From 9f50c6e61117d81592f6f87932d5380e19ea4226 Mon Sep 17 00:00:00 2001 From: Ray Date: Wed, 17 May 2017 16:01:55 +0200 Subject: [PATCH] Added gif file writter library Setup for a new amazing feature! ;) --- src/external/gif.h | 931 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 931 insertions(+) create mode 100644 src/external/gif.h diff --git a/src/external/gif.h b/src/external/gif.h new file mode 100644 index 000000000..1c0aeb18b --- /dev/null +++ b/src/external/gif.h @@ -0,0 +1,931 @@ +/********************************************************************************************** +* +* gif.h by Charlie Tangora [ctangora -at- gmail -dot- com] +* adapted to C99 and reformatted by Ramon Santamaria (@raysan5) +* +* This file offers a simple, very limited way to create animated GIFs directly in code. +* +* Those looking for particular cleverness are likely to be disappointed; it's pretty +* much a straight-ahead implementation of the GIF format with optional Floyd-Steinberg +* dithering. (It does at least use delta encoding - only the changed portions of each +* frame are saved.) +* +* So resulting files are often quite large. The hope is that it will be handy nonetheless +* as a quick and easily-integrated way for programs to spit out animations. +* +* Only RGBA8 is currently supported as an input format. (The alpha is ignored.) +* +* CONFIGURATION: +* +* #define GIF_IMPLEMENTATION +* Generates the implementation of the library into the included file. +* If not defined, the library is in header only mode and can be included in other headers +* or source files without problems. But only ONE file should hold the implementation. +* +* USAGE: +* 1) Create a GifWriter struct. Pass it to GifBegin() to initialize and write the header. +* 2) Pass subsequent frames to GifWriteFrame(). +* 3) Finally, call GifEnd() to close the file handle and free memory. +* +* +* LICENSE: 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. +* +**********************************************************************************************/ + +#ifndef GIF_H +#define GIF_H + +#include // Required for: FILE +#include // Required for for integer typedefs + +//#define GIF_STATIC +#ifdef GIF_STATIC + #define GIFDEF static // Functions just visible to module including this file +#else + #ifdef __cplusplus + #define GIFDEF extern "C" // Functions visible from other files (no name mangling of functions in C++) + #else + #define GIFDEF extern // Functions visible from other files + #endif +#endif + +//---------------------------------------------------------------------------------- +// Defines and Macros +//---------------------------------------------------------------------------------- +//#define MAX_RESOURCES_SUPPORTED 256 + +//---------------------------------------------------------------------------------- +// Types and Structures Definition +//---------------------------------------------------------------------------------- +typedef struct GifWriter { + FILE *f; + uint8_t *oldImage; + bool firstFrame; +} GifWriter; + +//---------------------------------------------------------------------------------- +// Global variables +//---------------------------------------------------------------------------------- +//... + +//---------------------------------------------------------------------------------- +// Module Functions Declaration +//---------------------------------------------------------------------------------- + +// NOTE: By default use bitDepth = 8, dither = false +GIFDEF bool GifBegin(GifWriter *writer, const char *filename, uint32_t width, uint32_t height, uint32_t delay, int32_t bitDepth, bool dither); +GIFDEF bool GifWriteFrame(GifWriter *writer, const uint8_t *image, uint32_t width, uint32_t height, uint32_t delay, int bitDepth, bool dither); +GIFDEF bool GifEnd(GifWriter *writer); + +#endif // GIF_H + + +/*********************************************************************************** +* + * GIF IMPLEMENTATION +* +************************************************************************************/ + +#if defined(GIF_IMPLEMENTATION) + +#include // Required for: FILE, fopen(), fclose() +#include // Required for: memcpy() +#include // Required for for integer typedefs + +// Define these macros to hook into a custom memory allocator. +// GIF_TEMP_MALLOC and GIF_TEMP_FREE will only be called in stack fashion - frees in the reverse order of mallocs +// and any temp memory allocated by a function will be freed before it exits. +#if !defined(GIF_TEMP_MALLOC) + #include + + #define GIF_TEMP_MALLOC malloc + #define GIF_TEMP_FREE free +#endif + +// Check if custom malloc/free functions defined, if not, using standard ones +// GIF_MALLOC and GIF_FREE are used only by GifBegin and GifEnd respectively, +// to allocate a buffer the size of the image, which is used to find changed pixels for delta-encoding. +#if !defined(GIF_MALLOC) + #include // Required for: malloc(), free() + + #define GIF_MALLOC(size) malloc(size) + #define GIF_FREE(ptr) free(ptr) +#endif + +//---------------------------------------------------------------------------------- +// Defines and Macros +//---------------------------------------------------------------------------------- +#define GIFMIN(a, b) (((a)<(b))?(a):(b)) +#define GIFMAX(a, b) (((a)>(b))?(a):(b)) +#define GIFABS(x) ((x)<0?-(x):(x)) + +//---------------------------------------------------------------------------------- +// Types and Structures Definition +//---------------------------------------------------------------------------------- + +//Gif palette structure +typedef struct GifPalette { + int bitDepth; + + uint8_t r[256]; + uint8_t g[256]; + uint8_t b[256]; + + // k-d tree over RGB space, organized in heap fashion + // i.e. left child of node i is node i*2, right child is node i*2 + 1 + // nodes 256-511 are implicitly the leaves, containing a color + uint8_t treeSplitElt[255]; + uint8_t treeSplit[255]; +} GifPalette; + + +// Simple structure to write out the LZW-compressed +// portion of the imageone bit at a time +typedef struct GifBitStatus { + uint8_t bitIndex; // how many bits in the partial byte written so far + uint8_t byte; // current partial byte + + uint32_t chunkIndex; + uint8_t chunk[256]; // bytes are written in here until we have 256 of them, then written to the file +} GifBitStatus; + +// The LZW dictionary is a 256-ary tree constructed +// as the file is encoded, this is one node +typedef struct GifLzwNode { + uint16_t m_next[256]; +} GifLzwNode; + +//---------------------------------------------------------------------------------- +// Global Variables Definition +//---------------------------------------------------------------------------------- +const int kGifTransIndex = 0; + +//---------------------------------------------------------------------------------- +// Module specific Functions Declaration +//---------------------------------------------------------------------------------- +static void