lodepng: sync with mainstream, merged up to latest commit f6155a420604.

git-svn-id: svn://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@1611 af15c1b1-3010-417e-b628-4374ebc0bcbd

Quake/lodepng.h

@@ -1,7 +1,7 @@
 /*
-LodePNG version 20180326
+LodePNG version 20190714
 
-Copyright (c) 2005-2018 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 
 This software is provided 'as-is', without any express or implied
 warranty. In no event will the authors be held liable for any damages
@@ -44,36 +44,44 @@ the custom_zlib field of the compress and decompress settings*/
 #ifndef LODEPNG_NO_COMPILE_ZLIB
 #define LODEPNG_COMPILE_ZLIB
 #endif
+
 /*png encoder and png decoder*/
 #ifndef LODEPNG_NO_COMPILE_PNG
 #define LODEPNG_COMPILE_PNG
 #endif
+
 /*deflate&zlib decoder and png decoder*/
 #ifndef LODEPNG_NO_COMPILE_DECODER
 #define LODEPNG_COMPILE_DECODER
 #endif
+
 /*deflate&zlib encoder and png encoder*/
 #ifndef LODEPNG_NO_COMPILE_ENCODER
 #define LODEPNG_COMPILE_ENCODER
 #endif
+
 /*the optional built in harddisk file loading and saving functions*/
 #ifndef LODEPNG_NO_COMPILE_DISK
 #define LODEPNG_COMPILE_DISK
 #endif
+
 /*support for chunks other than IHDR, IDAT, PLTE, tRNS, IEND: ancillary and unknown chunks*/
 #ifndef LODEPNG_NO_COMPILE_ANCILLARY_CHUNKS
 #define LODEPNG_COMPILE_ANCILLARY_CHUNKS
 #endif
+
 /*ability to convert error numerical codes to English text string*/
 #ifndef LODEPNG_NO_COMPILE_ERROR_TEXT
 #define LODEPNG_COMPILE_ERROR_TEXT
 #endif
+
 /*Compile the default allocators (C's free, malloc and realloc). If you disable this,
 you can define the functions lodepng_free, lodepng_malloc and lodepng_realloc in your
 source files with custom allocators.*/
 #ifndef LODEPNG_NO_COMPILE_ALLOCATORS
 #define LODEPNG_COMPILE_ALLOCATORS
 #endif
+
 /*compile the C++ version (you can disable the C++ wrapper here even when compiling for C++)*/
 #ifdef __cplusplus
 #ifndef LODEPNG_NO_COMPILE_CPP
@@ -88,12 +96,11 @@ source files with custom allocators.*/
 
 #ifdef LODEPNG_COMPILE_PNG
 /*The PNG color types (also used for raw).*/
-typedef enum LodePNGColorType
+typedef enum LodePNGColorType {
-{
+  LCT_GREY = 0, /*grayscale: 1,2,4,8,16 bit*/
-  LCT_GREY = 0, /*greyscale: 1,2,4,8,16 bit*/
   LCT_RGB = 2, /*RGB: 8,16 bit*/
   LCT_PALETTE = 3, /*palette: 1,2,4,8 bit*/
-  LCT_GREY_ALPHA = 4, /*greyscale with alpha: 8,16 bit*/
+  LCT_GREY_ALPHA = 4, /*grayscale with alpha: 8,16 bit*/
   LCT_RGBA = 6 /*RGB with alpha: 8,16 bit*/
 } LodePNGColorType;
 
@@ -196,8 +203,7 @@ unsigned lodepng_encode24_file(const char* filename,
 
 
 #ifdef LODEPNG_COMPILE_CPP
-namespace lodepng
+namespace lodepng {
-{
 #ifdef LODEPNG_COMPILE_DECODER
 /*Same as lodepng_decode_memory, but decodes to an std::vector. The colortype
 is the format to output the pixels to. Default is RGBA 8-bit per channel.*/
@@ -253,10 +259,10 @@ const char* lodepng_error_text(unsigned code);
 #ifdef LODEPNG_COMPILE_DECODER
 /*Settings for zlib decompression*/
 typedef struct LodePNGDecompressSettings LodePNGDecompressSettings;
-struct LodePNGDecompressSettings
+struct LodePNGDecompressSettings {
-{
+  /* Check LodePNGDecoderSettings for more ignorable errors such as ignore_crc */
-  /* Check LodePNGDecoderSettings for more ignorable errors */
   unsigned ignore_adler32; /*if 1, continue and don't give an error message if the Adler32 checksum is corrupted*/
+  unsigned ignore_nlen; /*ignore complement of len checksum in uncompressed blocks*/
 
