718 lines
34 KiB
C
718 lines
34 KiB
C
/*
|
|
HOW TO USE:
|
|
|
|
In exactly one translation unit (.c or .cpp file), #define MSF_GIF_IMPL before including the header, like so:
|
|
|
|
#define MSF_GIF_IMPL
|
|
#include "msf_gif.h"
|
|
|
|
Everywhere else, just include the header like normal.
|
|
|
|
|
|
USAGE EXAMPLE:
|
|
|
|
int width = 480, height = 320, centisecondsPerFrame = 5, bitDepth = 16;
|
|
MsfGifState gifState = {};
|
|
// msf_gif_bgra_flag = true; //optionally, set this flag if your pixels are in BGRA format instead of RGBA
|
|
// msf_gif_alpha_threshold = 128; //optionally, enable transparency (see function documentation below for details)
|
|
msf_gif_begin(&gifState, width, height);
|
|
msf_gif_frame(&gifState, ..., centisecondsPerFrame, bitDepth, width * 4); //frame 1
|
|
msf_gif_frame(&gifState, ..., centisecondsPerFrame, bitDepth, width * 4); //frame 2
|
|
msf_gif_frame(&gifState, ..., centisecondsPerFrame, bitDepth, width * 4); //frame 3, etc...
|
|
MsfGifResult result = msf_gif_end(&gifState);
|
|
if (result.data) {
|
|
FILE * fp = fopen("MyGif.gif", "wb");
|
|
fwrite(result.data, result.dataSize, 1, fp);
|
|
fclose(fp);
|
|
}
|
|
msf_gif_free(result);
|
|
|
|
Detailed function documentation can be found in the header section below.
|
|
|
|
|
|
ERROR HANDLING:
|
|
|
|
If memory allocation fails, the functions will signal the error via their return values.
|
|
If one function call fails, the library will free all of its allocations,
|
|
and all subsequent calls will safely no-op and return 0 until the next call to `msf_gif_begin()`.
|
|
Therefore, it's safe to check only the return value of `msf_gif_end()`.
|
|
|
|
|
|
REPLACING MALLOC:
|
|
|
|
This library uses malloc+realloc+free internally for memory allocation.
|
|
To facilitate integration with custom memory allocators, these calls go through macros, which can be redefined.
|
|
The expected function signature equivalents of the macros are as follows:
|
|
|
|
void * MSF_GIF_MALLOC(void * context, size_t newSize)
|
|
void * MSF_GIF_REALLOC(void * context, void * oldMemory, size_t oldSize, size_t newSize)
|
|
void MSF_GIF_FREE(void * context, void * oldMemory, size_t oldSize)
|
|
|
|
If your allocator needs a context pointer, you can set the `customAllocatorContext` field of the MsfGifState struct
|
|
before calling msf_gif_begin(), and it will be passed to all subsequent allocator macro calls.
|
|
|
|
The maximum number of bytes the library will allocate to encode a single gif is bounded by the following formula:
|
|
`(2 * 1024 * 1024) + (width * height * 8) + ((1024 + width * height * 1.5) * 3 * frameCount)`
|
|
The peak heap memory usage in bytes, if using a general-purpose heap allocator, is bounded by the following formula:
|
|
`(2 * 1024 * 1024) + (width * height * 9.5) + 1024 + (16 * frameCount) + (2 * sizeOfResultingGif)
|
|
|
|
|
|
See end of file for license information.
|
|
*/
|
|
|
|
//version 2.2
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
/// HEADER ///
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef MSF_GIF_H
|
|
#define MSF_GIF_H
|
|
|
|
#include <stdint.h>
|
|
#include <stddef.h>
|
|
|
|
typedef struct {
|
|
void * data;
|
|
size_t dataSize;
|
|
|
|
size_t allocSize; //internal use
|
|
void * contextPointer; //internal use
|
|
} MsfGifResult;
|
|
|
|
typedef struct { //internal use
|
|
uint32_t * pixels;
|
|
int depth, count, rbits, gbits, bbits;
|
|
} MsfCookedFrame;
|
|
|
|
typedef struct MsfGifBuffer {
|
|
struct MsfGifBuffer * next;
|
|
size_t size;
|
|
uint8_t data[1];
|
|
} MsfGifBuffer;
|
|
|
|
typedef size_t (* MsfGifFileWriteFunc) (const void * buffer, size_t size, size_t count, void * stream);
|
|
typedef struct {
|
|
MsfGifFileWriteFunc fileWriteFunc;
|
|
void * fileWriteData;
|
|
MsfCookedFrame previousFrame;
|
|
MsfCookedFrame currentFrame;
|
|
int16_t * lzwMem;
|
|
MsfGifBuffer * listHead;
|
|
MsfGifBuffer * listTail;
|
|
int width, height;
|
|
void * customAllocatorContext;
|
|
int framesSubmitted; //needed for transparency to work correctly (because we reach into the previous frame)
|
|
} MsfGifState;
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif //__cplusplus
|
|
|
|
/**
|
|
* @param width Image width in pixels.
