Developer CD Series 2000 August: Tool Chest/Dev.CD Aug 00 TC Disk 2.toast/pc/sample code/quicktime/effects/dimmer2effect/effect.c

Text File | 2000-06-23 | 27.2 KB | 980 lines

/*
    Dimmer2Effect.c - a sample QuickTime video effect.

    This effect uses a single source as input, and renders that source with
    a dim value that starts at full on, and ramps to full off.  This isn't very
    useful as a real effect, but shows instead how to create an effect.

    READ THIS PARAGRAPH BEFORE DOING ANYTHING ELSE IN THIS FILE:
    To find things to change to implement your effect, seach for *** CHANGE ***.
    Code that will require modification is bracketted by CHANGE/END CHANGE.

    There are eleven places to change code, and one place where you write new
    code that implements your actual effect.  MAKE SURE YOU LOOK AT ALL OF THEM.

    *IMPORTANT*

    You MUST also ensure that the Effect.r file is kept in sync with this code.
    In particular it is very important that you update the 'atms' resource
    description so that the parameters of your effect are correctly described.
    Full details of the format of the 'atms' resource can be found in the Effects
    chapter of the QT 3.0 documentation

    ALSO PLEASE NOTE THAT THE LINK WARNING ABOUT THE COMPONENT DISPATCH ENTRY POINT
    NOT BEING A ROUTINE DESCRIPTOR IS NORMAL AND CAN BE IGNORED!

    written by Tom Dowdy and Dan Crow
    copyright © 1997-1998 Apple Computer, Inc.
    All rights reserved.
*/


// --------------------------------------------------------------------------------------
// INCLUDES
// --------------------------------------------------------------------------------------

#include <MacMemory.h>
#include <Resources.h>
#include <Quickdraw.h>
#include <QDOffscreen.h>
#include <OSUtils.h>
#include <Errors.h>
#include <FixMath.h>
#include <Movies.h>
#include <Endian.h>
#include <ImageCodec.h>

#include "EffectDefinitions.h"

#if PRAGMA_STRUCT_ALIGN
    #pragma options align=mac68k
#endif

#include "EffectUtilities.h"


// --------------------------------------------------------------------------------------
// INTERNAL DEFINES
// --------------------------------------------------------------------------------------

// *** CHANGE *** This defines the number of frames that can be queued for
// asynchronous rendering by this effect.  The value 0 indicates the effect
// runs synchronously.
#define kMaxAsyncFrames        0
// *** END CHANGE ***

// *** CHANGE *** Change if your effect accepts multiple sources.  This value
// is the maximum number of sources this effect operates on.
#define    kMaxSources            2
// *** END CHANGE ***

// --------------------------------------------------------------------------------------
// INTERNAL TYPEDEFS
// --------------------------------------------------------------------------------------

// Structure used to store inforation about each source
typedef struct SourceRecord {
    CDSequenceDataSourcePtr    src;
    void                    *srcBaseAddr;
    long                    srcRowBytes;
} SourceRecord;

// This is the structure used to store information for drawing a single frame of the effect
typedef struct BlitGlobals {
    SourceRecord        sources[kMaxSources];    // inputs

    void                *dstBaseAddr;            // output base address
    long                dstRowBytes;            // output row bytes
    long                height;                    // output height
    long                width;                    // output width
    short                destDepth;                // output depth
    OSType                dstPixelFormat;            // output pixel format

    // *** CHANGE *** Here is where we store values relating to a single frame
    // of the effect.  These are the parameters to the effect, modified by the
    // percentage into the effect which we are.

    long                direction;
    short                dimValue;                // dimming value, from 0 to 255

    // *** END CHANGE ***
} BlitGlobals;


// global data per instance. This holds data for the entire effect as it runs its course.
typedef struct EffectGlobals
    {
    ComponentInstance    self;        // ourselves
    ComponentInstance    target;        // top of the calling chain
    ComponentInstance    delegate;    // if we can't handle an effect, this one can

    BlitGlobals            blitter;    // information for drawing the data
    OSType                **wantedDestinationPixelTypeH;

    #if kMaxAsyncFrames > 0
        volatile short    asyncCount;    // number of outstanding frames we have
    #endif

    // parameter/source/dest seed tracking
    long                        initialized;
    long                        frameNumber;
    long                        virtualDuration;
    long                        majorSourceChangeSeed;

