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Diffstat (limited to 'converter/other/pngtopam.c')
| -rw-r--r-- | converter/other/pngtopam.c | 1281 |
1 files changed, 1281 insertions, 0 deletions
diff --git a/converter/other/pngtopam.c b/converter/other/pngtopam.c new file mode 100644 index 00000000..89ac100a --- /dev/null +++ b/converter/other/pngtopam.c @@ -0,0 +1,1281 @@ +/* +** Copyright (C) 1995,1998 by Alexander Lehmann <alex@hal.rhein-main.de> +** and Willem van Schaik <willem@schaik.com> +** +** Permission to use, copy, modify, and distribute this software and its +** documentation for any purpose and without fee is hereby granted, provided +** that the above copyright notice appear in all copies and that both that +** copyright notice and this permission notice appear in supporting +** documentation. This software is provided "as is" without express or +** implied warranty. +** +** modeled after giftopnm by David Koblas and +** with lots of bits pasted from libpng.txt by Guy Eric Schalnat +*/ + +#ifndef PNMTOPNG_WARNING_LEVEL +# define PNMTOPNG_WARNING_LEVEL 0 /* use 0 for backward compatibility, */ +#endif /* 2 for warnings (1 == error) */ + + +#include <assert.h> +#include <math.h> +#include <float.h> +#include <png.h> /* includes zlib.h and setjmp.h */ +#define VERSION "2.37.4 (5 December 1999) +netpbm" + +#include "pm_c_util.h" +#include "mallocvar.h" +#include "nstring.h" +#include "shhopt.h" +#include "pam.h" + +/* A hack until we can remove direct access to png_info from the program */ +#if PNG_LIBPNG_VER >= 10400 +#define trans_values trans_color +#define TRANS_ALPHA trans_alpha +#else +#define TRANS_ALPHA trans +#endif + +typedef struct _jmpbuf_wrapper { + jmp_buf jmpbuf; +} jmpbuf_wrapper; + +enum alpha_handling {ALPHA_NONE, ALPHA_ONLY, ALPHA_MIX, ALPHA_IN}; + +struct cmdlineInfo { + /* All the information the user supplied in the command line, + in a form easy for the program to use. + */ + const char *inputFilespec; /* '-' if stdin */ + unsigned int verbose; + enum alpha_handling alpha; + const char * background; + float gamma; /* -1.0 means unspecified */ + const char * text; + unsigned int time; +}; + + +typedef struct { +/*---------------------------------------------------------------------------- + A color in a format compatible with the PNG library. + + Note that the PNG library declares types png_color and png_color_16 + which are similar. +-----------------------------------------------------------------------------*/ + png_uint_16 r; + png_uint_16 g; + png_uint_16 b; +} pngcolor; + + +static png_uint_16 maxval; +static bool verbose; +static jmpbuf_wrapper pngtopnm_jmpbuf_struct; + + +static void +parseCommandLine(int argc, + const char ** argv, + struct cmdlineInfo * cmdlineP ) { +/*---------------------------------------------------------------------------- + Parse program command line described in Unix standard form by argc + and argv. Return the information in the options as *cmdlineP. + + If command line is internally inconsistent (invalid options, etc.), + issue error message to stderr and abort program. + + Note that the strings we return are stored in the storage that + was passed to us as the argv array. We also trash *argv. +-----------------------------------------------------------------------------*/ + optEntry * option_def; + /* Instructions to optParseOptions3 on how to parse our options. + */ + optStruct3 opt; + + unsigned int option_def_index; + + unsigned int alphaSpec, alphapamSpec, mixSpec, + backgroundSpec, gammaSpec, textSpec; + + MALLOCARRAY(option_def, 100); + + option_def_index = 0; /* incremented by OPTENT3 */ + OPTENT3(0, "verbose", OPT_FLAG, NULL, + &cmdlineP->verbose, 0); + OPTENT3(0, "alpha", OPT_FLAG, NULL, + &alphaSpec, 0); + OPTENT3(0, "alphapam", OPT_FLAG, NULL, + &alphapamSpec, 0); + OPTENT3(0, "mix", OPT_FLAG, NULL, + &mixSpec, 0); + OPTENT3(0, "background", OPT_STRING, &cmdlineP->background, + &backgroundSpec, 0); + OPTENT3(0, "gamma", OPT_FLOAT, &cmdlineP->gamma, + &gammaSpec, 0); + OPTENT3(0, "text", OPT_STRING, &cmdlineP->text, + &textSpec, 0); + OPTENT3(0, "time", OPT_FLAG, NULL, + &cmdlineP->time, 0); + + opt.opt_table = option_def; + opt.short_allowed = FALSE; /* We have no short (old-fashioned) options */ + opt.allowNegNum = FALSE; /* We have no parms that are negative numbers */ + + optParseOptions3(&argc, (char **)argv, opt, sizeof(opt), 0); + /* Uses and sets argc, argv, and some of *cmdlineP and others. */ + + + if (alphaSpec + mixSpec + alphapamSpec > 1) + pm_error("You cannot specify more than one of -alpha -alphapam -mix"); + else if (alphaSpec) + cmdlineP->alpha = ALPHA_ONLY; + else if (mixSpec) + cmdlineP->alpha = ALPHA_MIX; + else if (alphapamSpec) + cmdlineP->alpha = ALPHA_IN; + else + cmdlineP->alpha = ALPHA_NONE; + + if (backgroundSpec && !mixSpec) + pm_error("-background is useless without -mix"); + + if (!backgroundSpec) + cmdlineP->background = NULL; + + if (!gammaSpec) + cmdlineP->gamma = -1.0; + + if (!textSpec) + cmdlineP->text = NULL; + + if (argc-1 < 1) + cmdlineP->inputFilespec = "-"; + else if (argc-1 == 1) + cmdlineP->inputFilespec = argv[1]; + else + pm_error("Program takes at most one argument: input file name. " + "you specified %d", argc-1); +} + + + +static png_uint_16 +get_png_val(const png_byte ** const pp, + int const bit_depth) { + + png_uint_16 c; + + if (bit_depth == 16) + c = (*((*pp)++)) << 8; + else + c = 0; + + c |= (*((*pp)++)); + + return c; +} + + + +static bool +isGrayscale(pngcolor const color) { + + return color.r == color.g && color.r == color.b; +} + + + +static sample +alphaMix(png_uint_16 const foreground, + png_uint_16 const background, + png_uint_16 const alpha, + sample const maxval) { + + double const opacity = (double)alpha / maxval; + double const transparency = 1.0 - opacity; + + return ROUNDU(foreground * opacity + background * transparency); +} + + + +static void +setTuple(const struct pam * const pamP, + tuple const tuple, + pngcolor const foreground, + pngcolor const background, + enum alpha_handling const alphaHandling, + png_uint_16 const alpha) { + + if (alphaHandling == ALPHA_ONLY) + tuple[0] = alpha; + else if (alphaHandling == ALPHA_NONE || + (alphaHandling == ALPHA_MIX && alpha == maxval)) { + if (pamP->depth < 3) + tuple[0] = foreground.r; + else { + tuple[PAM_RED_PLANE] = foreground.r; + tuple[PAM_GRN_PLANE] = foreground.g; + tuple[PAM_BLU_PLANE] = foreground.b; + } + } else if (alphaHandling == ALPHA_IN) { + if (pamP->depth < 4) { + tuple[0] = foreground.r; + tuple[PAM_GRAY_TRN_PLANE] = alpha; + } else { + tuple[PAM_RED_PLANE] = foreground.r; + tuple[PAM_GRN_PLANE] = foreground.g; + tuple[PAM_BLU_PLANE] = foreground.b; + tuple[PAM_TRN_PLANE] = alpha; + } + } else { + assert(alphaHandling == ALPHA_MIX); + + if (pamP->depth < 3) + tuple[0] = + alphaMix(foreground.r, background.r, alpha, maxval); + else { + tuple[PAM_RED_PLANE] = + alphaMix(foreground.r, background.r, alpha, maxval); + tuple[PAM_GRN_PLANE] = + alphaMix(foreground.g, background.g, alpha, maxval); + tuple[PAM_BLU_PLANE] = + alphaMix(foreground.b, background.b, alpha, maxval); + } + } +} + + + +static png_uint_16 +gamma_correct(png_uint_16 const v, + float const g) { + + if (g != -1.0) + return (png_uint_16) ROUNDU(pow((double) v / maxval, (1.0 / g)) * + maxval); + else + return v; +} + + + +static int iscolor (png_color c) +{ + return c.red != c.green || c.green != c.blue; +} + +static void save_text (png_info *info_ptr, FILE *tfp) +{ + int i, j, k; + + for (i = 0 ; i < info_ptr->num_text ; i++) { + j = 0; + while (info_ptr->text[i].key[j] != '\0' && info_ptr->text[i].key[j] != ' ') + j++; + if (info_ptr->text[i].key[j] != ' ') { + fprintf (tfp, "%s", info_ptr->text[i].key); + for (j = strlen (info_ptr->text[i].key) ; j < 15 ; j++) + putc (' ', tfp); + } else { + fprintf (tfp, "\"%s\"", info_ptr->text[i].key); + for (j = strlen (info_ptr->text[i].key) ; j < 13 ; j++) + putc (' ', tfp); + } + putc (' ', tfp); /* at least one space between key and text */ + + for (j = 0 ; j < info_ptr->text[i].text_length ; j++) { + putc (info_ptr->text[i].text[j], tfp); + if (info_ptr->text[i].text[j] == '\n') + for (k = 0 ; k < 16 ; k++) + putc ((int)' ', tfp); + } + putc ((int)'\n', tfp); + } +} + +static void show_time (png_info *info_ptr) +{ + static const char * const month[] = { + "", "January", "February", "March", "April", "May", "June", + "July", "August", "September", "October", "November", "December" + }; + + if (info_ptr->valid & PNG_INFO_tIME) { + if (info_ptr->mod_time.month < 1 || + info_ptr->mod_time.month >= ARRAY_SIZE(month)) { + pm_message("tIME chunk in PNG input is invalid; " + "modification time of image is unknown. " + "The month value, which should be in the range " + "1-12, is %u", info_ptr->mod_time.month); + } else + pm_message ("modification time: %02d %s %d %02d:%02d:%02d", + info_ptr->mod_time.day, month[info_ptr->mod_time.month], + info_ptr->mod_time.year, info_ptr->mod_time.hour, + info_ptr->mod_time.minute, info_ptr->mod_time.second); + } +} + +static void pngtopnm_error_handler (png_structp png_ptr, png_const_charp msg) +{ + jmpbuf_wrapper *jmpbuf_ptr; + + /* this function, aside from the extra step of retrieving the "error + * pointer" (below) and the fact that it exists within the application + * rather than within libpng, is essentially identical to libpng's + * default error handler. The second point is critical: since both + * setjmp() and longjmp() are called from the same code, they are + * guaranteed to have compatible notions of how big a jmp_buf is, + * regardless of whether _BSD_SOURCE or anything else has (or has not) + * been defined. */ + + pm_message("fatal libpng error: %s", msg); + + jmpbuf_ptr = png_get_error_ptr(png_ptr); + if (jmpbuf_ptr == NULL) { + /* we are completely hosed now */ + pm_error("EXTREMELY fatal error: jmpbuf unrecoverable; terminating."); + } + + longjmp(jmpbuf_ptr->jmpbuf, 1); +} + + + +static void +dump_png_info(png_info *info_ptr) { + + const char *type_string; + const char *filter_string; + + switch (info_ptr->color_type) { + case PNG_COLOR_TYPE_GRAY: + type_string = "gray"; + break; + + case PNG_COLOR_TYPE_GRAY_ALPHA: + type_string = "gray+alpha"; + break; + + case PNG_COLOR_TYPE_PALETTE: + type_string = "palette"; + break; + + case PNG_COLOR_TYPE_RGB: + type_string = "truecolor"; + break; + + case PNG_COLOR_TYPE_RGB_ALPHA: + type_string = "truecolor+alpha"; + break; + } + + switch (info_ptr->filter_type) { + case PNG_FILTER_TYPE_BASE: + asprintfN(&filter_string, "base filter"); + break; + default: + asprintfN(&filter_string, "unknown filter type %d", + info_ptr->filter_type); + } + + pm_message("reading a %ldw x %ldh image, %d bit%s", + info_ptr->width, info_ptr->height, + info_ptr->bit_depth, info_ptr->bit_depth > 1 ? "s" : ""); + pm_message("%s, %s, %s", + type_string, + info_ptr->interlace_type ? + "Adam7 interlaced" : "not interlaced", + filter_string); + pm_message("background {index, gray, red, green, blue} = " + "{%d, %d, %d, %d, %d}", + info_ptr->background.index, + info_ptr->background.gray, + info_ptr->background.red, + info_ptr->background.green, + info_ptr->background.blue); + + strfree(filter_string); + + if (info_ptr->valid & PNG_INFO_tRNS) + pm_message("tRNS chunk (transparency): %u entries", + info_ptr->num_trans); + else + pm_message("tRNS chunk (transparency): not present"); + + if (info_ptr->valid & PNG_INFO_gAMA) + pm_message("gAMA chunk (image gamma): gamma = %4.2f", info_ptr->gamma); + else + pm_message("gAMA chunk (image gamma): not present"); + + if (info_ptr->valid & PNG_INFO_sBIT) + pm_message("sBIT chunk: present"); + else + pm_message("sBIT chunk: not present"); + + if (info_ptr->valid & PNG_INFO_cHRM) + pm_message("cHRM chunk: present"); + else + pm_message("cHRM chunk: not present"); + + if (info_ptr->valid & PNG_INFO_PLTE) + pm_message("PLTE chunk: %d entries", info_ptr->num_palette); + else + pm_message("PLTE chunk: not present"); + + if (info_ptr->valid & PNG_INFO_bKGD) + pm_message("bKGD chunk: present"); + else + pm_message("bKGD chunk: not present"); + + if (info_ptr->valid & PNG_INFO_hIST) + pm_message("hIST chunk: present"); + else + pm_message("hIST chunk: not present"); + + if (info_ptr->valid & PNG_INFO_pHYs) + pm_message("pHYs chunk: present"); + else + pm_message("pHYs chunk: not present"); + + if (info_ptr->valid & PNG_INFO_oFFs) + pm_message("oFFs chunk: present"); + else + pm_message("oFFs chunk: not present"); + + if (info_ptr->valid & PNG_INFO_tIME) + pm_message("tIME chunk: present"); + else + pm_message("tIME chunk: not present"); + + if (info_ptr->valid & PNG_INFO_pCAL) + pm_message("pCAL chunk: present"); + else + pm_message("pCAL chunk: not present"); + + if (info_ptr->valid & PNG_INFO_sRGB) + pm_message("sRGB chunk: present"); + else + pm_message("sRGB chunk: not present"); +} + + + +static unsigned int +computePngLineSize(png_info * const pngInfoP) { + + unsigned int const bytesPerSample = pngInfoP->bit_depth == 16 ? 