|
|
* @param height Image height in pixels.
|
|
* @return Non-zero on success, 0 on error.
|
|
*/
|
|
int msf_gif_begin(MsfGifState * handle, int width, int height);
|
|
|
|
/**
|
|
* @param pixelData Pointer to raw framebuffer data. Rows must be contiguous in memory, in RGBA8 format
|
|
* (or BGRA8 if you have set `msf_gif_bgra_flag = true`).
|
|
* Note: This function does NOT free `pixelData`. You must free it yourself afterwards.
|
|
* @param centiSecondsPerFrame How many hundredths of a second this frame should be displayed for.
|
|
* Note: This being specified in centiseconds is a limitation of the GIF format.
|
|
* @param maxBitDepth Limits how many bits per pixel can be used when quantizing the gif.
|
|
* The actual bit depth chosen for a given frame will be less than or equal to
|
|
* the supplied maximum, depending on the variety of colors used in the frame.
|
|
* `maxBitDepth` will be clamped between 1 and 16. The recommended default is 16.
|
|
* Lowering this value can result in faster exports and smaller gifs,
|
|
* but the quality may suffer.
|
|
* Please experiment with this value to find what works best for your application.
|
|
* @param pitchInBytes The number of bytes from the beginning of one row of pixels to the beginning of the next.
|
|
* If you want to flip the image, just pass in a negative pitch.
|
|
* @return Non-zero on success, 0 on error.
|
|
*/
|
|
int msf_gif_frame(MsfGifState * handle, uint8_t * pixelData, int centiSecondsPerFame, int maxBitDepth, int pitchInBytes);
|
|
|
|
/**
|
|
* @return A block of memory containing the gif file data, or NULL on error.
|
|
* You are responsible for freeing this via `msf_gif_free()`.
|
|
*/
|
|
MsfGifResult msf_gif_end(MsfGifState * handle);
|
|
|
|
/**
|
|
* @param result The MsfGifResult struct, verbatim as it was returned from `msf_gif_end()`.
|
|
*/
|
|
void msf_gif_free(MsfGifResult result);
|
|
|
|
//The gif format only supports 1-bit transparency, meaning a pixel will either be fully transparent or fully opaque.
|
|
//Pixels with an alpha value less than the alpha threshold will be treated as transparent.
|
|
//To enable exporting transparent gifs, set it to a value between 1 and 255 (inclusive) before calling msf_gif_frame().
|
|
//Setting it to 0 causes the alpha channel to be ignored. Its initial value is 0.
|
|
extern int msf_gif_alpha_threshold;
|
|
|
|
//Set `msf_gif_bgra_flag = true` before calling `msf_gif_frame()` if your pixels are in BGRA byte order instead of RBGA.
|
|
extern int msf_gif_bgra_flag;
|
|
|
|
|
|
|
|
//TO-FILE FUNCTIONS
|
|
//These functions are equivalent to the ones above, but they write results to a file incrementally,
|
|
//instead of building a buffer in memory. This can result in lower memory usage when saving large gifs,
|
|
//because memory usage is bounded by only the size of a single frame, and is not dependent on the number of frames.
|
|
//There is currently no reason to use these unless you are on a memory-constrained platform.
|
|
//If in doubt about which API to use, for now you should use the normal (non-file) functions above.
|
|
//The signature of MsfGifFileWriteFunc matches fwrite for convenience, so that you can use the C file API like so:
|
|
// FILE * fp = fopen("MyGif.gif", "wb");
|
|
// msf_gif_begin_to_file(&handle, width, height, (MsfGifFileWriteFunc) fwrite, (void *) fp);
|
|
// msf_gif_frame_to_file(...)
|
|
// msf_gif_end_to_file(&handle);
|
|
// fclose(fp);
|
|
//If you use a custom file write function, you must take care to return the same values that fwrite() would return.
|
|
//Note that all three functions will potentially write to the file.
|
|
int msf_gif_begin_to_file(MsfGifState * handle, int width, int height, MsfGifFileWriteFunc func, void * filePointer);
|
|
int msf_gif_frame_to_file(MsfGifState * handle, uint8_t * pixelData, int centiSecondsPerFame, int maxBitDepth, int pitchInBytes);
|
|
int msf_gif_end_to_file(MsfGifState * handle); //returns 0 on error and non-zero on success
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif //__cplusplus
|
|
|
|
#endif //MSF_GIF_H
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
/// IMPLEMENTATION ///
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#ifdef MSF_GIF_IMPL
|
|
#ifndef MSF_GIF_ALREADY_IMPLEMENTED_IN_THIS_TRANSLATION_UNIT
|
|
#define MSF_GIF_ALREADY_IMPLEMENTED_IN_THIS_TRANSLATION_UNIT
|
|
|
|
//ensure the library user has either defined all of malloc/realloc/free, or none
|
|
#if defined(MSF_GIF_MALLOC) && defined(MSF_GIF_REALLOC) && defined(MSF_GIF_FREE) //ok
|
|
#elif !defined(MSF_GIF_MALLOC) && !defined(MSF_GIF_REALLOC) && !defined(MSF_GIF_FREE) //ok
|
|
#else
|
|
#error "You must either define all of MSF_GIF_MALLOC, MSF_GIF_REALLOC, and MSF_GIF_FREE, or define none of them"
|
|
#endif
|
|
|
|
//provide default allocator definitions that redirect to the standard global allocator
|
|
#if !defined(MSF_GIF_MALLOC)
|
|
#include <stdlib.h> //malloc, etc.
