FreonLinux/system/tinyx/fb/fbedgeimp.h

/*
 *
 * Copyright © 2004 Keith Packard
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of Keith Packard not be used in
 * advertising or publicity pertaining to distribution of the software without
 * specific, written prior permission.  Keith Packard makes no
 * representations about the suitability of this software for any purpose.  It
 * is provided "as is" without express or implied warranty.
 *
 * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#ifndef rasterizeSpan
#endif

static void
rasterizeEdges(FbBits * buf,
               int width,
               int stride, RenderEdge * l, RenderEdge * r, xFixed t, xFixed b)
{
    xFixed y = t;

    FbBits *line;

    line = buf + xFixedToInt(y) * stride;

    for (;;) {
        xFixed lx, rx;

        int lxi, rxi;

        /* clip X */
        lx = l->x;
        if (lx < 0)
            lx = 0;
        rx = r->x;
        if (xFixedToInt(rx) >= width)
            rx = IntToxFixed(width);

        /* Skip empty (or backwards) sections */
        if (rx > lx) {

            /* Find pixel bounds for span */
            lxi = xFixedToInt(lx);
            rxi = xFixedToInt(rx);

#if N_BITS == 1
            {
                FbBits *a = line;

                FbBits startmask, endmask;

                int nmiddle;

                int width = rxi - lxi;

                int x = lxi;

                a += x >> FB_SHIFT;
                x &= FB_MASK;

                FbMaskBits(x, width, startmask, nmiddle, endmask);
                if (startmask)
                    *a++ |= startmask;
                while (nmiddle--)
                    *a++ = FB_ALLONES;
                if (endmask)
                    *a |= endmask;
            }
#else
            {
                DefineAlpha(line, lxi);
                int lxs, rxs;

                /* Sample coverage for edge pixels */
                lxs = RenderSamplesX(lx, N_BITS);
                rxs = RenderSamplesX(rx, N_BITS);

                /* Add coverage across row */
                if (lxi == rxi) {
                    AddAlpha(rxs - lxs);
                }
                else {
                    int xi;

                    AddAlpha(N_X_FRAC(N_BITS) - lxs);
                    StepAlpha;
                    for (xi = lxi + 1; xi < rxi; xi++) {
                        AddAlpha(N_X_FRAC(N_BITS));
                        StepAlpha;
                    }
                    /* Do not add in a 0 alpha here. This check is necessary
                     * to avoid a buffer overrun when rx is exactly on a pixel
                     * boundary.
                     */
                    if (rxs != 0)
                        AddAlpha(rxs);
                }
            }
#endif
        }

        if (y == b)
            break;

#if N_BITS > 1
        if (xFixedFrac(y) != Y_FRAC_LAST(N_BITS)) {
            RenderEdgeStepSmall(l);
            RenderEdgeStepSmall(r);
            y += STEP_Y_SMALL(N_BITS);
        }
        else
#endif
        {
            RenderEdgeStepBig(l);
            RenderEdgeStepBig(r);
            y += STEP_Y_BIG(N_BITS);
            line += stride;
        }
    }
}

#undef rasterizeSpan