GifGetClosestPaletteColor(GifPalette *pPal, int r, int g, int b, int *bestInd, int *bestDiff, int treeRoot); +static void GifSwapPixels(uint8_t *image, int pixA, int pixB); +static int GifPartition(uint8_t *image, const int left, const int right, const int elt, int pivotIndex); +static void GifPartitionByMedian(uint8_t *image, int left, int right, int com, int neededCenter); +static void GifSplitPalette(uint8_t *image, int numPixels, int firstElt, int lastElt, int splitElt, int splitDist, int treeNode, bool buildForDither, GifPalette *pal); +static int GifPickChangedPixels(const uint8_t *lastFrame, uint8_t *frame, int numPixels); +static void GifMakePalette(const uint8_t *lastFrame, const uint8_t *nextFrame, uint32_t width, uint32_t height, int bitDepth, bool buildForDither, GifPalette *pPal); +static void GifDitherImage(const uint8_t *lastFrame, const uint8_t *nextFrame, uint8_t *outFrame, uint32_t width, uint32_t height, GifPalette *pPal); +static void GifThresholdImage(const uint8_t *lastFrame, const uint8_t *nextFrame, uint8_t *outFrame, uint32_t width, uint32_t height, GifPalette *pPal); +static void GifWriteBit(GifBitStatus *stat, uint32_t bit); +static void GifWriteChunk(FILE *f, GifBitStatus *stat); +static void GifWriteCode(FILE *f, GifBitStatus *stat, uint32_t code, uint32_t length); +static void GifWritePalette(const GifPalette *pPal, FILE *f); +static void GifWriteLzwImage(FILE *f, uint8_t *image, uint32_t left, uint32_t top, uint32_t width, uint32_t height, uint32_t delay, GifPalette *pPal); + +//---------------------------------------------------------------------------------- +// Module Functions Definition +//---------------------------------------------------------------------------------- + +// Creates a gif file. +// The input GIFWriter is assumed to be uninitialized. +// The delay value is the time between frames in hundredths of a second - note that not all viewers pay much attention to this value. +GIFDEF bool GifBegin(GifWriter *writer, const char *filename, uint32_t width, uint32_t height, uint32_t delay, int32_t bitDepth, bool dither) +{ +#if _MSC_VER >= 1400 + writer->f = 0; + fopen_s(&writer->f, filename, "wb"); +#else + writer->f = fopen(filename, "wb"); +#endif + if (!writer->f) return false; + + writer->firstFrame = true; + + // allocate + writer->oldImage = (uint8_t*)GIF_MALLOC(width*height*4); + + fputs("GIF89a", writer->f); + + // screen descriptor + fputc(width & 0xff, writer->f); + fputc((width >> 8) & 0xff, writer->f); + fputc(height & 0xff, writer->f); + fputc((height >> 8) & 0xff, writer->f); + + fputc(0xf0, writer->f); // there is an unsorted global color table of 2 entries + fputc(0, writer->f); // background color + fputc(0, writer->f); // pixels are square (we need to specify this because it's 1989) + + // now the "global" palette (really just a dummy palette) + // color 0: black + fputc(0, writer->f); + fputc(0, writer->f); + fputc(0, writer->f); + // color 1: also black + fputc(0, writer->f); + fputc(0, writer->f); + fputc(0, writer->f); + + if (delay != 0) + { + // animation header + fputc(0x21, writer->f); // extension + fputc(0xff, writer->f); // application specific + fputc(11, writer->f); // length 11 + fputs("NETSCAPE2.0", writer->f); // yes, really + fputc(3, writer->f); // 3 bytes of NETSCAPE2.0 data + + fputc(1, writer->f); // JUST BECAUSE + fputc(0, writer->f); // loop infinitely (byte 0) + fputc(0, writer->f); // loop infinitely (byte 1) + + fputc(0, writer->f); // block terminator + } + + return