|
|
#define MSF_GIF_MALLOC(contextPointer, newSize) malloc(newSize)
|
|
#define MSF_GIF_REALLOC(contextPointer, oldMemory, oldSize, newSize) realloc(oldMemory, newSize)
|
|
#define MSF_GIF_FREE(contextPointer, oldMemory, oldSize) free(oldMemory)
|
|
#endif
|
|
|
|
//instrumentation for capturing profiling traces (useless for the library user, but useful for the library author)
|
|
#ifdef MSF_GIF_ENABLE_TRACING
|
|
#define MsfTimeFunc TimeFunc
|
|
#define MsfTimeLoop TimeLoop
|
|
#define msf_init_profiling_thread init_profiling_thread
|
|
#else
|
|
#define MsfTimeFunc
|
|
#define MsfTimeLoop(name)
|
|
#define msf_init_profiling_thread()
|
|
#endif //MSF_GIF_ENABLE_TRACING
|
|
|
|
#include <string.h> //memcpy
|
|
|
|
//TODO: use compiler-specific notation to force-inline functions currently marked inline
|
|
#if defined(__GNUC__) //gcc, clang
|
|
static inline int msf_bit_log(int i) { return 32 - __builtin_clz(i); }
|
|
#elif defined(_MSC_VER) //msvc
|
|
#include <intrin.h>
|
|
static inline int msf_bit_log(int i) { unsigned long idx; _BitScanReverse(&idx, i); return idx + 1; }
|
|
#else //fallback implementation for other compilers
|
|
//from https://stackoverflow.com/a/31718095/3064745 - thanks!
|
|
static inline int msf_bit_log(int i) {
|
|
static const int MultiplyDeBruijnBitPosition[32] = {
|
|
0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30,
|
|
8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31,
|
|
};
|
|
i |= i >> 1;
|
|
i |= i >> 2;
|
|
i |= i >> 4;
|
|
i |= i >> 8;
|
|
i |= i >> 16;
|
|
return MultiplyDeBruijnBitPosition[(uint32_t)(i * 0x07C4ACDDU) >> 27] + 1;
|
|
}
|
|
#endif
|
|
static inline int msf_imin(int a, int b) { return a < b? a : b; }
|
|
static inline int msf_imax(int a, int b) { return b < a? a : b; }
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
/// Frame Cooking ///
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#if (defined (__SSE2__) || defined (_M_X64) || _M_IX86_FP == 2) && !defined(MSF_GIF_NO_SSE2)
|
|
#include <emmintrin.h>
|
|
#endif
|
|
|
|
int msf_gif_alpha_threshold = 0;
|
|
int msf_gif_bgra_flag = 0;
|
|
|
|
static void msf_cook_frame(MsfCookedFrame * frame, uint8_t * raw, uint8_t * used,
|
|
int width, int height, int pitch, int depth)
|
|
{ MsfTimeFunc
|
|
//bit depth for each channel
|
|
const static int rdepthsArray[17] = { 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5 };
|
|
const static int gdepthsArray[17] = { 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6 };
|
|
const static int bdepthsArray[17] = { 0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5 };
|
|
//this extra level of indirection looks unnecessary but we need to explicitly decay the arrays to pointers
|
|
//in order to be able to swap them because of C's annoying not-quite-pointers, not-quite-value-types stack arrays.