   /*use custom zlib decoder instead of built in one (default: null)*/
   unsigned (*custom_zlib)(unsigned char**, size_t*,
@@ -282,8 +288,7 @@ Settings for zlib compression. Tweaking these settings tweaks the balance
 between speed and compression ratio.
 */
 typedef struct LodePNGCompressSettings LodePNGCompressSettings;
-struct LodePNGCompressSettings /*deflate = compress*/
+struct LodePNGCompressSettings /*deflate = compress*/ {
-{
   /*LZ77 related settings*/
   unsigned btype; /*the block type for LZ (0, 1, 2 or 3, see zlib standard). Should be 2 for proper compression.*/
   unsigned use_lz77; /*whether or not to use LZ77. Should be 1 for proper compression.*/
@@ -316,8 +321,7 @@ Color mode of an image. Contains all information required to decode the pixel
 bits to RGBA colors. This information is the same as used in the PNG file
 format, and is used both for PNG and raw image data in LodePNG.
 */
-typedef struct LodePNGColorMode
+typedef struct LodePNGColorMode {
-{
   /*header (IHDR)*/
   LodePNGColorType colortype; /*color type, see PNG standard or documentation further in this header file*/
   unsigned bitdepth;  /*bits per sample, see PNG standard or documentation further in this header file*/
@@ -342,7 +346,7 @@ typedef struct LodePNGColorMode
   transparent color key (tRNS)
 
   This color uses the same bit depth as the bitdepth value in this struct, which can be 1-bit to 16-bit.
-  For greyscale PNGs, r, g and b will all 3 be set to the same.
+  For grayscale PNGs, r, g and b will all 3 be set to the same.
 
   When decoding, by default you can ignore this information, since LodePNG sets
   pixels with this key to transparent already in the raw RGBA output.
@@ -350,7 +354,7 @@ typedef struct LodePNGColorMode
   The color key is only supported for color types 0 and 2.
   */
   unsigned key_defined; /*is a transparent color key given? 0 = false, 1 = true*/
-  unsigned key_r;       /*red/greyscale component of color key*/
+  unsigned key_r;       /*red/grayscale component of color key*/
   unsigned key_g;       /*green component of color key*/
   unsigned key_b;       /*blue component of color key*/
 } LodePNGColorMode;
@@ -360,6 +364,8 @@ void lodepng_color_mode_init(LodePNGColorMode* info);
 void lodepng_color_mode_cleanup(LodePNGColorMode* info);
 /*return value is error code (0 means no error)*/
 unsigned lodepng_color_mode_copy(LodePNGColorMode* dest, const LodePNGColorMode* source);
+/* Makes a temporary LodePNGColorMode that does not need cleanup (no palette) */
+LodePNGColorMode lodepng_color_mode_make(LodePNGColorType colortype, unsigned bitdepth);
 
 void lodepng_palette_clear(LodePNGColorMode* info);
 /*add 1 color to the palette*/
@@ -371,7 +377,7 @@ unsigned lodepng_get_bpp(const LodePNGColorMode* info);
 /*get the amount of color channels used, based on colortype in the struct.
 If a palette is used, it counts as 1 channel.*/
 unsigned lodepng_get_channels(const LodePNGColorMode* info);
-/*is it a greyscale type? (only colortype 0 or 4)*/
+/*is it a grayscale type? (only colortype 0 or 4)*/
 unsigned lodepng_is_greyscale_type(const LodePNGColorMode* info);
 /*has it got an alpha channel? (only colortype 2 or 6)*/
 unsigned lodepng_is_alpha_type(const LodePNGColorMode* info);
@@ -393,8 +399,7 @@ size_t lodepng_get_raw_size(unsigned w, unsigned h, const LodePNGColorMode* colo
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
 /*The information of a Time chunk in PNG.*/
-typedef struct LodePNGTime
+typedef struct LodePNGTime {
-{
   unsigned year;    /*2 bytes used (0-65535)*/
   unsigned month;   /*1-12*/
   unsigned day;     /*1-31*/
@@ -405,28 +410,39 @@ typedef struct LodePNGTime
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
 /*Information about the PNG image, except pixels, width and height.*/
-typedef struct LodePNGInfo
+typedef struct LodePNGInfo {
-{
   /*header (IHDR), palette (PLTE) and transparency (tRNS) chunks*/
   unsigned compression_method;/*compression method of the original file. Always 0.*/
   unsigned filter_method;     /*filter method of the original file*/
-  unsigned interlace_method;  /*interlace method of the original file*/
+  unsigned interlace_method;  /*interlace method of the original file: 0=none, 1=Adam7*/
   LodePNGColorMode color;     /*color type and bits, palette and transparency of the PNG file*/
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
   /*
-  suggested background color chunk (bKGD)
+  Suggested background color chunk (bKGD)
-  This color uses the same color mode as the PNG (except alpha channel), which can be 1-bit to 16-bit.
 
