godot/thirdparty/libpng/pngwutil.c

/* pngwutil.c - utilities to write a PNG file
 *
 * Copyright (c) 2018-2024 Cosmin Truta
 * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
 * Copyright (c) 1996-1997 Andreas Dilger
 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

#include "pngpriv.h"

#ifdef PNG_WRITE_SUPPORTED

#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
/* Place a 32-bit number into a buffer in PNG byte order.  We work
 * with unsigned numbers for convenience, although one supported
 * ancillary chunk uses signed (two's complement) numbers.
 */
void PNGAPI
png_save_uint_32(png_bytep buf, png_uint_32 i)
{ … }

/* Place a 16-bit number into a buffer in PNG byte order.
 * The parameter is declared unsigned int, not png_uint_16,
 * just to avoid potential problems on pre-ANSI C compilers.
 */
void PNGAPI
png_save_uint_16(png_bytep buf, unsigned int i)
{ … }
#endif

/* Simple function to write the signature.  If we have already written
 * the magic bytes of the signature, or more likely, the PNG stream is
 * being embedded into another stream and doesn't need its own signature,
 * we should call png_set_sig_bytes() to tell libpng how many of the
 * bytes have already been written.
 */
void PNGAPI
png_write_sig(png_structrp png_ptr)
{ … }

/* Write the start of a PNG chunk.  The type is the chunk type.
 * The total_length is the sum of the lengths of all the data you will be
 * passing in png_write_chunk_data().
 */
static void
png_write_chunk_header(png_structrp png_ptr, png_uint_32 chunk_name,
    png_uint_32 length)
{ … }

void PNGAPI
png_write_chunk_start(png_structrp png_ptr, png_const_bytep chunk_string,
    png_uint_32 length)
{ … }

/* Write the data of a PNG chunk started with png_write_chunk_header().
 * Note that multiple calls to this function are allowed, and that the
 * sum of the lengths from these calls *must* add up to the total_length
 * given to png_write_chunk_header().
 */
void PNGAPI
png_write_chunk_data(png_structrp png_ptr, png_const_bytep data, size_t length)
{ … }

/* Finish a chunk started with png_write_chunk_header(). */
void PNGAPI
png_write_chunk_end(png_structrp png_ptr)
{ … }

/* Write a PNG chunk all at once.  The type is an array of ASCII characters
 * representing the chunk name.  The array must be at least 4 bytes in
 * length, and does not need to be null terminated.  To be safe, pass the
 * pre-defined chunk names here, and if you need a new one, define it
 * where the others are defined.  The length is the length of the data.
 * All the data must be present.  If that is not possible, use the
 * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
 * functions instead.
 */
static void
png_write_complete_chunk(png_structrp png_ptr, png_uint_32 chunk_name,
    png_const_bytep data, size_t length)
{ … }

/* This is the API that calls the internal function above. */
void PNGAPI
png_write_chunk(png_structrp png_ptr, png_const_bytep chunk_string,
    png_const_bytep data, size_t length)
{ … }

/* This is used below to find the size of an image to pass to png_deflate_claim,
 * so it only needs to be accurate if the size is less than 16384 bytes (the
 * point at which a lower LZ window size can be used.)
 */
static png_alloc_size_t
png_image_size(png_structrp png_ptr)
{ … }

#ifdef PNG_WRITE_OPTIMIZE_CMF_SUPPORTED
   /* This is the code to hack the first two bytes of the deflate stream (the
    * deflate header) to correct the windowBits value to match the actual data
    * size.  Note that the second argument is the *uncompressed* size but the
    * first argument is the *compressed* data (and it must be deflate
    * compressed.)
    */
static void
optimize_cmf(png_bytep data, png_alloc_size_t data_size)
{ … }
#endif /* WRITE_OPTIMIZE_CMF */

/* Initialize the compressor for the appropriate type of compression. */
static int
png_deflate_claim(png_structrp png_ptr, png_uint_32 owner,
    png_alloc_size_t data_size)
{ … }

/* Clean up (or trim) a linked list of compression buffers. */
void /* PRIVATE */
png_free_buffer_list(png_structrp png_ptr, png_compression_bufferp *listp)
{ … }

#ifdef PNG_WRITE_COMPRESSED_TEXT_SUPPORTED
/* This pair of functions encapsulates the operation of (a) compressing a
 * text string, and (b) issuing it later as a series of chunk data writes.
 * The compression_state structure is shared context for these functions
 * set up by the caller to allow access to the relevant local variables.
 *
 * compression_buffer (new in 1.6.0) is just a linked list of zbuffer_size
 * temporary buffers.  From 1.6.0 it is retained in png_struct so that it will
 * be correctly freed in the event of a write error (previous implementations
 * just leaked memory.)
 */
compression_state;

static void
png_text_compress_init(compression_state *comp, png_const_bytep input,
    png_alloc_size_t input_len)
{ … }