|
|
const int * rdepths = msf_gif_bgra_flag? bdepthsArray : rdepthsArray;
|
|
const int * gdepths = gdepthsArray;
|
|
const int * bdepths = msf_gif_bgra_flag? rdepthsArray : bdepthsArray;
|
|
|
|
const static int ditherKernel[16] = {
|
|
0 << 12, 8 << 12, 2 << 12, 10 << 12,
|
|
12 << 12, 4 << 12, 14 << 12, 6 << 12,
|
|
3 << 12, 11 << 12, 1 << 12, 9 << 12,
|
|
15 << 12, 7 << 12, 13 << 12, 5 << 12,
|
|
};
|
|
|
|
uint32_t * cooked = frame->pixels;
|
|
int count = 0;
|
|
MsfTimeLoop("do") do {
|
|
int rbits = rdepths[depth], gbits = gdepths[depth], bbits = bdepths[depth];
|
|
int paletteSize = (1 << (rbits + gbits + bbits)) + 1;
|
|
memset(used, 0, paletteSize * sizeof(uint8_t));
|
|
|
|
//TODO: document what this math does and why it's correct
|
|
int rdiff = (1 << (8 - rbits)) - 1;
|
|
int gdiff = (1 << (8 - gbits)) - 1;
|
|
int bdiff = (1 << (8 - bbits)) - 1;
|
|
short rmul = (short) ((255.0f - rdiff) / 255.0f * 257);
|
|
short gmul = (short) ((255.0f - gdiff) / 255.0f * 257);
|
|
short bmul = (short) ((255.0f - bdiff) / 255.0f * 257);
|
|
|
|
int gmask = ((1 << gbits) - 1) << rbits;
|
|
int bmask = ((1 << bbits) - 1) << rbits << gbits;
|
|
|
|
MsfTimeLoop("cook") for (int y = 0; y < height; ++y) {
|
|
int x = 0;
|
|
|
|
#if (defined (__SSE2__) || defined (_M_X64) || _M_IX86_FP == 2) && !defined(MSF_GIF_NO_SSE2)
|
|
__m128i k = _mm_loadu_si128((__m128i *) &ditherKernel[(y & 3) * 4]);
|
|
__m128i k2 = _mm_or_si128(_mm_srli_epi32(k, rbits), _mm_slli_epi32(_mm_srli_epi32(k, bbits), 16));
|
|
for (; x < width - 3; x += 4) {
|
|
uint8_t * pixels = &raw[y * pitch + x * 4];
|
|
__m128i p = _mm_loadu_si128((__m128i *) pixels);
|
|
|
|
__m128i rb = _mm_and_si128(p, _mm_set1_epi32(0x00FF00FF));
|
|
__m128i rb1 = _mm_mullo_epi16(rb, _mm_set_epi16(bmul, rmul, bmul, rmul, bmul, rmul, bmul, rmul));
|
|
__m128i rb2 = _mm_adds_epu16(rb1, k2);
|
|
__m128i r3 = _mm_srli_epi32(_mm_and_si128(rb2, _mm_set1_epi32(0x0000FFFF)), 16 - rbits);
|
|
__m128i b3 = _mm_and_si128(_mm_srli_epi32(rb2, 32 - rbits - gbits - bbits), _mm_set1_epi32(bmask));
|
|
|
|
__m128i g = _mm_and_si128(_mm_srli_epi32(p, 8), _mm_set1_epi32(0x000000FF));
|
|
__m128i g1 = _mm_mullo_epi16(g, _mm_set1_epi32(gmul));
|
|
__m128i g2 = _mm_adds_epu16(g1, _mm_srli_epi32(k, gbits));
|
|
__m128i g3 = _mm_and_si128(_mm_srli_epi32(g2, 16 - rbits - gbits), _mm_set1_epi32(gmask));
|
|
|
|
__m128i out = _mm_or_si128(_mm_or_si128(r3, g3), b3);
|
|
|
|
//mask in transparency based on threshold
|
|
//NOTE: we can theoretically do a sub instead of srli by doing an unsigned compare via bias
|
|
// to maybe save a TINY amount of throughput? but lol who cares maybe I'll do it later -m
|
|
__m128i invAlphaMask = _mm_cmplt_epi32(_mm_srli_epi32(p, 24), _mm_set1_epi32(msf_gif_alpha_threshold));
|
|
out = _mm_or_si128(_mm_and_si128(invAlphaMask, _mm_set1_epi32(paletteSize - 1)), _mm_andnot_si128(invAlphaMask, out));
|
|
|
|
//TODO: does storing this as a __m128i then reading it back as a uint32_t violate strict aliasing?
