Пример #1
0
static void
composeRow(int              const originleft, 
           struct pam *     const underlayPamP,
           struct pam *     const overlayPamP,
           bool             const invertAlpha,
           float            const masterOpacity,
           struct pam *     const composedPamP,
           enum sampleScale const sampleScale,
           enum alphaMix    const alphaMix,
           const tuple *    const underlayTuplerow,
           const tuple *    const overlayTuplerow,
           const tuplen *   const alphaTuplerown,
           tuple *          const composedTuplerow) {
/*----------------------------------------------------------------------------
   Create a row of tuples ('composedTupleRow') which is the composition of
   row 'overlayTupleRow' laid over row 'underlayTupleRow', starting at
   column 'originLeft'.

   *underlayPamP and *overlayPamP describe the respective tuple rows.
-----------------------------------------------------------------------------*/
    unsigned int col;

    for (col = 0; col < composedPamP->width; ++col) {
        int const ovlcol = col - originleft;

        if (ovlcol >= 0 && ovlcol < overlayPamP->width) {
            tuplen const alphaTuplen = 
                alphaTuplerown ? alphaTuplerown[ovlcol] : NULL;

            overlayPixel(overlayTuplerow[ovlcol], overlayPamP,
                         underlayTuplerow[col], underlayPamP,
                         alphaTuplen, invertAlpha,
                         composedTuplerow[col], composedPamP,
                         masterOpacity, sampleScale, alphaMix);
        } else
            /* Overlay image does not touch this column. */
            pnm_assigntuple(composedPamP, composedTuplerow[col],
                            underlayTuplerow[col]);
    }
}
Пример #2
0
static void
composite(int          const originleft, 
          int          const origintop, 
          struct pam * const underlayPamP,
          struct pam * const overlayPamP,
          struct pam * const alphaPamP,
          bool         const invertAlpha,
          float        const masterOpacity,
          struct pam * const composedPamP,
          bool         const assumeLinear) {
/*----------------------------------------------------------------------------
   Overlay the overlay image in the array 'overlayImage', described by
   *overlayPamP, onto the underlying image from the input image file
   as described by *underlayPamP, output the composite to the image
   file as described by *composedPamP.

   Apply the overlay image with transparency described by the array
   'alpha' and *alphaPamP.

   The underlying image is positioned after its header.

   'originleft' and 'origintop' are the coordinates in the underlying
   image plane where the top left corner of the overlay image is to
   go.  It is not necessarily inside the underlying image (in fact,
   may be negative).  Only the part of the overlay that actually
   intersects the underlying image, if any, gets into the output.
-----------------------------------------------------------------------------*/
    enum sampleScale const sampleScale = 
        assumeLinear ? INTENSITY_SAMPLE : GAMMA_SAMPLE;

    int underlayRow;  /* NB may be negative */
    int overlayRow;   /* NB may be negative */
    tuple * composedTuplerow;
    tuple * underlayTuplerow;
    tuple * overlayTuplerow;
    tuplen * alphaTuplerown;
    bool overlayHasOpacity;
    unsigned int opacityPlane;

    pnm_getopacity(overlayPamP, &overlayHasOpacity, &opacityPlane);

    composedTuplerow = pnm_allocpamrow(composedPamP);
    underlayTuplerow = pnm_allocpamrow(underlayPamP);
    overlayTuplerow  = pnm_allocpamrow(overlayPamP);
    if (alphaPamP)
        alphaTuplerown = pnm_allocpamrown(alphaPamP);

    pnm_writepaminit(composedPamP);

    for (underlayRow = MIN(0, origintop), overlayRow = MIN(0, -origintop);
         underlayRow < MAX(underlayPamP->height, 
                           origintop + overlayPamP->height);
         ++underlayRow, ++overlayRow) {

        if (overlayRow >= 0 && overlayRow < overlayPamP->height) {
            pnm_readpamrow(overlayPamP, overlayTuplerow);
            adaptRowToOutputFormat(overlayPamP, overlayTuplerow, composedPamP);
            if (alphaPamP)
                pnm_readpamrown(alphaPamP, alphaTuplerown);
        }
        if (underlayRow >= 0 && underlayRow < underlayPamP->height) {
            pnm_readpamrow(underlayPamP, underlayTuplerow);
            adaptRowToOutputFormat(underlayPamP, underlayTuplerow, 
                                   composedPamP);

            if (underlayRow < origintop || 
                underlayRow >= origintop + overlayPamP->height) {
            
                /* Overlay image does not touch this underlay row. */

                pnm_writepamrow(composedPamP, underlayTuplerow);
            } else {
                unsigned int col;
                for (col = 0; col < composedPamP->width; ++col) {
                    int const ovlcol = col - originleft;

                    if (ovlcol >= 0 && ovlcol < overlayPamP->width) {
                        tuplen const alphaTuplen = 
                            alphaPamP ? alphaTuplerown[ovlcol] : NULL;

                        overlayPixel(overlayTuplerow[ovlcol], overlayPamP,
                                     underlayTuplerow[col], underlayPamP,
                                     alphaTuplen, invertAlpha,
                                     overlayHasOpacity, opacityPlane,
                                     composedTuplerow[col], composedPamP,
                                     masterOpacity, sampleScale);
                    } else
                        /* Overlay image does not touch this column. */
                        pnm_assigntuple(composedPamP, composedTuplerow[col],
                                        underlayTuplerow[col]);
                }
                pnm_writepamrow(composedPamP, composedTuplerow);
            }
        }
    }
    pnm_freepamrow(composedTuplerow);
    pnm_freepamrow(underlayTuplerow);
    pnm_freepamrow(overlayTuplerow);
    if (alphaPamP)
        pnm_freepamrown(alphaTuplerown);
}