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新增屏幕录制控件
2019-09-29 02:57:47 +00:00
//
// gif.h
// by Charlie Tangora
// Public domain.
// Email me : ctangora -at- gmail -dot- com
//
// 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.)
//
// USAGE:
// Create a GifWriter struct. Pass it to GifBegin() to initialize and write the header.
// Pass subsequent frames to GifWriteFrame().
// Finally, call GifEnd() to close the file handle and free memory.
//
#ifndef __gif_h__
#define __gif_h__
#include <stdio.h> // for FILE*
#include <string.h> // for memcpy and bzero
#include <stdint.h> // for integer typedefs
// Define these macros to hook into a custom memory allocator.
// TEMP_MALLOC and 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.
// MALLOC and 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.)
#ifndef GIF_TEMP_MALLOC
#include <stdlib.h>
#define GIF_TEMP_MALLOC malloc
#endif
#ifndef GIF_TEMP_FREE
#include <stdlib.h>
#define GIF_TEMP_FREE free
#endif
#ifndef GIF_MALLOC
#include <stdlib.h>
#define GIF_MALLOC malloc
#endif
#ifndef GIF_FREE
#include <stdlib.h>
#define GIF_FREE free
#endif
class Gif
{
public:
int kGifTransIndex;
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];
};
// max, min, and abs functions
int GifIMax(int l, int r)
{
return l > r ? l : r;
}
int GifIMin(int l, int r)
{
return l < r ? l : r;
}
int GifIAbs(int i)
{
return i < 0 ? -i : i;
}
// 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.
void GifGetClosestPaletteColor(GifPalette *pPal, int r, int g, int b, int &bestInd, int &bestDiff, int treeRoot = 1)
{
// base case, reached the bottom of the tree
if(treeRoot > (1 << pPal->bitDepth) - 1) {
int ind = treeRoot - (1 << pPal->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 = GifIAbs(r_err) + GifIAbs(g_err) + GifIAbs(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);
}
}
}
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
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 < right - 1; ++ii) {
int arrayVal = image[ii * 4 + elt];
if( arrayVal < pivotValue ) {
GifSwapPixels(image, ii, storeIndex);
++storeIndex;
} else if( arrayVal == pivotValue ) {
if(split) {
GifSwapPixels(image, ii, storeIndex);
++storeIndex;
}
split = !split;
}
}
GifSwapPixels(image, storeIndex, right - 1);
return storeIndex;
}
// Perform an incomplete sort, finding all elements above and below the desired median
void GifPartitionByMedian(uint8_t *image, int left, int right, int com, int neededCenter)
{
if (left < right - 1) {
int pivotIndex = left + (right - left) / 2;
pivotIndex = GifPartition(image, left, right, com, pivotIndex);
// Only "sort" the section of the array that contains the median
if(pivotIndex > 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
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; ii < numPixels; ++ii) {
r = (uint32_t)GifIMin((int32_t)r, image[ii * 4 + 0]);
g = (uint32_t)GifIMin((int32_t)g, image[ii * 4 + 1]);
b = (uint32_t)GifIMin((int32_t)b, image[ii * 4 + 2]);
}
pal->r[firstElt] = (uint8_t)r;
pal->g[firstElt] = (uint8_t)g;
pal->b[firstElt] = (uint8_t)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; ii < numPixels; ++ii) {
r = (uint32_t)GifIMax((int32_t)r, image[ii * 4 + 0]);
g = (uint32_t)GifIMax((int32_t)g, image[ii * 4 + 1]);
b = (uint32_t)GifIMax((int32_t)b, image[ii * 4 + 2]);
}
pal->r[firstElt] = (uint8_t)r;
pal->g[firstElt] = (uint8_t)g;
pal->b[firstElt] = (uint8_t)b;
return;
}
}
// otherwise, take the average of all colors in this subcube
uint64_t r = 0, g = 0, b = 0;
for (int ii = 0; ii < numPixels; ++ii) {
r += image[ii * 4 + 0];
g += image[ii * 4 + 1];
b += image[ii * 4 + 2];
}
r += (uint64_t)numPixels / 2; // round to nearest
g += (uint64_t)numPixels / 2;
b += (uint64_t)numPixels / 2;
r /= (uint64_t)numPixels;
g /= (uint64_t)numPixels;
b /= (uint64_t)numPixels;
pal->r[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 < numPixels; ++ii) {
int r = image[ii * 4 + 0];
int g = image[ii * 4 + 1];
int b = image[ii * 4 + 2];
if(r > 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] = (uint8_t)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.
int GifPickChangedPixels( const uint8_t *lastFrame, uint8_t *frame, int numPixels )
{
int numChanged = 0;
uint8_t *writeIter = frame;
for (int ii = 0; ii < numPixels; ++ii) {
if(lastFrame[0] != frame[0] ||
lastFrame[1] != frame[1] ||
lastFrame[2] != frame[2]) {
writeIter[0] = frame[0];
writeIter[1] = frame[1];
writeIter[2] = frame[2];
++numChanged;
writeIter += 4;
}
lastFrame += 4;
frame += 4;
}
return numChanged;
}
// Creates a palette by placing all the image pixels in a k-d tree and then averaging the blocks at the bottom.