|
|
uint32_t * c = &cooked[y * width + x];
|
|
_mm_storeu_si128((__m128i *) c, out);
|
|
}
|
|
#endif
|
|
|
|
//scalar cleanup loop
|
|
for (; x < width; ++x) {
|
|
uint8_t * p = &raw[y * pitch + x * 4];
|
|
|
|
//transparent pixel if alpha is low
|
|
if (p[3] < msf_gif_alpha_threshold) {
|
|
cooked[y * width + x] = paletteSize - 1;
|
|
continue;
|
|
}
|
|
|
|
int dx = x & 3, dy = y & 3;
|
|
int k = ditherKernel[dy * 4 + dx];
|
|
cooked[y * width + x] =
|
|
(msf_imin(65535, p[2] * bmul + (k >> bbits)) >> (16 - rbits - gbits - bbits) & bmask) |
|
|
(msf_imin(65535, p[1] * gmul + (k >> gbits)) >> (16 - rbits - gbits ) & gmask) |
|
|
msf_imin(65535, p[0] * rmul + (k >> rbits)) >> (16 - rbits );
|
|
}
|
|
}
|
|
|
|
count = 0;
|
|
MsfTimeLoop("mark") for (int i = 0; i < width * height; ++i) {
|
|
used[cooked[i]] = 1;
|
|
}
|
|
|
|
//count used colors, transparent is ignored
|
|
MsfTimeLoop("count") for (int j = 0; j < paletteSize - 1; ++j) {
|
|
count += used[j];
|
|
}
|
|
} while (count >= 256 && --depth);
|
|
|
|
MsfCookedFrame ret = { cooked, depth, count, rdepths[depth], gdepths[depth], bdepths[depth] };
|
|
*frame = ret;
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
/// Frame Compression ///
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
static inline void msf_put_code(uint8_t * * writeHead, uint32_t * blockBits, int len, uint32_t code) {
|
|
//insert new code into block buffer
|
|
int idx = *blockBits / 8;
|
|
int bit = *blockBits % 8;
|
|
(*writeHead)[idx + 0] |= code << bit ;
|
|
(*writeHead)[idx + 1] |= code >> ( 8 - bit);
|
|
(*writeHead)[idx + 2] |= code >> (16 - bit);
|
|
*blockBits += len;
|
|
|
|
//prep the next block buffer if the current one is full
|
|
if (*blockBits >= 256 * 8) {
|
|
*blockBits -= 255 * 8;
|
|
(*writeHead) += 256;
|
|
(*writeHead)[2] = (*writeHead)[1];
|
|
(*writeHead)[1] = (*writeHead)[0];
|
|
(*writeHead)[0] = 255;
|
|
memset((*writeHead) + 4, 0, 256);
|
|
}
|
|
}
|
|
|
|
typedef struct {
|
|
int16_t * data;
|
|
int len;
|
|
int stride;
|
|
} MsfStridedList;
|
|
|
|
static inline void msf_lzw_reset(MsfStridedList * lzw, int tableSize, int stride) { MsfTimeFunc
|
|
memset(lzw->data, 0xFF, 4096 * stride * sizeof(int16_t));
|
|
lzw->len = tableSize + 2;
|
|
lzw->stride = stride;
|
|
}
|
|
|
|
static MsfGifBuffer * msf_compress_frame(void * allocContext, int width, int height, int centiSeconds,
|
|
MsfCookedFrame frame, MsfGifState * handle, uint8_t * used, int16_t * lzwMem)
|
|
{ MsfTimeFunc
|
|
//NOTE: we reserve enough memory for theoretical the worst case upfront because it's a reasonable amount,
|
|
// and prevents us from ever having to check size or realloc during compression
|
|
int maxBufSize = offsetof(MsfGifBuffer, data) + 32 + 256 * 3 + width * height * 3 / 2; //headers + color table + data
|
|
MsfGifBuffer * buffer = (MsfGifBuffer *) MSF_GIF_MALLOC(allocContext, maxBufSize);
|
|
if (!buffer) { return NULL; }
|
|
uint8_t * writeHead = buffer->data;
|
|
MsfStridedList lzw = { lzwMem };
|
|
|
|
//allocate tlb
|
|
int totalBits = frame.rbits + frame.gbits + frame.bbits;
|
|
int tlbSize = (1 << totalBits) + 1;
|
|
uint8_t tlb[(1 << 16) + 1]; //only 64k, so stack allocating is fine
|
|
|
|
//generate palette
|
|
typedef struct { uint8_t r, g, b; } Color3;
|
|
Color3 table[256] = { {0} };
|
|
int tableIdx = 1; //we start counting at 1 because 0 is the transparent color
|
|
//transparent is always last in the table
|
|
tlb[tlbSize-1] = 0;
|
|
MsfTimeLoop("table") for (int i = 0; i < tlbSize-1; ++i) {
|
|
if (used[i]) {
|
|
tlb[i] = tableIdx;
|
|
int rmask = (1 << frame.rbits) - 1;
|
|
int gmask = (1 << frame.gbits) - 1;
|
|
//isolate components
|
|
int r = i & rmask;
|
|
int g = i >> frame.rbits & gmask;
|
|
int b = i >> (frame.rbits + frame.gbits);
|
|
//shift into highest bits
|
|
r <<= 8 - frame.rbits;
|
|
g <<= 8 - frame.gbits;
|
|
b <<= 8 - frame.bbits;
|
|
table[tableIdx].r = r | r >> frame.rbits | r >> (frame.rbits * 2) | r >> (frame.rbits * 3);
|
|
table[tableIdx].g = g | g >> frame.gbits | g >> (frame.gbits * 2) | g >> (frame.gbits * 3);
|
|
table[tableIdx].b = b | b >> frame.bbits | b >> (frame.bbits * 2) | b >> (frame.bbits * 3);
|
|
if (msf_gif_bgra_flag) {
|
|
uint8_t temp = table[tableIdx].r;
|
|
table[tableIdx].r = table[tableIdx].b;
|
|
table[tableIdx].b = temp;
|
|
}
|
|
++tableIdx;
|
|
}
|
|
}
|
|
int hasTransparentPixels = used[tlbSize-1];
|
|
|
|
//SPEC: "Because of some algorithmic constraints however, black & white images which have one color bit
|
|
// must be indicated as having a code size of 2."