    TweenGlobals                tweenGlobals;

    // *** CHANGE *** PLACE PARAMETERS FOR YOUR EFFECT HERE

    long                        direction;    // direction of blit.  0 for dim to bright, 255 for bright to dim

    TweenContainerRecord        percentage;

    // *** END CHANGE ***
} EffectGlobals;

// --------------------------------------------------------------------------------------
// DISPATCHER
// --------------------------------------------------------------------------------------
/************************************************************************************
 *    This is the main dispatcher for our codec. All calls from the codec manager
 *    will come through here, with a unique selector and corresponding parameter block.
 *
 *    This routine must be first in the code segment of the codec component.
 *
 *    We use the normal dispatcher rather than the codec dispatcher as we need to
 *    implement the extra effects routines on top of the codec ones.
 */
/************************************************************************************/
// Begin Dispatch Stuff

// Used by Component Dispatch Helper to call our routines
#define CALLCOMPONENT_BASENAME()        EffectsFrame
#define    CALLCOMPONENT_GLOBALS()            EffectGlobals * storage

// Used by Type's .k.h to create prototypes for our routines
#define    IMAGECODEC_BASENAME()            CALLCOMPONENT_BASENAME()
#define    IMAGECODEC_GLOBALS()            CALLCOMPONENT_GLOBALS()

// Used by SubType's .k.h to create prototypes for our routines
#define    IMAGECODECEFFECT_BASENAME()        CALLCOMPONENT_BASENAME()
#define    IMAGECODECEFFECT_GLOBALS()        CALLCOMPONENT_GLOBALS()

// Other defines for Component Dispatch Helper
#define COMPONENT_DISPATCH_FILE            "EffectDispatch.h"    // describes what to dispatch
#define    GET_DELEGATE_COMPONENT()        (storage->delegate)    // how to find delegate component

#define COMPONENT_UPP_SELECT_ROOT()        ImageCodec            // root for Type's UPP_PREFIX and SELECT_PREFIX

#include "Components.k.h"                // StdComponent's .k.h
#include "ImageCodec.k.h"                // Type's .k.h
#include "ComponentDispatchHelper.c"    // make our dispatcher and cando

// End Dispatch Stuff
/************************************************************************************/

// --------------------------------------------------------------------------------------
// MULTIPLE BIT-DEPTH AND PIXEL FORMATS
//    For clarity/reuse sake, the drawing code is being kept separate from the component
//    interface code.
// --------------------------------------------------------------------------------------


// 16BE555
#define EffectFilter16 EffectFilter16BE555
#define srcIs16BE555 1
#define dstIs16BE555 1
#include "EffectFilter16.c"
#undef EffectFilter16
#undef srcIs16BE555
#undef dstIs16BE555

#if NON_MAC_PIXEL_FORMATS
// 16LE555
#define EffectFilter16 EffectFilter16LE555
#define srcIs16LE555 1
#define dstIs16LE555 1
#include "EffectFilter16.c"
#undef EffectFilter16
#undef srcIs16LE555
#undef dstIs16LE555

// 16LE565
#define EffectFilter16 EffectFilter16LE565
#define srcIs16LE565 1
#define dstIs16LE565 1
#include "EffectFilter16.c"
#undef EffectFilter16
#undef srcIs16LE565
#undef dstIs16LE565

#endif

// 32ARGB
#define EffectFilter32 EffectFilter32ARGB
#define srcIs32ARGB 1
#define dstIs32ARGB 1
#include "EffectFilter32.c"
#undef EffectFilter32
#undef srcIs32ARGB
#undef dstIs32ARGB
#if NON_MAC_PIXEL_FORMATS
// 32BGRA
#define EffectFilter32 EffectFilter32BGRA
#define srcIs32BGRA 1
#define dstIs32BGRA 1
#include "EffectFilter32.c"
#undef EffectFilter32
#undef srcIs32BGRA
#undef dstIs32BGRA
// 32RGBA
#define EffectFilter32 EffectFilter32RGBA
#define srcIs32RGBA 1
#define dstIs32RGBA 1
#include "EffectFilter32.c"
#undef EffectFilter32
#undef srcIs32RGBA
#undef dstIs32RGBA
// 32ABGR
#define EffectFilter32 EffectFilter32ABGR
#define srcIs32ABGR 1
#define dstIs32ABGR 1
#include "EffectFilter32.c"
#undef EffectFilter32
#undef srcIs32ABGR
#undef dstIs32ABGR
#endif