true; +} + +// Writes out a new frame to a GIF in progress. +// The GIFWriter should have been created by GIFBegin. +// AFAIK, it is legal to use different bit depths for different frames of an image - +// this may be handy to save bits in animations that don't change much. +GIFDEF bool GifWriteFrame(GifWriter *writer, const uint8_t *image, uint32_t width, uint32_t height, uint32_t delay, int bitDepth, bool dither) +{ + if (!writer->f) return false; + + const uint8_t *oldImage = writer->firstFrame? NULL : writer->oldImage; + writer->firstFrame = false; + + GifPalette pal; + GifMakePalette((dither? NULL : oldImage), image, width, height, bitDepth, dither, &pal); + + if (dither) + GifDitherImage(oldImage, image, writer->oldImage, width, height, &pal); + else + GifThresholdImage(oldImage, image, writer->oldImage, width, height, &pal); + + GifWriteLzwImage(writer->f, writer->oldImage, 0, 0, width, height, delay, &pal); + + return true; +} + +// Writes the EOF code, closes the file handle, and frees temp memory used by a GIF. +// Many if not most viewers will still display a GIF properly if the EOF code is missing, +// but it's still a good idea to write it out. +GIFDEF bool GifEnd(GifWriter *writer) +{ + if (!writer->f) return false; + + fputc(0x3b, writer->f); // end of file + fclose(writer->f); + GIF_FREE(writer->oldImage); + + writer->f = NULL; + writer->oldImage = NULL; + + return true; +} + +//---------------------------------------------------------------------------------- +// Module specific Functions Definition +//---------------------------------------------------------------------------------- +// walks the k-d tree to pick the palette entry for a desired color. +// Takes as in/out parameters the current best color and its error - +// only changes them if it finds a better color in its subtree. +// this is the major hotspot in the code at the moment. +static void GifGetClosestPaletteColor(GifPalette *pPal, int r, int g, int b, int *bestInd, int *bestDiff, int treeRoot) +{ + // base case, reached the bottom of the tree + if (treeRoot > (1<bitDepth)-1) + { + int ind = treeRoot-(1<bitDepth); + if (ind == kGifTransIndex) return; + + // check whether this color is better than the current winner + int r_err = r - ((int32_t)pPal->r[ind]); + int g_err = g - ((int32_t)pPal->g[ind]); + int b_err = b - ((int32_t)pPal->b[ind]); + int diff = GIFABS(r_err)+GIFABS(g_err)+GIFABS(b_err); + + if (diff < *bestDiff) + { + *bestInd = ind; + *bestDiff = diff; + } + + return; + } + + // take the appropriate color (r, g, or b) for this node of the k-d tree + int comps[3]; comps[0] = r; comps[1] = g; comps[2] = b; + int splitComp = comps[pPal->treeSplitElt[treeRoot]]; + + int splitPos = pPal->treeSplit[treeRoot]; + if (splitPos > splitComp) + { + // check the left subtree + GifGetClosestPaletteColor(pPal, r, g, b, bestInd, bestDiff, treeRoot*2); + + if (*bestDiff > (splitPos - splitComp)) + { + // cannot prove there's not a better value in the right subtree, check that too + GifGetClosestPaletteColor(pPal, r, g, b, bestInd, bestDiff, treeRoot*2 + 1); + } + } + else + { + GifGetClosestPaletteColor(pPal, r, g, b, bestInd, bestDiff, treeRoot*2 + 1); + + if (*bestDiff > splitComp - splitPos) + { + GifGetClosestPaletteColor(pPal, r, g, b, bestInd, bestDiff, treeRoot*2); + } + } +} + +static void GifSwapPixels(uint8_t *image, int pixA, int pixB) +{ + uint8_t rA = image[pixA*4]; + uint8_t gA = image[pixA*4 + 1]; + uint8_t bA = image[pixA*4+2]; + uint8_t