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
26static void
27RASTERIZE_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