/* * libcaca Colour ASCII-Art library * Copyright © 2002—2018 Sam Hocevar * All Rights Reserved * * This library is free software. It comes without any warranty, to * the extent permitted by applicable law. You can redistribute it * and/or modify it under the terms of the Do What the Fuck You Want * to Public License, Version 2, as published by the WTFPL Task Force. * See http://www.wtfpl.net/ for more details. */ /* * This file contains bitmap dithering functions. */ #include "config.h" #if !defined(__KERNEL__) # if defined(HAVE_ENDIAN_H) # include # endif # include # include # include # include #endif #include "caca.h" #include "caca_internals.h" #define CP437 0 /* * Local variables */ #if !defined(_DOXYGEN_SKIP_ME) # define LOOKUP_VAL 32 # define LOOKUP_SAT 32 # define LOOKUP_HUE 16 #endif static uint8_t hsv_distances[LOOKUP_VAL][LOOKUP_SAT][LOOKUP_HUE]; static uint16_t lookup_colors[8]; static int lookup_initialised = 0; static int const hsv_palette[] = { /* weight, hue, saturation, value */ 4, 0x0, 0x0, 0x0, /* black */ 5, 0x0, 0x0, 0x5ff, /* 30% */ 5, 0x0, 0x0, 0x9ff, /* 70% */ 4, 0x0, 0x0, 0xfff, /* white */ 3, 0x1000, 0xfff, 0x5ff, /* dark yellow */ 2, 0x1000, 0xfff, 0xfff, /* light yellow */ 3, 0x0, 0xfff, 0x5ff, /* dark red */ 2, 0x0, 0xfff, 0xfff /* light red */ }; /* RGB palette for the new colour picker */ static int const rgb_palette[] = { 0x0, 0x0, 0x0, 0x0, 0x0, 0x7ff, 0x0, 0x7ff, 0x0, 0x0, 0x7ff, 0x7ff, 0x7ff, 0x0, 0x0, 0x7ff, 0x0, 0x7ff, 0x7ff, 0x7ff, 0x0, 0xaaa, 0xaaa, 0xaaa, 0x555, 0x555, 0x555, 0x000, 0x000, 0xfff, 0x000, 0xfff, 0x000, 0x000, 0xfff, 0xfff, 0xfff, 0x000, 0x000, 0xfff, 0x000, 0xfff, 0xfff, 0xfff, 0x000, 0xfff, 0xfff, 0xfff, }; static int const rgb_weight[] = { /* 2, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 2 */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 }; /* List of glyphs */ static uint32_t ascii_glyphs[] = { ' ', '.', ':', ';', 't', '%', 'S', 'X', '@', '8', '?' }; static uint32_t shades_glyphs[] = { /* ' '. '·', '░', '▒', '?' */ ' ', 0xb7, 0x2591, 0x2592, '?' }; static uint32_t blocks_glyphs[] = { /* ' ', '▘', '▚', '?' */ ' ', 0x2598, 0x259a, '?' }; #if !defined(_DOXYGEN_SKIP_ME) enum color_mode { COLOR_MODE_MONO, COLOR_MODE_GRAY, COLOR_MODE_8, COLOR_MODE_16, COLOR_MODE_FULLGRAY, COLOR_MODE_FULL8, COLOR_MODE_FULL16 }; struct caca_dither { int bpp, has_palette, has_alpha; size_t w, h, pitch; int rmask, gmask, bmask, amask; int rright, gright, bright, aright; int rleft, gleft, bleft, aleft; void (*get_hsv)(caca_dither_t *, char *, int, int); int red[256], green[256], blue[256], alpha[256]; /* Colour features */ float gamma, brightness, contrast; int gammatab[4097]; /* Dithering features */ char const *antialias_name; int antialias; char const *color_name; enum color_mode color; char const *algo_name; void (*init_dither) (int); int (*get_dither) (void); void (*increment_dither) (void); char const *glyph_name; uint32_t const * glyphs; int glyph_count; int invert; }; #define HSV_XRATIO 6 #define HSV_YRATIO 3 #define HSV_HRATIO 3 #define HSV_DISTANCE(h, s, v, index) \ (hsv_palette[index * 4] \ * ((HSV_XRATIO * ((v) - hsv_palette[index * 4 + 3]) \ * ((v) - hsv_palette[index * 4 + 3])) \ + (hsv_palette[index * 4 + 3] \ ? (HSV_YRATIO * ((s) - hsv_palette[index * 4 + 2]) \ * ((s) - hsv_palette[index * 4 + 2])) \ : 0) \ + (hsv_palette[index * 4 + 2] \ ? (HSV_HRATIO * ((h) - hsv_palette[index * 4 + 1]) \ * ((h) - hsv_palette[index * 4 + 1])) \ : 0))) #endif /* * Local prototypes */ static void mask2shift(uint32_t, int *, int *); static float gammapow(float x, float y); static void get_rgba_default(caca_dither_t const *, uint8_t const *, int, int, unsigned int *); static int init_lookup(void); /* Dithering algorithms */ static void init_no_dither(int); static int get_no_dither(void); static void increment_no_dither(void); static void init_fstein_dither(int); static int get_fstein_dither(void); static void increment_fstein_dither(void); static void init_ordered2_dither(int); static int get_ordered2_dither(void); static void increment_ordered2_dither(void); static void init_ordered4_dither(int); static int get_ordered4_dither(void); static void increment_ordered4_dither(void); static void init_ordered8_dither(int); static int get_ordered8_dither(void); static void