aA = image[pixA*4+3]; + + uint8_t rB = image[pixB*4]; + uint8_t gB = image[pixB*4 + 1]; + uint8_t bB = image[pixB*4+2]; + uint8_t aB = image[pixA*4+3]; + + image[pixA*4] = rB; + image[pixA*4 + 1] = gB; + image[pixA*4+2] = bB; + image[pixA*4+3] = aB; + + image[pixB*4] = rA; + image[pixB*4 + 1] = gA; + image[pixB*4+2] = bA; + image[pixB*4+3] = aA; +} + +// just the partition operation from quicksort +static int GifPartition(uint8_t *image, const int left, const int right, const int elt, int pivotIndex) +{ + const int pivotValue = image[(pivotIndex)*4+elt]; + GifSwapPixels(image, pivotIndex, right-1); + int storeIndex = left; + bool split = 0; + for (int ii=left; ii neededCenter) + GifPartitionByMedian(image, left, pivotIndex, com, neededCenter); + + if (pivotIndex < neededCenter) + GifPartitionByMedian(image, pivotIndex + 1, right, com, neededCenter); + } +} + +// Builds a palette by creating a balanced k-d tree of all pixels in the image +static void GifSplitPalette(uint8_t *image, int numPixels, int firstElt, int lastElt, int splitElt, int splitDist, + int treeNode, bool buildForDither, GifPalette *pal) +{ + if (lastElt <= firstElt || numPixels == 0) + return; + + // base case, bottom of the tree + if (lastElt == firstElt + 1) + { + if (buildForDither) + { + // Dithering needs at least one color as dark as anything + // in the image and at least one brightest color - + // otherwise it builds up error and produces strange artifacts + if (firstElt == 1) + { + // special case: the darkest color in the image + uint32_t r=255, g=255, b=255; + for (int ii=0; iir[firstElt] = r; + pal->g[firstElt] = g; + pal->b[firstElt] = b; + + return; + } + + if (firstElt == (1 << pal->bitDepth)-1) + { + // special case: the lightest color in the image + uint32_t r=0, g=0, b=0; + for (int ii=0; iir[firstElt] = r; + pal->g[firstElt] = g; + pal->b[firstElt] = b; + + return; + } + } + + // otherwise, take the average of all colors in this subcube + uint64_t r=0, g=0, b=0; + for (int ii=0; iir[firstElt] = (uint8_t)r; + pal->g[firstElt] = (uint8_t)g; + pal->b[firstElt] = (uint8_t)b; + + return; + } + + // Find the axis with the largest range + int minR = 255, maxR = 0; + int minG = 255, maxG = 0; + int minB = 255, maxB = 0; + for (int ii=0; ii maxR) maxR = r; + if (r < minR) minR = r; + + if (g > maxG) maxG = g; + if (g < minG) minG = g; + + if (b > maxB) maxB = b; + if (b < minB) minB = b; + } + + int rRange = maxR - minR; + int gRange = maxG - minG; + int bRange = maxB - minB; + + // and split along that axis. (incidentally, this means this isn't a "proper" k-d tree but I don't know what else to call it) + int splitCom = 1; + if (bRange > gRange) splitCom = 2; + if (rRange > bRange && rRange > gRange) splitCom = 0; + + int subPixelsA = numPixels *(splitElt - firstElt) / (lastElt - firstElt); + int subPixelsB = numPixels-subPixelsA; + + GifPartitionByMedian(image, 0, numPixels, splitCom, subPixelsA); + + pal->treeSplitElt[treeNode] = splitCom; + pal->treeSplit[treeNode] = image[subPixelsA*4+splitCom]; + + GifSplitPalette(image, subPixelsA, firstElt, splitElt, splitElt-splitDist, splitDist/2, treeNode*2, buildForDither, pal); + GifSplitPalette(image+subPixelsA*4, subPixelsB, splitElt, lastElt, splitElt+splitDist, splitDist/2, treeNode*2 + 1, buildForDither, pal); +} + +// Finds all pixels that have changed from the previous image and +// moves them to the fromt of th buffer. +// This allows us to build a palette optimized for the colors of the +// changed