|
|
int tableBits = msf_imax(2, msf_bit_log(tableIdx - 1));
|
|
int tableSize = 1 << tableBits;
|
|
//NOTE: we don't just compare `depth` field here because it will be wrong for the first frame and we will segfault
|
|
MsfCookedFrame previous = handle->previousFrame;
|
|
int hasSamePal = frame.rbits == previous.rbits && frame.gbits == previous.gbits && frame.bbits == previous.bbits;
|
|
int framesCompatible = hasSamePal && !hasTransparentPixels;
|
|
|
|
//NOTE: because __attribute__((__packed__)) is annoyingly compiler-specific, we do this unreadable weirdness
|
|
char headerBytes[19] = "\x21\xF9\x04\x05\0\0\0\0" "\x2C\0\0\0\0\0\0\0\0\x80";
|
|
//NOTE: we need to check the frame number because if we reach into the buffer prior to the first frame,
|
|
// we'll just clobber the file header instead, which is a bug
|
|
if (hasTransparentPixels && handle->framesSubmitted > 0) {
|
|
handle->listTail->data[3] = 0x09; //set the previous frame's disposal to background, so transparency is possible
|
|
}
|
|
memcpy(&headerBytes[4], ¢iSeconds, 2);
|
|
memcpy(&headerBytes[13], &width, 2);
|
|
memcpy(&headerBytes[15], &height, 2);
|
|
headerBytes[17] |= tableBits - 1;
|
|
memcpy(writeHead, headerBytes, 18);
|
|
writeHead += 18;
|
|
|
|
//local color table
|
|
memcpy(writeHead, table, tableSize * sizeof(Color3));
|
|
writeHead += tableSize * sizeof(Color3);
|
|
*writeHead++ = tableBits;
|
|
|
|
//prep block
|
|
memset(writeHead, 0, 260);
|
|
writeHead[0] = 255;
|
|
uint32_t blockBits = 8; //relative to block.head
|
|
|
|
//SPEC: "Encoders should output a Clear code as the first code of each image data stream."
|
|
msf_lzw_reset(&lzw, tableSize, tableIdx);
|
|
msf_put_code(&writeHead, &blockBits, msf_bit_log(lzw.len - 1), tableSize);
|
|
|
|
int lastCode = framesCompatible && frame.pixels[0] == previous.pixels[0]? 0 : tlb[frame.pixels[0]];
|
|
MsfTimeLoop("compress") for (int i = 1; i < width * height; ++i) {
|
|
//PERF: branching vs. branchless version of this line is observed to have no discernable impact on speed
|
|
int color = framesCompatible && frame.pixels[i] == previous.pixels[i]? 0 : tlb[frame.pixels[i]];
|
|
int code = (&lzw.data[lastCode * lzw.stride])[color];
|
|
if (code < 0) {
|
|
//write to code stream
|
|
int codeBits = msf_bit_log(lzw.len - 1);
|
|
msf_put_code(&writeHead, &blockBits, codeBits, lastCode);
|
|
|
|
if (lzw.len > 4095) {
|
|
//reset buffer code table
|
|
msf_put_code(&writeHead, &blockBits, codeBits, tableSize);
|
|
msf_lzw_reset(&lzw, tableSize, tableIdx);
|
|
} else {
|
|
(&lzw.data[lastCode * lzw.stride])[color] = lzw.len;
|
|
++lzw.len;
|
|
}
|
|
|
|
lastCode = color;
|
|
} else {
|
|
lastCode = code;
|
|
}
|
|
}
|
|
|
|
//write code for leftover index buffer contents, then the end code
|
|
msf_put_code(&writeHead, &blockBits, msf_imin(12, msf_bit_log(lzw.len - 1)), lastCode);
|
|
msf_put_code(&writeHead, &blockBits, msf_imin(12, msf_bit_log(lzw.len)), tableSize + 1);
|
|
|
|
//flush remaining data
|
|
if (blockBits > 8) {
|
|
int bytes = (blockBits + 7) / 8; //round up
|
|
writeHead[0] = bytes - 1;
|
|
writeHead += bytes;
|
|
}
|
|
*writeHead++ = 0; //terminating block
|
|
|
|
//fill in buffer header and shrink buffer to fit data
|
|
buffer->next = NULL;
|
|
buffer->size = writeHead - buffer->data;
|
|
MsfGifBuffer * moved =
|
|
(MsfGifBuffer *) MSF_GIF_REALLOC(allocContext, buffer, maxBufSize, offsetof(MsfGifBuffer, data) + buffer->size);
|
|
if (!moved) { MSF_GIF_FREE(allocContext, buffer, maxBufSize); return NULL; }
|
|
return moved;
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
/// To-memory API ///
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
static const int lzwAllocSize = 4096 * 256 * sizeof(int16_t);
|
|
|
|
//NOTE: by C standard library conventions, freeing NULL should be a no-op,
|
|
// but just in case the user's custom free doesn't follow that rule, we do null checks on our end as well.