// --------------------------------------------------------------------------------------
// INTERNAL ROUTINES
//    For clarity/reuse sake, the drawing code is being kept separate from the component
//    interface code.
// --------------------------------------------------------------------------------------


static OSErr RequestImageFormat(
                                EffectGlobals*    glob,     // input: globals for rendering
                                EffectSourcePtr         source,     // input: source to potentially convert
                                short                    width,        // input: desired width
                                short                    height,        // input: desired height
                                OSType                    pixelFormat)// input: desired pixel format (depth & format)
/*
    If the data is already in the requested height and depth, returns.
    Otherwise, calls decompression to get it into the format we can handle
*/
{
    OSErr                    err = noErr;
    CDSequenceDataSourcePtr    sourceData = source->source.image;
    ImageDescriptionHandle    curDesc = (ImageDescriptionHandle) sourceData->dataDescription;
    ImageDescriptionHandle    newDesc = nil;
    ImageDescriptionPtr        dp;

    dp = *curDesc;
    if (
        (source->effectType == kEffectRawSource) &&
        ( ((dp->cType == kRawCodecType) && (dp->depth == (short)pixelFormat)) || ( dp->cType == pixelFormat) ) &&

        (dp->width == width) &&
        (dp->height == height))
    {
        /* already got what we need */
        return noErr;
    }

    // otherwise, call the ICM to convert to desired data format
    newDesc = (ImageDescriptionHandle) NewHandleClear(sizeof(ImageDescription));
    err = MemError();

    if (err == noErr)
    {
        short pixelSize = QTGetPixelSize(pixelFormat);



        dp = *newDesc;
#if ! NON_MAC_PIXEL_FORMATS

        if ((pixelFormat >> 24) != 0) {

            // non-Mac format

            dp->cType             = pixelFormat;

            dp->depth             = pixelSize;

        } else     {

            dp->cType             = kRawCodecType;

            dp->depth             = pixelFormat;

        }

#else

        dp->cType             = pixelFormat;

        dp->depth             = pixelSize;

#endif

        dp->width  = width;
        dp->height = height;
        dp->clutID = -1;

        /* the source is a stacked effect - or one in a format we can't handle. */
        /* pass it off to the Generic Effect to convert */
        /* it to a normal source */
        err = ImageCodecEffectConvertEffectSourceToFormat(glob->target, source, newDesc);

        if (newDesc)
        {
            DisposeHandle((Handle) newDesc);
        }
    }

    return err;

} // RequestImageFormat

// --------------------------------------------------------------------------------------
static long BlitterPreflight(BlitGlobals    *glob,     // input: globals for rendering
                             short            width,     // input: width of data
                             short            height, // input: height of data
                             long            *depth)    // input/output: depth of data
{
    // *** CHANGE *** If your effect handles different bit depths, change this code to return
    // what bit depths you want.

    // our blitter can handle 16 and 32 bit deep -- otherwise, we request a change to 16 bit
    switch (*depth)
    {
        case 16:
        case 32:
            break;

        default:
            *depth = 16;
            break;
    }
    // *** END CHANGE ***

    // save away the actual depth we are running at
    glob->width     = width;
    glob->height    = height;
    glob->destDepth = *depth;

    return noErr;

} // BlitterPreflight

// --------------------------------------------------------------------------------------
static long BlitterSetSource(EffectGlobals                *glob,             // input: our globals
                             long                         sourceNumber,    // input: source index to set
                             EffectSourcePtr            source)            // input: source value
{
    OSErr    err = noErr;

    if (sourceNumber >= kMaxSources)
    {
        // too many sources for us to handle
        err = -1;
    }
    else
    {
        // a source we can handle, save it away
        err = RequestImageFormat(glob, source, glob->blitter.width, glob->blitter.height, glob->blitter.dstPixelFormat);
        if (err == noErr)
        {
            glob->blitter.sources[sourceNumber].src = source->source.image;
        }
        else
        {
            glob->blitter.sources[sourceNumber].src = nil;
        }
    }

    return (err);

