Using Win32 functions in Visual FoxPro Image Gallery
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Using Video Capture: displaying on FoxPro form frames and previewing video obtained from a digital camera

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Before you begin:

This code sample has been tested with Logitech QuickCam Pro 4000 and with Dimera 350C USB Camera (an ancient camera from the year 2000) both operating under Windows XP.

Also I tested the code with Microsoft LifeCam VS-6000 on Vista Business 64-bit PC (the picture below).



No ActiveX controls are required, actually not much of programming is required either. Two API functions, capCreateCaptureWindow and SendMessage do practically all the job. The FoxPro form hosts a child window (the capture window) connected to existing capturing driver.

See also:
  • FoxTalk article: Using the Video Capture API in Visual FoxPro
  • //In [Project Properties - Linker - Input - Additional Dependencies] 
    //add Vfw32.lib
    #include "Vfw.h"
    
    HWND hCapture;
    
    //skipped...
    
    VOID DriverDisconnect()
    {
        SendMessage(hCapture, 
            WM_CAP_DRIVER_DISCONNECT, NULL, NULL);
    }
    
    BOOL IsCaptureConnected()
    {
        CAPDRIVERCAPS psCaps ;
        ZeroMemory(&psCaps, sizeof(psCaps));
    
        SendMessage(hCapture, WM_CAP_DRIVER_GET_CAPS, 
            (WPARAM) sizeof(CAPDRIVERCAPS), (LPARAM) &psCaps);
        return psCaps.fCaptureInitialized;
    }
    
    BOOL DriverConnect()
    {
        SendMessage(hCapture, WM_CAP_DRIVER_CONNECT, NULL, NULL);
        return IsCaptureConnected();
    }
    
    VOID StartPreview()
    {
        SendMessage(hCapture, WM_CAP_SET_PREVIEWRATE, 15,0);
        SendMessage(hCapture, WM_CAP_SET_PREVIEW, 1,0);
        SendMessage(hCapture, WM_CAP_SET_OVERLAY, 1,0);
    }
    
    VOID ReleaseCaptureWindow()
    {
        if (hCapture != NULL)
        {
            DriverDisconnect();
            DestroyWindow(hCapture);
            hCapture=NULL;
        }
    }
    
    VOID ResizeCaptureWindow()
    {
        BITMAPINFOHEADER bmpinfo;
        ZeroMemory(&bmpinfo, sizeof(bmpinfo));
        bmpinfo.biSize = sizeof(bmpinfo);
    
        SendMessage(hCapture, WM_CAP_GET_VIDEOFORMAT, 
            (WPARAM) sizeof(bmpinfo), (LPARAM) &bmpinfo);
    
        SetWindowPos(hCapture, 0,0,0, bmpinfo.biWidth, 
            bmpinfo.biHeight, SWP_SHOWWINDOW);
    }
    
    VOID InitCaptureWindow(HWND hWnd)
    {
       hCapture = capCreateCaptureWindow(NULL, 
           WS_CHILD|WS_VISIBLE, 0,0,1,1, hWnd, 1);
    
       if (hCapture == NULL) return;
    
       if (DriverConnect())
       {
            SendMessage(hCapture, WM_CAP_SET_SCALE, 1,0);
            ResizeCaptureWindow();
            StartPreview();
       }
    }
    

    User rating: 9.5/10 (4 votes)
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    1560 bytes  
    Created: 2004-06-04 18:30:44  
    Modified: 2013-09-20 13:28:29  
    Visits in 7 days: 144  
    Listed functions:
    capCreateCaptureWindow
    DestroyWindow
    SendMessage
    SetWindowPos
    Printer friendly API declarations
    My comment:
    Apr.15, 2008: C++ version added
    May 27, 2007: all capWindow functionality moved to Custom control
    Oct.12, 2004: SaveToDib method captures and saves a single image as a device-independent bitmap (DIB).

    Windows Image Acquisition Automation Layer

    The Microsoft Windows Image Acquisition (WIA) Automation Layer 2.0 is a full-featured image manipulation component that provides end-to-end image processing capabilities. The WIA Automation Layer makes it easy to acquire images on digital cameras, scanners, or Web cameras, and to rotate, scale, and annotate your image files.

    Applications that use the WIA Automation LayerAPI require Windows XPService Pack 1 (SP1) or later. Earlier versions of Windows are not supported. You will need WIAAut.dll to use the WIA Automation Layer.

    * * *
    You may have several capture windows created and fed from different Video Sources. You can not feed two capture windows from same source.

    For example, now I have two digital cameras connected through USB -- Dimera 350C and Logitech QuickCam -- and one more video source, ATI TV Wonder Pro card that receives TV channels through coaxial cable.


    With slightly modified code I can create three capture windows, one for each video source. All three windows simultaneously display preview from their sources.

    * * *
    Window styles WS_SYSMENU, WS_CAPTION and WS_THICKFRAME applied to the capture window make it movable and resizable. WS_CHILD must be present in any combination of window styles.
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    User Contributed Notes:
    nestor hdz | 2005-05-16 11:48:49
    esta muy bueno, pero no sabras algo acerca de los lectores digitales ya que no he podido poner el que tenemos y es un U.are.U 4000sensor de digitalpersona

    mi correo es nareas@parkerseal.com
    stuff@data-lite.com | 2005-07-22 17:58:31
    I get "Failed to connect to video input device." when I run this code in VFP 9.0.

    Clearly I need to be able to select the camera, but I fail to figure out how to select a camera at this time!

    Please help!

    Dennis Kean
    A.M. | 2005-07-22 18:05:34
    Dennis, I tried but found nothing in the API that could allow to select video source.

    When testing I had three sources connected to my computer -- two USB cameras and TV card. Every time the system tries to connect to the last device that was active.
    Alex | 2005-10-14 02:58:20
    Hi,

    I have not tested it, but think it might help.

    Have a look at

    WM_CAP_GET_MCI_DEVICE
    WM_CAP_SET_MCI_DEVICE

    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/multimed/htm/_win32_wm_cap_get_videoformat.asp


    Regards
    Alex
    A.M. | 2005-10-14 07:23:24
    Alex, I think I already tried those two and it did not work. Will give another try.
    robertosegovia@hotmail.com | 2007-01-15 12:31:14
    I have the complete program that you sent in June 2005 and it operate. But upon executing this program by means of a command button of a form selected from a option of menu of user, it don't show the image of video.

    They could help me, thank you
    help | 2007-06-22 09:03:34
    Dear sir
    guide me to retrieve the saved image (.dib) and display in the form pls
    regards
    balu
    A.M. | 2007-06-25 21:41:58
    The SaveToDib method in the code above saves current frame in a DIB file.

    In VFP8/9 such DIB file can be directly assigned to the Picture property of VFP Image control, no format conversion is required. The control will display the image.

    As well such DIB image can be directly stored in General field of VFP table, for example:

    CREATE CURSOR csTmp (filename C(30), imagedata G)
    APPEND BLANK
    REPLACE filename WITH 'GRAB_3G17JDE3.DIB'
    APPEND GENERAL imagedata FROM 'GRAB_3G17JDE3.DIB'

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