pixels only. +static int GifPickChangedPixels(const uint8_t *lastFrame, uint8_t *frame, int numPixels) +{ + int numChanged = 0; + uint8_t *writeIter = frame; + + for (int ii=0; iibitDepth = bitDepth; + + // SplitPalette is destructive (it sorts the pixels by color) so + // we must create a copy of the image for it to destroy + int imageSize = width*height*4*sizeof(uint8_t); + uint8_t *destroyableImage = (uint8_t*)GIF_TEMP_MALLOC(imageSize); + memcpy(destroyableImage, nextFrame, imageSize); + + int numPixels = width*height; + if (lastFrame) + numPixels = GifPickChangedPixels(lastFrame, destroyableImage, numPixels); + + const int lastElt = 1 << bitDepth; + const int splitElt = lastElt/2; + const int splitDist = splitElt/2; + + GifSplitPalette(destroyableImage, numPixels, 1, lastElt, splitElt, splitDist, 1, buildForDither, pPal); + + GIF_TEMP_FREE(destroyableImage); + + // add the bottom node for the transparency index + pPal->treeSplit[1 << (bitDepth-1)] = 0; + pPal->treeSplitElt[1 << (bitDepth-1)] = 0; + + pPal->r[0] = pPal->g[0] = pPal->b[0] = 0; +} + +// Implements Floyd-Steinberg dithering, writes palette value to alpha +static void GifDitherImage(const uint8_t *lastFrame, const uint8_t *nextFrame, uint8_t *outFrame, uint32_t width, uint32_t height, GifPalette *pPal) +{ + int numPixels = width*height; + + // quantPixels initially holds color*256 for all pixels + // The extra 8 bits of precision allow for sub-single-color error values + // to be propagated + int32_t *quantPixels = (int32_t*)GIF_TEMP_MALLOC(sizeof(int32_t)*numPixels*4); + + for (int ii=0; iir[bestInd])*256; + int32_t g_err = nextPix[1] - (int32_t)(pPal->g[bestInd])*256; + int32_t b_err = nextPix[2] - (int32_t)(pPal->b[bestInd])*256; + + nextPix[0] = pPal->r[bestInd]; + nextPix[1] = pPal->g[bestInd]; + nextPix[2] = pPal->b[bestInd]; + nextPix[3] = bestInd; + + // Propagate the error to the four adjacent locations + // that we haven't touched yet + int quantloc_7 = (yy*width+xx + 1); + int quantloc_3 = (yy*width+width+xx-1); + int quantloc_5 = (yy*width+width+xx); + int quantloc_1 = (yy*width+width+xx + 1); + + if (quantloc_7 < numPixels) + { + int32_t *pix7 = quantPixels+4*quantloc_7; + pix7[0] += GIFMAX(-pix7[0], r_err*7 / 16); + pix7[1] += GIFMAX(-pix7[1], g_err*7 / 16); + pix7[2] += GIFMAX(-pix7[2], b_err*7 / 16); + } + + if (quantloc_3 < numPixels) + { + int32_t *pix3 = quantPixels+4*quantloc_3; + pix3[0] += GIFMAX(-pix3[0], r_err*3 / 16); + pix3[1] += GIFMAX(-pix3[1], g_err*3 / 16); + pix3[2] += GIFMAX(-pix3[2], b_err*3 / 16); + } + + if (quantloc_5 < numPixels) + { + int32_t *pix5 = quantPixels+4*quantloc_5; + pix5[0] += GIFMAX(-pix5[0], r_err*5 / 16); + pix5[1] += GIFMAX(-pix5[1], g_err*5 / 16); + pix5[2] += GIFMAX(-pix5[2], b_err*5 / 16); + } + + if (quantloc_1 < numPixels) + { + int32_t *pix1 = quantPixels+4*quantloc_1; + pix1[0] += GIFMAX(-pix1[0], r_err / 16); + pix1[1] += GIFMAX(-pix1[1], g_err / 16); + pix1[2] += GIFMAX(-pix1[2], b_err / 16); + } + } + } + + // Copy the palettized result to the output buffer + for (int ii=0; iir[bestInd]; + outFrame[1] = pPal->g[bestInd]; + outFrame[2] = pPal->b[bestInd]; + outFrame[3] = bestInd; + } + + if (lastFrame) lastFrame += 4; + outFrame += 4; + nextFrame += 4; + } +} + + +// insert a single bit +static void GifWriteBit(GifBitStatus *stat, uint32_t bit) +{ + bit = bit & 1; + bit = bit << stat->bitIndex; + stat->byte |= bit; + + ++stat->bitIndex; + if (stat->bitIndex > 7) + { + // move the newly-finished byte to