/* Compress the data in the compression state input */
static int
png_text_compress(png_structrp png_ptr, png_uint_32 chunk_name,
    compression_state *comp, png_uint_32 prefix_len)
{ … }

/* Ship the compressed text out via chunk writes */
static void
png_write_compressed_data_out(png_structrp png_ptr, compression_state *comp)
{ … }
#endif /* WRITE_COMPRESSED_TEXT */

/* Write the IHDR chunk, and update the png_struct with the necessary
 * information.  Note that the rest of this code depends upon this
 * information being correct.
 */
void /* PRIVATE */
png_write_IHDR(png_structrp png_ptr, png_uint_32 width, png_uint_32 height,
    int bit_depth, int color_type, int compression_type, int filter_type,
    int interlace_type)
{ … }

/* Write the palette.  We are careful not to trust png_color to be in the
 * correct order for PNG, so people can redefine it to any convenient
 * structure.
 */
void /* PRIVATE */
png_write_PLTE(png_structrp png_ptr, png_const_colorp palette,
    png_uint_32 num_pal)
{ … }

/* This is similar to png_text_compress, above, except that it does not require
 * all of the data at once and, instead of buffering the compressed result,
 * writes it as IDAT chunks.  Unlike png_text_compress it *can* png_error out
 * because it calls the write interface.  As a result it does its own error
 * reporting and does not return an error code.  In the event of error it will
 * just call png_error.  The input data length may exceed 32-bits.  The 'flush'
 * parameter is exactly the same as that to deflate, with the following
 * meanings:
 *
 * Z_NO_FLUSH: normal incremental output of compressed data
 * Z_SYNC_FLUSH: do a SYNC_FLUSH, used by png_write_flush
 * Z_FINISH: this is the end of the input, do a Z_FINISH and clean up
 *
 * The routine manages the acquire and release of the png_ptr->zstream by
 * checking and (at the end) clearing png_ptr->zowner; it does some sanity
 * checks on the 'mode' flags while doing this.
 */
void /* PRIVATE */
png_compress_IDAT(png_structrp png_ptr, png_const_bytep input,
    png_alloc_size_t input_len, int flush)
{ … }

/* Write an IEND chunk */
void /* PRIVATE */
png_write_IEND(png_structrp png_ptr)
{ … }

#ifdef PNG_WRITE_gAMA_SUPPORTED
/* Write a gAMA chunk */
void /* PRIVATE */
png_write_gAMA_fixed(png_structrp png_ptr, png_fixed_point file_gamma)
{ … }
#endif

#ifdef PNG_WRITE_sRGB_SUPPORTED
/* Write a sRGB chunk */
void /* PRIVATE */
png_write_sRGB(png_structrp png_ptr, int srgb_intent)
{ … }
#endif

#ifdef PNG_WRITE_iCCP_SUPPORTED
/* Write an iCCP chunk */
void /* PRIVATE */
png_write_iCCP(png_structrp png_ptr, png_const_charp name,
    png_const_bytep profile)
{ … }
#endif

#ifdef PNG_WRITE_sPLT_SUPPORTED
/* Write a sPLT chunk */
void /* PRIVATE */
png_write_sPLT(png_structrp png_ptr, png_const_sPLT_tp spalette)
{ … }
#endif

#ifdef PNG_WRITE_sBIT_SUPPORTED
/* Write the sBIT chunk */
void /* PRIVATE */
png_write_sBIT(png_structrp png_ptr, png_const_color_8p sbit, int color_type)
{ … }
#endif

#ifdef PNG_WRITE_cHRM_SUPPORTED
/* Write the cHRM chunk */
void /* PRIVATE */
png_write_cHRM_fixed(png_structrp png_ptr, const png_xy *xy)
{ … }
#endif

#ifdef PNG_WRITE_tRNS_SUPPORTED
/* Write the tRNS chunk */
void /* PRIVATE */
png_write_tRNS(png_structrp png_ptr, png_const_bytep trans_alpha,
    png_const_color_16p tran, int num_trans, int color_type)
{ … }
#endif

#ifdef PNG_WRITE_bKGD_SUPPORTED
/* Write the background chunk */
void /* PRIVATE */
png_write_bKGD(png_structrp png_ptr, png_const_color_16p back, int color_type)
{ … }
#endif

#ifdef PNG_WRITE_eXIf_SUPPORTED
/* Write the Exif data */
void /* PRIVATE */
png_write_eXIf(png_structrp png_ptr, png_bytep exif, int num_exif)
{ … }
#endif

#ifdef PNG_WRITE_hIST_SUPPORTED
/* Write the histogram */
void /* PRIVATE */
png_write_hIST(png_structrp png_ptr, png_const_uint_16p hist, int num_hist)
{ … }
#endif

