getform.pas

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unit GetForm;

interface

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

type
  TFormGetData = class(TForm)
    Memo1: TMemo;
    Label1: TLabel;
    Label2: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
  private
    { Private declarations }
  public
    procedure GetCopyData (var Msg: TWmCopyData);
      message wm_CopyData;
    procedure UserData (var Msg: TMessage);
      message wm_User;
  end;

var
  FormGetData: TFormGetData;

implementation

{$R *.DFM}

procedure TFormGetData.GetCopyData (var Msg: TWmCopyData);
var
  FromTitle: string;
begin
  Memo1.Clear;
  SetLength (FromTitle, 100);
  GetWindowText (Msg.From, PChar(FromTitle), 100);
  FromTitle := pChar (FromTitle);
  Memo1.Lines.Add ('Message from: ' + FromTitle);
  with Memo1.Lines, Msg.CopyDataStruct^ do
  begin
    Add ('Small data: ' + IntToStr (dwData));
    Add ('Large block size: ' + IntToStr (cbData));
    Add ('String: ' + PChar (lpData));
  end;
  // received (true)
  Msg.Result := 1;
end;

procedure TFormGetData.UserData (var Msg: TMessage);
begin
  Edit1.Text := 'Address: ' + IntToHex (Msg.LParam, 16);
  // usually creates a GpFault!!!
  Edit2.Text := 'String: ' + string (PChar (Msg.LParam));
end;

end.