increment_ordered8_dither(void); static void init_random_dither(int); static int get_random_dither(void); static void increment_random_dither(void); static inline int sq(int x) { return x * x; } static inline void rgb2hsv_default(int r, int g, int b, int *hue, int *sat, int *val) { int min, max, delta; min = r; max = r; if(min > g) min = g; if(max < g) max = g; if(min > b) min = b; if(max < b) max = b; delta = max - min; /* 0 - 0xfff */ *val = max; /* 0 - 0xfff */ if(delta) { *sat = 0xfff * delta / max; /* 0 - 0xfff */ /* Generate *hue between 0 and 0x5fff */ if( r == max ) *hue = 0x1000 + 0x1000 * (g - b) / delta; else if( g == max ) *hue = 0x3000 + 0x1000 * (b - r) / delta; else *hue = 0x5000 + 0x1000 * (r - g) / delta; } else { *sat = 0; *hue = 0; } } /** \brief Create an internal dither object. * * Create a dither structure from its coordinates (depth, width, height and * pitch) and pixel mask values. If the depth is 8 bits per pixel, the mask * values are ignored and the colour palette should be set using the * caca_set_dither_palette() function. For depths greater than 8 bits per * pixel, a zero alpha mask causes the alpha values to be ignored. * * If an error occurs, NULL is returned and \b errno is set accordingly: * - \c EINVAL Requested width, height, pitch or bits per pixel value was * invalid. * - \c ENOMEM Not enough memory to allocate dither structure. * * \param bpp Bitmap depth in bits per pixel. * \param w Bitmap width in pixels. * \param h Bitmap height in pixels. * \param pitch Bitmap pitch in bytes. * \param rmask Bitmask for red values. * \param gmask Bitmask for green values. * \param bmask Bitmask for blue values. * \param amask Bitmask for alpha values. * \return Dither object upon success, NULL if an error occurred. */ caca_dither_t *caca_create_dither(int bpp, int w, int h, int pitch, uint32_t rmask, uint32_t gmask, uint32_t bmask, uint32_t amask) { caca_dither_t *d; int i; /* Minor sanity test */ if(w < 0 || h < 0 || pitch < 0 || bpp > 32 || bpp < 8) { seterrno(EINVAL); return NULL; } d = malloc(sizeof(caca_dither_t)); if(!d) { seterrno(ENOMEM); return NULL; } if(!lookup_initialised) { /* XXX: because we do not wish to be thread-safe, there is a slight * chance that the following code will be executed twice. It is * totally harmless. */ init_lookup(); lookup_initialised = 1; } d->bpp = bpp; d->has_palette = 0; d->has_alpha = amask ? 1 : 0; d->w = w; d->h = h; d->pitch = pitch; d->rmask = rmask; d->gmask = gmask; d->bmask = bmask; d->amask = amask; /* Load bitmasks */ if(rmask || gmask || bmask || amask) { mask2shift(rmask, &d->rright, &d->rleft); mask2shift(gmask, &d->gright, &d->gleft); mask2shift(bmask, &d->bright, &d->bleft); mask2shift(amask, &d->aright, &d->aleft); } /* In 8 bpp mode, default to a grayscale palette */ if(bpp == 8) { d->has_palette = 1; d->has_alpha = 0; for(i = 0; i < 256; i++) { d->red[i] = i * 0xfff / 256; d->green[i] = i * 0xfff / 256; d->blue[i] = i * 0xfff / 256; } } /* Default gamma value */ d->gamma = 1.0; for(i = 0; i < 4096; i++) d->gammatab[i] = i; /* Default colour properties */ d->brightness = 1.0; d->contrast = 1.0; /* Default features */ d->antialias_name = "prefilter"; d->antialias = 1; d->color_name = "full16"; d->color = COLOR_MODE_FULL16; d->glyph_name = "ascii"; d->glyphs = ascii_glyphs; d->glyph_count = sizeof(ascii_glyphs) / sizeof(*ascii_glyphs); d->algo_name = "fstein"; d->init_dither = init_fstein_dither; d->get_dither = get_fstein_dither; d->increment_dither = increment_fstein_dither; d->invert = 0; return d; } /** \brief Set the palette of an 8bpp dither object. * * Set the palette of an 8 bits per pixel bitmap. Values should be between * 0 and 4095 (0xfff). * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Dither bits per pixel value is not 8, or one of the pixel * values was outside the range 0 - 4095. * * \param d Dither object. * \param red Array of 256 red values. * \param green Array of 256 green values. * \param blue Array of 256 blue values. * \param alpha Array of 256 alpha values. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_palette(caca_dither_t *d, uint32_t red[], uint32_t green[], uint32_t blue[], uint32_t alpha[]) { int i, has_alpha = 0; if(d->bpp != 8) { seterrno(EINVAL); return -1; } for(i = 0; i < 256; i++) { if((red[i] | green[i] | blue[i] | alpha[i]) >= 0x1000) { seterrno(EINVAL); return -1; } } for(i = 0; i < 256; i++) { d->red[i] = red[i]; d->green[i] = green[i]; d->blue[i] = blue[i]; if(alpha[i]) { d->alpha[i] = alpha[i]; has_alpha = 1; } } d->has_alpha = has_alpha; return 0; } /** \brief Set the brightness of a dither object. * * Set the brightness of dither. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Brightness value was out of range. * * \param d Dither object. * \param brightness brightness value. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_brightness(caca_dither_t *d, float brightness) { /* FIXME */ d->brightness = brightness; return 0; } /** \brief Get the brightness of a dither object. * * Get the brightness of the given dither object. * * This function never fails. * * \param d Dither object. * \return Brightness value. */ float caca_get_dither_brightness(caca_dither_t const *d) { return d->brightness; } /** \brief Set the gamma of a dither object. * * Set the gamma of the given dither object. A negative value causes * colour inversion. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Gamma value was out of range. * * \param d Dither object. * \param gamma Gamma value. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_gamma(caca_dither_t *d, float gamma) { /* FIXME: we don't need 4096 calls to gammapow(), we could just compute * a few of them and do linear interpolation for the rest. This will * probably speed up things a lot. */ int i; if(gamma < 0.0) { d->invert = 1; gamma = -gamma; } else if(gamma == 0.0) { seterrno(EINVAL); return -1; } d->gamma = gamma; for(i = 0; i < 4096; i++) d->gammatab[i] = 4096.0 * gammapow((float)i / 4096.0, 1.0 / gamma); return 0; } /** \brief Get the gamma of a dither object. * * Get the gamma of the given dither object. * * This function never fails. * * \param d Dither object. * \return Gamma value. */ float caca_get_dither_gamma(caca_dither_t const *d) { return d->gamma; } /** \brief Set the contrast of a dither object. * * Set the contrast of dither. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Contrast value was out of range. * * \param d Dither object. * \param contrast contrast value. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_contrast(caca_dither_t *d, float contrast) { /* FIXME */ d->contrast = contrast; return 0; } /** \brief Get the contrast of a dither object. * * Get the contrast of the given dither object. * * This function never fails. * * \param d Dither object. * \return Contrast value. */ float caca_get_dither_contrast(caca_dither_t const *d) { return d->contrast; } /** \brief Set dither antialiasing * * Tell the renderer whether to antialias the dither. Antialiasing smoothens * the rendered image and avoids the commonly seen staircase effect. * - \c "none": no antialiasing. * - \c "prefilter" or \c "default": simple prefilter antialiasing. This * is the default value. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Invalid antialiasing mode. * * \param d Dither object. * \param str A string describing the antialiasing method that will be used * for the dithering. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_antialias(caca_dither_t *d, char const *str) { if(!strcasecmp(str, "none")) { d->antialias_name = "none"; d->antialias = 0; } else if(!strcasecmp(str, "prefilter") || !strcasecmp(str, "default")) { d->antialias_name = "prefilter"; d->antialias = 1; } else { seterrno(EINVAL); return -1; } return 0; } /** \brief Get available antialiasing methods * * Return a list of available antialiasing methods for a given dither. The * list is a NULL-terminated array of strings, interleaving a string * containing the internal value for the antialiasing method to be used with * caca_set_dither_antialias(), and a string containing the natural * language description for that antialiasing method. * * This function never fails. * * \param d Dither object. * \return An array of strings. */ char const * const * caca_get_dither_antialias_list(caca_dither_t const *d) { static char const * const list[] = { "none", "No antialiasing", "prefilter", "Prefilter antialiasing", NULL, NULL }; return list; } /** \brief Get current antialiasing method * * Return the given dither's current antialiasing method. * * This function never fails. * * \param