-  For greyscale PNGs, r, g and b will all 3 be set to the same. When encoding
+  This uses the same color mode and bit depth as the PNG (except no alpha channel),
-  the encoder writes the red one. For palette PNGs: When decoding, the RGB value
+  with values truncated to the bit depth in the unsigned integer.
-  will be stored, not a palette index. But when encoding, specify the index of
-  the palette in background_r, the other two are then ignored.
 
-  The decoder does not use this background color to edit the color of pixels.
+  For grayscale and palette PNGs, the value is stored in background_r. The values
+  in background_g and background_b are then unused.
+
+  So when decoding, you may get these in a different color mode than the one you requested
+  for the raw pixels.
+
+  When encoding with auto_convert, you must use the color model defined in info_png.color for
+  these values. The encoder normally ignores info_png.color when auto_convert is on, but will
+  use it to interpret these values (and convert copies of them to its chosen color model).
+
+  When encoding, avoid setting this to an expensive color, such as a non-gray value
+  when the image is gray, or the compression will be worse since it will be forced to
+  write the PNG with a more expensive color mode (when auto_convert is on).
+
+  The decoder does not use this background color to edit the color of pixels. This is a
+  completely optional metadata feature.
   */
   unsigned background_defined; /*is a suggested background color given?*/
-  unsigned background_r;       /*red component of suggested background color*/
+  unsigned background_r;       /*red/gray/palette component of suggested background color*/
   unsigned background_g;       /*green component of suggested background color*/
   unsigned background_b;       /*blue component of suggested background color*/
 
@@ -437,6 +453,10 @@ typedef struct LodePNGInfo
   text_strings, while text_keys are keywords that give a short description what
   the actual text represents, e.g. Title, Author, Description, or anything else.
 
+  All the string fields below including keys, names and language tags are null terminated.
+  The PNG specification uses null characters for the keys, names and tags, and forbids null
+  characters to appear in the main text which is why we can use null termination everywhere here.
+
   A keyword is minimum 1 character and maximum 79 characters long. It's
   discouraged to use a single line length longer than 79 characters for texts.
 
@@ -469,11 +489,86 @@ typedef struct LodePNGInfo
   unsigned phys_unit; /*may be 0 (unknown unit) or 1 (metre)*/
 
   /*
-  unknown chunks
+  Color profile related chunks: gAMA, cHRM, sRGB, iCPP
-  There are 3 buffers, one for each position in the PNG where unknown chunks can appear
+
-  each buffer contains all unknown chunks for that position consecutively
+  LodePNG does not apply any color conversions on pixels in the encoder or decoder and does not interpret these color
-  The 3 buffers are the unknown chunks between certain critical chunks:
+  profile values. It merely passes on the information. If you wish to use color profiles and convert colors, please
-  0: IHDR-PLTE, 1: PLTE-IDAT, 2: IDAT-IEND
+  use these values with a color management library.
+
+  See the PNG, ICC and sRGB specifications for more information about the meaning of these values.
+  */
+
+  /* gAMA chunk: optional, overridden by sRGB or iCCP if those are present. */
+  unsigned gama_defined; /* Whether a gAMA chunk is present (0 = not present, 1 = present). */
+  unsigned gama_gamma;   /* Gamma exponent times 100000 */
+
+  /* cHRM chunk: optional, overridden by sRGB or iCCP if those are present. */
+  unsigned chrm_defined; /* Whether a cHRM chunk is present (0 = not present, 1 = present). */
+  unsigned chrm_white_x; /* White Point x times 100000 */
+  unsigned chrm_white_y; /* White Point y times 100000 */
+  unsigned chrm_red_x;   /* Red x times 100000 */
+  unsigned chrm_red_y;   /* Red y times 100000 */
+  unsigned chrm_green_x; /* Green x times 100000 */
+  unsigned chrm_green_y; /* Green y times 100000 */
+  unsigned chrm_blue_x;  /* Blue x times 100000 */
+  unsigned chrm_blue_y;  /* Blue y times 100000 */
+
+  /*
+  sRGB chunk: optional. May not appear at the same time as iCCP.
+  If gAMA is also present gAMA must contain value 45455.
+  If cHRM is also present cHRM must contain respectively 31270,32900,64000,33000,30000,60000,15000,6000.
+  */
+  unsigned srgb_defined; /* Whether an sRGB chunk is present (0 = not present, 1 = present). */
+  unsigned srgb_intent;  /* Rendering intent: 0=perceptual, 1=rel. colorimetric, 2=saturation, 3=abs. colorimetric */
+
+  /*
+  iCCP chunk: optional. May not appear at the same time as sRGB.
+
+  LodePNG does not parse or use the ICC profile (except its color space header field for an edge case), a
+  separate library to handle the ICC data (not included in LodePNG) format is needed to use it for color
+  management and conversions.
+
+  For encoding, if iCCP is present, gAMA and cHRM are recommended to be added as well with values that match the ICC
+  profile as closely as possible, if you wish to do this you should provide the correct values for gAMA and cHRM and
+  enable their '_defined' flags since LodePNG will not automatically compute them from the ICC profile.
+
+  For encoding, the ICC profile is required by the PNG specification to be an "RGB" profile for non-gray
+  PNG color types and a "GRAY" profile for gray PNG color types. If you disable auto_convert, you must ensure
+  the ICC profile type matches your requested color type, else the encoder gives an error. If auto_convert is
+  enabled (the default), and the ICC profile is not a good match for the pixel data, this will result in an encoder
+  error if the pixel data has non-gray pixels for a GRAY profile, or a silent less-optimal compression of the pixel
+  data if the pixels could be encoded as grayscale but the ICC profile is RGB.
+
+  To avoid this do not set an ICC profile in the image unless there is a good reason for it, and when doing so
+  make sure you compute it carefully to avoid the above problems.
+  */
+  unsigned iccp_defined;      /* Whether an iCCP chunk is present (0 = not present, 1 = present). */
+  char* iccp_name;            /* Null terminated string with profile name, 1-79 bytes */
+  /*
+  The ICC profile in iccp_profile_size bytes.
+  Don't allocate this buffer yourself. Use the init/cleanup functions
+  correctly and use lodepng_set_icc and lodepng_clear_icc.
+  */
+  unsigned char* iccp_profile;
+  unsigned iccp_profile_size; /* The size of iccp_profile in bytes */
+
+  /* End of color profile related chunks */
+
+
+  /*
+  unknown chunks: chunks not known by LodePNG, passed on byte for byte.
+
+  There are 3 buffers, one for each position in the PNG where unknown chunks can appear.
+  Each buffer contains all unknown chunks for that position consecutively.
+  The 3 positions are:
+  0: between IHDR and PLTE, 1: between PLTE and IDAT, 2: between IDAT and IEND.
+
+  For encoding, do not store critical chunks or known chunks that are enabled with a "_defined" flag
+  above in here, since the encoder will blindly follow this and could then encode an invalid PNG file
+  (such as one with two IHDR chunks or the disallowed combination of sRGB with iCCP). But do use
+  this if you wish to store an ancillary chunk that is not supported by LodePNG (such as sPLT or hIST),
+  or any non-standard PNG chunk.
+
   Do not allocate or traverse this data yourself. Use the chunk traversing functions declared
   later, such as lodepng_chunk_next and lodepng_chunk_append, to read/write this struct.
   */
@@ -489,12 +584,16 @@ void lodepng_info_cleanup(LodePNGInfo* info);
 unsigned lodepng_info_copy(LodePNGInfo* dest, const LodePNGInfo* source);
 