|
|
static void msf_free_gif_state(MsfGifState * handle) {
|
|
if (handle->previousFrame.pixels) MSF_GIF_FREE(handle->customAllocatorContext, handle->previousFrame.pixels,
|
|
handle->width * handle->height * sizeof(uint32_t));
|
|
if (handle->currentFrame.pixels) MSF_GIF_FREE(handle->customAllocatorContext, handle->currentFrame.pixels,
|
|
handle->width * handle->height * sizeof(uint32_t));
|
|
if (handle->lzwMem) MSF_GIF_FREE(handle->customAllocatorContext, handle->lzwMem, lzwAllocSize);
|
|
for (MsfGifBuffer * node = handle->listHead; node;) {
|
|
MsfGifBuffer * next = node->next; //NOTE: we have to copy the `next` pointer BEFORE freeing the node holding it
|
|
MSF_GIF_FREE(handle->customAllocatorContext, node, offsetof(MsfGifBuffer, data) + node->size);
|
|
node = next;
|
|
}
|
|
handle->listHead = NULL; //this implicitly marks the handle as invalid until the next msf_gif_begin() call
|
|
}
|
|
|
|
int msf_gif_begin(MsfGifState * handle, int width, int height) { MsfTimeFunc
|
|
//NOTE: we cannot stomp the entire struct to zero because we must preserve `customAllocatorContext`.
|
|
MsfCookedFrame empty = {0}; //god I hate MSVC...
|
|
handle->previousFrame = empty;
|
|
handle->currentFrame = empty;
|
|
handle->width = width;
|
|
handle->height = height;
|
|
handle->framesSubmitted = 0;
|
|
|
|
//allocate memory for LZW buffer
|
|
//NOTE: Unfortunately we can't just use stack memory for the LZW table because it's 2MB,
|
|
// which is more stack space than most operating systems give by default,
|
|
// and we can't realistically expect users to be willing to override that just to use our library,
|
|
// so we have to allocate this on the heap.
|
|
handle->lzwMem = (int16_t *) MSF_GIF_MALLOC(handle->customAllocatorContext, lzwAllocSize);
|
|
handle->previousFrame.pixels =
|
|
(uint32_t *) MSF_GIF_MALLOC(handle->customAllocatorContext, handle->width * handle->height * sizeof(uint32_t));
|
|
handle->currentFrame.pixels =
|
|
(uint32_t *) MSF_GIF_MALLOC(handle->customAllocatorContext, handle->width * handle->height * sizeof(uint32_t));
|
|
|
|
//setup header buffer header (lol)
|
|
handle->listHead = (MsfGifBuffer *) MSF_GIF_MALLOC(handle->customAllocatorContext, offsetof(MsfGifBuffer, data) + 32);
|
|
if (!handle->listHead || !handle->lzwMem || !handle->previousFrame.pixels || !handle->currentFrame.pixels) {
|
|
msf_free_gif_state(handle);
|
|
return 0;
|
|
}
|
|
handle->listTail = handle->listHead;
|
|
handle->listHead->next = NULL;
|
|
handle->listHead->size = 32;
|
|
|
|
//NOTE: because __attribute__((__packed__)) is annoyingly compiler-specific, we do this unreadable weirdness
|
|
char headerBytes[33] = "GIF89a\0\0\0\0\x70\0\0" "\x21\xFF\x0BNETSCAPE2.0\x03\x01\0\0\0";
|
|
memcpy(&headerBytes[6], &width, 2);
|
|
memcpy(&headerBytes[8], &height, 2);
|
|
memcpy(handle->listHead->data, headerBytes, 32);
|
|
return 1;
|
|
}
|
|
|
|
int msf_gif_frame(MsfGifState * handle, uint8_t * pixelData, int centiSecondsPerFame, int maxBitDepth, int pitchInBytes)
|
|
{ MsfTimeFunc
|
|
if (!handle->listHead) { return 0; }
|
|
|
|
maxBitDepth = msf_imax(1, msf_imin(16, maxBitDepth));
|
|
if (pitchInBytes == 0) pitchInBytes = handle->width * 4;
|
|
if (pitchInBytes < 0) pixelData -= pitchInBytes * (handle->height - 1);
|
|
|
|
uint8_t used[(1 << 16) + 1]; //only 64k, so stack allocating is fine
|
|
msf_cook_frame(&handle->currentFrame, pixelData, used, handle->width, handle->height, pitchInBytes,
|
|
msf_imin(maxBitDepth, handle->previousFrame.depth + 160 / msf_imax(1, handle->previousFrame.count)));
|
|
|
|
MsfGifBuffer * buffer = msf_compress_frame(handle->customAllocatorContext, handle->width, handle->height,
|
|
centiSecondsPerFame, handle->currentFrame, handle, used, handle->lzwMem);
|
|
if (!buffer) { msf_free_gif_state(handle); return 0; }
|
|
handle->listTail->next = buffer;
|
|
handle->listTail = buffer;
|
|
|
|
//swap current and previous frames
|
|
MsfCookedFrame tmp = handle->previousFrame;
|
|
handle->previousFrame = handle->currentFrame;
|
|
handle->currentFrame = tmp;
|
|
|
|
handle->framesSubmitted += 1;
|
|
return 1;
|
|
}
|
|
|
|
MsfGifResult msf_gif_end(MsfGifState * handle) { MsfTimeFunc
|
|
if (!handle->listHead) { MsfGifResult empty = {0}; return empty; }
|
|
|
|
//first pass: determine total size
|
|
size_t total = 1; //1 byte for trailing marker
|
|
for (MsfGifBuffer * node = handle->listHead; node; node = node->next) { total += node->size; }
