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      1 /*
      2  * Copyright  2004 Keith Packard
      3  *
      4  * Permission to use, copy, modify, distribute, and sell this software and its
      5  * documentation for any purpose is hereby granted without fee, provided that
      6  * the above copyright notice appear in all copies and that both that
      7  * copyright notice and this permission notice appear in supporting
      8  * documentation, and that the name of Keith Packard not be used in
      9  * advertising or publicity pertaining to distribution of the software without
     10  * specific, written prior permission.  Keith Packard makes no
     11  * representations about the suitability of this software for any purpose.  It
     12  * is provided "as is" without express or implied warranty.
     13  *
     14  * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
     15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
     16  * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
     17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
     18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
     19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
     20  * PERFORMANCE OF THIS SOFTWARE.
     21  */
     22 
     23 #ifndef rasterize_span
     24 #endif
     25 
     26 static void
     27 RASTERIZE_EDGES (pixman_image_t  *image,
     28 		pixman_edge_t	*l,
     29 		pixman_edge_t	*r,
     30 		pixman_fixed_t		t,
     31 		pixman_fixed_t		b)
     32 {
     33     pixman_fixed_t  y = t;
     34     uint32_t  *line;
     35     uint32_t *buf = (image)->bits.bits;
     36     int stride = (image)->bits.rowstride;
     37     int width = (image)->bits.width;
     38 
     39     line = buf + pixman_fixed_to_int (y) * stride;
     40 
     41     for (;;)
     42     {
     43 	pixman_fixed_t	lx;
     44 	pixman_fixed_t      rx;
     45 	int	lxi;
     46 	int rxi;
     47 
     48 	lx = l->x;
     49 	rx = r->x;
     50 #if N_BITS == 1
     51 	/* For the non-antialiased case, round the coordinates up, in effect
     52 	 * sampling just slightly to the left of the pixel. This is so that
     53 	 * when the sample point lies exactly on the line, we round towards
     54 	 * north-west.
     55 	 *
     56 	 * (The AA case does a similar  adjustment in RENDER_SAMPLES_X)
     57 	 */
     58 	lx += X_FRAC_FIRST(1) - pixman_fixed_e;
     59 	rx += X_FRAC_FIRST(1) - pixman_fixed_e;
     60 #endif
     61 	/* clip X */
     62 	if (lx < 0)
     63 	    lx = 0;
     64 	if (pixman_fixed_to_int (rx) >= width)
     65 #if N_BITS == 1
     66 	    rx = pixman_int_to_fixed (width);
     67 #else
     68 	    /* Use the last pixel of the scanline, covered 100%.
     69 	     * We can't use the first pixel following the scanline,
     70 	     * because accessing it could result in a buffer overrun.
     71 	     */
     72 	    rx = pixman_int_to_fixed (width) - 1;
     73 #endif
     74 
     75 	/* Skip empty (or backwards) sections */
     76 	if (rx > lx)
     77 	{
     78 
     79 	    /* Find pixel bounds for span */
     80 	    lxi = pixman_fixed_to_int (lx);
     81 	    rxi = pixman_fixed_to_int (rx);
     82 
     83 #if N_BITS == 1
     84 	    {
     85 
     86 #define LEFT_MASK(x)							\
     87 		(((x) & 0x1f) ?						\
     88 		 SCREEN_SHIFT_RIGHT (0xffffffff, (x) & 0x1f) : 0)
     89 #define RIGHT_MASK(x)							\
     90 		(((32 - (x)) & 0x1f) ?					\
     91 		 SCREEN_SHIFT_LEFT (0xffffffff, (32 - (x)) & 0x1f) : 0)
     92 
     93 #define MASK_BITS(x,w,l,n,r) {						\
     94 		    n = (w);						\
     95 		    r = RIGHT_MASK ((x) + n);				\
     96 		    l = LEFT_MASK (x);					\
     97 		    if (l) {						\
     98 			n -= 32 - ((x) & 0x1f);				\
     99 			if (n < 0) {					\
    100 			    n = 0;					\
    101 			    l &= r;					\
    102 			    r = 0;					\
    103 			}						\
    104 		    }							\
    105 		    n >>= 5;						\
    106 		}
    107 
    108 		uint32_t  *a = line;
    109 		uint32_t  startmask;
    110 		uint32_t  endmask;
    111 		int	    nmiddle;
    112 		int	    width = rxi - lxi;
    113 		int	    x = lxi;
    114 
    115 		a += x >> 5;
    116 		x &= 0x1f;
    117 
    118 		MASK_BITS (x, width, startmask, nmiddle, endmask);
    119 
    120 		if (startmask) {
    121 		    WRITE(image, a, READ(image, a) | startmask);
    122 		    a++;
    123 		}
    124 		while (nmiddle--)
    125 		    WRITE(image, a++, 0xffffffff);
    126 		if (endmask)
    127 		    WRITE(image, a, READ(image, a) | endmask);
    128 	    }
    129 #else
    130 	    {
    131 		DEFINE_ALPHA(line,lxi);
    132 		int	    lxs;
    133 		int     rxs;
    134 
    135 		/* Sample coverage for edge pixels */
    136 		lxs = RENDER_SAMPLES_X (lx, N_BITS);
    137 		rxs = RENDER_SAMPLES_X (rx, N_BITS);
    138 
    139 		/* Add coverage across row */
    140 		if (lxi == rxi)
    141 		{
    142 		    ADD_ALPHA (rxs - lxs);
    143 		}
    144 		else
    145 		{
    146 		    int	xi;
    147 
    148 		    ADD_ALPHA (N_X_FRAC(N_BITS) - lxs);
    149 		    STEP_ALPHA;
    150 		    for (xi = lxi + 1; xi < rxi; xi++)
    151 		    {
    152 			ADD_ALPHA (N_X_FRAC(N_BITS));
    153 			STEP_ALPHA;
    154 		    }
    155 		    ADD_ALPHA (rxs);
    156 		}
    157 	    }
    158 #endif
    159 	}
    160 
    161 	if (y == b)
    162 	    break;
    163 
    164 #if N_BITS > 1
    165 	if (pixman_fixed_frac (y) != Y_FRAC_LAST(N_BITS))
    166 	{
    167 	    RENDER_EDGE_STEP_SMALL (l);
    168 	    RENDER_EDGE_STEP_SMALL (r);
    169 	    y += STEP_Y_SMALL(N_BITS);
    170 	}
    171 	else
    172 #endif
    173 	{
    174 	    RENDER_EDGE_STEP_BIG (l);
    175 	    RENDER_EDGE_STEP_BIG (r);
    176 	    y += STEP_Y_BIG(N_BITS);
    177 	    line += stride;
    178 	}
    179     }
    180 }
    181 
    182 #undef rasterize_span
    183