 #ifdef LODEPNG_COMPILE_ANCILLARY_CHUNKS
-void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
 unsigned lodepng_add_text(LodePNGInfo* info, const char* key, const char* str); /*push back both texts at once*/
+void lodepng_clear_text(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
 
-void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/
 unsigned lodepng_add_itext(LodePNGInfo* info, const char* key, const char* langtag,
                            const char* transkey, const char* str); /*push back the 4 texts of 1 chunk at once*/
+void lodepng_clear_itext(LodePNGInfo* info); /*use this to clear the itexts again after you filled them in*/
+
+/*replaces if exists*/
+unsigned lodepng_set_icc(LodePNGInfo* info, const char* name, const unsigned char* profile, unsigned profile_size);
+void lodepng_clear_icc(LodePNGInfo* info); /*use this to clear the texts again after you filled them in*/
 #endif /*LODEPNG_COMPILE_ANCILLARY_CHUNKS*/
 
 /*
@@ -517,14 +616,17 @@ unsigned lodepng_convert(unsigned char* out, const unsigned char* in,
 Settings for the decoder. This contains settings for the PNG and the Zlib
 decoder, but not the Info settings from the Info structs.
 */
-typedef struct LodePNGDecoderSettings
+typedef struct LodePNGDecoderSettings {
-{
   LodePNGDecompressSettings zlibsettings; /*in here is the setting to ignore Adler32 checksums*/
 
-  /* Check LodePNGDecompressSettings for more ignorable errors */
+  /* Check LodePNGDecompressSettings for more ignorable errors such as ignore_adler32 */
   unsigned ignore_crc; /*ignore CRC checksums*/
   unsigned ignore_critical; /*ignore unknown critical chunks*/
   unsigned ignore_end; /*ignore issues at end of file if possible (missing IEND chunk, too large chunk, ...)*/
+  /* TODO: make a system involving warnings with levels and a strict mode instead. Other potentially recoverable
+     errors: srgb rendering intent value, size of content of ancillary chunks, more than 79 characters for some
+     strings, placement/combination rules for ancillary chunks, crc of unknown chunks, allowed characters
+     in string keys, etc... */
 
   unsigned color_convert; /*whether to convert the PNG to the color type you want. Default: yes*/
 
@@ -540,8 +642,7 @@ void lodepng_decoder_settings_init(LodePNGDecoderSettings* settings);
 