|
|
|
|
//second pass: write data
|
|
uint8_t * buffer = (uint8_t *) MSF_GIF_MALLOC(handle->customAllocatorContext, total);
|
|
if (buffer) {
|
|
uint8_t * writeHead = buffer;
|
|
for (MsfGifBuffer * node = handle->listHead; node; node = node->next) {
|
|
memcpy(writeHead, node->data, node->size);
|
|
writeHead += node->size;
|
|
}
|
|
*writeHead++ = 0x3B;
|
|
}
|
|
|
|
//third pass: free buffers
|
|
msf_free_gif_state(handle);
|
|
|
|
MsfGifResult ret = { buffer, total, total, handle->customAllocatorContext };
|
|
return ret;
|
|
}
|
|
|
|
void msf_gif_free(MsfGifResult result) { MsfTimeFunc
|
|
if (result.data) { MSF_GIF_FREE(result.contextPointer, result.data, result.allocSize); }
|
|
}
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
/// To-file API ///
|
|
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
|
|
|
|
int msf_gif_begin_to_file(MsfGifState * handle, int width, int height, MsfGifFileWriteFunc func, void * filePointer) {
|
|
handle->fileWriteFunc = func;
|
|
handle->fileWriteData = filePointer;
|
|
return msf_gif_begin(handle, width, height);
|
|
}
|
|
|
|
int msf_gif_frame_to_file(MsfGifState * handle, uint8_t * pixelData, int centiSecondsPerFame, int maxBitDepth, int pitchInBytes) {
|
|
if (!msf_gif_frame(handle, pixelData, centiSecondsPerFame, maxBitDepth, pitchInBytes)) { return 0; }
|
|
|
|
//NOTE: this is a somewhat hacky implementation which is not perfectly efficient, but it's good enough for now
|
|
MsfGifBuffer * head = handle->listHead;
|
|
if (!handle->fileWriteFunc(head->data, head->size, 1, handle->fileWriteData)) { msf_free_gif_state(handle); return 0; }
|
|
handle->listHead = head->next;
|
|
MSF_GIF_FREE(handle->customAllocatorContext, head, offsetof(MsfGifBuffer, data) + head->size);
|
|
return 1;
|
|
}
|
|
|
|
int msf_gif_end_to_file(MsfGifState * handle) {
|
|
//NOTE: this is a somewhat hacky implementation which is not perfectly efficient, but it's good enough for now
|
|
MsfGifResult result = msf_gif_end(handle);
|
|
int ret = (int) handle->fileWriteFunc(result.data, result.dataSize, 1, handle->fileWriteData);
|
|
msf_gif_free(result);
|
|
return ret;
|
|
}
|
|
|
|
#endif //MSF_GIF_ALREADY_IMPLEMENTED_IN_THIS_TRANSLATION_UNIT
|
|
#endif //MSF_GIF_IMPL
|
|
|
|
/*
|
|
------------------------------------------------------------------------------
|
|
This software is available under 2 licenses -- choose whichever you prefer.
|
|
------------------------------------------------------------------------------
|
|
ALTERNATIVE A - MIT License
|
|
Copyright (c) 2021 Miles Fogle
|
|
Permission is hereby granted, free of charge, to any person obtaining a copy of
|
|
this software and associated documentation files (the "Software"), to deal in
|
|
the Software without restriction, including without limitation the rights to
|
|
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
|
|
of the Software, and to permit persons to whom the Software is furnished to do
|
|
so, subject to the following conditions:
|
|
The above copyright notice and this permission notice shall be included in all
|
|
copies or substantial portions of the Software.
|
|
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
|
|
SOFTWARE.
|
|
------------------------------------------------------------------------------
|
|
ALTERNATIVE B - Public Domain (www.unlicense.org)
|
|
This is free and unencumbered software released into the public domain.
|
|
Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
|
|
software, either in source code form or as a compiled binary, for any purpose,
|
|
commercial or non-commercial, and by any means.
|
|
In jurisdictions that recognize copyright laws, the author or authors of this
|
|
software dedicate any and all copyright interest in the software to the public
|
|
domain. We make this dedication for the benefit of the public at large and to
|
|
the detriment of our heirs and successors. We intend this dedication to be an
|
|
overt act of relinquishment in perpetuity of all present and future rights to
|
|
this software under copyright law.
|
|
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
|
AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
|
|
ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
|
|
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|
|
------------------------------------------------------------------------------
|
|
*/
|