Webcam with Delphi (I)

I present you the software that allows manage your Webcam with Delphi.

First you have to install the software on your system "Microsoft Video for Windows SDK" that contains the library avicap32.dll.

Among the functions contained use "capCreateCaptureWindowA" to initialize the driver and image capture.

After handling the capture window will have to use the "SendMessage" making it easier and greatly simplifies the developers work.

Now we are goint to the program:

We add global variables:

Ventana: hwnd; //Handle de la ventana de captura

In the section "const" we write


WM_CAP_START = WM_USER;
WM_CAP_STOP = WM_CAP_START + 68;
WM_CAP_DRIVER_CONNECT = WM_CAP_START + 10;
WM_CAP_DRIVER_DISCONNECT = WM_CAP_START + 11;
WM_CAP_SAVEDIB = WM_CAP_START + 25;
WM_CAP_GRAB_FRAME = WM_CAP_START + 60;
WM_CAP_SEQUENCE = WM_CAP_START + 62;
WM_CAP_FILE_SET_CAPTURE_FILEA = WM_CAP_START + 20;
WM_CAP_EDIT_COPY = WM_CAP_START + 30;
WM_CAP_SET_PREVIEW = WM_CAP_START + 50;
WM_CAP_SET_PREVIEWRATE = WM_CAP_START + 52;


Section "implementation":


FUNCTION capCreateCaptureWindowA(lpszWindowName: PCHAR; dwStyle: longint; x: integer; y: integer; nWidth: integer; nHeight: integer; ParentWin: HWND; nId: integer): HWND; STDCALL EXTERNAL 'AVICAP32.DLL';


is the call of the external library Avicap32.dll

Elements of the interface:

-Botón "iniciar" (Pressing start capturing the image from the Webcam)

-Botón "detener" (Press to stop capturing)

-Control de Imagen "tImage" (We called "Image1")

The code to be included within the buttons is as follows:
Botón "Iniciar"

PROCEDURE TForm1.Button1Click(Sender: TObject);
BEGIN
   Ventana := capCreateCaptureWindowA('Ventana de captura',
      WS_CHILD OR WS_VISIBLE, image1.Left, image1.Top, image1.Width,
      image1.Height, form1.Handle, 0);
   IF Ventana <> 0 THEN
   BEGIN
      TRY
         SendMessage(Ventana, WM_CAP_DRIVER_CONNECT, 0, 0);
         SendMessage(Ventana, WM_CAP_SET_PREVIEWRATE, 40, 0);
         SendMessage(Ventana, WM_CAP_SET_PREVIEW, 1, 0);
      EXCEPT
         RAISE;
      END;
   END
   ELSE
   BEGIN
      MessageDlg('Error al conectar Webcam', mtError, [mbok], 0);
   END;
END;

Botón "Detener"

PROCEDURE TForm1.Button2Click(Sender: TObject);
BEGIN
   IF Ventana <> 0 THEN
   BEGIN
      SendMessage(Ventana, WM_CAP_DRIVER_DISCONNECT, 0, 0);
      Ventana := 0;
   END;
END;

In the event:  Onclose we make a call to the procedure included in the button "Detener".

And that's all for now, we will be adding more items and tips.

Related links:
Webcam con Delphi ( II )
WebCam con Delphi ( III )