2 : 1; + + unsigned int samplesPerPixel; + + switch (pngInfoP->color_type) { + case PNG_COLOR_TYPE_GRAY_ALPHA: samplesPerPixel = 2; break; + case PNG_COLOR_TYPE_RGB: samplesPerPixel = 3; break; + case PNG_COLOR_TYPE_RGB_ALPHA: samplesPerPixel = 4; break; + default: samplesPerPixel = 1; + } + + if (UINT_MAX / bytesPerSample / samplesPerPixel < pngInfoP->width) + pm_error("Width %u of PNG is uncomputably large", + (unsigned int)pngInfoP->width); + + return pngInfoP->width * bytesPerSample * samplesPerPixel; +} + + + +static void +allocPngRaster(png_info * const pngInfoP, + png_byte *** const pngImageP) { + + unsigned int const lineSize = computePngLineSize(pngInfoP); + + png_byte ** pngImage; + unsigned int row; + + MALLOCARRAY(pngImage, pngInfoP->height); + + if (pngImage == NULL) + pm_error("couldn't allocate space for %u PNG raster rows", + (unsigned int)pngInfoP->height); + + for (row = 0; row < pngInfoP->height; ++row) { + MALLOCARRAY(pngImage[row], lineSize); + if (pngImage[row] == NULL) + pm_error("couldn't allocate space for %uth row of PNG raster", + row); + } + *pngImageP = pngImage; +} + + + +static void +freePngRaster(png_byte ** const pngRaster, + png_info * const pngInfoP) { + + unsigned int row; + + for (row = 0; row < pngInfoP->height; ++row) + free(pngRaster[row]); + + free(pngRaster); +} + + + +static bool +isTransparentColor(pngcolor const color, + png_info * const pngInfoP, + double const totalgamma) { +/*---------------------------------------------------------------------------- + Return TRUE iff pixels of color 'color' are supposed to be transparent + everywhere they occur. Assume it's an RGB image. + + 'color' has been gamma-corrected. +-----------------------------------------------------------------------------*/ + bool retval; + + if (pngInfoP->valid & PNG_INFO_tRNS) { + const png_color_16 * const transColorP = &pngInfoP->trans_values; + + /* It seems odd that libpng lets you get gamma-corrected pixel + values, but not gamma-corrected transparency or background + values. But as that is the case, we have to gamma-correct + the transparency values. + + Note that because we compare the gamma-corrected values and + there may be many-to-one mapping of uncorrected to corrected + values, more pixels may be transparent than what the user + intended. + + We could fix this by not letting libpng gamma-correct the + pixels, and just do it ourselves. + */ + + switch (pngInfoP->color_type) { + case PNG_COLOR_TYPE_GRAY: + retval = color.r == gamma_correct(transColorP->gray, totalgamma); + break; + default: + retval = + color.r == gamma_correct(transColorP->red, totalgamma) && + color.g == gamma_correct(transColorP->green, totalgamma) && + color.b == gamma_correct(transColorP->blue, totalgamma); + } + } else + retval = FALSE; + + return retval; +} + + + +#define SIG_CHECK_SIZE 4 + +static void +read_sig_buf(FILE * const ifP) { + + unsigned char sig_buf[SIG_CHECK_SIZE]; + size_t bytesRead; + + bytesRead = fread(sig_buf, 1, SIG_CHECK_SIZE, ifP); + if (bytesRead != SIG_CHECK_SIZE) + pm_error ("input file is empty or too short"); + + if (png_sig_cmp(sig_buf, (png_size_t) 0, (png_size_t) SIG_CHECK_SIZE) + != 0) + pm_error ("input file is not a PNG file"); +} + + + +static void +setupGammaCorrection(png_struct * const png_ptr, + png_info * const info_ptr, + float const displaygamma, + float * const totalgammaP) { + + if (displaygamma == -1.0) + *totalgammaP = -1.0; + else { + float imageGamma; + if (info_ptr->valid & PNG_INFO_gAMA) + imageGamma = info_ptr->gamma; + else { + if (verbose) + pm_message("PNG doesn't specify image gamma. Assuming 1.0"); + imageGamma = 1.0; + } + + if (fabs(displaygamma * imageGamma - 1.0) < .01) { + *totalgammaP = -1.0; + if (verbose) + pm_message("image gamma %4.2f matches " + "display gamma %4.2f. No conversion.", + imageGamma, displaygamma); + } else { + png_set_gamma(png_ptr, displaygamma, imageGamma); + *totalgammaP = imageGamma * displaygamma; + /* in case of gamma-corrections, sBIT's as in the + PNG-file are not valid anymore + */ + info_ptr->valid &= ~PNG_INFO_sBIT; + if (verbose) + pm_message("image gamma is %4.2f, " + "converted for display gamma of %4.2f", + imageGamma, displaygamma); + } + } +} + + + +static bool +paletteHasPartialTransparency(png_info * const info_ptr) { + + bool retval; + + if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { + if (info_ptr->valid & PNG_INFO_tRNS) { + bool foundGray; + unsigned int i; + + for (i = 0, foundGray = FALSE; + i < info_ptr->num_trans && !foundGray; + ++i) { + if (info_ptr->TRANS_ALPHA[i] != 0 && + info_ptr->TRANS_ALPHA[i] != maxval) { + foundGray = TRUE; + } + } + retval = foundGray; + } else + retval = FALSE; + } else + retval = FALSE; + + return retval; +} + + + +static void +getComponentSbitFg(png_info * const pngInfoP, + png_byte * const fgSbitP, + bool * const notUniformP) { + + if (pngInfoP->color_type == PNG_COLOR_TYPE_RGB || + pngInfoP->color_type == PNG_COLOR_TYPE_RGB_ALPHA || + pngInfoP->color_type == PNG_COLOR_TYPE_PALETTE) { + if (pngInfoP->sig_bit.red == pngInfoP->sig_bit.blue && + pngInfoP->sig_bit.red == pngInfoP->sig_bit.green) { + *notUniformP = false; + *fgSbitP = pngInfoP->sig_bit.red; + } else + *notUniformP = true; + } else { + /* It has only a gray channel so it's obviously uniform */ + *notUniformP = false; + *fgSbitP = pngInfoP->sig_bit.gray; + } +} + + + +static void +getComponentSbit(png_info * const pngInfoP, + enum alpha_handling const alphaHandling, + png_byte * const componentSbitP, + bool * const notUniformP) { + + switch (alphaHandling) { + + case ALPHA_ONLY: + /* We care only about the alpha channel, so the uniform Sbit is + the alpha Sbit + */ + *notUniformP = false; + *componentSbitP = pngInfoP->sig_bit.alpha; + break; + case ALPHA_NONE: + case ALPHA_MIX: + /* We aren't going to produce an alpha channel, so we care only + about the uniformity of the foreground channels. + */ + getComponentSbitFg(pngInfoP, componentSbitP, notUniformP); + break; + case ALPHA_IN: { + /* We care about both the foreground and the alpha */ + bool fgNotUniform; + png_byte fgSbit; + + getComponentSbitFg(pngInfoP, &fgSbit, &fgNotUniform); + + if (fgNotUniform) + *notUniformP = true; + else { + if (fgSbit == pngInfoP->sig_bit.alpha) { + *notUniformP = false; + *componentSbitP = fgSbit; + } else + *notUniformP = true; + } + } break; + } +} + + + +static void +shiftPalette(png_info * const pngInfoP, + unsigned int const shift) { +/*---------------------------------------------------------------------------- + Shift every component of every color in the PNG palette right by + 'shift' bits because sBIT chunk says only those are significant. +-----------------------------------------------------------------------------*/ + if (shift > 7) + pm_error("Invalid PNG: paletted image can't have " + "more than 8 significant bits per component, " + "but sBIT chunk says %u bits", + shift); + else { + unsigned int i; + + for (i = 0; i < pngInfoP->num_palette; ++i) { + pngInfoP->palette[i].red >>= (8 - shift); + pngInfoP->palette[i].green >>= (8 - shift); + pngInfoP->palette[i].blue >>= (8 - shift); + } + } +} + + + +static void +computeMaxvalFromSbit(png_struct * const pngP, + png_info * const pngInfoP, + enum alpha_handling const alphaHandling, + png_uint_16 * const maxvalP, + bool * const succeededP, + int * const errorlevelP) { + + /* sBIT handling is very tricky. If we are extracting only the + image, we can use the sBIT info for grayscale and color images, + if the three values agree. If we extract the transparency/alpha + mask, sBIT is irrelevant for trans and valid for alpha. If we + mix both, the multiplication may result in values that require + the normal bit depth, so we will use the sBIT info only for + transparency, if we know that only solid and fully transparent + is used + */ + + bool notUniform; + /* The sBIT chunk says the number of significant high-order bits + in each component varies among the components we care about. + */ + png_byte componentSigBit; + /* The number of high-order significant bits in each RGB component. + Meaningless if they aren't all the same (i.e. 