From 3fc743ce2831c77e0ac948e5cdd9c0911c36c9f2 Mon Sep 17 00:00:00 2001 From: cosmonaut Date: Tue, 4 Apr 2023 00:14:20 +0000 Subject: [PATCH] Add support for QOI format and reading images from memory (#39) Reviewed-on: https://gitea.moonside.games/MoonsideGames/Refresh/pulls/39 --- include/Refresh_Image.h | 81 ++++- src/Refresh_Image.c | 74 ++++- src/qoi.h | 649 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 792 insertions(+), 12 deletions(-) create mode 100644 src/qoi.h diff --git a/include/Refresh_Image.h b/include/Refresh_Image.h index c3240eb..b887cad 100644 --- a/include/Refresh_Image.h +++ b/include/Refresh_Image.h @@ -51,20 +51,77 @@ extern "C" { * numChannels: Filled with the number of channels in the image. * * Returns a block of memory suitable for use with Refresh_SetTextureData2D. - * Be sure to free the memory with Refresh_Image_Free after use! + * Be sure to free the memory with Refresh_Image_FreePNG after use! */ -REFRESHAPI uint8_t* Refresh_Image_Load( +REFRESHAPI uint8_t* Refresh_Image_LoadPNGFromFile( char const *filename, int32_t *w, int32_t *h, int32_t *numChannels ); -/* Frees memory returned by Refresh_Image_Load. (Do NOT free the memory yourself!) +/* Decodes PNG data into raw RGBA8 texture data. * - * mem: A pointer previously returned by Refresh_Image_Load. + * w: Filled with the width of the image. + * h: Filled with the height of the image. + * numChannels: Filled with the number of channels in the image. + * + * Returns a block of memory suitable for use with Refresh_SetTextureData2D. + * Be sure to free the memory with Refresh_Image_FreePNG after use! */ -REFRESHAPI void Refresh_Image_Free(uint8_t *mem); +REFRESHAPI uint8_t* Refresh_Image_LoadPNGFromMemory( + uint8_t *buffer, + int32_t bufferLength, + int32_t *w, + int32_t *h, + int32_t *numChannels +); + +/* Frees memory returned by Refresh_Image_LoadPNG functions. (Do NOT free the memory yourself!) + * + * mem: A pointer previously returned by Refresh_Image_LoadPNG. + */ +REFRESHAPI void Refresh_Image_FreePNG(uint8_t *mem); + +/* Decodes QOI data into raw RGBA8 texture data. + * + * w: Filled with the width of the image. + * h: Filled with the height of the image. + * numChannels: Filled with the number of channels in the image. + * + * Returns a block of memory suitable for use with Refresh_SetTextureData2D. + * Be sure to free the memory with Refresh_Image_FreeQOI after use! + */ +REFRESHAPI uint8_t* Refresh_Image_LoadQOIFromFile( + char const *filename, + int32_t *w, + int32_t *h, + int32_t *numChannels +); + +/* Decodes QOI data into raw RGBA8 texture data. + * + * bufferLength: The length of the input buffer to be decoded. + * w: Filled with the width of the image. + * h: Filled with the height of the image. + * numChannels: Filled with the number of channels in the image. + * + * Returns a block of memory suitable for use with Refresh_SetTextureData2D. + * Be sure to free the memory with Refresh_Image_FreeQOI after use! + */ +REFRESHAPI uint8_t* Refresh_Image_LoadQOIFromMemory( + uint8_t *buffer, + int32_t bufferLength, + int32_t *w, + int32_t *h, + int32_t *numChannels +); + +/* Frees memory returned by Refresh_Image_LoadQOI functions. (Do NOT free the memory yourself!) + * + * mem: A pointer previously returned by Refresh_Image_LoadQOI. + */ +REFRESHAPI void Refresh_Image_FreeQOI(uint8_t *mem); /* Image Write API */ @@ -84,6 +141,20 @@ REFRESHAPI void Refresh_Image_SavePNG( uint8_t *data ); +/* Encodes 32-bit color data into PNG data. + * + * filename: The filename that the image will be