} // BlitterSetSource


// --------------------------------------------------------------------------------------
static long BlitterSetDest(BlitGlobals    *glob,         // input: our globals
                           PixMap        *dstPixMap, // input: pixels we will draw into
                           Rect            *dstRect)    // input: area of pixels we will draw into
{
    OSErr    result = noErr;
    long    offsetH,offsetV;
    char    *baseAddr;
    OSType                dstPixelFormat;



    dstPixelFormat = GETPIXMAPPIXELFORMAT(dstPixMap);



    glob->dstPixelFormat = dstPixelFormat;




    // *** CHANGE *** If your effect handles different bit depths, change this code
    /* adjust the destination baseaddress to be at the beginning of the desired rect */
    offsetH = (dstRect->left - dstPixMap->bounds.left);
    if (dstPixMap->pixelSize == 16)
    {
        offsetH <<= 1;                    /* 1 pixel = 2 bytes */
    }
    else
    {
        if (dstPixMap->pixelSize == 32)
        {
            offsetH <<= 2;                    /* 1 pixel = 4 bytes */
        }
        else
        {
            result = -1;                    /* a data format we can't handle */
        }
    }
    // *** END CHANGE ***

    offsetV = (dstRect->top - dstPixMap->bounds.top) * dstPixMap->rowBytes;
    baseAddr = dstPixMap->baseAddr + offsetH + offsetV;

    glob->dstBaseAddr = baseAddr;
    glob->dstRowBytes = dstPixMap->rowBytes;

    return result;

} // BlitterSetDest


// --------------------------------------------------------------------------------------
static long BlitterRenderFrame(BlitGlobals    *glob)        // input: our globals
{
    SInt8            mmuMode;

    // render with proper memory mode
    mmuMode = true32b;
    SwapMMUMode(&mmuMode);

    // convert data into base/size
    {
        short    i;

        for (i = 0; i < kMaxSources; ++i)
        {
            if (glob->sources[i].src)
            {
                glob->sources[i].srcBaseAddr = glob->sources[i].src->dataPtr;
                glob->sources[i].srcRowBytes = glob->sources[i].src->dataSize / glob->height;
            }
        }
    }

    // *** CHANGE *** If your effect handles different bit depths, write other bit depth routines and
    // call them from here

    // do the actual render
    switch (glob->dstPixelFormat)
    {
        case k32ARGBPixelFormat:
            EffectFilter32ARGB(glob);
            break;
#if NON_MAC_PIXEL_FORMATS
        case k32ABGRPixelFormat:
            EffectFilter32ABGR(glob); break;
        case k32BGRAPixelFormat:     // we know how to do these pixel formats
            EffectFilter32BGRA(glob); break;
        case k32RGBAPixelFormat:
            EffectFilter32RGBA(glob); break;
#endif
        case k16BE555PixelFormat:
            EffectFilter16BE555(glob);
            break;
#if NON_MAC_PIXEL_FORMATS
        case k16LE565PixelFormat:
            EffectFilter16LE565(glob); break;
        case k16LE555PixelFormat:
            EffectFilter16LE555(glob); break;
#endif
    }
    // *** END CHANGE ***

    SwapMMUMode(&mmuMode);

    return noErr;

} // BlitterRenderFrame


// --------------------------------------------------------------------------------------
// COMPONENT ENTRY POINTS
// --------------------------------------------------------------------------------------


#define kNumPixelFormatsSupported 0x20

pascal ComponentResult EffectsFrameOpen(EffectGlobals        *glob,    // input/output: our globals
                                       ComponentInstance    self)    // input: reference to ourself
/*
    This is called once per instance of our component.  Allocate our storage at
    this point.  If we have any shared storage, we would check here to make sure
    it exists, else create it.
*/
{
    ComponentResult    result;

    result = noErr;

    // first, allocate our local storage
    if ((glob = (EffectGlobals*) NewPtrClear(sizeof(EffectGlobals)))==nil)
    {
        result = MemError();
        goto bail;
    }

    SetComponentInstanceStorage(self, (Handle) glob);

    // we are ourselves, and the current top of chain is us
    glob->self = self;
    glob->target = self;
    glob->wantedDestinationPixelTypeH = (OSType **) NewHandleClear(sizeof(OSType) * (kNumPixelFormatsSupported + 1));