d Dither object. * \return A static string. */ char const * caca_get_dither_antialias(caca_dither_t const *d) { return d->antialias_name; } /** \brief Choose colours used for dithering * * Tell the renderer which colours should be used to render the * bitmap. Valid values for \c str are: * - \c "mono": use light gray on a black background. * - \c "gray": use white and two shades of gray on a black background. * - \c "8": use the 8 ANSI colours on a black background. * - \c "16": use the 16 ANSI colours on a black background. * - \c "fullgray": use black, white and two shades of gray for both the * characters and the background. * - \c "full8": use the 8 ANSI colours for both the characters and the * background. * - \c "full16" or \c "default": use the 16 ANSI colours for both the * characters and the background. This is the default value. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Invalid colour set. * * \param d Dither object. * \param str A string describing the colour set that will be used * for the dithering. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_color(caca_dither_t *d, char const *str) { if(!strcasecmp(str, "mono")) { d->color_name = "mono"; d->color = COLOR_MODE_MONO; } else if(!strcasecmp(str, "gray")) { d->color_name = "gray"; d->color = COLOR_MODE_GRAY; } else if(!strcasecmp(str, "8")) { d->color_name = "8"; d->color = COLOR_MODE_8; } else if(!strcasecmp(str, "16")) { d->color_name = "16"; d->color = COLOR_MODE_16; } else if(!strcasecmp(str, "fullgray")) { d->color_name = "fullgray"; d->color = COLOR_MODE_FULLGRAY; } else if(!strcasecmp(str, "full8")) { d->color_name = "full8"; d->color = COLOR_MODE_FULL8; } else if(!strcasecmp(str, "full16") || !strcasecmp(str, "default")) { d->color_name = "full16"; d->color = COLOR_MODE_FULL16; } else { seterrno(EINVAL); return -1; } return 0; } /** \brief Get available colour modes * * Return a list of available colour modes for a given dither. The list * is a NULL-terminated array of strings, interleaving a string containing * the internal value for the colour mode, to be used with * caca_set_dither_color(), and a string containing the natural * language description for that colour mode. * * This function never fails. * * \param d Dither object. * \return An array of strings. */ char const * const * caca_get_dither_color_list(caca_dither_t const *d) { static char const * const list[] = { "mono", "white on black", "gray", "grayscale on black", "8", "8 colours on black", "16", "16 colours on black", "fullgray", "full grayscale", "full8", "full 8 colours", "full16", "full 16 colours", NULL, NULL }; return list; } /** \brief Get current colour mode * * Return the given dither's current colour mode. * * This function never fails. * * \param d Dither object. * \return A static string. */ char const * caca_get_dither_color(caca_dither_t const *d) { return d->color_name; } /** \brief Choose characters used for dithering * * Tell the renderer which characters should be used to render the * dither. Valid values for \c str are: * - \c "ascii" or \c "default": use only ASCII characters. This is the * default value. * - \c "shades": use Unicode characters "U+2591 LIGHT SHADE", "U+2592 * MEDIUM SHADE" and "U+2593 DARK SHADE". These characters are also * present in the CP437 codepage available on DOS and VGA. * - \c "blocks": use Unicode quarter-cell block combinations. These * characters are only found in the Unicode set. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Invalid character set. * * \param d Dither object. * \param str A string describing the characters that need to be used * for the dithering. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_charset(caca_dither_t *d, char const *str) { if(!strcasecmp(str, "shades")) { d->glyph_name = "shades"; d->glyphs = shades_glyphs; d->glyph_count = sizeof(shades_glyphs) / sizeof(*shades_glyphs); } else if(!strcasecmp(str, "blocks")) { d->glyph_name = "blocks"; d->glyphs = blocks_glyphs; d->glyph_count = sizeof(blocks_glyphs) / sizeof(*blocks_glyphs); } else if(!strcasecmp(str, "ascii") || !strcasecmp(str, "default")) { d->glyph_name = "ascii"; d->glyphs = ascii_glyphs; d->glyph_count = sizeof(ascii_glyphs) / sizeof(*ascii_glyphs); } else { seterrno(EINVAL); return -1; } return 0; } /** \brief