| 1 | /* Libart_LGPL - library of basic graphic primitives |
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| 2 | * Copyright (C) 1998 Raph Levien |
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| 3 | * |
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| 4 | * This library is free software; you can redistribute it and/or |
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| 5 | * modify it under the terms of the GNU Library General Public |
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| 6 | * License as published by the Free Software Foundation; either |
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| 7 | * version 2 of the License, or (at your option) any later version. |
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| 8 | * |
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| 9 | * This library is distributed in the hope that it will be useful, |
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| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | * Library General Public License for more details. |
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| 13 | * |
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| 14 | * You should have received a copy of the GNU Library General Public |
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| 15 | * License along with this library; if not, write to the |
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| 16 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
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| 17 | * Boston, MA 02111-1307, USA. |
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| 18 | */ |
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| 19 | |
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| 20 | #ifndef __ART_FILTERLEVEL_H__ |
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| 21 | #define __ART_FILTERLEVEL_H__ |
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| 22 | |
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| 23 | #ifdef __cplusplus |
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| 24 | extern "C" { |
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| 25 | #endif /* __cplusplus */ |
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| 26 | |
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| 27 | typedef enum { |
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| 28 | ART_FILTER_NEAREST, |
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| 29 | ART_FILTER_TILES, |
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| 30 | ART_FILTER_BILINEAR, |
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| 31 | ART_FILTER_HYPER |
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| 32 | } ArtFilterLevel; |
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| 33 | |
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| 34 | /* NEAREST is nearest neighbor. It is the fastest and lowest quality. |
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| 35 | |
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| 36 | TILES is an accurate simulation of the PostScript image operator |
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| 37 | without any interpolation enabled; each pixel is rendered as a tiny |
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| 38 | parallelogram of solid color, the edges of which are implemented |
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| 39 | with antialiasing. It resembles nearest neighbor for enlargement, |
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| 40 | and bilinear for reduction. |
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| 41 | |
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| 42 | BILINEAR is bilinear interpolation. For enlargement, it is |
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| 43 | equivalent to point-sampling the ideal bilinear-interpolated |
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| 44 | image. For reduction, it is equivalent to laying down small tiles |
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| 45 | and integrating over the coverage area. |
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| 46 | |
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| 47 | HYPER is the highest quality reconstruction function. It is derived |
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| 48 | from the hyperbolic filters in Wolberg's "Digital Image Warping," |
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| 49 | and is formally defined as the hyperbolic-filter sampling the ideal |
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| 50 | hyperbolic-filter interpolated image (the filter is designed to be |
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| 51 | idempotent for 1:1 pixel mapping). It is the slowest and highest |
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| 52 | quality. |
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| 53 | |
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| 54 | Note: at this stage of implementation, most filter modes are likely |
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| 55 | not to be implemented. |
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| 56 | |
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| 57 | Note: cubic filtering is missing from this list, because there isn't |
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| 58 | much point - hyper is just as fast to implement and slightly better |
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| 59 | in quality. |
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| 60 | |
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| 61 | */ |
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| 62 | |
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| 63 | |
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| 64 | #ifdef __cplusplus |
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| 65 | } |
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| 66 | #endif /* __cplusplus */ |
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| 67 | |
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| 68 | #endif /* __ART_PATHCODE_H__ */ |
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