root/lang/c/cairo-hacking/src/cairo-operator.c @ 1347

Revision 1307, 3.4 kB (checked in by gyuque, 6 years ago)

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1/* cairo - a vector graphics library with display and print output
2 *
3 * Copyright © 2006 Keith Packard
4 * Copyright © 2006 Red Hat, Inc
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it either under the terms of the GNU Lesser General Public
8 * License version 2.1 as published by the Free Software Foundation
9 * (the "LGPL") or, at your option, under the terms of the Mozilla
10 * Public License Version 1.1 (the "MPL"). If you do not alter this
11 * notice, a recipient may use your version of this file under either
12 * the MPL or the LGPL.
13 *
14 * You should have received a copy of the LGPL along with this library
15 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 * You should have received a copy of the MPL along with this library
18 * in the file COPYING-MPL-1.1
19 *
20 * The contents of this file are subject to the Mozilla Public License
21 * Version 1.1 (the "License"); you may not use this file except in
22 * compliance with the License. You may obtain a copy of the License at
23 * http://www.mozilla.org/MPL/
24 *
25 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
26 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
27 * the specific language governing rights and limitations.
28 *
29 * The Original Code is the cairo graphics library.
30 *
31 * The Initial Developer of the Original Code is University of Southern
32 * California.
33 *
34 * Contributor(s):
35 *      Carl D. Worth <cworth@cworth.org>
36 *      Keith Packard <keithp@keithp.com>
37 */
38
39#include "cairoint.h"
40
41/* The analysis here assumes destination alpha semantics (that is
42 * CAIRO_CONTENT_COLOR_ALPHA). More things can be considered opaque
43 * otherwise (CAIRO_CONTENT_COLOR) so we'll probably want to add a
44 * cairo_content_t parameter to this function
45 *
46 * We also need a definition of what "opaque" means. Is it, "does not
47 * requiring 'knowing' the original contents of destination, nor does
48 * it set the destination alpha to anything but 1.0" ?
49 */
50cairo_bool_t
51_cairo_operator_always_opaque (cairo_operator_t op)
52{
53    switch (op) {
54    case CAIRO_OPERATOR_CLEAR:
55        return FALSE;
56
57    case CAIRO_OPERATOR_SOURCE:
58        return FALSE;
59
60    case CAIRO_OPERATOR_OVER:
61    case CAIRO_OPERATOR_IN:
62    case CAIRO_OPERATOR_OUT:
63    case CAIRO_OPERATOR_ATOP:
64        return FALSE;
65
66    case CAIRO_OPERATOR_DEST:
67        return TRUE;
68
69    case CAIRO_OPERATOR_DEST_OVER:
70    case CAIRO_OPERATOR_DEST_IN:
71    case CAIRO_OPERATOR_DEST_OUT:
72    case CAIRO_OPERATOR_DEST_ATOP:
73        return FALSE;
74
75    case CAIRO_OPERATOR_XOR:
76    case CAIRO_OPERATOR_ADD:
77    case CAIRO_OPERATOR_SATURATE:
78        return FALSE;
79    }
80    return FALSE;
81}
82
83/* As above, we'll probably want to add a cairo_content_t parameter to
84 * this function
85 *
86 * We also need a definition of what "translucent" means.
87 */
88cairo_bool_t
89_cairo_operator_always_translucent (cairo_operator_t op)
90{
91    switch (op) {
92    case CAIRO_OPERATOR_CLEAR:
93        return TRUE;
94
95    case CAIRO_OPERATOR_SOURCE:
96        return FALSE;
97
98    case CAIRO_OPERATOR_OVER:
99    case CAIRO_OPERATOR_IN:
100    case CAIRO_OPERATOR_OUT:
101    case CAIRO_OPERATOR_ATOP:
102        return FALSE;
103
104    case CAIRO_OPERATOR_DEST:
105        return FALSE;
106
107    case CAIRO_OPERATOR_DEST_OVER:
108    case CAIRO_OPERATOR_DEST_IN:
109    case CAIRO_OPERATOR_DEST_OUT:
110    case CAIRO_OPERATOR_DEST_ATOP:
111        return FALSE;
112
113    case CAIRO_OPERATOR_XOR:
114    case CAIRO_OPERATOR_ADD:
115    case CAIRO_OPERATOR_SATURATE:
116        return TRUE;
117    }
118    return TRUE;
119}
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