Get available dither character sets * * Return a list of available character sets for a given dither. The list * is a NULL-terminated array of strings, interleaving a string containing * the internal value for the character set, to be used with * caca_set_dither_charset(), and a string containing the natural * language description for that character set. * * This function never fails. * * \param d Dither object. * \return An array of strings. */ char const * const * caca_get_dither_charset_list(caca_dither_t const *d) { static char const * const list[] = { "ascii", "plain ASCII", "shades", "CP437 shades", "blocks", "Unicode blocks", NULL, NULL }; return list; } /** \brief Get current character set * * Return the given dither's current character set. * * This function never fails. * * \param d Dither object. * \return A static string. */ char const * caca_get_dither_charset(caca_dither_t const *d) { return d->glyph_name; } /** \brief Set dithering algorithm * * Tell the renderer which dithering algorithm should be used. Dithering is * necessary because the picture being rendered has usually far more colours * than the available palette. Valid values for \c str are: * - \c "none": no dithering is used, the nearest matching colour is used. * - \c "ordered2": use a 2x2 Bayer matrix for dithering. * - \c "ordered4": use a 4x4 Bayer matrix for dithering. * - \c "ordered8": use a 8x8 Bayer matrix for dithering. * - \c "random": use random dithering. * - \c "fstein": use Floyd-Steinberg dithering. This is the default value. * * If an error occurs, -1 is returned and \b errno is set accordingly: * - \c EINVAL Unknown dithering mode. * * \param d Dither object. * \param str A string describing the algorithm that needs to be used * for the dithering. * \return 0 in case of success, -1 if an error occurred. */ int caca_set_dither_algorithm(caca_dither_t *d, char const *str) { if(!strcasecmp(str, "none")) { d->algo_name = "none"; d->init_dither = init_no_dither; d->get_dither = get_no_dither; d->increment_dither = increment_no_dither; } else if(!strcasecmp(str, "ordered2")) { d->algo_name = "ordered2"; d->init_dither = init_ordered2_dither; d->get_dither = get_ordered2_dither; d->increment_dither = increment_ordered2_dither; } else if(!strcasecmp(str, "ordered4")) { d->algo_name = "ordered4"; d->init_dither = init_ordered4_dither; d->get_dither = get_ordered4_dither; d->increment_dither = increment_ordered4_dither; } else if(!strcasecmp(str, "ordered8")) { d->algo_name = "ordered8"; d->init_dither = init_ordered8_dither; d->get_dither = get_ordered8_dither; d->increment_dither = increment_ordered8_dither; } else if(!strcasecmp(str, "random")) { d->algo_name = "random"; d->init_dither = init_random_dither; d->get_dither = get_random_dither; d->increment_dither = increment_random_dither; } else if(!strcasecmp(str, "fstein") || !strcasecmp(str, "default")) { d->algo_name = "fstein"; d->init_dither = init_fstein_dither; d->get_dither = get_fstein_dither; d->increment_dither = increment_fstein_dither; } else { seterrno(EINVAL); return -1; } return 0; } /** \brief Get dithering algorithms * * Return a list of available dithering algorithms for a given dither. The * list is a NULL-terminated array of strings, interleaving a string * containing the internal value for the dithering algorithm, to be used * with caca_set_dither_dithering(), and a string containing the natural * language description for that algorithm. * * This function never fails. * * \param d Dither object. * \return An array of strings. */ char const * const * caca_get_dither_algorithm_list(caca_dither_t const *d) { static char const * const list[] = { "none", "no dithering", "ordered2", "2x2 ordered dithering", "ordered4", "4x4 ordered dithering", "ordered8", "8x8 ordered dithering", "random", "random dithering", "fstein", "Floyd-Steinberg dithering", NULL, NULL }; return list; } /** \brief Get current dithering algorithm * * Return the given dither's current dithering algorithm. * * This function never fails. * * \param d Dither object. * \return A static string. */ char const * caca_get_dither_algorithm(caca_dither_t const *d) { return d->algo_name; } /** \brief Dither a bitmap on the canvas. * * Dither a bitmap at the given coordinates. The dither can be of any