'notUniform') + */ + + getComponentSbit(pngInfoP, alphaHandling, &componentSigBit, ¬Uniform); + + if (notUniform) { + pm_message("This program cannot handle " + "different bit depths for color channels"); + pm_message("writing file with %u bit resolution", pngInfoP->bit_depth); + *succeededP = false; + *errorlevelP = PNMTOPNG_WARNING_LEVEL; + } else if (componentSigBit > 15) { + pm_message("Invalid PNG: says %u significant bits for a component; " + "max possible is 16. Ignoring sBIT chunk.", + componentSigBit); + *succeededP = false; + *errorlevelP = PNMTOPNG_WARNING_LEVEL; + } else { + if (alphaHandling == ALPHA_MIX && + (pngInfoP->color_type == PNG_COLOR_TYPE_RGB_ALPHA || + pngInfoP->color_type == PNG_COLOR_TYPE_GRAY_ALPHA || + paletteHasPartialTransparency(pngInfoP))) + *succeededP = false; + else { + if (componentSigBit < pngInfoP->bit_depth) { + pm_message("Image has fewer significant bits, " + "writing file with %u bits", componentSigBit); + *maxvalP = (1l << componentSigBit) - 1; + *succeededP = true; + + if (pngInfoP->color_type == PNG_COLOR_TYPE_PALETTE) + shiftPalette(pngInfoP, componentSigBit); + else + png_set_shift(pngP, &pngInfoP->sig_bit); + } else + *succeededP = false; + } + } +} + + + +static void +setupSignificantBits(png_struct * const pngP, + png_info * const pngInfoP, + enum alpha_handling const alphaHandling, + png_uint_16 * const maxvalP, + int * const errorlevelP) { +/*---------------------------------------------------------------------------- + Figure out what maxval would best express the information in the PNG + described by *pngP and *pngInfoP, with 'alpha' telling which + information in the PNG we care about (image or alpha mask). + + Return the result as *maxvalP. + + Also set up *pngP for the corresponding significant bits. +-----------------------------------------------------------------------------*/ + bool gotItFromSbit; + + if (pngInfoP->valid & PNG_INFO_sBIT) + computeMaxvalFromSbit(pngP, pngInfoP, alphaHandling, + maxvalP, &gotItFromSbit, errorlevelP); + else + gotItFromSbit = false; + + if (!gotItFromSbit) { + if (pngInfoP->color_type == PNG_COLOR_TYPE_PALETTE) { + if (alphaHandling == ALPHA_ONLY) { + if (pngInfoP->color_type == PNG_COLOR_TYPE_GRAY || + pngInfoP->color_type == PNG_COLOR_TYPE_RGB) + /* The alpha mask will be all opaque, so maxval 1 + is plenty + */ + *maxvalP = 1; + else if (paletteHasPartialTransparency(pngInfoP)) + /* Use same maxval as PNG transparency palette for + simplicity + */ + *maxvalP = 255; + else + /* A common case, so we conserve bits */ + *maxvalP = 1; + } else + /* Use same maxval as PNG palette for simplicity */ + *maxvalP = 255; + } else { + *maxvalP = (1l << pngInfoP->bit_depth) - 1; + } + } +} + + + +static bool +imageHasColor(png_info * const info_ptr) { + + bool retval; + + if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY || + info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) + + retval = FALSE; + else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { + bool foundColor; + unsigned int i; + + for (i = 0, foundColor = FALSE; + i < info_ptr->num_palette && !foundColor; + ++i) { + if (iscolor(info_ptr->palette[i])) + foundColor = TRUE; + } + retval = foundColor; + } else + retval = TRUE; + + return retval; +} + + + +static void +determineOutputType(png_info * const pngInfoP, + enum alpha_handling const alphaHandling, + pngcolor const bgColor, + xelval const maxval, + int * const formatP, + unsigned int * const depthP, + char * const tupleType) { + + if (alphaHandling == ALPHA_ONLY) { + /* The output is a old style pseudo-PNM transparency image */ + *depthP = 1; + *formatP = maxval > 1 ? PGM_FORMAT : PBM_FORMAT; + } else { + /* The output is a normal Netpbm image */ + bool const outputIsColor = + imageHasColor(pngInfoP) || !isGrayscale(bgColor); + + if (alphaHandling == ALPHA_IN) { + *formatP = PAM_FORMAT; + if (outputIsColor) { + *depthP = 4; + strcpy(tupleType, "RGB_ALPHA"); + } else { + *depthP = 2; + strcpy(tupleType, "GRAYSCALE_ALPHA"); + } + } else { + if (outputIsColor) { + *formatP = PPM_FORMAT; + *depthP = 3; + } else { + *depthP = 1; + *formatP = maxval > 1 ? PGM_FORMAT : PBM_FORMAT; + } + } + } +} + + + +static void +getBackgroundColor(png_info * const info_ptr, + const char * const requestedColor, + float const totalgamma, + xelval const maxval, + pngcolor * const bgColorP) { +/*---------------------------------------------------------------------------- + Figure out what the