 #ifdef LODEPNG_COMPILE_ENCODER
 /*automatically use color type with less bits per pixel if losslessly possible. Default: AUTO*/
-typedef enum LodePNGFilterStrategy
+typedef enum LodePNGFilterStrategy {
-{
   /*every filter at zero*/
   LFS_ZERO,
   /*Use filter that gives minimum sum, as described in the official PNG filter heuristic.*/
@@ -558,36 +659,45 @@ typedef enum LodePNGFilterStrategy
   LFS_PREDEFINED
 } LodePNGFilterStrategy;
 
-/*Gives characteristics about the colors of the image, which helps decide which color model to use for encoding.
+/*Gives characteristics about the integer RGBA colors of the image (count, alpha channel usage, bit depth, ...),
+which helps decide which color model to use for encoding.
 Used internally by default if "auto_convert" is enabled. Public because it's useful for custom algorithms.*/
-typedef struct LodePNGColorProfile
+typedef struct LodePNGColorStats {
-{
+  unsigned colored; /*not grayscale*/
-  unsigned colored; /*not greyscale*/
   unsigned key; /*image is not opaque and color key is possible instead of full alpha*/
   unsigned short key_r; /*key values, always as 16-bit, in 8-bit case the byte is duplicated, e.g. 65535 means 255*/
   unsigned short key_g;
   unsigned short key_b;
   unsigned alpha; /*image is not opaque and alpha channel or alpha palette required*/
-  unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16.*/
+  unsigned numcolors; /*amount of colors, up to 257. Not valid if bits == 16 or allow_palette is disabled.*/
-  unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order*/
+  unsigned char palette[1024]; /*Remembers up to the first 256 RGBA colors, in no particular order, only valid when numcolors is valid*/
-  unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for greyscale only. 16 if 16-bit per channel required.*/
+  unsigned bits; /*bits per channel (not for palette). 1,2 or 4 for grayscale only. 16 if 16-bit per channel required.*/
-} LodePNGColorProfile;
+  size_t numpixels;
 
-void lodepng_color_profile_init(LodePNGColorProfile* profile);
+  /*user settings for computing/using the stats*/
+  unsigned allow_palette; /*default 1. if 0, disallow choosing palette colortype in auto_choose_color, and don't count numcolors*/
+  unsigned allow_greyscale; /*default 1. if 0, choose RGB or RGBA even if the image only has gray colors*/
+} LodePNGColorStats;
 
-/*Get a LodePNGColorProfile of the image.*/
+void lodepng_color_stats_init(LodePNGColorStats* stats);
-unsigned lodepng_get_color_profile(LodePNGColorProfile* profile,
+
+/*Get a LodePNGColorStats of the image. The stats must already have been inited.*/
+void lodepng_compute_color_stats(LodePNGColorStats* stats,
                                  const unsigned char* image, unsigned w, unsigned h,
                                  const LodePNGColorMode* mode_in);
-/*The function LodePNG uses internally to decide the PNG color with auto_convert.
+/*Computes a minimal PNG color model that can contain all colors as indicated by the stats and it settings.
-Chooses an optimal color model, e.g. grey if only grey pixels, palette if < 256 colors, ...*/
+The stats should be computed with lodepng_compute_color_stats.
+mode_in is raw color profile of the image the stats were computed on, to copy palette order from when relevant.
+Minimal PNG color model means the color type and bit depth that gives smallest amount of bits in the output image,
+e.g. gray if only grayscale pixels, palette if less than 256 colors, color key if only single transparent color, ...
+LodePNG uses this function internally if auto_convert is enabled (it is by default).
+*/
 unsigned lodepng_auto_choose_color(LodePNGColorMode* mode_out,
-                                   const unsigned char* image, unsigned w, unsigned h,
+                                   const LodePNGColorMode* mode_in,
-                                   const LodePNGColorMode* mode_in);
+                                   const LodePNGColorMode* stats);
 
 /*Settings for the encoder.*/
-typedef struct LodePNGEncoderSettings
+typedef struct LodePNGEncoderSettings {
-{
   LodePNGCompressSettings zlibsettings; /*settings for the zlib encoder, such as window size, ...*/
 
   unsigned auto_convert; /*automatically choose output PNG color type. Default: true*/
@@ -623,8 +733,7 @@ void lodepng_encoder_settings_init(LodePNGEncoderSettings* settings);
 
 #if defined(LODEPNG_COMPILE_DECODER) || defined(LODEPNG_COMPILE_ENCODER)
 /*The settings, state and information for extended encoding and decoding.*/
-typedef struct LodePNGState
+typedef struct LodePNGState {
-{
 #ifdef LODEPNG_COMPILE_DECODER
   LodePNGDecoderSettings decoder; /*the decoding settings*/
 #endif /*LODEPNG_COMPILE_DECODER*/
@@ -657,7 +766,7 @@ unsigned lodepng_decode(unsigned char** out, unsigned* w, unsigned* h,
 