#ifdef PNG_WRITE_tEXt_SUPPORTED
/* Write a tEXt chunk */
void /* PRIVATE */
png_write_tEXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
    size_t text_len)
{ … }
#endif

#ifdef PNG_WRITE_zTXt_SUPPORTED
/* Write a compressed text chunk */
void /* PRIVATE */
png_write_zTXt(png_structrp png_ptr, png_const_charp key, png_const_charp text,
    int compression)
{ … }
#endif

#ifdef PNG_WRITE_iTXt_SUPPORTED
/* Write an iTXt chunk */
void /* PRIVATE */
png_write_iTXt(png_structrp png_ptr, int compression, png_const_charp key,
    png_const_charp lang, png_const_charp lang_key, png_const_charp text)
{ … }
#endif

#ifdef PNG_WRITE_oFFs_SUPPORTED
/* Write the oFFs chunk */
void /* PRIVATE */
png_write_oFFs(png_structrp png_ptr, png_int_32 x_offset, png_int_32 y_offset,
    int unit_type)
{ … }
#endif
#ifdef PNG_WRITE_pCAL_SUPPORTED
/* Write the pCAL chunk (described in the PNG extensions document) */
void /* PRIVATE */
png_write_pCAL(png_structrp png_ptr, png_charp purpose, png_int_32 X0,
    png_int_32 X1, int type, int nparams, png_const_charp units,
    png_charpp params)
{ … }
#endif

#ifdef PNG_WRITE_sCAL_SUPPORTED
/* Write the sCAL chunk */
void /* PRIVATE */
png_write_sCAL_s(png_structrp png_ptr, int unit, png_const_charp width,
    png_const_charp height)
{ … }
#endif

#ifdef PNG_WRITE_pHYs_SUPPORTED
/* Write the pHYs chunk */
void /* PRIVATE */
png_write_pHYs(png_structrp png_ptr, png_uint_32 x_pixels_per_unit,
    png_uint_32 y_pixels_per_unit,
    int unit_type)
{ … }
#endif

#ifdef PNG_WRITE_tIME_SUPPORTED
/* Write the tIME chunk.  Use either png_convert_from_struct_tm()
 * or png_convert_from_time_t(), or fill in the structure yourself.
 */
void /* PRIVATE */
png_write_tIME(png_structrp png_ptr, png_const_timep mod_time)
{ … }
#endif

/* Initializes the row writing capability of libpng */
void /* PRIVATE */
png_write_start_row(png_structrp png_ptr)
{ … }

/* Internal use only.  Called when finished processing a row of data. */
void /* PRIVATE */
png_write_finish_row(png_structrp png_ptr)
{ … }

#ifdef PNG_WRITE_INTERLACING_SUPPORTED
/* Pick out the correct pixels for the interlace pass.
 * The basic idea here is to go through the row with a source
 * pointer and a destination pointer (sp and dp), and copy the
 * correct pixels for the pass.  As the row gets compacted,
 * sp will always be >= dp, so we should never overwrite anything.
 * See the default: case for the easiest code to understand.
 */
void /* PRIVATE */
png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
{ … }
#endif


/* This filters the row, chooses which filter to use, if it has not already
 * been specified by the application, and then writes the row out with the
 * chosen filter.
 */
static void /* PRIVATE */
png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
    size_t row_bytes);

#ifdef PNG_WRITE_FILTER_SUPPORTED
static size_t /* PRIVATE */
png_setup_sub_row(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes, size_t lmins)
{ … }

static void /* PRIVATE */
png_setup_sub_row_only(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes)
{ … }

static size_t /* PRIVATE */
png_setup_up_row(png_structrp png_ptr, size_t row_bytes, size_t lmins)
{ … }
static void /* PRIVATE */
png_setup_up_row_only(png_structrp png_ptr, size_t row_bytes)
{ … }

static size_t /* PRIVATE */
png_setup_avg_row(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes, size_t lmins)
{ … }
static void /* PRIVATE */
png_setup_avg_row_only(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes)
{ … }

static size_t /* PRIVATE */
png_setup_paeth_row(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes, size_t lmins)
{ … }
static void /* PRIVATE */
png_setup_paeth_row_only(png_structrp png_ptr, png_uint_32 bpp,
    size_t row_bytes)
{ … }
#endif /* WRITE_FILTER */

void /* PRIVATE */
png_write_find_filter(png_structrp png_ptr, png_row_infop row_info)
{ … }


/* Do the actual writing of a previously filtered row. */
static void
png_write_filtered_row(png_structrp png_ptr, png_bytep filtered_row,
    size_t full_row_length/*includes filter byte*/)
{ … }
#endif /* WRITE */