// This is known as the "modified median split" technique
void GifMakePalette( const uint8_t *lastFrame,
const uint8_t *nextFrame,
uint32_t width, uint32_t height,
int bitDepth, bool buildForDither,
GifPalette *pPal )
{
pPal->bitDepth = bitDepth;
// SplitPalette is destructive (it sorts the pixels by color) so
// we must create a copy of the image for it to destroy
size_t imageSize = (size_t)(width * height * 4 * sizeof(uint8_t));
uint8_t *destroyableImage = (uint8_t *)GIF_TEMP_MALLOC(imageSize);
memcpy(destroyableImage, nextFrame, imageSize);
int numPixels = (int)(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
void GifDitherImage( const uint8_t *lastFrame, const uint8_t *nextFrame,
uint8_t *outFrame, uint32_t width,
uint32_t height, GifPalette *pPal )
{
int numPixels = (int)(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) * (size_t)numPixels * 4);
for( int ii = 0; ii < numPixels * 4; ++ii ) {
uint8_t pix = nextFrame[ii];
int32_t pix16 = int32_t(pix) * 256;
quantPixels[ii] = pix16;
}
for( uint32_t yy = 0; yy < height; ++yy ) {
for( uint32_t xx = 0; xx < width; ++xx ) {
int32_t *nextPix = quantPixels + 4 * (yy * width + xx);
const uint8_t *lastPix = lastFrame ? lastFrame + 4 * (yy * width + xx) : NULL;
// Compute the colors we want (rounding to nearest)
int32_t rr = (nextPix[0] + 127) / 256;
int32_t gg = (nextPix[1] + 127) / 256;
int32_t bb = (nextPix[2] + 127) / 256;
// if it happens that we want the color from last frame, then just write out
// a transparent pixel
if( lastFrame &&
lastPix[0] == rr &&
lastPix[1] == gg &&
lastPix[2] == bb ) {
nextPix[0] = rr;
nextPix[1] = gg;
nextPix[2] = bb;
nextPix[3] = kGifTransIndex;
continue;
}
int32_t bestDiff = 1000000;
int32_t bestInd = kGifTransIndex;
// Search the palete
GifGetClosestPaletteColor(pPal, rr, gg, bb, bestInd, bestDiff);
// Write the result to the temp buffer
int32_t r_err = nextPix[0] - int32_t(pPal->r[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 = (int)(yy * width + xx + 1);
int quantloc_3 = (int)(yy * width + width + xx - 1);
int quantloc_5 = (int)(yy * width + width + xx);
int quantloc_1 = (int)(yy * width + width + xx + 1);
if(quantloc_7 < numPixels) {
int32_t *pix7 = quantPixels + 4 * quantloc_7;
pix7[0] += GifIMax( -pix7[0], r_err * 7 / 16 );
pix7[1] += GifIMax( -pix7[1], g_err * 7 / 16 );
pix7[2] += GifIMax( -pix7[2], b_err * 7 / 16 );
}
if(quantloc_3 < numPixels) {
int32_t *pix3 = quantPixels + 4 * quantloc_3;
pix3[0] += GifIMax( -pix3[0], r_err * 3 / 16 );
pix3[1] += GifIMax( -pix3[1], g_err * 3 / 16 );
pix3[2] += GifIMax( -pix3[2], b_err * 3 / 16 );
}
if(quantloc_5 < numPixels) {
int32_t *pix5 = quantPixels + 4 * quantloc_5;
pix5[0] += GifIMax( -pix5[0], r_err * 5 / 16 );
pix5[1] += GifIMax( -pix5[1], g_err * 5 / 16 );
pix5[2] += GifIMax( -pix5[2], b_err * 5 / 16 );
}
if(quantloc_1 < numPixels) {
int32_t *pix1 = quantPixels + 4 * quantloc_1;
pix1[0] += GifIMax( -pix1[0], r_err / 16 );
pix1[1] += GifIMax( -pix1[1], g_err / 16 );
pix1[2] += GifIMax( -pix1[2], b_err / 16 );
}
}
}
// Copy the palettized result to the output buffer
for( int ii = 0; ii < numPixels * 4; ++ii ) {
outFrame[ii] = (uint8_t)quantPixels[ii];
}
GIF_TEMP_FREE(quantPixels);
}
// Picks palette colors for the image using simple thresholding, no dithering
void GifThresholdImage( const uint8_t *lastFrame, const uint8_t *nextFrame,
uint8_t *outFrame, uint32_t width, uint32_t height,
GifPalette *pPal )
{
uint32_t numPixels = width * height;
for( uint32_t ii = 0; ii < numPixels; ++ii ) {
// if a previous color is available, and it matches the current color,
