/* png.c - Handles output to PNG file */
/*
libzint - the open source barcode library
Copyright (C) 2009-2025 Robin Stuart <rstuart114@gmail.com>
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the project nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
*/
/* SPDX-License-Identifier: BSD-3-Clause */
#ifndef ZINT_NO_PNG
#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <png.h>
#include <zlib.h>
#include <setjmp.h>
#include "common.h"
#include "filemem.h"
#include "output.h"
/* Note using "wpng_" prefix not "png_" (except for `png_pixel_plot()`) to avoid clashing with libpng */
/* Note if change this need to change "backend/tests/test_png.c" definition also */
struct wpng_error_type {
struct zint_symbol *symbol;
jmp_buf jmpbuf;
};
static void wpng_error_handler(png_structp png_ptr, png_const_charp msg) {
struct wpng_error_type *wpng_error_ptr;
wpng_error_ptr = (struct wpng_error_type *) png_get_error_ptr(png_ptr);
if (wpng_error_ptr == NULL) {
/* we are completely hosed now */
fprintf(stderr, "Error 636: libpng error: %s\n", msg ? msg : "<NULL>");
fprintf(stderr, "Error 637: jmpbuf not recoverable, terminating\n");
fflush(stderr);
return; /* libpng will call abort() */
}
errtxtf(0, wpng_error_ptr->symbol, 635, "libpng error: %s", msg ? msg : "<NULL>");
longjmp(wpng_error_ptr->jmpbuf, 1);
}
#ifdef ZINT_TEST /* Wrapper for direct testing */
INTERNAL void wpng_error_handler_test(png_structp png_ptr, png_const_charp msg) {
wpng_error_handler(png_ptr, msg);
}
#endif
/* libpng write callback */
static void wpng_write(png_structp png_ptr, png_bytep ptr, size_t size) {
struct filemem *fmp = (struct filemem *) png_get_io_ptr(png_ptr);
(void) fm_write(ptr, 1, size, fmp);
}
/* libpng flush callback */
static void wpng_flush(png_structp png_ptr) {
struct filemem *fmp = (struct filemem *) png_get_io_ptr(png_ptr);
(void) fm_flush(fmp);
}
/* Guestimate best compression strategy */
static int wpng_guess_compression_strategy(struct zint_symbol *symbol, const unsigned char *pixelbuf) {
(void)pixelbuf;
/* TODO: Do properly */
/* It seems the best choice for typical barcode pngs is one of Z_DEFAULT_STRATEGY and Z_FILTERED */
/* Some guesses */
if (symbol->symbology == BARCODE_MAXICODE) {
return Z_DEFAULT_STRATEGY;
}
if (symbol->symbology == BARCODE_AZTEC && symbol->bitmap_width <= 30) {
return Z_DEFAULT_STRATEGY;
}
/* Z_FILTERED seems to work better for slightly more barcodes+data so default to that */
return Z_FILTERED;
}
INTERNAL int png_pixel_plot(struct zint_symbol *symbol, const unsigned char *pixelbuf) {
struct wpng_error_type wpng_error;
struct filemem fm;
struct filemem *const fmp = &fm;
png_structp png_ptr;
png_infop info_ptr;
int i;
int row, column;
png_color bg, fg;
unsigned char bg_alpha, fg_alpha;
unsigned char map[128];
png_color palette[32];
int num_palette;
unsigned char trans_alpha[32];
int num_trans; /* Note initialize below to avoid gcc -Wclobbered warning due to `longjmp()` */
int bit_depth;
int compression_strategy;
const unsigned char *pb;
unsigned char *outdata = (unsigned char *) z_alloca(symbol->bitmap_width);
wpng_error.symbol = symbol;
(void) out_colour_get_rgb(symbol->fgcolour, &fg.red, &fg.green, &fg.blue, &fg_alpha);
(void) out_colour_get_rgb(symbol->bgcolour, &bg.red, &bg.green, &bg.blue, &bg_alpha);
num_trans = 0;
if (symbol->symbology == BARCODE_ULTRA) {
static const unsigned char ultra_chars[8] = { 'W', 'C', 'B', 'M', 'R', 'Y', 'G', 'K' };
for (i = 0; i < 8; i++) {
map[ultra_chars[i]] = i;
out_colour_char_to_rgb(ultra_chars[i], &palette[i].red, &palette[i].green, &palette[i].blue);
if (fg_alpha != 0xff) {
trans_alpha[i] = fg_alpha;
}
}
num_palette = 8;
if (fg_alpha != 0xff) {
num_trans = 8;
}
/* For Ultracode, have foreground only if have bind/box */
if (symbol->border_width > 0 && (symbol->output_options & (BARCODE_BIND | BARCODE_BOX | BARCODE_BIND_TOP))) {
/* Check whether can re-use black */
if (fg.red == 0 && fg.green == 0 && fg.blue == 0) {
map['1'] = 7; /* Re-use black */
} else {
map['1'] = num_palette;
palette[num_palette++] = fg;
if (fg_alpha != 0xff) {
trans_alpha[num_trans++] = fg_alpha;
}
}
}
/* For Ultracode, have background only if have whitespace/quiet zones */
if (symbol->whitespace_width > 0 || symbol->whitespace_height > 0
|| ((symbol->output_options & BARCODE_QUIET_ZONES)
&& !(symbol->output_options & BARCODE_NO_QUIET_ZONES))) {
/* Check whether can re-use white */
if (bg.red == 0xff && bg.green == 0xff && bg.blue == 0xff && bg_alpha == fg_alpha) {
map['0'] = 0; /* Re-use white */
} else {
if (bg_alpha == 0xff || fg_alpha != 0xff) {