    // open the generic effect, this will handle effects we can't handle ourselves
    result = OpenADefaultComponent(decompressorComponentType, kEffectGenericType, &glob->delegate);
    if (result)
        goto bail;

    // set up the target for the components below us
    EffectsFrameTarget(glob, self);

bail:
    return(result);

} // EffectsFrameOpen


// --------------------------------------------------------------------------------------
// Called each time an instance of our component is going away.  Toss anything we allocated.
pascal ComponentResult EffectsFrameClose(EffectGlobals        *glob,    // input: our globals
                                        ComponentInstance    self)    // input: reference to ourself
{
#pragma unused (self)

    if (glob)
    {
        /*     *** CHANGE *** DISPOSE OF YOUR TWEENERS */
        DisposeTweenRecord(&glob->percentage);

        /* *** END CHANGE *** */



        DisposeTweenGlobals(&glob->tweenGlobals);

        CloseComponent(glob->delegate);


        DisposeHandle((Handle) glob->wantedDestinationPixelTypeH);


        DisposePtr((Ptr) glob);
    }
    return(noErr);

} // EffectsFrameClose


// --------------------------------------------------------------------------------------

pascal ComponentResult EffectsFrameTarget(EffectGlobals        *glob,    // input: our globals
                                          ComponentInstance target)    // input: reference to new top of chain
/*
    Called when there is a new top of the calling chain.  Remember that ourselves, and tell
    those below us as well.
*/
{
    // remember who is top of chain
    glob->target = target;

    // and tell folks below us, too.
    ComponentSetTarget(glob->delegate, target);

    return(noErr);

} // EffectsFrameTarget


// --------------------------------------------------------------------------------------

pascal ComponentResult EffectsFrameVersion(EffectGlobals    *glob)        // input: our globals
/*
    Called to obtain the version of our component.
*/
{
#pragma unused (glob)

    return kDimmerEffectVersion;

} // EffectsFrameVersion


// --------------------------------------------------------------------------------------
//    Called to prepare for a sequence of frames.
//    Return in p->capabilities anything in particular your effect requires, such as
//    limitations on bitdepth.
pascal long EffectsFrameEffectSetup(EffectGlobals            *glob,     // input: our globals
                                     CodecDecompressParams    *p)        // input: information about the thing being decompressed

{
    CodecCapabilities     *capabilities = p->capabilities;
    OSErr                err;
    OSType                 *formats = *glob->wantedDestinationPixelTypeH;
    long                wantedPixelSize = capabilities->wantedPixelSize;
    OSType                dstPixelFormat;

    dstPixelFormat = GETPIXMAPPIXELFORMAT(&p->dstPixMap);



    switch (dstPixelFormat)
    {
        case k32ARGBPixelFormat:
        case k16BE555PixelFormat:
#if NON_MAC_PIXEL_FORMATS
        case k32BGRAPixelFormat:     // we know how to do these pixel formats
        case k32ABGRPixelFormat:
        case k32RGBAPixelFormat:
        case k16LE565PixelFormat:
        case k16LE555PixelFormat:
#endif
            *formats++ = dstPixelFormat;
            break;
        default:                    // we prefer 16 over 32
#if NON_MAC_PIXEL_FORMATS
            *formats++ = k16LE555PixelFormat;
            *formats++ = k16LE565PixelFormat;
            *formats++ = k32BGRAPixelFormat;
            *formats++ = k32RGBAPixelFormat;
            *formats++ = k32ABGRPixelFormat;
#endif
            *formats++ = k16BE555PixelFormat;
            *formats++ = k32ARGBPixelFormat;
            break;
    }



    // NOTE: 0 marks the end of the format list

    *formats++ = 0;


    /* set up our blitter */
    err = BlitterPreflight(&glob->blitter,
                           (*p->imageDescription)->width,
                           (*p->imageDescription)->height,
                           &wantedPixelSize);

    capabilities->wantedPixelSize = 0;

    p->wantedDestinationPixelTypes = glob->wantedDestinationPixelTypeH;


    return (err);

} // EffectsFrameEffectSetup

// --------------------------------------------------------------------------------------

//    Called for each frame, before the request to actually draw
pascal long EffectsFrameEffectBegin(EffectGlobals            *glob,    // input: our globals
                             CodecDecompressParams    *p,     // input: info about frame being drawn
                             EffectsFrameParamsPtr    effect)    // input: info about this effect frame
{
    OSErr                    err = noErr;
    EffectSourcePtr            source;
    long                    numSources = 0;
    wide                    percentage;

