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| Rev | Author | Line No. | Line |
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| 3584 | sourcerer | 1 | /* |
| 2 | * Copyright 2012 Michael Drake |
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| 3 | * |
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| 4 | * This file is part of libnsfb, http://www.netsurf-browser.org/ |
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| 5 | * Licenced under the MIT License, |
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| 6 | * http://www.opensource.org/licenses/mit-license.php |
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| 7 | */ |
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| 8 | |||
| 9 | /** \file |
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| 10 | * Palette (implementation). |
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| 11 | */ |
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| 12 | |||
| 13 | #include |
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| 14 | #include |
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| 15 | #include |
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| 16 | #include |
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| 17 | |||
| 18 | #include "palette.h" |
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| 19 | |||
| 20 | |||
| 21 | /** Create an empty palette object. */ |
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| 22 | bool nsfb_palette_new(struct nsfb_palette_s **palette, int width) |
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| 23 | { |
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| 24 | *palette = malloc(sizeof(struct nsfb_palette_s)); |
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| 25 | if (*palette == NULL) { |
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| 26 | return false; |
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| 27 | } |
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| 28 | |||
| 29 | (*palette)->type = NSFB_PALETTE_EMPTY; |
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| 30 | (*palette)->last = 0; |
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| 31 | |||
| 32 | (*palette)->dither = false; |
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| 33 | (*palette)->dither_ctx.data_len = width * 3; |
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| 34 | (*palette)->dither_ctx.data = malloc(width * 3 * sizeof(int)); |
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| 35 | if ((*palette)->dither_ctx.data == NULL) { |
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| 36 | nsfb_palette_free(*palette); |
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| 37 | return false; |
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| 38 | } |
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| 39 | |||
| 40 | return true; |
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| 41 | } |
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| 42 | |||
| 43 | /** Free a palette object. */ |
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| 44 | void nsfb_palette_free(struct nsfb_palette_s *palette) |
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| 45 | { |
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| 46 | if (palette != NULL) { |
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| 47 | if (palette->dither_ctx.data != NULL) { |
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| 48 | free(palette->dither_ctx.data); |
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| 49 | } |
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| 50 | free(palette); |
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| 51 | } |
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| 52 | } |
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| 53 | |||
| 54 | /** Init error diffusion for a plot. */ |
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| 55 | void nsfb_palette_dither_init(struct nsfb_palette_s *palette, int width) |
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| 56 | { |
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| 57 | palette->dither = true; |
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| 58 | memset(palette->dither_ctx.data, 0, palette->dither_ctx.data_len); |
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| 59 | palette->dither_ctx.width = width * 3; |
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| 60 | palette->dither_ctx.current = 0; |
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| 61 | } |
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| 62 | |||
| 63 | /** Finalise error diffusion after a plot. */ |
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| 64 | void nsfb_palette_dither_fini(struct nsfb_palette_s *palette) |
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| 65 | { |
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| 66 | palette->dither = false; |
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| 67 | } |
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| 68 | |||
| 69 | /** Generate libnsfb 8bpp default palette. */ |
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| 70 | void nsfb_palette_generate_nsfb_8bpp(struct nsfb_palette_s *palette) |
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| 71 | { |
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| 72 | int rloop, gloop, bloop; |
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| 73 | int loop = 0; |
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| 74 | uint8_t r, g, b; |
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| 75 | |||
| 76 | /* Build a linear 6-8-5 levels RGB colour cube palette. |
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| 77 | * This accounts for 240 colours */ |
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| 78 | #define RLIM 6 |
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| 79 | #define GLIM 8 |
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| 80 | #define BLIM 5 |
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| 81 | for (rloop = 0; rloop < RLIM; rloop++) { |
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| 82 | for (gloop = 0; gloop < GLIM; gloop++) { |
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| 83 | for (bloop = 0; bloop < BLIM; bloop++) { |
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| 84 | r = ((rloop * 255 * 2) + RLIM - 1) / |
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| 85 | (2 * (RLIM - 1)); |
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| 86 | g = ((gloop * 255 * 2) + GLIM - 1) / |
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| 87 | (2 * (GLIM - 1)); |
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| 88 | b = ((bloop * 255 * 2) + BLIM - 1) / |
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| 89 | (2 * (BLIM - 1)); |
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| 90 | |||
| 91 | palette->data[loop] = r | g << 8 | b << 16; |
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| 92 | loop++; |
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| 93 | } |
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| 94 | } |
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| 95 | } |
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| 96 | #undef RLIM |
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| 97 | #undef GLIM |
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| 98 | #undef BLIM |
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| 99 | |||
| 100 | /* Should have 240 colours set */ |
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| 101 | assert(loop == 240); |
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| 102 | |||
| 103 | /* Fill index 240 to index 255 with grayscales */ |
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| 104 | /* Note: already have full black and full white from RGB cube */ |
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| 105 | for (; loop < 256; loop++) { |
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| 106 | int ngray = loop - 240 + 1; |
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| 107 | r = ngray * 15; /* 17*15 = 255 */ |
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| 108 | |||
| 109 | g = b = r; |
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| 110 | |||
| 111 | palette->data[loop] = r | g << 8 | b << 16; |
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| 112 | } |
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| 113 | |||
| 114 | /* Set palette details */ |
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| 115 | palette->type = NSFB_PALETTE_NSFB_8BPP; |
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| 116 | palette->last = 255; |
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| 117 | } |