background color should be. If the user requested + a particular color ('requestedColor' not null), that's the one. + Otherwise, if the PNG specifies a background color, that's the one. + And otherwise, it's white. +-----------------------------------------------------------------------------*/ + if (requestedColor) { + /* Background was specified from the command-line; we always + use that. I chose to do no gamma-correction in this case; + which is a bit arbitrary. + */ + pixel const backcolor = ppm_parsecolor(requestedColor, maxval); + + bgColorP->r = PPM_GETR(backcolor); + bgColorP->g = PPM_GETG(backcolor); + bgColorP->b = PPM_GETB(backcolor); + + } else if (info_ptr->valid & PNG_INFO_bKGD) { + /* didn't manage to get libpng to work (bugs?) concerning background + processing, therefore we do our own. + */ + switch (info_ptr->color_type) { + case PNG_COLOR_TYPE_GRAY: + case PNG_COLOR_TYPE_GRAY_ALPHA: + bgColorP->r = bgColorP->g = bgColorP->b = + gamma_correct(info_ptr->background.gray, totalgamma); + break; + case PNG_COLOR_TYPE_PALETTE: { + png_color const rawBgcolor = + info_ptr->palette[info_ptr->background.index]; + bgColorP->r = gamma_correct(rawBgcolor.red, totalgamma); + bgColorP->g = gamma_correct(rawBgcolor.green, totalgamma); + bgColorP->b = gamma_correct(rawBgcolor.blue, totalgamma); + } + break; + case PNG_COLOR_TYPE_RGB: + case PNG_COLOR_TYPE_RGB_ALPHA: { + png_color_16 const rawBgcolor = info_ptr->background; + + bgColorP->r = gamma_correct(rawBgcolor.red, totalgamma); + bgColorP->g = gamma_correct(rawBgcolor.green, totalgamma); + bgColorP->b = gamma_correct(rawBgcolor.blue, totalgamma); + } + break; + } + } else + /* when no background given, we use white [from version 2.37] */ + bgColorP->r = bgColorP->g = bgColorP->b = maxval; +} + + + +#define GET_PNG_VAL(p) get_png_val(&(p), pngInfoP->bit_depth) + + + +static void +makeTupleRow(const struct pam * const pamP, + const tuple * const tuplerow, + png_info * const pngInfoP, + const png_byte * const pngRasterRow, + pngcolor const bgColor, + enum alpha_handling const alphaHandling, + double const totalgamma) { + + const png_byte * pngPixelP; + unsigned int col; + + pngPixelP = &pngRasterRow[0]; /* initial value */ + for (col = 0; col < pngInfoP->width; ++col) { + switch (pngInfoP->color_type) { + case PNG_COLOR_TYPE_GRAY: { + pngcolor fgColor; + fgColor.r = fgColor.g = fgColor.b = GET_PNG_VAL(pngPixelP); + setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, + isTransparentColor(fgColor, pngInfoP, totalgamma) ? + 0 : maxval); + } + break; + + case PNG_COLOR_TYPE_GRAY_ALPHA: { + pngcolor fgColor; + png_uint_16 alpha; + + fgColor.r = fgColor.g = fgColor.b = GET_PNG_VAL(pngPixelP); + alpha = GET_PNG_VAL(pngPixelP); + setTuple(pamP, tuplerow[col], fgColor, bgColor, + alphaHandling, alpha); + } + break; + + case PNG_COLOR_TYPE_PALETTE: { + png_uint_16 const index = GET_PNG_VAL(pngPixelP); + png_color const paletteColor = pngInfoP->palette[index]; + + pngcolor fgColor; + + fgColor.r = paletteColor.red; + fgColor.g = paletteColor.green; + fgColor.b = paletteColor.blue; + + setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, + (pngInfoP->valid & PNG_INFO_tRNS) && + index < pngInfoP->num_trans ? + pngInfoP->TRANS_ALPHA[index] : maxval); + } + break; + + case PNG_COLOR_TYPE_RGB: { + pngcolor fgColor; + + fgColor.r = GET_PNG_VAL(pngPixelP); + fgColor.g = GET_PNG_VAL(pngPixelP); + fgColor.b = GET_PNG_VAL(pngPixelP); + setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, + isTransparentColor(fgColor, pngInfoP, totalgamma) ? + 0 : maxval); + } + break; + + case PNG_COLOR_TYPE_RGB_ALPHA: { + pngcolor fgColor; + png_uint_16 alpha; + + fgColor.r = GET_PNG_VAL(pngPixelP); + fgColor.g = GET_PNG_VAL(pngPixelP); + fgColor.b = GET_PNG_VAL(pngPixelP); + alpha = GET_PNG_VAL(pngPixelP); + setTuple(pamP, tuplerow[col], fgColor, bgColor, + alphaHandling, alpha); + } + break; + + default: + pm_error("unknown PNG color type: %d", pngInfoP->color_type); + } + } +} + + + +static void +reportOutputFormat(const struct pam * const pamP) { + + switch (pamP->format) { + + case PBM_FORMAT: + pm_message("Writing a PBM file"); + break; + case PGM_FORMAT: + pm_message("Writing a PGM file with maxval %lu", pamP->maxval); + break; + case PPM_FORMAT: + pm_message("Writing a PPM file with maxval %lu", pamP->maxval); + break; + case PAM_FORMAT: + pm_message("Writing a PAM file with tuple type %s, maxval %u", + pamP->tuple_type, maxval); + break; + default: + assert(false); /* Every possible value handled above */ + } +} + + + +static void +writeNetpbm(struct pam * const pamP, + png_info * const pngInfoP, + png_byte ** const pngRaster, + pngcolor const bgColor, + enum alpha_handling const alphaHandling, + double const totalgamma) { +/*---------------------------------------------------------------------------- + Write a Netpbm image of either the image or the alpha mask, according to + 'alphaHandling' that is in the PNG image described by 'pngInfoP' and + pngRaster. + + *pamP describes the required output image and is consistent with + *pngInfoP. + + Use background color 'bgColor' in the output if the PNG is such that a + background color is needed. +-----------------------------------------------------------------------------*/ + tuple * tuplerow; + unsigned int row; + + if (verbose) + reportOutputFormat(pamP); + + pnm_writepaminit(pamP); + + tuplerow = pnm_allocpamrow(pamP); + + for (row = 0; row < pngInfoP->height; ++row) { + makeTupleRow(pamP, tuplerow, pngInfoP, pngRaster[row], bgColor, + alphaHandling, totalgamma); + + pnm_writepamrow(pamP, tuplerow); + } + pnm_freepamrow(tuplerow); +} + + + +static void +convertpng(FILE * const ifp, + FILE * const tfp, + struct cmdlineInfo const cmdline, + int * const errorlevelP) { + + png_struct * png_ptr; + png_info * info_ptr; + png_byte ** png_image; + pngcolor bgColor; + float totalgamma; + struct pam pam; + + *errorlevelP = 0; + + read_sig_buf(ifp); + + png_ptr = png_create_read_struct( + PNG_LIBPNG_VER_STRING, + &pngtopnm_jmpbuf_struct, pngtopnm_error_handler, NULL); + if (png_ptr == NULL) + pm_error("cannot allocate main libpng structure (png_ptr)"); + + info_ptr = png_create_info_struct (png_ptr); + if (info_ptr == NULL) + pm_error("cannot allocate LIBPNG structures"); + + if (setjmp(pngtopnm_jmpbuf_struct.jmpbuf)) + pm_error ("setjmp returns error condition"); + + png_init_io (png_ptr, ifp); + png_set_sig_bytes (png_ptr, SIG_CHECK_SIZE); + png_read_info (png_ptr, info_ptr); + + allocPngRaster(info_ptr, &png_image); + + if (info_ptr->bit_depth < 8) + png_set_packing (png_ptr); + + setupGammaCorrection(png_ptr, info_ptr, cmdline.gamma, &totalgamma); + + setupSignificantBits(png_ptr, info_ptr, cmdline.alpha, + &maxval, errorlevelP); + + getBackgroundColor(info_ptr, cmdline.background, totalgamma, maxval, + &bgColor); + + png_read_image(png_ptr, png_image); + png_read_end(png_ptr, info_ptr); + + if (verbose) + /* Note that some of info_ptr is not defined until png_read_end() + completes. That's because it comes from chunks that are at the + end of the stream. + */ + dump_png_info(info_ptr); + + if (cmdline.time) + show_time(info_ptr); + if (tfp) + save_text(info_ptr, tfp); + + if (info_ptr->valid & PNG_INFO_pHYs) { + float const r = + (float)info_ptr->x_pixels_per_unit / info_ptr->y_pixels_per_unit; + if (r != 1.0) { + pm_message ("warning - non-square pixels; " + "to fix do a 'pamscale -%cscale %g'", + r < 1.0 ? 'x' : 'y', + r < 1.0 ? 1.0 / r : r ); + *errorlevelP = PNMTOPNG_WARNING_LEVEL; + } + } + + pam.size = sizeof(pam); + pam.len = PAM_STRUCT_SIZE(tuple_type); + pam.file = stdout; + pam.plainformat = 0; + pam.height = info_ptr->height; + pam.width = info_ptr->width; + pam.maxval = maxval; + + determineOutputType(info_ptr, cmdline.alpha, bgColor, maxval, + &pam.format, &pam.depth, pam.tuple_type); + + writeNetpbm(&pam, info_ptr, png_image, bgColor, cmdline.alpha, totalgamma); + + fflush(stdout); + + freePngRaster(png_image, info_ptr); + + png_destroy_read_struct(&png_ptr, &info_ptr, NULL); +} + + + +int +main(int argc, const char *argv[]) { + + struct cmdlineInfo cmdline; + FILE * ifP; + FILE * tfP; + int errorlevel; + + pm_proginit(&argc, argv); + + parseCommandLine(argc, argv, &cmdline); + + verbose = cmdline.verbose; + + ifP = pm_openr(cmdline.inputFilespec); + + if (cmdline.text) + tfP = pm_openw(cmdline.text); + else + tfP = NULL; + + convertpng(ifP, tfP, cmdline, &errorlevel); + + if (tfP) + pm_close(tfP); + + pm_close(ifP); + pm_close(stdout); + + return errorlevel; +} |