    #if kMaxAsyncFrames > 0
        /* we can go async if we don't already have an effect scheduled */
        if (glob->asyncCount < kMaxAsyncFrames)
        {
            glob->asyncCount++;
            effect->doAsync = true;
        }
    #endif

    // dest changed?
    if (p->conditionFlags &
            (codecConditionNewClut+codecConditionFirstFrame+codecConditionNewDepth+codecConditionNewDestination+codecConditionNewTransform))
    {
        // re-scan the sources
        glob->majorSourceChangeSeed = 0;

        // re-read the parameters
        glob->frameNumber = 0;

        err = BlitterSetDest(&glob->blitter, &p->dstPixMap, &p->dstRect);
        if (err != noErr)
            goto bail;

    }

    // new sources?  make note of them!
    if (p->majorSourceChangeSeed != glob->majorSourceChangeSeed)
    {
        // grab start of input chain for this effect
        source = effect->source;

        /* we can play with up to kMaxSources sources, so go get them */
        while (source != nil && numSources < kMaxSources)
        {
            /* now give that source to our blitter */
            err = BlitterSetSource(glob, numSources, source);
            if (err != noErr)
                goto bail;

            source = source->next;
            ++numSources;
        }



        glob->majorSourceChangeSeed = p->majorSourceChangeSeed;
    }

    /* if this is a new frame, or the same frame with a new length, get rid of our old parameters & tweeners */
    if ((effect->frameTime.frameNumber != glob->frameNumber) || (effect->frameTime.virtualDuration != glob->virtualDuration) )
    {
        /*     *** CHANGE *** DISPOSE OF YOUR TWEENERS */
        DisposeTweenRecord(&glob->percentage);

        /* *** END CHANGE *** */



        DisposeTweenGlobals(&glob->tweenGlobals);

        glob->initialized = false;
        glob->frameNumber = effect->frameTime.frameNumber;
        glob->virtualDuration = effect->frameTime.virtualDuration;
    }

    // Read in effect parameters
    if (!glob->initialized)
    {
        Ptr                     data = p->data;
        OSErr                    err;
        long                    index = 1;

        err = InitializeTweenGlobals(&glob->tweenGlobals, p);
        if (err!=noErr)
            goto bail;

        /*     *** CHANGE *** TIME TO READ IN PARAMETERS TO YOUR EFFECT:
            You can read any number of atoms you wish from the container.  For example, you might have a
            'star' (start) and 'end ' (end) value.  They might be expressed as percentages, numbers, or other values.
            Or, you might have multiple atoms of type 'para' (param) which would be read in by calling
            QTFindChildByIndex with various index values.  If you want to know how many parameters of a given
            type there are, call QTCountChildrenOfType.  These parameters are specific to your particular effect,
            and will need to be placed there by whoever is authoring the title.

            If you require parameters, and they aren't there, return an error.  If you can default the values
            if they are missing, do so and continue.  In general, I'd recommend having a default case unless
            you really are unable to implement it for a technical reason.

            These parameters are those that apply to the effect itself.  Later, we'll translate some of these parameters
            into how they relate to *where* in the effect we are.  For example, an effect that runs from a starting
            percentage of 10 to an ending percentage of 90 will have 10 and 90 as parameters here.
        */

        /* make our tweener, return if we already have it */
        err = CreateTweenRecord(&glob->tweenGlobals, &glob->percentage,
                        kParameterUsagePercent, 1,
                        sizeof(Fixed), kTweenTypeFixed, (void*)0, (void*)fixed1,
                        effect->frameTime.virtualDuration);
        if (err!=noErr)
            goto bail;



        /* *** END CHANGE *** */



        glob->initialized = true;
    }

    /* determine the amount we are along the tween via the current time - start time */
    percentage = effect->frameTime.value;
    CompSub(&effect->frameTime.virtualStartTime, &percentage);


    /*     Tween our parameters and get the current value for this frame, prepare to render
        it when the RenderFrame happens. */
    if (err == noErr)
        {
        Fixed    thePercentage;