written to. + * w: The width of the PNG data. + * h: The height of the PNG data. + * data: The raw color data. + */ +REFRESHAPI void Refresh_Image_SaveQOI( + char const *filename, + int32_t w, + int32_t h, + uint8_t *data +); + #ifdef __cplusplus } #endif /* __cplusplus */ diff --git a/src/Refresh_Image.c b/src/Refresh_Image.c index 950a0e1..64ed264 100644 --- a/src/Refresh_Image.c +++ b/src/Refresh_Image.c @@ -48,7 +48,6 @@ #define floorf SDL_floorf #define ldexp SDL_scalbn #define pow SDL_pow -#define strtol SDL_strtol #ifdef memcmp #undef memcmp @@ -74,10 +73,6 @@ #undef strlen #endif #define strlen SDL_strlen -#ifdef strncmp -#undef strncmp -#endif -#define strncmp SDL_strncmp /* These are per the Texture2D.FromStream spec */ #define STBI_ONLY_PNG @@ -140,6 +135,7 @@ SDL_SIMDRealloc(void *mem, const size_t len) #endif #define STB_IMAGE_STATIC +#define STBI_NO_HDR #define STBI_ASSERT SDL_assert #define STBI_MALLOC SDL_SIMDAlloc #define STBI_REALLOC SDL_SIMDRealloc @@ -150,6 +146,12 @@ SDL_SIMDRealloc(void *mem, const size_t len) #endif #include "stb_image.h" +#define QOI_IMPLEMENTATION +#define QOI_MALLOC SDL_SIMDAlloc +#define QOI_FREE SDL_SIMDFree +#define QOI_ZEROARR SDL_zero +#include "qoi.h" + #define MINIZ_NO_STDIO #define MINIZ_NO_TIME #define MINIZ_SDL_MALLOC @@ -189,7 +191,7 @@ static unsigned char* dgibson_stbi_zlib_compress( /* Image Read API */ -uint8_t* Refresh_Image_Load( +uint8_t* Refresh_Image_LoadPNGFromFile( char const *filename, int32_t *w, int32_t *h, @@ -198,11 +200,55 @@ uint8_t* Refresh_Image_Load( return stbi_load(filename, w, h, numChannels, STBI_rgb_alpha); } -void Refresh_Image_Free(uint8_t *mem) +uint8_t* Refresh_Image_LoadPNGFromMemory( + uint8_t *buffer, + int32_t bufferLength, + int32_t *w, + int32_t *h, + int32_t *numChannels +) { + return stbi_load_from_memory(buffer, bufferLength, w, h, numChannels, STBI_rgb_alpha); +} + +void Refresh_Image_FreePNG(uint8_t *mem) { stbi_image_free(mem); } +uint8_t *Refresh_Image_LoadQOIFromFile( + char const *filename, + int32_t *w, + int32_t *h, + int32_t *numChannels +) { + qoi_desc desc; + uint8_t *pixels = qoi_read(filename, &desc, 0); + *w = desc.width; + *h = desc.height; + *numChannels = desc.channels; + return pixels; +} + +uint8_t* Refresh_Image_LoadQOIFromMemory( + uint8_t *buffer, + int32_t bufferLength, + int32_t *w, + int32_t *h, + int32_t *numChannels +) { + qoi_desc desc; + uint8_t *pixels = qoi_decode(buffer, bufferLength, &desc, 0); + *w = desc.width; + *h = desc.height; + *numChannels = desc.channels; + return pixels; +} + +void Refresh_Image_FreeQOI(uint8_t *mem) +{ + QOI_FREE(mem); +} + /* Image Write API */ void Refresh_Image_SavePNG( @@ -237,4 +283,18 @@ void Refresh_Image_SavePNG( } } +void Refresh_Image_SaveQOI( + char const *filename, + int32_t w, + int32_t h, + uint8_t *data +) { + qoi_desc desc; + desc.width = w; + desc.height = h; + desc.channels = 4; + desc.colorspace = QOI_LINEAR; + qoi_write(filename, data, &desc); +} + /* vim: set noexpandtab shiftwidth=8 tabstop=8: */ diff --git a/src/qoi.h b/src/qoi.h new file mode 100644 index 0000000..95ad186 --- /dev/null +++ b/src/qoi.h @@ -0,0 +1,649 @@ +/* + +Copyright (c) 2021, Dominic Szablewski - https://phoboslab.org +SPDX-License-Identifier: MIT + + +QOI - The "Quite OK Image" format for fast, lossless image compression + +-- About + +QOI encodes and decodes images in a lossless format. Compared to stb_image and +stb_image_write QOI offers 20x-50x faster encoding, 3x-4x faster decoding and +20% better compression. + + +-- Synopsis + +// Define `QOI_IMPLEMENTATION` in *one* C/C++ file before including this +// library to create the implementation. + +#define QOI_IMPLEMENTATION +#include "qoi.h" + +// Encode and store an RGBA buffer to the file system. The qoi_desc describes +// the input pixel data. +qoi_write("image_new.qoi", rgba_pixels, &(qoi_desc){ + .width = 1920, + .height = 1080, + .channels = 4, + .colorspace = QOI_SRGB +}); + +// Load and decode a QOI image from the file system into a 32bbp RGBA buffer. +// The qoi_desc struct will be filled with the width, height, number of channels +// and colorspace read from the file header. +qoi_desc desc; +void *rgba_pixels = qoi_read("image.qoi", &desc, 4); + + + +-- Documentation + +This library provides the following functions; +- qoi_read -- read and decode a QOI file +- qoi_decode -- decode the raw bytes of a QOI image from memory +- qoi_write -- encode and write a QOI file +- qoi_encode -- encode an rgba buffer into a QOI image in memory + +See the function declaration below for the signature and more information. + +If you don't want/need the qoi_read and qoi_write functions, you can define +QOI_NO_STDIO before including this library. + +This library uses malloc() and free(). To supply your own malloc implementation +you can define QOI_MALLOC and QOI_FREE before including this library. + +This library uses memset() to zero-initialize the index. To supply your own +implementation you can define QOI_ZEROARR before including this library. + + +-- Data Format + +A QOI file has a 14 byte header, followed by any number of data "chunks" and an +8-byte end marker. + +struct qoi_header_t { + char magic[4]; // magic bytes "qoif" + uint32_t width; // image width in pixels (BE) + uint32_t height; // image height in pixels (BE) + uint8_t channels; // 3 = RGB, 4 = RGBA + uint8_t colorspace; // 0 = sRGB with linear alpha, 1 = all channels linear +}; + +Images are encoded row by row, left to right, top to bottom. The decoder and +encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous pixel value. An +image is complete when all pixels specified by width * height have been covered. + +Pixels are encoded as + - a run of the previous pixel + - an index into an array of previously seen pixels + - a difference to the previous pixel value in r,g,b + - full r,g,b or r,g,b,a values + +The color channels are assumed to not be premultiplied with the alpha channel +("un-premultiplied alpha"). + +A running array[64] (zero-initialized) of previously seen pixel values is +maintained by the encoder and decoder. Each pixel that is seen by the encoder +and decoder is put into this array at the position formed by a hash function of +the color value. In the encoder, if the pixel value at the index matches the +current pixel, this index position is written to the stream as QOI_OP_INDEX. +The hash function for the index is: + + index_position = (r * 3 + g * 5 + b * 7 + a * 11) % 64 + +Each chunk starts with a 2- or 8-bit tag, followed by a number of data bits. The +bit length of chunks is divisible by 8 - i.e. all chunks are byte aligned. All +values encoded in these data bits have the most significant bit on the left. + +The 8-bit tags have precedence over the 2-bit tags. A decoder must check for the +presence of an 8-bit tag first. + +The byte stream's end is marked with 7 0x00 bytes followed a single 0x01 byte. + + +The possible chunks are: + + +.