 /*
 Read the PNG header, but not the actual data. This returns only the information
-that is in the header chunk of the PNG, such as width, height and color type. The
+that is in the IHDR chunk of the PNG, such as width, height and color type. The
 information is placed in the info_png field of the LodePNGState.
 */
 unsigned lodepng_inspect(unsigned* w, unsigned* h,
@@ -665,6 +774,20 @@ unsigned lodepng_inspect(unsigned* w, unsigned* h,
                          const unsigned char* in, size_t insize);
 #endif /*LODEPNG_COMPILE_DECODER*/
 
+/*
+Reads one metadata chunk (other than IHDR) of the PNG file and outputs what it
+read in the state. Returns error code on failure.
+Use lodepng_inspect first with a new state, then e.g. lodepng_chunk_find_const
+to find the desired chunk type, and if non null use lodepng_inspect_chunk (with
+chunk_pointer - start_of_file as pos).
+Supports most metadata chunks from the PNG standard (gAMA, bKGD, tEXt, ...).
+Ignores unsupported, unknown, non-metadata or IHDR chunks (without error).
+Requirements: &in[pos] must point to start of a chunk, must use regular
+lodepng_inspect first since format of most other chunks depends on IHDR, and if
+there is a PLTE chunk, that one must be inspected before tRNS or bKGD.
+*/
+unsigned lodepng_inspect_chunk(LodePNGState* state, size_t pos,
+                               const unsigned char* in, size_t insize);
 
 #ifdef LODEPNG_COMPILE_ENCODER
 /*This function allocates the out buffer with standard malloc and stores the size in *outsize.*/
@@ -678,11 +801,23 @@ The lodepng_chunk functions are normally not needed, except to traverse the
 unknown chunks stored in the LodePNGInfo struct, or add new ones to it.
 It also allows traversing the chunks of an encoded PNG file yourself.
 
-PNG standard chunk naming conventions:
+The chunk pointer always points to the beginning of the chunk itself, that is
-First byte: uppercase = critical, lowercase = ancillary
+the first byte of the 4 length bytes.
-Second byte: uppercase = public, lowercase = private
+
-Third byte: must be uppercase
+In the PNG file format, chunks have the following format:
-Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy
+-4 bytes length: length of the data of the chunk in bytes (chunk itself is 12 bytes longer)
+-4 bytes chunk type (ASCII a-z,A-Z only, see below)
+-length bytes of data (may be 0 bytes if length was 0)
+-4 bytes of CRC, computed on chunk name + data
+
+The first chunk starts at the 8th byte of the PNG file, the entire rest of the file
+exists out of concatenated chunks with the above format.
+
+PNG standard chunk ASCII naming conventions:
+-First byte: uppercase = critical, lowercase = ancillary
+-Second byte: uppercase = public, lowercase = private
+-Third byte: must be uppercase
+-Fourth byte: uppercase = unsafe to copy, lowercase = safe to copy
 */
 
 /*
@@ -717,10 +852,24 @@ unsigned lodepng_chunk_check_crc(const unsigned char* chunk);
 /*generates the correct CRC from the data and puts it in the last 4 bytes of the chunk*/
 void lodepng_chunk_generate_crc(unsigned char* chunk);
 
-/*iterate to next chunks. don't use on IEND chunk, as there is no next chunk then*/
+/*
+Iterate to next chunks, allows iterating through all chunks of the PNG file.
+Input must be at the beginning of a chunk (result of a previous lodepng_chunk_next call,
+or the 8th byte of a PNG file which always has the first chunk), or alternatively may
+point to the first byte of the PNG file (which is not a chunk but the magic header, the
+function will then skip over it and return the first real chunk).
+Expects at least 8 readable bytes of memory in the input pointer.
+Will output pointer to the start of the next chunk or the end of the file if there
+is no more chunk after this. Start this process at the 8th byte of the PNG file.
+In a non-corrupt PNG file, the last chunk should have name "IEND".
+*/
 unsigned char* lodepng_chunk_next(unsigned char* chunk);
 const unsigned char* lodepng_chunk_next_const(const unsigned char* chunk);
 
+/*Finds the first chunk with the given type in the range [chunk, end), or returns NULL if not found.*/
+unsigned char* lodepng_chunk_find(unsigned char* chunk, const unsigned char* end, const char type[5]);
+const unsigned char* lodepng_chunk_find_const(const unsigned char* chunk, const unsigned char* end, const char type[5]);
+
 /*
 Appends chunk to the data in out. The given chunk should already have its chunk header.
 The out variable and outlength are updated to reflect the new reallocated buffer.
@@ -818,11 +967,9 @@ unsigned lodepng_save_file(const unsigned char* buffer, size_t buffersize, const
 