        /* ***** CHANGE TO TWEEN YOUR EFFECTS PARAMETERS */

        if (glob->percentage.tween)
            QTDoTween(glob->percentage.tween, percentage.lo, glob->percentage.tweenData, nil, nil, nil );

        thePercentage = **(Fixed**)(glob->percentage.tweenData);
        // If we are before the half-way point of this transition, we should
        // be fading the first source to black
        if (thePercentage < fixed1/2)
        {
            (glob->blitter).direction = 1;
            (glob->blitter).dimValue = FixedToInt(FixMul(IntToFixed(512), thePercentage));
        }
        // Otherwise, we are fading up onto the new source
        else
        {
            (glob->blitter).direction = 0;
            (glob->blitter).dimValue = FixedToInt(FixMul(IntToFixed(512), thePercentage)) - 255;
        }

        /* ***** END CHANGE */
        }

    if (glob->tweenGlobals.atLeastOneTweener)
        {
        // this effect runs constantly
        p->needUpdateOnTimeChange = true;
        p->needUpdateOnSourceChange = false;
        }
    else
        {
        // this effect only needs to run when the sources actually change
        p->needUpdateOnTimeChange = false;
        p->needUpdateOnSourceChange = true;
        }


// EXCEPTION HANDLING
bail:
    #if kMaxAsyncFrames > 0
        // if we didn't queue the frame, then remove it from used list
        if (err != noErr)
            glob->asyncCount--;
    #endif

    return err;

} // EffectsFrameEffectBegin


// --------------------------------------------------------------------------------------
pascal long EffectsFrameEffectRenderFrame(EffectGlobals             *glob,         // input: our globals
                                    EffectsFrameParamsPtr    effect)        // input: effect frame to be rendered
/*
    Start rendering of the given frame.
*/
{
#pragma unused (effect)

    /* render the frame */
    BlitterRenderFrame(&glob->blitter);

    #if kMaxAsyncFrames > 0
        glob->asyncCount--;
    #endif

    return noErr;

} // EffectsFrameEffectRenderFrame


// --------------------------------------------------------------------------------------
pascal long EffectsFrameEffectCancel(EffectGlobals            *glob,         // input: our globals
                                    EffectsFrameParamsPtr    effect)        // input: effect frame to be canceled
/*
    Halt rendering of the given frame, even if it is only partially completed.
*/
{
#pragma unused (effect)
#pragma unused (glob)

    #if kMaxAsyncFrames > 0
        glob->asyncCount--;
    #endif

    return noErr;

} // EffectsFrameEffectCancel


// ----------------------------------------------------------------------------------------

pascal ComponentResult EffectsFrameGetCodecInfo(EffectGlobals    *glob,
                                                CodecInfo        *info)
/*
 *    CDGetCodecInfo allows us to return information about ourselves to the codec manager.
 *
 *    There will be a tool for determining appropriate values for the accuracy, speed
 *    and level information. For now we estimate with scientific wild guessing.
 *
 *  The info is stored as a resource in the same file with our component.
 */
{
    OSErr err = noErr;

    if (info == nil)
    {
        err = paramErr;
    }
    else
    {
        CodecInfo **tempCodecInfo;

        err = GetComponentResource((Component) glob->self,
                                   codecInfoResourceType,
                                   kEffectcdciRes,
                                   (Handle *) &tempCodecInfo);
        if (err == noErr)
        {
            *info = **tempCodecInfo;
            DisposeHandle((Handle) tempCodecInfo);
        }
    }

    return err;

} // EffectsFrameGetCodecInfo


// ---------------------------------------------------------------------------------------------------------------------------
pascal ComponentResult EffectsFrameGetParameterListHandle(EffectGlobals    *glob,        // input: our globals
                                                         Handle            *theHandle)    // output: the parameter description for this effect
{
    OSErr                    err = noErr;

    err = GetComponentResource((Component) glob->self,
                               FOUR_CHAR_CODE('atms'),
                               kEffectatmsRes,
                               theHandle);

    return(err);

} // EffectsFrameGetParameterListHandle

// ----------------------------------------------------------------------------------------
pascal long EffectsFrameEffectGetSpeed(EffectGlobals * glob, QTAtomContainer parameters, Fixed *pFPS)
{
#pragma unused (glob, parameters)

    if (pFPS)
        *pFPS = IntToFixed(30);

    return noErr;

} // EffectsFrameEffectGetSpeed