- QOI_OP_INDEX ----------. +| Byte[0] | +| 7 6 5 4 3 2 1 0 | +|-------+-----------------| +| 0 0 | index | +`-------------------------` +2-bit tag b00 +6-bit index into the color index array: 0..63 + +A valid encoder must not issue 2 or more consecutive QOI_OP_INDEX chunks to the +same index. QOI_OP_RUN should be used instead. + + +.- QOI_OP_DIFF -----------. +| Byte[0] | +| 7 6 5 4 3 2 1 0 | +|-------+-----+-----+-----| +| 0 1 | dr | dg | db | +`-------------------------` +2-bit tag b01 +2-bit red channel difference from the previous pixel between -2..1 +2-bit green channel difference from the previous pixel between -2..1 +2-bit blue channel difference from the previous pixel between -2..1 + +The difference to the current channel values are using a wraparound operation, +so "1 - 2" will result in 255, while "255 + 1" will result in 0. + +Values are stored as unsigned integers with a bias of 2. E.g. -2 is stored as +0 (b00). 1 is stored as 3 (b11). + +The alpha value remains unchanged from the previous pixel. + + +.- QOI_OP_LUMA -------------------------------------. +| Byte[0] | Byte[1] | +| 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 | +|-------+-----------------+-------------+-----------| +| 1 0 | green diff | dr - dg | db - dg | +`---------------------------------------------------` +2-bit tag b10 +6-bit green channel difference from the previous pixel -32..31 +4-bit red channel difference minus green channel difference -8..7 +4-bit blue channel difference minus green channel difference -8..7 + +The green channel is used to indicate the general direction of change and is +encoded in 6 bits. The red and blue channels (dr and db) base their diffs off +of the green channel difference and are encoded in 4 bits. I.e.: + dr_dg = (cur_px.r - prev_px.r) - (cur_px.g - prev_px.g) + db_dg = (cur_px.b - prev_px.b) - (cur_px.g - prev_px.g) + +The difference to the current channel values are using a wraparound operation, +so "10 - 13" will result in 253, while "250 + 7" will result in 1. + +Values are stored as unsigned integers with a bias of 32 for the green channel +and a bias of 8 for the red and blue channel. + +The alpha value remains unchanged from the previous pixel. + + +.- QOI_OP_RUN ------------. +| Byte[0] | +| 7 6 5 4 3 2 1 0 | +|-------+-----------------| +| 1 1 | run | +`-------------------------` +2-bit tag b11 +6-bit run-length repeating the previous pixel: 1..62 + +The run-length is stored with a bias of -1. Note that the run-lengths 63 and 64 +(b111110 and b111111) are illegal as they are occupied by the QOI_OP_RGB and +QOI_OP_RGBA tags. + + +.- QOI_OP_RGB ------------------------------------------. +| Byte[0] | Byte[1] | Byte[2] | Byte[3] | +| 7 6 5 4 3 2 1 0 | 7 .. 0 | 7 .. 0 | 7 .. 0 | +|-------------------------+---------+---------+---------| +| 1 1 1 1 1 1 1 0 | red | green | blue | +`-------------------------------------------------------` +8-bit tag b11111110 +8-bit red channel value +8-bit green channel value +8-bit blue channel value + +The alpha value remains unchanged from the previous pixel. + + +.- QOI_OP_RGBA ---------------------------------------------------. +| Byte[0] | Byte[1] | Byte[2] | Byte[3] | Byte[4] | +| 7 6 5 4 3 2 1 0 | 7 .. 0 | 7 .. 0 | 7 .. 0 | 7 .. 