Новая WinProc



Автор: Xavier Pacheco

unit Scwndprc;
interface
uses Forms, Messages;
const
DDGM_FOOMSG = WM_USER;
implementation
uses Windows, SysUtils, Dialogs;
var
WProc: Pointer;
function NewWndProc(Handle: hWnd; Msg, wParam, lParam: Longint): Longint;
stdcall;
{ This is a Win32 API-level window procedure. It handles the messages }
{ received by the Application window. }
begin
if Msg = DDGM_FOOMSG then
{ If it's our user-defined message, then alert the user. }
ShowMessage(Format('Message seen by WndProc! Value is: $%x', [Msg]));
{ Pass message on to old window procedure }
Result := CallWindowProc(WProc, Handle, Msg, wParam, lParam);
end;
initialization
{ Set window procedure of Application window. }
WProc := Pointer(SetWindowLong(Application.Handle, gwl_WndProc,
Integer(@NewWndProc)));
end.
unit Main;
interface
uses
SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
Forms, Dialogs, StdCtrls;
type
TMainForm = class(TForm)
SendBtn: TButton;
PostBtn: TButton;
procedure SendBtnClick(Sender: TObject);
procedure PostBtnClick(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
private
OldWndProc: Pointer;
WndProcPtr: Pointer;
procedure WndMethod(var Msg: TMessage);
procedure HandleAppMessage(var Msg: TMsg; var Handled: Boolean);
end;
var
MainForm: TMainForm;
implementation
{$R *.DFM}
uses ScWndPrc;
procedure TMainForm.HandleAppMessage(var Msg: TMsg; var Handled: Boolean);
{ OnMessage handler for Application object. }
begin
if Msg.Message = DDGM_FOOMSG then
{ if it's the user-defined message, then alert the user. }
ShowMessage(Format('Message seen by OnMessage! Value is: $%x',
[Msg.Message]));
end;
procedure TMainForm.WndMethod(var Msg: TMessage);
begin
if Msg.Msg = DDGM_FOOMSG then
{ if it's the user-defined message, then alert the user. }
ShowMessage(Format('Message seen by WndMethod! Value is: $%x', [Msg.Msg]));
with Msg do
{ Pass message on to old window procedure. }
Result := CallWindowProc(OldWndProc, Application.Handle, Msg, wParam,
lParam);
end;
procedure TMainForm.SendBtnClick(Sender: TObject);
begin
SendMessage(Application.Handle, DDGM_FOOMSG, 0, 0);
end;
procedure TMainForm.PostBtnClick(Sender: TObject);
begin
PostMessage(Application.Handle, DDGM_FOOMSG, 0, 0);
end;
procedure TMainForm.FormCreate(Sender: TObject);
begin
Application.OnMessage := HandleAppMessage; // set OnMessage handler
WndProcPtr := MakeObjectInstance(WndMethod); // make window proc
{ Set window procedure of application window. }
OldWndProc := Pointer(SetWindowLong(Application.Handle, GWL_WNDPROC,
Integer(WndProcPtr)));
end;
procedure TMainForm.FormDestroy(Sender: TObject);
begin
{ Restore old window procedure for Application window }
SetWindowLong(Application.Handle, GWL_WNDPROC, Longint(OldWndProc));
{ Free our user-created window procedure }
FreeObjectInstance(WndProcPtr);
end;
end.

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