// set the pixel to transparent
if(lastFrame &&
lastFrame[0] == nextFrame[0] &&
lastFrame[1] == nextFrame[1] &&
lastFrame[2] == nextFrame[2]) {
outFrame[0] = lastFrame[0];
outFrame[1] = lastFrame[1];
outFrame[2] = lastFrame[2];
outFrame[3] = kGifTransIndex;
} else {
// palettize the pixel
int32_t bestDiff = 1000000;
int32_t bestInd = 1;
GifGetClosestPaletteColor(pPal, nextFrame[0], nextFrame[1], nextFrame[2], bestInd, bestDiff);
// Write the resulting color to the output buffer
outFrame[0] = pPal->r[bestInd];
outFrame[1] = pPal->g[bestInd];
outFrame[2] = pPal->b[bestInd];
outFrame[3] = (uint8_t)bestInd;
}
if(lastFrame) {
lastFrame += 4;
}
outFrame += 4;
nextFrame += 4;
}
}
// Simple structure to write out the LZW-compressed portion of the image
// one bit at a time
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
};
// insert a single bit
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
void GifWriteChunk( FILE *f, GifBitStatus &stat )
{
fputc((int)stat.chunkIndex, f);
fwrite(stat.chunk, 1, stat.chunkIndex, f);
stat.bitIndex = 0;
stat.byte = 0;
stat.chunkIndex = 0;
}
void GifWriteCode( FILE *f, GifBitStatus &stat, uint32_t code, uint32_t length )
{
for( uint32_t ii = 0; ii < length; ++ii ) {
GifWriteBit(stat, code);
code = code >> 1;
if( stat.chunkIndex == 255 ) {
GifWriteChunk(f, stat);
}
}
}
// The LZW dictionary is a 256-ary tree constructed as the file is encoded,
// this is one node
struct GifLzwNode {
uint16_t m_next[256];
};
// write a 256-color (8-bit) image palette to the file
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((int)r, f);
fputc((int)g, f);
fputc((int)b, f);
}
}
// write the image header, LZW-compress and write out the image
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 = (uint32_t)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 < height; ++yy) {
for(uint32_t xx = 0; xx < width; ++xx) {
uint8_t nextValue = image[(yy * width + xx) * 4 + 3];
// "loser mode" - no compression, every single code is followed immediately by a clear
//WriteCode( f, stat, nextValue, codeSize );
//WriteCode( f, stat, 256, codeSize );
if( curCode < 0 ) {
// first value in a new run
curCode = nextValue;
} else if( codetree[curCode].m_next[nextValue] ) {
// current run already in the dictionary
curCode = codetree[curCode].m_next[nextValue];
} else {
// finish the current run, write a code
GifWriteCode(f, stat, (uint32_t)curCode, codeSize);
// insert the new run into the dictionary
codetree[curCode].m_next[nextValue] = (uint16_t)++maxCode;
if( maxCode >= (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);
codeSize = (uint32_t)(minCodeSize + 1);
maxCode = clearCode + 1;
}
curCode = nextValue;
}
}
}
// compression footer
GifWriteCode(f, stat, (uint32_t)curCode, codeSize);
GifWriteCode(f, stat, clearCode, codeSize);
GifWriteCode(f, stat, clearCode + 1, (uint32_t)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);
}
struct GifWriter {
FILE *f;
uint8_t *oldImage;
bool firstFrame;
};
// 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.
bool GifBegin( GifWriter *writer, const char *filename,
uint32_t width, uint32_t height,
uint32_t delay, int32_t bitDepth = 8,
bool dither = false )
{
(void)bitDepth;
(void)dither; // Mute "Unused argument" warnings
#if defined(_MSC_VER) && (_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.
bool GifWriteFrame( GifWriter *writer, const uint8_t *image,
uint32_t width, uint32_t height,
uint32_t delay, int bitDepth = 8, bool dither = false )
{
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.
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;
}
};
#endif