 #ifdef LODEPNG_COMPILE_CPP
 /* The LodePNG C++ wrapper uses std::vectors instead of manually allocated memory buffers. */
-namespace lodepng
+namespace lodepng {
-{
 #ifdef LODEPNG_COMPILE_PNG
-class State : public LodePNGState
+class State : public LodePNGState {
-{
   public:
     State();
     State(const State& other);
@@ -894,16 +1041,22 @@ TODO:
 [.] test if there are no memory leaks or security exploits - done a lot but needs to be checked often
 [.] check compatibility with various compilers  - done but needs to be redone for every newer version
 [X] converting color to 16-bit per channel types
-[ ] read all public PNG chunk types (but never let the color profile and gamma ones touch RGB values)
+[X] support color profile chunk types (but never let them touch RGB values by default)
+[ ] support all public PNG chunk types (almost done except sBIT, sPLT and hIST)
 [ ] make sure encoder generates no chunks with size > (2^31)-1
 [ ] partial decoding (stream processing)
 [X] let the "isFullyOpaque" function check color keys and transparent palettes too
 [X] better name for the variables "codes", "codesD", "codelengthcodes", "clcl" and "lldl"
-[ ] don't stop decoding on errors like 69, 57, 58 (make warnings)
+[ ] allow treating some errors like warnings, when image is recoverable (e.g. 69, 57, 58)
 [ ] make warnings like: oob palette, checksum fail, data after iend, wrong/unknown crit chunk, no null terminator in text, ...
+[ ] error messages with line numbers (and version)
+[ ] errors in state instead of as return code?
+[ ] new errors/warnings like suspiciously big decompressed ztxt or iccp chunk
 [ ] let the C++ wrapper catch exceptions coming from the standard library and return LodePNG error codes
 [ ] allow user to provide custom color conversion functions, e.g. for premultiplied alpha, padding bits or not, ...
 [ ] allow user to give data (void*) to custom allocator
+[ ] provide alternatives for C library functions not present on some platforms (memcpy, ...)
+[ ] rename "grey" to "gray" everywhere since "color" also uses US spelling (keep "grey" copies for backwards compatibility)
 */
 
 #endif /*LODEPNG_H inclusion guard*/
@@ -998,8 +1151,10 @@ The following features are supported by the decoder:
 *) zlib decompression (inflate)
 *) zlib compression (deflate)
 *) CRC32 and ADLER32 checksums
+*) colorimetric color profile conversions: currently experimentally available in lodepng_util.cpp only,
+   plus alternatively ability to pass on chroma/gamma/ICC profile information to other color management system.
 *) handling of unknown chunks, allowing making a PNG editor that stores custom and unknown chunks.
-*) the following chunks are supported (generated/interpreted) by both encoder and decoder:
+*) the following chunks are supported by both encoder and decoder:
     IHDR: header information
     PLTE: color palette
     IDAT: pixel data
@@ -1011,6 +1166,10 @@ The following features are supported by the decoder:
     bKGD: suggested background color
     pHYs: physical dimensions
     tIME: modification time
+    cHRM: RGB chromaticities
+    gAMA: RGB gamma correction
+    iCCP: ICC color profile
+    sRGB: rendering intent
 
 1.2. features not supported
 ---------------------------
@@ -1019,10 +1178,10 @@ The following features are _not_ supported:
 
 *) some features needed to make a conformant PNG-Editor might be still missing.
 *) partial loading/stream processing. All data must be available and is processed in one call.
-*) The following public chunks are not supported but treated as unknown chunks by LodePNG
+*) The following public chunks are not (yet) supported but treated as unknown chunks by LodePNG:
-    cHRM, gAMA, iCCP, sRGB, sBIT, hIST, sPLT
+    sBIT
-   Some of these are not supported on purpose: LodePNG wants to provide the RGB values
+    hIST
-   stored in the pixels, not values modified by system dependent gamma or color models.
+    sPLT
 
 
 2. C and C++ version
@@ -1096,7 +1255,7 @@ LodePNGColorMode info_raw
 When decoding, here you can specify which color type you want
 the resulting raw image to be. If this is different from the colortype of the
 PNG, then the decoder will automatically convert the result. This conversion
-always works, except if you want it to convert a color PNG to greyscale or to
+always works, except if you want it to convert a color PNG to grayscale or to
 a palette with missing colors.
 
 By default, 32-bit color is used for the result.
@@ -1192,7 +1351,7 @@ can encode the colors of all pixels without information loss.
 An important thing to note about LodePNG, is that the color type of the PNG, and
 the color type of the raw image, are completely independent. By default, when
 you decode a PNG, you get the result as a raw image in the color type you want,
-no matter whether the PNG was encoded with a palette, greyscale or RGBA color.
+no matter whether the PNG was encoded with a palette, grayscale or RGBA color.
 And if you encode an image, by default LodePNG will automatically choose the PNG
 color type that gives good compression based on the values of colors and amount
 of colors in the image. It can be configured to let you control it instead as
@@ -1200,10 +1359,10 @@ well, though.
 