size * and will be stretched to the text area. * * This function never fails. * * \param cv A handle to the libcaca canvas. * \param x X coordinate of the upper-left corner of the drawing area. * \param y Y coordinate of the upper-left corner of the drawing area. * \param w Width of the drawing area. * \param h Height of the drawing area. * \param d Dither object to be drawn. * \param pixels Bitmap's pixels. * \return This function always returns 0. */ int caca_dither_bitmap(caca_canvas_t *cv, int x, int y, int w, int h, caca_dither_t const *d, void const *pixels) { int *floyd_steinberg, *fs_r, *fs_g, *fs_b; uint32_t savedattr; int fs_length; int x1, y1, x2, y2, pitch, deltax, deltay, dchmax; if(!d || !pixels) return 0; savedattr = caca_get_attr(cv, -1, -1); x1 = x; x2 = x + w - 1; y1 = y; y2 = y + h - 1; /* FIXME: do not overwrite arguments */ w = d->w; h = d->h; pitch = d->pitch; deltax = x2 - x1 + 1; deltay = y2 - y1 + 1; dchmax = d->glyph_count; fs_length = ((int)cv->width <= x2 ? (int)cv->width : x2) + 1; floyd_steinberg = malloc(3 * (fs_length + 2) * sizeof(int)); memset(floyd_steinberg, 0, 3 * (fs_length + 2) * sizeof(int)); fs_r = floyd_steinberg + 1; fs_g = fs_r + fs_length + 2; fs_b = fs_g + fs_length + 2; for(y = y1 > 0 ? y1 : 0; y <= y2 && y <= (int)cv->height; y++) { int remain_r = 0, remain_g = 0, remain_b = 0; for(x = x1 > 0 ? x1 : 0, d->init_dither(y); x <= x2 && x <= (int)cv->width; x++) { unsigned int rgba[4]; int error[3]; int i, ch = 0, distmin; int fg_r = 0, fg_g = 0, fg_b = 0, bg_r, bg_g, bg_b; int fromx, fromy, tox, toy, myx, myy, dots, dist; int outfg = 0, outbg = 0; uint32_t outch; rgba[0] = rgba[1] = rgba[2] = rgba[3] = 0; /* First get RGB */ if(d->antialias) { fromx = (uint64_t)(x - x1) * w / deltax; fromy = (uint64_t)(y - y1) * h / deltay; tox = (uint64_t)(x - x1 + 1) * w / deltax; toy = (uint64_t)(y - y1 + 1) * h / deltay; /* We want at least one pixel */ if(tox == fromx) tox++; if(toy == fromy) toy++; dots = 0; for(myx = fromx; myx < tox; myx++) for(myy = fromy; myy < toy; myy++) { dots++; get_rgba_default(d, pixels, myx, myy, rgba); } /* Normalize */ rgba[0] /= dots; rgba[1] /= dots; rgba[2] /= dots; rgba[3] /= dots; } else { fromx = (uint64_t)(x - x1) * w / deltax; fromy = (uint64_t)(y - y1) * h / deltay; tox = (uint64_t)(x - x1 + 1) * w / deltax; toy = (uint64_t)(y - y1 + 1) * h / deltay; /* tox and toy can overflow the canvas, but they cannot overflow * when averaged with fromx and fromy because these are guaranteed * to be within the pixel boundaries. */ myx = (fromx + tox) / 2; myy = (fromy + toy) / 2; get_rgba_default(d, pixels, myx, myy, rgba); } /* FIXME: hack to force greyscale */ if(d->color == COLOR_MODE_FULLGRAY) { unsigned int gray = (3 * rgba[0] + 4 * rgba[1] + rgba[2] + 4) / 8; rgba[0] = rgba[1] = rgba[2] = gray; } if(d->has_alpha && rgba[3] < 0x800) { remain_r = remain_g = remain_b = 0; fs_r[x] = 0; fs_g[x] = 0; fs_b[x] = 0; continue; } /* XXX: OMG HAX */ if(d->init_dither == init_fstein_dither) { rgba[0] += remain_r; rgba[1] += remain_g; rgba[2] += remain_b; } else { rgba[0] += (d->get_dither() - 0x80) * 4; rgba[1] += (d->get_dither() - 0x80) * 4; rgba[2] += (d->get_dither() - 0x80) * 4; } distmin = INT_MAX; for(i = 0; i < 16; i++) { if(d->color == COLOR_MODE_FULLGRAY && (rgb_palette[i * 3] != rgb_palette[i * 3 + 1] || rgb_palette[i * 3] != rgb_palette[i * 3 + 2])) continue; dist = sq(rgba[0] - rgb_palette[i * 3]) + sq(rgba[1] - rgb_palette[i * 3 + 1]) + sq(rgba[2] - rgb_palette[i * 3 + 2]); dist *= rgb_weight[i]; if(dist < distmin) { outbg = i; distmin = dist; } } bg_r = rgb_palette[outbg * 3]; bg_g = rgb_palette[outbg * 3 + 1]; bg_b = rgb_palette[outbg * 3 + 2]; /* FIXME: we currently only honour "full16" */ if(d->color == COLOR_MODE_FULL16 || d->color == COLOR_MODE_FULLGRAY) { distmin = INT_MAX; for(i = 0; i < 16; i++) { if(i == outbg) continue; if(d->color == COLOR_MODE_FULLGRAY && (rgb_palette[i * 3] != rgb_palette[i * 3 + 1] || rgb_palette[i * 3] != rgb_palette[i * 3 + 2])) continue; dist = sq(rgba[0] - rgb_palette[i * 3]) + sq(rgba[1] - rgb_palette[i * 3 + 1]) + sq(rgba[2] - rgb_palette[i * 3 + 2]); dist *= rgb_weight[i]; if(dist < distmin) { outfg = i; distmin = dist; } } fg_r = rgb_palette[outfg * 3]; fg_g = rgb_palette[outfg * 3 + 1]; fg_b = rgb_palette[outfg * 3 + 2]; distmin = INT_MAX; for(i = 0; i < dchmax - 1; i++) { int newr = i * fg_r + ((2*dchmax-1) - i) * bg_r; int newg = i * fg_g + ((2*dchmax-1) - i) * bg_g; int newb = i * fg_b + ((2*dchmax-1) - i) * bg_b; dist = abs(rgba[0] * (2*dchmax-1) - newr) + abs(rgba[1] * (2*dchmax-1) - newg) + abs(rgba[2] * (2*dchmax-1) - newb); if(dist < distmin) { ch = i; distmin = dist; } } outch = d->glyphs[ch]; /* XXX: OMG HAX */ if(d->init_dither == init_fstein_dither) { error[0] = rgba[0] - (fg_r * ch + bg_r * ((2*dchmax-1) - ch)) / (2*dchmax-1); error[1] = rgba[1] - (fg_g * ch + bg_g * ((2*dchmax-1) - ch)) / (2*dchmax-1); error[2] = rgba[2] - (fg_b * ch + bg_b * ((2*dchmax-1) - ch)) / (2*dchmax-1); } } else { unsigned int lum = rgba[0]; if(rgba[1] > lum) lum = rgba[1]; if(rgba[2] > lum) lum = rgba[2]; outfg = outbg; outbg = CACA_BLACK; ch = lum * dchmax / 0x1000; if(ch < 0) ch = 0; else if(ch > (int)(dchmax - 1)) ch = dchmax - 1; outch = d->glyphs[ch]; /* XXX: OMG HAX */ if(d->init_dither == init_fstein_dither) { error[0] = rgba[0] - bg_r * ch / (dchmax-1); error[1] = rgba[1] - bg_g * ch / (dchmax-1); error[2] = rgba[2] - bg_b * ch / (dchmax-1); } } /* XXX: OMG HAX */ if(d->init_dither == init_fstein_dither) { remain_r = fs_r[x+1] + 7 * error[0] / 16; remain_g = fs_g[x+1] + 7 * error[1] / 16; remain_b = fs_b[x+1] + 7 * error[2] / 16; fs_r[x-1] += 3 * error[0] / 16; fs_g[x-1] += 3 * error[1] / 16; fs_b[x-1] += 3 * error[2] / 16; fs_r[x] = 5 * error[0] / 16; fs_g[x] = 5 * error[1] / 16; fs_b[x] = 5 * error[2] / 16; fs_r[x+1] = 1 * error[0] / 16; fs_g[x+1] = 1 * error[1] / 16; fs_b[x+1] = 1 * error[2] / 16; } if(d->invert) { outfg = 15 - outfg; outbg = 15 - outbg; } /* Now output the character */ caca_set_color_ansi(cv, outfg, outbg); caca_put_char(cv, x, y, outch); d->increment_dither(); } /* end loop */ } free(floyd_steinberg); caca_set_attr(cv, savedattr); return 0; } /** \brief Free the memory associated with a dither. * * Free the memory allocated by caca_create_dither(). * * This function never fails. * * \param d Dither object. * \return This function always returns 0. */ int caca_free_dither(caca_dither_t *d) { if(!d) return 0; free(d); return 0; } /* * XXX: The following functions are local. */ /* Convert a mask, eg. 0x0000ff00, to shift values, eg. 8 and -4. */ static void mask2shift(uint32_t mask, int *right, int *left) { int rshift = 0, lshift = 0; if(!mask) { *right = *left = 0; return; } while(!(mask & 1)) { mask >>= 1; rshift++; } *right = rshift; while(mask & 1) { mask >>= 1; lshift++; } *left = 12 - lshift; } /* Compute x^y without relying on the math library */ static float gammapow(float x, float y) { #ifdef HAVE_FLDLN2 register double logx; register long double v, e; #else register float tmp, t, t2, r; int i; #endif if(x == 0.0) return y == 0.0 ? 1.0 : 0.0; #ifdef HAVE_FLDLN2 /* FIXME: this can be optimised by directly calling fyl2x for x and y */ asm volatile("fldln2; fxch; fyl2x" : "=t" (logx) : "0" (x) : "st(1)"); asm volatile("fldl2e\n\t" "fmul %%st(1)\n\t" "fst %%st(1)\n\t" "frndint\n\t" "fxch\n\t" "fsub %%st(1)\n\t" "f2xm1\n\t" : "=t" (v), "=u" (e) : "0" (y * logx)); v += 1.0; asm volatile("fscale" : "=t" (v) : "0" (v), "u" (e)); return v; #else /* Compute ln(x) for x ∈ ]0,1] * ln(x) = 2 * (t + t^3/3 + t^5/5 + ...) with t = (x-1)/(x+1) * The convergence is a bit slow, especially when x is near 0. */ t = (x - 1.0) / (x + 1.0); t2 = t * t; tmp = r = t; for(i = 3; i < 20; i += 2) { r *= t2; tmp += r / i; } /* Compute -y*ln(x) */ tmp = - y * 2.0 * tmp; /* Compute x^-y as e^t where t = -y*ln(x): * e^t = 1 + t/1! + t^2/2! + t^3/3! + t^4/4! + t^5/5! ... * The convergence is quite faster here, thanks to the factorial. */ r = t = tmp; tmp = 1.0 + t; for(i = 2; i < 16; i++) { r = r * t / i; tmp += r; } /* Return x^y as 1/(x^-y) */ return 1.0 / tmp; #endif } static void get_rgba_default(caca_dither_t const *d, uint8_t const *pixels, int x, int y, unsigned int *rgba) { uint32_t bits; pixels += (d->bpp / 8) * x + d->pitch * y; switch(d->bpp / 8) { case 4: bits = *(uint32_t const *)pixels; break; case 3: { #if defined(HAVE_ENDIAN_H) if(__BYTE_ORDER == __BIG_ENDIAN) #else /* This is compile-time optimised with at least -O1 or -Os */ uint32_t const tmp = 0x12345678; if(*(uint8_t const *)&tmp == 0x12) #endif bits = ((uint32_t)pixels[0] << 16) | ((uint32_t)pixels[1] << 8) | ((uint32_t)pixels[2]); else bits = ((uint32_t)pixels[2] << 16) | ((uint32_t)pixels[1] << 8) | ((uint32_t)pixels[0]); break; } case 2: bits = *(uint16_t const *)pixels; break; case 1: default: bits = pixels[0]; break; } if(d->has_palette) { rgba[0] += d->gammatab[d->red[bits]]; rgba[1] += d->gammatab[d->green[bits]]; rgba[2] += d->gammatab[d->blue[bits]]; rgba[3] += d->alpha[bits]; } else { rgba[0] += d->gammatab[((bits & d->rmask) >> d->rright) << d->rleft]; rgba[1] += d->gammatab[((bits & d->gmask) >> d->gright) << d->gleft]; rgba[2] += d->gammatab[((bits & d->bmask) >> d->bright) << d->bleft]; rgba[3] += ((bits & d->amask) >> d->aright) << d->aleft; } } /* * No dithering */ static void init_no_dither(int line) { ; } static int get_no_dither(void) { return 0x80; } static void increment_no_dither(void) { return; } /* * Floyd-Steinberg dithering */ static void init_fstein_dither(int line) { ; } static int get_fstein_dither(void) { return 0x80; } static void increment_fstein_dither(void) { return; } /* * Ordered 2 dithering */ static int const *ordered2_table; static int ordered2_index; static void init_ordered2_dither(int line) { static int const dither2x2[] = { 0x00, 0x80, 0xc0, 0x40, }; ordered2_table = dither2x2 + (line % 2) * 2; ordered2_index = 0; } static int get_ordered2_dither(void) { return ordered2_table[ordered2_index]; } static void increment_ordered2_dither(void) { ordered2_index = (ordered2_index + 1) % 2; } /* * Ordered 4 dithering */ /*static int dither4x4[] = { 5, 0, 1, 6, -1, -6, -5, 2, -2, -7, -8, 3, 4, -3, -4, -7};*/ static int const *ordered4_table; static int ordered4_index; static void init_ordered4_dither(int line) { static int const dither4x4[] = { 0x00, 0x80, 0x20, 0xa0, 0xc0, 0x40, 0xe0, 0x60, 0x30, 0xb0, 0x10, 0x90, 0xf0, 0x70, 0xd0, 0x50 }; ordered4_table = dither4x4 + (line % 4) * 4; ordered4_index = 0; } static int get_ordered4_dither(void) { return ordered4_table[ordered4_index]; } static void increment_ordered4_dither(void) { ordered4_index = (ordered4_index + 1) % 4; } /* * Ordered 8 dithering */ static int const *ordered8_table; static int ordered8_index; static void init_ordered8_dither(int line) { static int const dither8x8[] = { 0x00, 0x80, 0x20, 0xa0, 0x08, 0x88, 0x28, 0xa8, 0xc0, 0x40, 0xe0, 0x60, 0xc8, 0x48, 0xe8, 0x68, 0x30, 0xb0, 0x10, 0x90, 0x38, 0xb8, 0x18, 0x98, 0xf0, 0x70, 0xd0, 0x50, 0xf8, 0x78, 0xd8, 0x58, 0x0c, 0x8c, 0x2c, 0xac, 0x04, 0x84, 0x24, 0xa4, 0xcc, 0x4c, 0xec, 0x6c, 0xc4, 0x44, 0xe4, 0x64, 0x3c, 0xbc, 0x1c, 0x9c, 0x34, 0xb4, 0x14, 0x94, 0xfc, 0x7c, 0xdc, 0x5c, 0xf4, 0x74, 0xd4, 0x54, }; ordered8_table = dither8x8 + (line % 8) * 8; ordered8_index = 0; } static int get_ordered8_dither(void) { return ordered8_table[ordered8_index]; } static void increment_ordered8_dither(void) { ordered8_index = (ordered8_index + 1) % 8; } /* * Random dithering */ static void init_random_dither(int line) { ; } static int get_random_dither(void) { return caca_rand(0x00, 0x100); } static void increment_random_dither(void) { return; } /* * Lookup tables */ static int init_lookup(void) { int v, s, h; /* These ones are constant */ lookup_colors[0] = CACA_BLACK; lookup_colors[1] = CACA_DARKGRAY; lookup_colors[2] = CACA_LIGHTGRAY; lookup_colors[3] = CACA_WHITE; /* These ones will be overwritten */ lookup_colors[4] = CACA_MAGENTA; lookup_colors[5] = CACA_LIGHTMAGENTA; lookup_colors[6] = CACA_RED; lookup_colors[7] = CACA_LIGHTRED; for(v = 0; v < LOOKUP_VAL; v++) for(s = 0; s < LOOKUP_SAT; s++) for(h = 0; h < LOOKUP_HUE; h++) { int i, distbg, distfg, dist; int val, sat, hue; uint8_t outbg, outfg; val = 0xfff * v / (LOOKUP_VAL - 1); sat = 0xfff * s / (LOOKUP_SAT - 1); hue = 0xfff * h / (LOOKUP_HUE - 1); /* Initialise distances to the distance between pure black HSV * coordinates and our white colour (3) */ outbg = outfg = 3; distbg = distfg = HSV_DISTANCE(0, 0, 0, 3); /* Calculate distances to eight major colour values and store the * two nearest points in our lookup table. */ for(i = 0; i < 8; i++) { dist = HSV_DISTANCE(hue, sat, val, i); if(dist <= distbg) { outfg = outbg; distfg = distbg; outbg = i; distbg = dist; } else if(dist <= distfg) { outfg = i; distfg = dist; } } hsv_distances[v][s][h] = (outfg << 4) | outbg; } return 0; }