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| 1892 | serge | 1 | /* cairo - a vector graphics library with display and print output |
| 2 | * |
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| 3 | * Copyright © 2002 University of Southern California |
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| 4 | * Copyright © 2005 Red Hat, Inc. |
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| 5 | * |
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| 6 | * This library is free software; you can redistribute it and/or |
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| 7 | * modify it either under the terms of the GNU Lesser General Public |
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| 8 | * License version 2.1 as published by the Free Software Foundation |
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| 9 | * (the "LGPL") or, at your option, under the terms of the Mozilla |
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| 10 | * Public License Version 1.1 (the "MPL"). If you do not alter this |
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| 11 | * notice, a recipient may use your version of this file under either |
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| 12 | * the MPL or the LGPL. |
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| 13 | * |
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| 14 | * You should have received a copy of the LGPL along with this library |
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| 15 | * in the file COPYING-LGPL-2.1; if not, write to the Free Software |
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| 16 | * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA |
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| 17 | * You should have received a copy of the MPL along with this library |
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| 18 | * in the file COPYING-MPL-1.1 |
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| 19 | * |
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| 20 | * The contents of this file are subject to the Mozilla Public License |
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| 21 | * Version 1.1 (the "License"); you may not use this file except in |
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| 22 | * compliance with the License. You may obtain a copy of the License at |
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| 23 | * http://www.mozilla.org/MPL/ |
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| 24 | * |
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| 25 | * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY |
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| 26 | * OF ANY KIND, either express or implied. See the LGPL or the MPL for |
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| 27 | * the specific language governing rights and limitations. |
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| 28 | * |
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| 29 | * The Original Code is the cairo graphics library. |
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| 30 | * |
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| 31 | * The Initial Developer of the Original Code is University of Southern |
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| 32 | * California. |
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| 33 | * |
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| 34 | * Contributor(s): |
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| 35 | * Carl D. Worth |
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| 36 | */ |
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| 37 | |||
| 38 | #include "cairoint.h" |
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| 39 | |||
| 40 | static cairo_color_t const cairo_color_white = { |
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| 41 | 1.0, 1.0, 1.0, 1.0, |
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| 42 | 0xffff, 0xffff, 0xffff, 0xffff |
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| 43 | }; |
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| 44 | |||
| 45 | static cairo_color_t const cairo_color_black = { |
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| 46 | 0.0, 0.0, 0.0, 1.0, |
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| 47 | 0x0, 0x0, 0x0, 0xffff |
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| 48 | }; |
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| 49 | |||
| 50 | static cairo_color_t const cairo_color_transparent = { |
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| 51 | 0.0, 0.0, 0.0, 0.0, |
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| 52 | 0x0, 0x0, 0x0, 0x0 |
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| 53 | }; |
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| 54 | |||
| 55 | static cairo_color_t const cairo_color_magenta = { |
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| 56 | 1.0, 0.0, 1.0, 1.0, |
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| 57 | 0xffff, 0x0, 0xffff, 0xffff |
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| 58 | }; |
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| 59 | |||
| 60 | const cairo_color_t * |
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| 61 | _cairo_stock_color (cairo_stock_t stock) |
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| 62 | { |
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| 63 | switch (stock) { |
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| 64 | case CAIRO_STOCK_WHITE: |
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| 65 | return &cairo_color_white; |
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| 66 | case CAIRO_STOCK_BLACK: |
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| 67 | return &cairo_color_black; |
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| 68 | case CAIRO_STOCK_TRANSPARENT: |
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| 69 | return &cairo_color_transparent; |
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| 70 | |||
| 71 | case CAIRO_STOCK_NUM_COLORS: |
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| 72 | default: |
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| 73 | ASSERT_NOT_REACHED; |
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| 74 | /* If the user can get here somehow, give a color that indicates a |
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| 75 | * problem. */ |
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| 76 | return &cairo_color_magenta; |
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| 77 | } |
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| 78 | } |
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| 79 | |||
| 80 | /* Convert a double in [0.0, 1.0] to an integer in [0, 65535] |
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| 81 | * The conversion is designed to divide the input range into 65536 |
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| 82 | * equally-sized regions. This is achieved by multiplying by 65536 and |
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| 83 | * then special-casing the result of an input value of 1.0 so that it |
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| 84 | * maps to 65535 instead of 65536. |
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| 85 | */ |
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| 86 | uint16_t |
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| 87 | _cairo_color_double_to_short (double d) |
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| 88 | { |
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| 89 | uint32_t i; |
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| 90 | i = (uint32_t) (d * 65536); |
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| 91 | i -= (i >> 16); |
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| 92 | return i; |
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| 93 | } |
