procedure Popup(X, Y: Integer); override;
  published
    property OnMenuRightClick: TMenuRightClickEvent read FOnMenuRightClick write FOnMenuRightClick;
  end;

procedure Register;

var
  RCPopupList: TRCPopupList;

implementation

procedure Register;
begin
  RegisterComponents('Samples', [TRCPopupMenu]);
end;

{ TRCPopupList }

procedure TRCPopupList.WndProc(var Message: TMessage);
var
  i: Integer;
  pm: TPopupMenu;
begin
  if Message.Msg = WM_MENURBUTTONUP then
  begin
    for I := 0 to Count - 1 do
    begin
      pm := TPopupMenu(Items[i]);
      if pm is TRCPopupMenu then
        if TRCPopupMenu(Items[i]).DispatchRC(Message.lParam, Message.wParam) then
          Exit;
    end;
  end;
  inherited WndProc(Message);
end;

{ TRCPopupMenu }

constructor TRCPopupMenu.Create(AOwner: TComponent);
begin
  inherited;
  PopupList.Remove(Self);
  RCPopupList.Add(Self);
end;

destructor TRCPopupMenu.Destroy;
begin
  RCPopupList.Remove(Self);
  PopupList.Add(Self);
  inherited;
end;

function TRCPopupMenu.DispatchRC(aHandle: HMENU; aPosition: Integer): Boolean;
begin
  Result := False;
  if Handle = aHandle then
  begin
    RClick(Items[aPosition]);
    Result := True;
  end;
end;

procedure TRCPopupMenu.Popup(X, Y: Integer);
const
  Flags: array[Boolean, TPopupAlignment] of Word =
    ((TPM_LEFTALIGN, TPM_RIGHTALIGN, TPM_CENTERALIGN),
    (TPM_RIGHTALIGN, TPM_LEFTALIGN, TPM_CENTERALIGN));
  Buttons: array[TTrackButton] of Word = (TPM_RIGHTBUTTON, TPM_LEFTBUTTON);
var
  AFlags: Integer;
begin
  DoPopup(Self);
  AFlags := Flags[UseRightToLeftAlignment, Alignment] {or Buttons[TrackButton]};
  if (Win32MajorVersion > 4) or ((Win32MajorVersion = 4) and (Win32MinorVersion > 0)) then
  begin
    AFlags := AFlags or (Byte(MenuAnimation) shl 10);
    AFlags := AFlags or TPM_RECURSE;
  end;
  TrackPopupMenuEx(Items.Handle, AFlags, X, Y, RCPopupList.Window, nil);
end;

procedure TRCPopupMenu.RClick(aItem: TMenuItem);
begin
  if Assigned (FOnMenuRightClick) then
    FOnMenuRightClick(Self, aItem);
end;

var
  oldPL: TPopupList;

initialization
  RCPopupList := TRCPopupList.Create;
finalization
  RCPopupList.Free;

end.

You can then use the OnMenuRightClick event to perform some action on a right click!

Note: I didn’t make this unit – I don’t know who did but credit goes to whoever did… I have however just tested it in Delphi XE2 and it works fine.