 To be able to do this, LodePNG does conversions from one color mode to another.
 It can convert from almost any color type to any other color type, except the
-following conversions: RGB to greyscale is not supported, and converting to a
+following conversions: RGB to grayscale is not supported, and converting to a
 palette when the palette doesn't have a required color is not supported. This is
 not supported on purpose: this is information loss which requires a color
-reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to grey
+reduction algorithm that is beyong the scope of a PNG encoder (yes, RGB to gray
 is easy, but there are multiple ways if you want to give some channels more
 weight).
 
@@ -1224,10 +1383,10 @@ decoding to have another color type, a conversion is done by LodePNG.
 
 The PNG specification gives the following color types:
 
-0: greyscale, bit depths 1, 2, 4, 8, 16
+0: grayscale, bit depths 1, 2, 4, 8, 16
 2: RGB, bit depths 8 and 16
 3: palette, bit depths 1, 2, 4 and 8
-4: greyscale with alpha, bit depths 8 and 16
+4: grayscale with alpha, bit depths 8 and 16
 6: RGBA, bit depths 8 and 16
 
 Bit depth is the amount of bits per pixel per color channel. So the total amount
@@ -1276,15 +1435,22 @@ To avoid some confusion:
  the raw image correctly before encoding.
 -both encoder and decoder use the same color converter.
 
+The function lodepng_convert does the color conversion. It is available in the
+interface but normally isn't needed since the encoder and decoder already call
+it.
+
 Non supported color conversions:
--color to greyscale: no error is thrown, but the result will look ugly because
+-color to grayscale when non-gray pixels are present: no error is thrown, but
-only the red channel is taken
+the result will look ugly because only the red channel is taken (it assumes all
--anything to palette when that palette does not have that color in it: in this
+three channels are the same in this case so ignores green and blue). The reason
-case an error is thrown
+no error is given is to allow converting from three-channel grayscale images to
+one-channel even if there are numerical imprecisions.
+-anything to palette when the palette does not have an exact match for a from-color
+in it: in this case an error is thrown
 
 Supported color conversions:
 -anything to 8-bit RGB, 8-bit RGBA, 16-bit RGB, 16-bit RGBA
--any grey or grey+alpha, to grey or grey+alpha
+-any gray or gray+alpha, to gray or gray+alpha
 -anything to a palette, as long as the palette has the requested colors in it
 -removing alpha channel
 -higher to smaller bitdepth, and vice versa
@@ -1297,10 +1463,6 @@ false.
 as the PNG has, by setting the color_convert setting to false. Settings in
 info_raw are then ignored.
 
-The function lodepng_convert does the color conversion. It is available in the
-interface but normally isn't needed since the encoder and decoder already call
-it.
-
 6.3. padding bits
 -----------------
 
@@ -1524,8 +1686,7 @@ examples can be found on the LodePNG website.
 #include "lodepng.h"
 #include <iostream>
 
-int main(int argc, char *argv[])
+int main(int argc, char *argv[]) {
-{
   const char* filename = argc > 1 ? argv[1] : "test.png";
 
   //load and decode
@@ -1544,8 +1705,7 @@ int main(int argc, char *argv[])
 
 #include "lodepng.h"
 
-int main(int argc, char *argv[])
+int main(int argc, char *argv[]) {
-{
   unsigned error;
   unsigned char* image;
   size_t width, height;
@@ -1614,6 +1774,15 @@ yyyymmdd.
 Some changes aren't backwards compatible. Those are indicated with a (!)
 symbol.
 
+*) 15 jun 2019 (!): auto_choose_color API changed (for bugfix: don't use palette
+   if ICC profile) and non-ICC LodePNGColorProfile renamed to LodePNGColorStats.
+*) 30 dec 2018: code style changes only: removed newlines before opening braces.
+*) 10 sep 2018: added way to inspect metadata chunks without full decoding.
+*) 19 aug 2018 (!): fixed color mode bKGD is encoded with and made it use
+   palette index in case of palette.
+*) 10 aug 2018 (!): added support for gAMA, cHRM, sRGB and iCCP chunks. This
+   change is backwards compatible unless you relied on unknown_chunks for those.
+*) 11 jun 2018: less restrictive check for pixel size integer overflow
 *) 14 jan 2018: allow optionally ignoring a few more recoverable errors
 *) 17 sep 2017: fix memory leak for some encoder input error cases
 *) 27 nov 2016: grey+alpha auto color model detection bugfix
@@ -1765,5 +1934,5 @@ Domain: gmail dot com.
 Account: lode dot vandevenne.
 
 
-Copyright (c) 2005-2017 Lode Vandevenne
+Copyright (c) 2005-2019 Lode Vandevenne
 */