0 | +|-------------------------+---------+---------+---------+---------| +| 1 1 1 1 1 1 1 1 | red | green | blue | alpha | +`-----------------------------------------------------------------` +8-bit tag b11111111 +8-bit red channel value +8-bit green channel value +8-bit blue channel value +8-bit alpha channel value + +*/ + + +/* ----------------------------------------------------------------------------- +Header - Public functions */ + +#ifndef QOI_H +#define QOI_H + +#ifdef __cplusplus +extern "C" { +#endif + +/* A pointer to a qoi_desc struct has to be supplied to all of qoi's functions. +It describes either the input format (for qoi_write and qoi_encode), or is +filled with the description read from the file header (for qoi_read and +qoi_decode). + +The colorspace in this qoi_desc is an enum where + 0 = sRGB, i.e. gamma scaled RGB channels and a linear alpha channel + 1 = all channels are linear +You may use the constants QOI_SRGB or QOI_LINEAR. The colorspace is purely +informative. It will be saved to the file header, but does not affect +how chunks are en-/decoded. */ + +#define QOI_SRGB 0 +#define QOI_LINEAR 1 + +typedef struct { + unsigned int width; + unsigned int height; + unsigned char channels; + unsigned char colorspace; +} qoi_desc; + +#ifndef QOI_NO_STDIO + +/* Encode raw RGB or RGBA pixels into a QOI image and write it to the file +system. The qoi_desc struct must be filled with the image width, height, +number of channels (3 = RGB, 4 = RGBA) and the colorspace. + +The function returns 0 on failure (invalid parameters, or fopen or malloc +failed) or the number of bytes written on success. */ + +int qoi_write(const char *filename, const void *data, const qoi_desc *desc); + + +/* Read and decode a QOI image from the file system. If channels is 0, the +number of channels from the file header is used. If channels is 3 or 4 the +output format will be forced into this number of channels. + +The function either returns NULL on failure (invalid data, or malloc or fopen +failed) or a pointer to the decoded pixels. On success, the qoi_desc struct +will be filled with the description from the file header. + +The returned pixel data should be free()d after use. */ + +void *qoi_read(const char *filename, qoi_desc *desc, int channels); + +#endif /* QOI_NO_STDIO */ + + +/* Encode raw RGB or RGBA pixels into a QOI image in memory. + +The function either returns NULL on failure (invalid parameters or malloc +failed) or a pointer to the encoded data on success. On success the out_len +is set to the size in bytes of the encoded data. + +The returned qoi data should be free()d after use. */ + +void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len); + + +/* Decode a QOI image from memory. + +The function either returns NULL on failure (invalid parameters or malloc +failed) or a pointer to the decoded pixels. On success, the qoi_desc struct +is filled with the description from the file header. + +The returned pixel data should be free()d after use. */ + +void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels); + + +#ifdef __cplusplus +} +#endif +#endif /* QOI_H */ + + +/* ----------------------------------------------------------------------------- +Implementation */ + +#ifdef QOI_IMPLEMENTATION +#include +#include + +#ifndef QOI_MALLOC + #define QOI_MALLOC(sz) malloc(sz) + #define QOI_FREE(p) free(p) +#endif +#ifndef QOI_ZEROARR + #define QOI_ZEROARR(a) memset((a),0,sizeof(a)) +#endif + +#define QOI_OP_INDEX 0x00 /* 00xxxxxx */ +#define QOI_OP_DIFF 0x40 /* 01xxxxxx */ +#define QOI_OP_LUMA 0x80 /* 10xxxxxx */ +#define QOI_OP_RUN 0xc0 /* 11xxxxxx */ +#define QOI_OP_RGB 0xfe /* 11111110 */ +#define QOI_OP_RGBA 0xff /* 11111111 */ + +#define QOI_MASK_2 0xc0 /* 11000000 */ + +#define QOI_COLOR_HASH(C) (C.rgba.r*3 + C.rgba.g*5 + C.rgba.b*7 + C.rgba.a*11) +#define QOI_MAGIC \ + (((unsigned int)'q') << 24 | ((unsigned int)'o') << 16 | \ + ((unsigned int)'i') << 8 | ((unsigned int)'f')) +#define QOI_HEADER_SIZE 14 + +/* 2GB is the max file size that this implementation can safely handle. We guard +against anything larger than that, assuming the worst case with 5 bytes per +pixel, rounded down to a nice clean value. 