/* No alpha or have foreground alpha - add to end */
map['0'] = num_palette;
palette[num_palette++] = bg;
} else {
/* Alpha and no foreground alpha - add to front & move white to end */
png_color white = palette[0]; /* Take copy */
map['0'] = 0;
palette[0] = bg;
map['W'] = num_palette;
palette[num_palette++] = white;
}
if (bg_alpha != 0xff) {
trans_alpha[num_trans++] = bg_alpha;
}
}
}
} else {
int bg_idx = 0, fg_idx = 1;
/* Do alphas first so can swop indexes if background not alpha */
if (bg_alpha != 0xff) {
trans_alpha[num_trans++] = bg_alpha;
}
if (fg_alpha != 0xff) {
trans_alpha[num_trans++] = fg_alpha;
if (num_trans == 1) {
/* Only foreground has alpha so swop indexes - saves a byte! */
bg_idx = 1;
fg_idx = 0;
}
}
map['0'] = bg_idx;
palette[bg_idx] = bg;
map['1'] = fg_idx;
palette[fg_idx] = fg;
num_palette = 2;
}
if (num_palette <= 2) {
bit_depth = 1;
} else {
bit_depth = 4;
}
/* Open output file in binary mode */
if (!fm_open(fmp, symbol, "wb")) {
return ZEXT errtxtf(ZINT_ERROR_FILE_ACCESS, symbol, 632, "Could not open PNG output file (%1$d: %2$s)",
fmp->err, strerror(fmp->err));
}
/* Set up error handling routine as proc() above */
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, &wpng_error, wpng_error_handler, NULL);
if (!png_ptr) {
(void) fm_close(fmp, symbol);
return errtxt(ZINT_ERROR_MEMORY, symbol, 633, "Insufficient memory for PNG write structure buffer");
}
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_write_struct(&png_ptr, NULL);
(void) fm_close(fmp, symbol);
return errtxt(ZINT_ERROR_MEMORY, symbol, 634, "Insufficient memory for PNG info structure buffer");
}
/* catch jumping here */
if (setjmp(wpng_error.jmpbuf)) {
png_destroy_write_struct(&png_ptr, &info_ptr);
(void) fm_close(fmp, symbol);
return ZINT_ERROR_MEMORY;
}
/* Set our output functions */
png_set_write_fn(png_ptr, fmp, wpng_write, wpng_flush);
/* set compression */
png_set_compression_level(png_ptr, 9);
/* Compression strategy can make a difference */
compression_strategy = wpng_guess_compression_strategy(symbol, pixelbuf);
if (compression_strategy != Z_DEFAULT_STRATEGY) {
png_set_compression_strategy(png_ptr, compression_strategy);
}
if (symbol->dpmm) {
int resolution = (int) roundf(stripf(symbol->dpmm * 1000.0f)); /* pixels per metre */
png_set_pHYs(png_ptr, info_ptr, resolution, resolution, PNG_RESOLUTION_METER);
}
/* set Header block */
png_set_IHDR(png_ptr, info_ptr, symbol->bitmap_width, symbol->bitmap_height,
bit_depth, PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
png_set_PLTE(png_ptr, info_ptr, palette, num_palette);
if (num_trans) {
png_set_tRNS(png_ptr, info_ptr, trans_alpha, num_trans, NULL);
}
/* write all chunks up to (but not including) first IDAT */
png_write_info(png_ptr, info_ptr);
/* Pixel Plotting */
pb = pixelbuf;
if (bit_depth == 1) {
for (row = 0; row < symbol->bitmap_height; row++) {
if (row && memcmp(pb, pb - symbol->bitmap_width, symbol->bitmap_width) == 0) {
pb += symbol->bitmap_width;
} else {
unsigned char *image_data = outdata;
for (column = 0; column < symbol->bitmap_width; column += 8, image_data++) {
unsigned char byte = 0;
for (i = 0; i < 8 && column + i < symbol->bitmap_width; i++, pb++) {
byte |= map[*pb] << (7 - i);
}
*image_data = byte;
}
}
/* write row contents to file */
png_write_row(png_ptr, outdata);
}
} else { /* Bit depth 4 */
for (row = 0; row < symbol->bitmap_height; row++) {
if (row && memcmp(pb, pb - symbol->bitmap_width, symbol->bitmap_width) == 0) {
pb += symbol->bitmap_width;
} else {
unsigned char *image_data = outdata;
for (column = 0; column < symbol->bitmap_width; column += 2, image_data++) {
unsigned char byte = map[*pb++] << 4;
if (column + 1 < symbol->bitmap_width) {
byte |= map[*pb++];
}
*image_data = byte;
}
}
/* write row contents to file */
png_write_row(png_ptr, outdata);
}
}
/* End the file */
png_write_end(png_ptr, NULL);
/* make sure we have disengaged */
png_destroy_write_struct(&png_ptr, &info_ptr);
if (fm_error(fmp)) {
ZEXT errtxtf(0, symbol, 638, "Incomplete write of PNG output (%1$d: %2$s)", fmp->err, strerror(fmp->err));
(void) fm_close(fmp, symbol);
return ZINT_ERROR_FILE_WRITE;
}
if (!fm_close(fmp, symbol)) {
return ZEXT errtxtf(ZINT_ERROR_FILE_WRITE, symbol, 960, "Failure on closing PNG output file (%1$d: %2$s)",
fmp->err, strerror(fmp->err));
}
return 0;
}
/* vim: set ts=4 sw=4 et : */
#else
#if defined(__clang__)
/* Suppresses clang-tidy-18 "clang-diagnostic-empty-translation-unit" */
typedef int wpng_make_clang_tidy_compilers_happy;
#endif
#endif /* ZINT_NO_PNG */