the chunk buffer + stat->chunk[stat->chunkIndex++] = stat->byte; + // and start a new byte + stat->bitIndex = 0; + stat->byte = 0; + } +} + +// write all bytes so far to the file +static void GifWriteChunk(FILE *f, GifBitStatus *stat) +{ + fputc(stat->chunkIndex, f); + fwrite(stat->chunk, 1, stat->chunkIndex, f); + + stat->bitIndex = 0; + stat->byte = 0; + stat->chunkIndex = 0; +} + +static void GifWriteCode(FILE *f, GifBitStatus *stat, uint32_t code, uint32_t length) +{ + for (uint32_t ii=0; ii> 1; + + if (stat->chunkIndex == 255) + { + GifWriteChunk(f, stat); + } + } +} + +// write a 256-color (8-bit) image palette to the file +static void GifWritePalette(const GifPalette *pPal, FILE *f) +{ + fputc(0, f); // first color: transparency + fputc(0, f); + fputc(0, f); + + for (int ii=1; ii<(1 << pPal->bitDepth); ++ii) + { + uint32_t r = pPal->r[ii]; + uint32_t g = pPal->g[ii]; + uint32_t b = pPal->b[ii]; + + fputc(r, f); + fputc(g, f); + fputc(b, f); + } +} + +// write the image header, LZW-compress and write out the image +static void GifWriteLzwImage(FILE *f, uint8_t *image, uint32_t left, uint32_t top, uint32_t width, uint32_t height, uint32_t delay, GifPalette *pPal) +{ + // graphics control extension + fputc(0x21, f); + fputc(0xf9, f); + fputc(0x04, f); + fputc(0x05, f); // leave prev frame in place, this frame has transparency + fputc(delay & 0xff, f); + fputc((delay >> 8) & 0xff, f); + fputc(kGifTransIndex, f); // transparent color index + fputc(0, f); + + fputc(0x2c, f); // image descriptor block + + fputc(left & 0xff, f); // corner of image in canvas space + fputc((left >> 8) & 0xff, f); + fputc(top & 0xff, f); + fputc((top >> 8) & 0xff, f); + + fputc(width & 0xff, f); // width and height of image + fputc((width >> 8) & 0xff, f); + fputc(height & 0xff, f); + fputc((height >> 8) & 0xff, f); + + //fputc(0, f); // no local color table, no transparency + //fputc(0x80, f); // no local color table, but transparency + + fputc(0x80 + pPal->bitDepth-1, f); // local color table present, 2 ^ bitDepth entries + GifWritePalette(pPal, f); + + const int minCodeSize = pPal->bitDepth; + const uint32_t clearCode = 1 << pPal->bitDepth; + + fputc(minCodeSize, f); // min code size 8 bits + + GifLzwNode *codetree = (GifLzwNode *)GIF_TEMP_MALLOC(sizeof(GifLzwNode)*4096); + + memset(codetree, 0, sizeof(GifLzwNode)*4096); + int32_t curCode = -1; + uint32_t codeSize = minCodeSize + 1; + uint32_t maxCode = clearCode + 1; + + GifBitStatus stat; + stat.byte = 0; + stat.bitIndex = 0; + stat.chunkIndex = 0; + + GifWriteCode(f, &stat, clearCode, codeSize); // start with a fresh LZW dictionary + + for (uint32_t yy=0; yy= (1ul << codeSize)) + { + // dictionary entry count has broken a size barrier, + // we need more bits for codes + codeSize++; + } + if (maxCode == 4095) + { + // the dictionary is full, clear it out and begin anew + GifWriteCode(f, &stat, clearCode, codeSize); // clear tree + + memset(codetree, 0, sizeof(GifLzwNode)*4096); + curCode = -1; + codeSize = minCodeSize + 1; + maxCode = clearCode + 1; + } + + curCode = nextValue; + } + } + } + + // compression footer + GifWriteCode(f, &stat, curCode, codeSize); + GifWriteCode(f, &stat, clearCode, codeSize); + GifWriteCode(f, &stat, clearCode + 1, minCodeSize + 1); + + // write out the last partial chunk + while (stat.bitIndex) GifWriteBit(&stat, 0); + if (stat.chunkIndex) GifWriteChunk(f, &stat); + + fputc(0, f); // image block terminator + + GIF_TEMP_FREE(codetree); +} + +#endif // GIF_IMPLEMENTATION