/*

  File:         BigEasyVideoGrabber.c

  Contains:     Routines for Using the Video Digitizer.

  Written by:   David Van Brink / QT Engineering

  Copyright:    © 1991-1994 by Apple Computer, Inc., all rights reserved.

  Change History (most recent first):

  <2>       12/4/94     khs     changed the format of the file to the new look and feel

  <1>       12/18/94    dvb     1.0 Started

  To Do:

*/

// INCLUDES

#include <Memory.h>

#include <OSUtils.h>

#include "BigEasyVideoGrabber.h"

// FUNCTIONS

EasyVideoGrabber NewEasyVideoGrabber(Rect* outputSize)

/*

 * Gets the default video digitizer,

 * and returns the output size of the video image.

 */

{

    EasyVideoGrabber evg;

    ComponentResult thisError;

    evg = (void*)NewPtr(sizeof(EasyVideoGrabberRecord));

    if (!evg)

        goto fail;

    evg->sg = 0;

    evg->vc = 0;

    evg->sg = OpenDefaultComponent(SeqGrabComponentType, 0);

    if (!evg->sg)

        goto fail;

    thisError = SGInitialize(evg->sg);

    if (thisError)

        goto fail;

    thisError = SGNewChannel(evg->sg, VideoMediaType, &evg->vc);

    if (thisError)

        goto fail;

    if (outputSize)

    {

        thisError = SGGetSrcVideoBounds(evg->vc, outputSize);

        if (thisError)

            goto fail;

    }

    thisError = SGSetChannelUsage(evg->vc, seqGrabPreview);

    if (thisError)

        goto fail;

    goto goHome;

fail:if (evg)

    {

        if (evg->sg)

            CloseComponent(evg->sg);

        DisposePtr((void*)evg);

        evg = 0;

    }

goHome:return evg;

}

Boolean GrabEasyVideoGrabber(EasyVideoGrabber evg,

                             Rect* r)

/*

 * Grab a frame, and draw it in the current port, of size 'r'.

 * You can pass 'nil' for the EasyVideoGrabber, and one

 * will be allocated and disposed, while-u-wait.

 *

 * The boolean returned is 'true' iff a frame was actually captured and drawn.

 *

 * The 'while' loop is a real barnstorming technique. The "Sequence Grab"

 * component does not provide any way to know when a frame has actually

 * been grabbed. Therefore, the Sequence Grabber is simply idled for

 * a few ticks, on the _assumption_ that the video frame rate is high

 * enough that at least one frame is grabbed.

 *

 * While this may seem mildly inelegant, it, in fact, works.

 */

{

    ComponentResult thisError;

    GWorldPtr gw;

    GDHandle gd;

    Boolean localGrabber;

    unsigned long t;

    Boolean result;

    result = false;

    localGrabber = (evg == 0);

    if (localGrabber)

        evg = NewEasyVideoGrabber(nil);

    if (!evg)

        goto goHome;

    GetGWorld(&gw, &gd);

    thisError = SGSetGWorld(evg->sg, gw, gd);

    if (thisError)

        goto goHome;

    thisError = SGSetChannelBounds(evg->vc, r);

    if (thisError)

        goto goHome;

    thisError = SGStartPreview(evg->sg);

    if (thisError)

        goto goHome;

    t = TickCount() + 8;

    do

    {

        thisError = SGIdle(evg->sg);

        if (thisError)

            goto goHome;

    } while (TickCount() < t);

    thisError = SGStop(evg->sg);

    if (localGrabber)

        DisposeEasyVideoGrabber(evg);

    result = true;

goHome:;

    return result;

}

void DisposeEasyVideoGrabber(EasyVideoGrabber evg)

{

    CloseComponent(evg->sg);

    DisposePtr((void*)evg);

}