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
|
/* Copyright (C) 1998, 1999 Aladdin Enterprises. All rights reserved.
This software is licensed to a single customer by Artifex Software Inc.
under the terms of a specific OEM agreement.
*/
/*$RCSfile$ $Revision$ */
/* Internal definitions for shading rendering */
#ifndef gxshade_INCLUDED
# define gxshade_INCLUDED
#include "gsshade.h"
#include "gxfixed.h" /* for gxmatrix.h */
#include "gxmatrix.h" /* for gs_matrix_fixed */
#include "stream.h"
/*
All shadings are defined with respect to some parameter that varies
continuously over some range; the shading defines a mapping from the
parameter values to colors and user space coordinates. Here are the
mappings for the 7 currently defined shading types:
Type Param space Param => color Param => User space
---- ----------- -------------- -------------------
1 2-D Domain Function Matrix
2 1-D Domain Function + Extend perp. to Coords
3 1-D Domain Function + Extend circles per Coords
4,5 triangle x Gouraud interp. on Gouraud interp. on
2-D in tri. Decode => corner triangle corners
values => Function
6 patch x (u,v) Decode => bilinear Sc + Sd - Sb on each patch
in patch interp. on corner
values => Function
7 see 6 see 6 Sum(i) Sum(j) Pij*Bi(u)*Bj(v)
To be able to render a portion of a shading usefully, we must be able to
do two things:
- Determine what range of parameter values is sufficient to cover
the region being filled;
- Evaluate the color at enough points to fill the region (in
device space).
Note that the latter may be implemented by a mix of evaluation and
interpolation, especially for types 3, 6, and 7 where an exact mapping
may be prohibitively expensive.
Except for type 3, where circles turn into ellipses, the CTM can get
folded into the parameter => user space mapping, since in all other
cases, the mapping space is closed under linear transformations of
the output.
*/
/* Define types and rendering procedures for the individual shadings. */
typedef struct gs_shading_Fb_s {
gs_shading_head_t head;
gs_shading_Fb_params_t params;
} gs_shading_Fb_t;
shading_fill_rectangle_proc(gs_shading_Fb_fill_rectangle);
typedef struct gs_shading_A_s {
gs_shading_head_t head;
gs_shading_A_params_t params;
} gs_shading_A_t;
shading_fill_rectangle_proc(gs_shading_A_fill_rectangle);
typedef struct gs_shading_R_s {
gs_shading_head_t head;
gs_shading_R_params_t params;
} gs_shading_R_t;
shading_fill_rectangle_proc(gs_shading_R_fill_rectangle);
typedef struct gs_shading_FfGt_s {
gs_shading_head_t head;
gs_shading_FfGt_params_t params;
} gs_shading_FfGt_t;
shading_fill_rectangle_proc(gs_shading_FfGt_fill_rectangle);
typedef struct gs_shading_LfGt_s {
gs_shading_head_t head;
gs_shading_LfGt_params_t params;
} gs_shading_LfGt_t;
shading_fill_rectangle_proc(gs_shading_LfGt_fill_rectangle);
typedef struct gs_shading_Cp_s {
gs_shading_head_t head;
gs_shading_Cp_params_t params;
} gs_shading_Cp_t;
shading_fill_rectangle_proc(gs_shading_Cp_fill_rectangle);
typedef struct gs_shading_Tpp_s {
gs_shading_head_t head;
gs_shading_Tpp_params_t params;
} gs_shading_Tpp_t;
shading_fill_rectangle_proc(gs_shading_Tpp_fill_rectangle);
/* Define a stream for decoding packed coordinate values. */
typedef struct shade_coord_stream_s shade_coord_stream_t;
struct shade_coord_stream_s {
stream ds; /* stream if DataSource isn't one already -- */
/* first for GC-ability (maybe unneeded?) */
stream *s; /* DataSource or &ds */
uint bits; /* shifted bits of current byte */
int left; /* # of bits left in bits */
const gs_shading_mesh_params_t *params;
const gs_matrix_fixed *pctm;
int (*get_value)(P3(shade_coord_stream_t *cs, int num_bits, uint *pvalue));
int (*get_decoded)(P4(shade_coord_stream_t *cs, int num_bits,
const float decode[2], float *pvalue));
};
/* Define one vertex of a mesh. */
typedef struct mesh_vertex_s {
gs_fixed_point p;
float cc[GS_CLIENT_COLOR_MAX_COMPONENTS];
} mesh_vertex_t;
/* Initialize a packed value stream. */
void shade_next_init(P3(shade_coord_stream_t * cs,
const gs_shading_mesh_params_t * params,
const gs_imager_state * pis));
/* Get the next flag value. */
int shade_next_flag(P2(shade_coord_stream_t * cs, int BitsPerFlag));
/* Get one or more coordinate pairs. */
int shade_next_coords(P3(shade_coord_stream_t * cs, gs_fixed_point * ppt,
int num_points));
/* Get a color. Currently all this does is look up Indexed colors. */
int shade_next_color(P2(shade_coord_stream_t * cs, float *pc));
/* Get the next vertex for a mesh element. */
int shade_next_vertex(P2(shade_coord_stream_t * cs, mesh_vertex_t * vertex));
/*
Currently, all shading fill procedures follow the same algorithm:
- Conservatively inverse-transform the rectangle being filled to a linear
or rectangular range of values in the parameter space.
- Compute the color values at the extrema of the range.
- If possible, compute the parameter range corresponding to a single
device pixel.
- Recursively do the following, passing the parameter range and extremal
color values as the recursion arguments:
- If the color values are equal to within the tolerance given by the
smoothness in the graphics state, or if the range of parameters maps
to a single device pixel, fill the range with the (0) or (0,0) color.
- Otherwise, subdivide and recurse. If the parameter range is 2-D,
subdivide the axis with the largest color difference.
For shadings based on a function, if the function is not monotonic, the
smoothness test must only be applied when the parameter range extrema are
all interpolated from the same entries in the Function. (We don't
currently do this.)
*/
/* Define the common structure for recursive subdivision. */
#define shading_fill_state_common\
gx_device *dev;\
gs_imager_state *pis;\
int num_components; /* # of color components */\
float cc_max_error[GS_CLIENT_COLOR_MAX_COMPONENTS]
typedef struct shading_fill_state_s {
shading_fill_state_common;
} shading_fill_state_t;
/* Initialize the common parts of the recursion state. */
void shade_init_fill_state(P4(shading_fill_state_t * pfs,
const gs_shading_t * psh, gx_device * dev,
gs_imager_state * pis));
/* Transform a bounding box into device space. */
int shade_bbox_transform2fixed(P3(const gs_rect * rect,
const gs_imager_state * pis,
gs_fixed_rect * rfixed));
/* Check whether 4 colors fall within the smoothness criterion. */
bool shade_colors4_converge(P2(const gs_client_color cc[4],
const shading_fill_state_t * pfs));
/* Fill one piece of a shading. */
#ifndef gx_device_color_DEFINED
# define gx_device_color_DEFINED
typedef struct gx_device_color_s gx_device_color;
#endif
int shade_fill_path(P3(const shading_fill_state_t * pfs, gx_path * ppath,
gx_device_color * pdevc));
#endif /* gxshade_INCLUDED */
|
