1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
/*
* $Id$
*
* 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
#include "renderedge.h"
/*
* Compute the smallest value no less than y which is on a
* grid row
*/
_X_EXPORT xFixed
RenderSampleCeilY (xFixed y, int n)
{
xFixed f = xFixedFrac(y);
xFixed i = xFixedFloor(y);
f = ((f + Y_FRAC_FIRST(n)) / STEP_Y_SMALL(n)) * STEP_Y_SMALL(n) + Y_FRAC_FIRST(n);
if (f > Y_FRAC_LAST(n))
{
f = Y_FRAC_FIRST(n);
i += xFixed1;
}
return (i | f);
}
#define _div(a,b) ((a) >= 0 ? (a) / (b) : -((-(a) + (b) - 1) / (b)))
/*
* Compute the largest value no greater than y which is on a
* grid row
*/
_X_EXPORT xFixed
RenderSampleFloorY (xFixed y, int n)
{
xFixed f = xFixedFrac(y);
xFixed i = xFixedFloor (y);
f = _div(f - Y_FRAC_FIRST(n), STEP_Y_SMALL(n)) * STEP_Y_SMALL(n) + Y_FRAC_FIRST(n);
if (f < Y_FRAC_FIRST(n))
{
f = Y_FRAC_LAST(n);
i -= xFixed1;
}
return (i | f);
}
/*
* Step an edge by any amount (including negative values)
*/
_X_EXPORT void
RenderEdgeStep (RenderEdge *e, int n)
{
xFixed_48_16 ne;
e->x += n * e->stepx;
ne = e->e + n * (xFixed_48_16) e->dx;
if (n >= 0)
{
if (ne > 0)
{
int nx = (ne + e->dy - 1) / e->dy;
e->e = ne - nx * (xFixed_48_16) e->dy;
e->x += nx * e->signdx;
}
}
else
{
if (ne <= -e->dy)
{
int nx = (-ne) / e->dy;
e->e = ne + nx * (xFixed_48_16) e->dy;
e->x -= nx * e->signdx;
}
}
}
/*
* A private routine to initialize the multi-step
* elements of an edge structure
*/
static void
_RenderEdgeMultiInit (RenderEdge *e, int n, xFixed *stepx_p, xFixed *dx_p)
{
xFixed stepx;
xFixed_48_16 ne;
ne = n * (xFixed_48_16) e->dx;
stepx = n * e->stepx;
if (ne > 0)
{
int nx = ne / e->dy;
ne -= nx * e->dy;
stepx += nx * e->signdx;
}
*dx_p = ne;
*stepx_p = stepx;
}
/*
* Initialize one edge structure given the line endpoints and a
* starting y value
*/
_X_EXPORT void
RenderEdgeInit (RenderEdge *e,
int n,
xFixed y_start,
xFixed x_top,
xFixed y_top,
xFixed x_bot,
xFixed y_bot)
{
xFixed dx, dy;
e->x = x_top;
e->e = 0;
dx = x_bot - x_top;
dy = y_bot - y_top;
e->dy = dy;
e->dx = 0;
if (dy)
{
if (dx >= 0)
{
e->signdx = 1;
e->stepx = dx / dy;
e->dx = dx % dy;
e->e = -dy;
}
else
{
e->signdx = -1;
e->stepx = -(-dx / dy);
e->dx = -dx % dy;
e->e = 0;
}
_RenderEdgeMultiInit (e, STEP_Y_SMALL(n), &e->stepx_small, &e->dx_small);
_RenderEdgeMultiInit (e, STEP_Y_BIG(n), &e->stepx_big, &e->dx_big);
}
RenderEdgeStep (e, y_start - y_top);
}
/*
* Initialize one edge structure given a line, starting y value
* and a pixel offset for the line
*/
_X_EXPORT void
RenderLineFixedEdgeInit (RenderEdge *e,
int n,
xFixed y,
xLineFixed *line,
int x_off,
int y_off)
{
xFixed x_off_fixed = IntToxFixed(x_off);
xFixed y_off_fixed = IntToxFixed(y_off);
xPointFixed *top, *bot;
if (line->p1.y <= line->p2.y)
{
top = &line->p1;
bot = &line->p2;
}
else
{
top = &line->p2;
bot = &line->p1;
}
RenderEdgeInit (e, n, y,
top->x + x_off_fixed,
top->y + y_off_fixed,
bot->x + x_off_fixed,
bot->y + y_off_fixed);
}
|