400 million pixels ought to be +enough for anybody. */ +#define QOI_PIXELS_MAX ((unsigned int)400000000) + +typedef union { + struct { unsigned char r, g, b, a; } rgba; + unsigned int v; +} qoi_rgba_t; + +static const unsigned char qoi_padding[8] = {0,0,0,0,0,0,0,1}; + +static void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) { + bytes[(*p)++] = (0xff000000 & v) >> 24; + bytes[(*p)++] = (0x00ff0000 & v) >> 16; + bytes[(*p)++] = (0x0000ff00 & v) >> 8; + bytes[(*p)++] = (0x000000ff & v); +} + +static unsigned int qoi_read_32(const unsigned char *bytes, int *p) { + unsigned int a = bytes[(*p)++]; + unsigned int b = bytes[(*p)++]; + unsigned int c = bytes[(*p)++]; + unsigned int d = bytes[(*p)++]; + return a << 24 | b << 16 | c << 8 | d; +} + +void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) { + int i, max_size, p, run; + int px_len, px_end, px_pos, channels; + unsigned char *bytes; + const unsigned char *pixels; + qoi_rgba_t index[64]; + qoi_rgba_t px, px_prev; + + if ( + data == NULL || out_len == NULL || desc == NULL || + desc->width == 0 || desc->height == 0 || + desc->channels < 3 || desc->channels > 4 || + desc->colorspace > 1 || + desc->height >= QOI_PIXELS_MAX / desc->width + ) { + return NULL; + } + + max_size = + desc->width * desc->height * (desc->channels + 1) + + QOI_HEADER_SIZE + sizeof(qoi_padding); + + p = 0; + bytes = (unsigned char *) QOI_MALLOC(max_size); + if (!bytes) { + return NULL; + } + + qoi_write_32(bytes, &p, QOI_MAGIC); + qoi_write_32(bytes, &p, desc->width); + qoi_write_32(bytes, &p, desc->height); + bytes[p++] = desc->channels; + bytes[p++] = desc->colorspace; + + + pixels = (const unsigned char *)data; + + QOI_ZEROARR(index); + + run = 0; + px_prev.rgba.r = 0; + px_prev.rgba.g = 0; + px_prev.rgba.b = 0; + px_prev.rgba.a = 255; + px = px_prev; + + px_len = desc->width * desc->height * desc->channels; + px_end = px_len - desc->channels; + channels = desc->channels; + + for (px_pos = 0; px_pos < px_len; px_pos += channels) { + px.rgba.r = pixels[px_pos + 0]; + px.rgba.g = pixels[px_pos + 1]; + px.rgba.b = pixels[px_pos + 2]; + + if (channels == 4) { + px.rgba.a = pixels[px_pos + 3]; + } + + if (px.v == px_prev.v) { + run++; + if (run == 62 || px_pos == px_end) { + bytes[p++] = QOI_OP_RUN | (run - 1); + run = 0; + } + } + else { + int index_pos; + + if (run > 0) { + bytes[p++] = QOI_OP_RUN | (run - 1); + run = 0; + } + + index_pos = QOI_COLOR_HASH(px) % 64; + + if (index[index_pos].v == px.v) { + bytes[p++] = QOI_OP_INDEX | index_pos; + } + else { + index[index_pos] = px; + + if (px.rgba.a == px_prev.rgba.a) { + signed char vr = px.rgba.r - px_prev.rgba.r; + signed char vg = px.rgba.g - px_prev.rgba.g; + signed char vb = px.rgba.b - px_prev.rgba.b; + + signed char vg_r = vr - vg; + signed char vg_b = vb - vg; + + if ( + vr > -3 && vr < 2 && + vg > -3 && vg < 2 && + vb > -3 && vb < 2 + ) { + bytes[p++] = QOI_OP_DIFF | (vr + 2) << 4 | (vg + 2) << 2 | (vb + 2); + } + else if ( + vg_r > -9 && vg_r < 8 && + vg > -33 && vg < 32 && + vg_b > -9 && vg_b < 8 + ) { + bytes[p++] = QOI_OP_LUMA | (vg + 32); + bytes[p++] = (vg_r + 8) << 4 | (vg_b + 8); + } + else { + bytes[p++] = QOI_OP_RGB; + bytes[p++] = px.rgba.r; + bytes[p++] = px.rgba.g; + bytes[p++] = px.rgba.b; + } + } + else { + bytes[p++] = QOI_OP_RGBA; + bytes[p++] = px.rgba.r; + bytes[p++] = px.rgba.g; + bytes[p++] = px.rgba.b; + bytes[p++] = px.rgba.a; + } + } + } + px_prev = px; + } + + for (i = 0; i < (int)sizeof(qoi_padding); i++) { + bytes[p++] = qoi_padding[i]; + } + + *out_len = p; + return bytes; +} + +void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) { + const unsigned char *bytes; + unsigned int header_magic; + unsigned char *pixels; + qoi_rgba_t index[64]; + qoi_rgba_t px; + int px_len, chunks_len, px_pos; + int p = 0, run = 0; + + if ( + data == NULL || desc == NULL || + (channels != 0 && channels != 3 && channels != 4) || + size < QOI_HEADER_SIZE + (int)sizeof(qoi_padding) + ) { + return NULL; + } + + bytes = (const unsigned char *)data; + + header_magic = qoi_read_32(bytes, &p); + desc->width = qoi_read_32(bytes, &p); + desc->height = qoi_read_32(bytes, &p); + desc->channels = bytes[p++]; + desc->colorspace = bytes[p++]; + + if ( + desc->width == 0 || desc->height == 0 || + desc->channels < 3 || desc->channels > 4 || + desc->colorspace > 1 || + header_magic != QOI_MAGIC || + desc->height >= QOI_PIXELS_MAX / desc->width + ) { + return NULL; + } + + if (channels == 0) { + channels = desc->channels; + } + + px_len = desc->width * desc->height * channels; + pixels = (unsigned char *) QOI_MALLOC(px_len); + if (!pixels) { + return NULL; + } + + QOI_ZEROARR(index); + px.rgba.r = 0; + px.rgba.g = 0; + px.rgba.b = 0; + px.rgba.a = 255; + + chunks_len = size - (int)sizeof(qoi_padding); + for (px_pos = 0; px_pos < px_len; px_pos += channels) { + if (run > 0) { + run--; + } + else if (p < chunks_len) { + int b1 = bytes[p++]; + + if (b1 == QOI_OP_RGB) { + px.rgba.r = bytes[p++]; + px.rgba.g = bytes[p++]; + px.rgba.b = bytes[p++]; + } + else if (b1 == QOI_OP_RGBA) { + px.rgba.r = bytes[p++]; + px.rgba.g = bytes[p++]; + px.rgba.b = bytes[p++]; + px.rgba.a = bytes[p++]; + } + else if ((b1 & QOI_MASK_2) == QOI_OP_INDEX) { + px = index[b1]; + } + else if ((b1 & QOI_MASK_2) == QOI_OP_DIFF) { + px.rgba.r += ((b1 >> 4) & 0x03) - 2; + px.rgba.g += ((b1 >> 2) & 0x03) - 2; + px.rgba.b += ( b1 & 0x03) - 2; + } + else if ((b1 & QOI_MASK_2) == QOI_OP_LUMA) { + int b2 = bytes[p++]; + int vg = (b1 & 0x3f) - 32; + px.rgba.r += vg - 8 + ((b2 >> 4) & 0x0f); + px.rgba.g += vg; + px.rgba.b += vg - 8 + (b2 & 0x0f); + } + else if ((b1 & QOI_MASK_2) == QOI_OP_RUN) { + run = (b1 & 0x3f); + } + + index[QOI_COLOR_HASH(px) % 64] = px; + } + + pixels[px_pos + 0] = px.rgba.r; + pixels[px_pos + 1] = px.rgba.g; + pixels[px_pos + 2] = px.rgba.b; + + if (channels == 4) { + pixels[px_pos + 3] = px.rgba.a; + } + } + + return pixels; +} + +#ifndef QOI_NO_STDIO +#include + +int qoi_write(const char *filename, const void *data, const qoi_desc *desc) { + FILE *f = fopen(filename, "wb"); + int size; + void *encoded; + + if (!f) { + return 0; + } + + encoded = qoi_encode(data, desc, &size); + if (!encoded) { + fclose(f); + return 0; + } + + fwrite(encoded, 1, size, f); + fclose(f); + + QOI_FREE(encoded); + return size; +} + +void *qoi_read(const char *filename, qoi_desc *desc, int channels) { + FILE *f = fopen(filename, "rb"); + int size, bytes_read; + void *pixels, *data; + + if (!f) { + return NULL; + } + + fseek(f, 0, SEEK_END); + size = ftell(f); + if (size <= 0) { + fclose(f); + return NULL; + } + fseek(f, 0, SEEK_SET); + + data = QOI_MALLOC(size); + if (!data) { + fclose(f); + return NULL; + } + + bytes_read = fread(data, 1, size, f); + fclose(f); + + pixels = qoi_decode(data, bytes_read, desc, channels); + QOI_FREE(data); + return pixels; +} + +#endif /* QOI_NO_STDIO */ +#endif /* QOI_IMPLEMENTATION */