Hello!


I tried to capture the image of a foreign window but my
attempt is not perfect because the captured image is not similar
to the original window's image. For example like Microsoft Excel's window.
See example: http://img3.freeimagehosting.net/image.php?6a8267869d.jpg


My hook code is the following:

Project:

unit Unit1;

interface

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

const
    MSG_PROJECT = WM_USER + $1000;

type
  TForm1 = class(TForm)
    hook_on: TButton;
    hook_off: TButton;
    send_wm_paint: TButton;
    Edit1: TEdit;
    procedure hook_onClick(Sender: TObject);
    procedure hook_offClick(Sender: TObject);
    procedure MSGHOOK(var Msg: TMessage); message MSG_PROJECT;
    procedure send_wm_paintClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    gp: TPoint;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var hook : integer;


procedure TForm1.MSGHOOK(var Msg: TMessage);
begin
    //if Msg.WParam<>0 then
end;


procedure TForm1.hook_onClick(Sender: TObject);
begin
hook:=SetWindowsHookEx(WH_CALLWNDPROC,
GetProcAddress(GetModuleHandle('NewWndDll'),'NewWindowHookCallBack'),
GetModuleHandle('NewWndDll'), 0);
hook_on.Enabled:=False;
hook_off.Enabled:=True;
end;

procedure TForm1.hook_offClick(Sender: TObject);
begin
UnhookWindowsHookEx(hook);
hook_off.Enabled:=False;
hook_on.Enabled:=True;
end;

procedure TForm1.send_wm_paintClick(Sender: TObject);
begin
SendMessage(FindWindow(nil,PChar(Edit1.Text)),WM_PAINT,0,0);
end;

initialization
MessageBox(0,pchar(intToStr(LoadLibrary('NewWndDll'))),'LoadLibrary',0);


end.



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DLL:


library NewWndDll;

uses
   Windows,SysUtils,Classes,Dialogs,Messages,Graphics;

const
   MSG_PROJECT = WM_USER + $1000;

var
  MyHook : HHook;

function NewWindowHookCallBack(pCode: Integer; pHandle: WPARAM; pWindow: LPARAM): LRESULT; stdcall;
var
PCWP : ^CWPSTRUCT;
h: Hwnd;

  hbmScreen: HBitmap;
  hdcScreen, hdcCompatible : HDC;
  rect: TRect;
  bmp: TBitmap;
begin
PCWP:= Pointer(pWindow);
if PCWP^.Message = WM_PAINT then begin
h:=FindWindow(nil,'Microsoft Excel - Book1.xls'); //window to capture


       if PCWP.hwnd=h then
       begin
       hdcScreen:=GetWindowDC(PCWP.hwnd);
       hdcCompatible:=CreateCompatibleDC(hdcScreen);
       GetWindowRect(PCWP.hwnd, rect);
       hbmScreen:=CreateCompatibleBitmap(hdcScreen, rect.Right - rect.Left, rect.Bottom -
       rect.Top);
       SelectObject(hdcCompatible,hbmScreen);

       SendMessage(PCWP.hwnd,WM_PRINT, hdcCompatible,PRF_CHILDREN or PRF_CLIENT or PRF_ERASEBKGND or
       PRF_NONCLIENT or PRF_OWNED);

       bmp:=TBitmap.Create;
       try
       bmp.Handle:=hbmScreen;
       BitBlt(bmp.Canvas.Handle, 0, 0, rect.Right - rect.Left,rect.Bottom - rect.Top, hdcScreen, 0,
       0, SRCCOPY);
       ReleaseDc(0, hdcScreen);
       bmp.SaveToFile('C:\shot.bmp');
       finally
       bmp.Free;
       DeleteDC(hdcScreen);
       DeleteDC(hdcCompatible);
       end;


       end;


end;
    Result:=CallNextHookEx(MyHook, pCode, pHandle, pWindow);
end;


exports NewWindowHookCallBack index 1 name 'NewWindowHookCallBack';

end.



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I found an article/code about WM_PAINT hook by Feng Yuan.
http://www.fengyuan.com/article/wmprint.html

Dll code: http://www.fengyuan.com/article/capture.zip

But this code written in VC++ and i don't understand it because it contains some unknown things for me and i'm not feel at home in VC++.  Please help me to translate this code to Delphi.

Thanks in advance!