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| 94 | |||
| 95 | static void |
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| 96 | _cairo_color_compute_shorts (cairo_color_t *color) |
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| 97 | { |
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| 98 | color->red_short = _cairo_color_double_to_short (color->red * color->alpha); |
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| 99 | color->green_short = _cairo_color_double_to_short (color->green * color->alpha); |
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| 100 | color->blue_short = _cairo_color_double_to_short (color->blue * color->alpha); |
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| 101 | color->alpha_short = _cairo_color_double_to_short (color->alpha); |
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| 102 | } |
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| 103 | |||
| 104 | void |
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| 105 | _cairo_color_init_rgba (cairo_color_t *color, |
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| 106 | double red, double green, double blue, |
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| 107 | double alpha) |
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| 108 | { |
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| 109 | color->red = red; |
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| 110 | color->green = green; |
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| 111 | color->blue = blue; |
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| 112 | color->alpha = alpha; |
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| 113 | |||
| 114 | _cairo_color_compute_shorts (color); |
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| 115 | } |
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| 116 | |||
| 117 | void |
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| 118 | _cairo_color_multiply_alpha (cairo_color_t *color, |
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| 119 | double alpha) |
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| 120 | { |
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| 121 | color->alpha *= alpha; |
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| 122 | |||
| 123 | _cairo_color_compute_shorts (color); |
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| 124 | } |
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| 125 | |||
| 126 | void |
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| 127 | _cairo_color_get_rgba (cairo_color_t *color, |
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| 128 | double *red, |
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| 129 | double *green, |
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| 130 | double *blue, |
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| 131 | double *alpha) |
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| 132 | { |
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| 133 | *red = color->red; |
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| 134 | *green = color->green; |
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| 135 | *blue = color->blue; |
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| 136 | *alpha = color->alpha; |
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| 137 | } |
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| 138 | |||
| 139 | void |
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| 140 | _cairo_color_get_rgba_premultiplied (cairo_color_t *color, |
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| 141 | double *red, |
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| 142 | double *green, |
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| 143 | double *blue, |
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| 144 | double *alpha) |
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| 145 | { |
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| 146 | *red = color->red * color->alpha; |
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| 147 | *green = color->green * color->alpha; |
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| 148 | *blue = color->blue * color->alpha; |
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| 149 | *alpha = color->alpha; |
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| 150 | } |
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| 151 | |||
| 152 | /* NB: This function works both for unmultiplied and premultiplied colors */ |
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| 153 | cairo_bool_t |
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| 154 | _cairo_color_equal (const cairo_color_t *color_a, |
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| 155 | const cairo_color_t *color_b) |
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| 156 | { |
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| 157 | if (color_a == color_b) |
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| 158 | return TRUE; |
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| 159 | |||
| 160 | if (color_a->alpha_short != color_b->alpha_short) |
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| 161 | return FALSE; |
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| 162 | |||
| 163 | if (color_a->alpha_short == 0) |
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| 164 | return TRUE; |
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| 165 | |||
| 166 | return color_a->red_short == color_b->red_short && |
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| 167 | color_a->green_short == color_b->green_short && |
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| 168 | color_a->blue_short == color_b->blue_short; |
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| 169 | } |
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| 170 | |||
| 171 | cairo_bool_t |
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| 172 | _cairo_color_stop_equal (const cairo_color_stop_t *color_a, |
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| 173 | const cairo_color_stop_t *color_b) |
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| 174 | { |
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| 175 | if (color_a == color_b) |
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| 176 | return TRUE; |
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| 177 | |||
| 178 | return color_a->alpha_short == color_b->alpha_short && |
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| 179 | color_a->red_short == color_b->red_short && |
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| 180 | color_a->green_short == color_b->green_short && |
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| 181 | color_a->blue_short == color_b->blue_short; |
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| 182 | } |
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| 183 | |||
| 184 | cairo_content_t |
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| 185 | _cairo_color_get_content (const cairo_color_t *color) |
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| 186 | { |
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| 187 | if (CAIRO_COLOR_IS_OPAQUE (color)) |
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| 188 | return CAIRO_CONTENT_COLOR; |
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| 189 | |||
| 190 | if (color->red_short == 0 && |
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| 191 | color->green_short == 0 && |
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| 192 | color->blue_short == 0) |
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| 193 | { |
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| 194 | return CAIRO_CONTENT_ALPHA; |
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| 195 | } |
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| 196 | |||
| 197 | return CAIRO_CONTENT_COLOR_ALPHA; |
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| 198 | } |