// stb_image 2.28_tiny + stb_image_write 1.16_tiny - modified by sen - public domain image loader + writer - http://nothings.org/stb // #ifndef STBI_STDMEM #define STBI_MALLOC(s) mem_alloc(s, MEM_IMAGE) #define STBI_REALLOC(p, s) mem_realloc(p, s, MEM_IMAGE) #define STBI_FREE(p) mem_free(p) // #else // #define STBI_MALLOC(s) malloc(s) // #define STBI_REALLOC(p, s) realloc(p, s) // #define STBI_FREE(p) free(p) // #endif #define STBI_MEMMOVE(a,b,sz) memmove(a,b,sz) #define STBI_MAX_DIMENSIONS (1 << 24) // fast-way is faster to check than jpeg huffman, but slow way is slower #define STBI__ZFAST_BITS 9 // accelerate all cases in default tables #define STBI__ZFAST_MASK ((1 << STBI__ZFAST_BITS) - 1) #define STBI__ZNSYMS 288 // number of symbols in literal/length alphabet // stbi__err - error // stbi__errpuc - error returning pointer to byte #define stbi__errpuc(x,y) ((byte *)(ulong) (stbi__err(x,y)?NULL:NULL)) #define STBI__BYTECAST(x) ((byte) ((x) & 255)) // truncate int to byte without warnings #define STBI__PNG_TYPE(a,b,c,d) (((unsigned) (a) << 24) + ((unsigned) (b) << 16) + ((unsigned) (c) << 8) + (unsigned) (d)) #define stbiw__wpng4(o,a,b,c,d) ((o)[0]=STBI__BYTECAST(a),(o)[1]=STBI__BYTECAST(b),(o)[2]=STBI__BYTECAST(c),(o)[3]=STBI__BYTECAST(d),(o)+=4) #define stbiw__wp32(data,v) stbiw__wpng4(data, (v)>>24,(v)>>16,(v)>>8,(v)); #define stbiw__wptag(data,s) stbiw__wpng4(data, s[0],s[1],s[2],s[3]) // stretchy buffer; stbiw__sbpush() == vector<>::push_back() -- stbiw__sbcount() == vector<>::size() #define stbiw__sbraw(a) ((int *) (void *) (a) - 2) #define stbiw__sbm(a) stbiw__sbraw(a)[0] #define stbiw__sbn(a) stbiw__sbraw(a)[1] #define stbiw__sbneedgrow(a,n) ((a)==0 || stbiw__sbn(a)+n >= stbiw__sbm(a)) #define stbiw__sbmaybegrow(a,n) (stbiw__sbneedgrow(a,(n)) ? stbiw__sbgrow(a,n) : 0) #define stbiw__sbgrow(a,n) stbiw__sbgrowf((void **) &(a), (n), sizeof(*(a))) #define stbiw__sbpush(a, v) (stbiw__sbmaybegrow(a,1), (a)[stbiw__sbn(a)++] = (v)) #define stbiw__sbcount(a) ((a) ? stbiw__sbn(a) : 0) #define stbiw__sbfree(a) ((a) ? STBI_FREE(stbiw__sbraw(a)),0 : 0) #define stbiw__zlib_flush() (out = stbiw__zlib_flushf(out, &bitbuf, &bitcount)) #define stbiw__zlib_add(code,codebits) \ (bitbuf |= (code) << bitcount, bitcount += (codebits), stbiw__zlib_flush()) #define stbiw__zlib_huffa(b,c) stbiw__zlib_add(stbiw__zlib_bitrev(b,c),c) // default huffman tables #define stbiw__zlib_huff1(n) stbiw__zlib_huffa(0x30 + (n), 8) #define stbiw__zlib_huff2(n) stbiw__zlib_huffa(0x190 + (n)-144, 9) #define stbiw__zlib_huff3(n) stbiw__zlib_huffa(0 + (n)-256,7) #define stbiw__zlib_huff4(n) stbiw__zlib_huffa(0xc0 + (n)-280,8) #define stbiw__zlib_huff(n) ((n) <= 143 ? stbiw__zlib_huff1(n) : (n) <= 255 ? stbiw__zlib_huff2(n) : (n) <= 279 ? stbiw__zlib_huff3(n) : stbiw__zlib_huff4(n)) #define stbiw__zlib_huffb(n) ((n) <= 143 ? stbiw__zlib_huff1(n) : stbiw__zlib_huff2(n)) #define stbiw__ZHASH 16384 typedef struct { int (*read) (void *user,char *data,int size); // fill 'data' with 'size' bytes. return number of bytes actually read void (*skip) (void *user,int n); // skip the next 'n' bytes, or 'unget' the last -n bytes if negative int (*eof) (void *user); // returns nonzero if we are at end of file/data } stbi_io_callbacks; // stbi__context structure is our basic context used by all images, so it // contains all the IO context, plus some basic image information typedef struct { uint img_x, img_y; int img_n, img_out_n; stbi_io_callbacks io; void *io_user_data; int read_from_callbacks; int buflen; byte buffer_start[128]; int callback_already_read; byte *img_buffer, *img_buffer_end; byte *img_buffer_original, *img_buffer_original_end; } stbi__context; typedef struct { int bits_per_channel; int num_channels; } stbi__result_info; // zlib-style huffman encoding // (jpegs packs from left, zlib from right, so can't share code) typedef struct { ushort fast[1 << STBI__ZFAST_BITS]; ushort firstcode[16]; int maxcode[17]; ushort firstsymbol[16]; byte size[STBI__ZNSYMS]; ushort value[STBI__ZNSYMS]; } stbi__zhuffman; typedef struct { byte *zbuffer, *zbuffer_end; int num_bits; uint code_buffer; char *zout; char *zout_start; char *zout_end; int z_expandable; stbi__zhuffman z_length, z_distance; } stbi__zbuf; typedef struct { uint length; uint type; } stbi__pngchunk; typedef struct { stbi__context *s; byte *idata, *expanded, *out; int depth; } stbi__png; static const char *stbi__g_failure_reason; static const char *stbi__g_failure_desc; static int stbi__unpremultiply_on_load = 0; static int stbi__de_iphone_flag = 0; static int stbi_write_png_compression_level = 8; static int stbi_write_force_png_filter = -1; // get a VERY brief reason for failure static const char *stbi_failure_reason(void) { return stbi__g_failure_reason; } // get a VERY brief reason for failure (user message) static const char *stbi_failure_desc(void) { return stbi__g_failure_desc; } // for image formats that explicitly notate that they have premultiplied alpha, // we just return the colors as stored in the file. set this flag to force // unpremultiplication. results are undefined if the unpremultiply overflow. static void stbi_set_unpremultiply_on_load(int should_unpremultiply) { stbi__unpremultiply_on_load = should_unpremultiply; } // indicate whether we should process iphone images back to canonical format, // or just pass them through "as-is" static void stbi_convert_iphone_png_to_rgb(int should_convert) { stbi__de_iphone_flag = should_convert; } static void stbi_set_png_compression_level(int png_compression_level) { stbi_write_png_compression_level = png_compression_level; } static void stbi_set_force_png_filter(int force_png_filter) { stbi_write_force_png_filter = force_png_filter; } static int stbi__err(const char *reason, const char *desc) { stbi__g_failure_reason = reason; stbi__g_failure_desc = desc; return 0; } // ZLIB client - used by PNG, available for other purposes static char *stbi_zlib_decode_malloc_guesssize(const char *buffer, int len, int initial_size, int *outlen); static char *stbi_zlib_decode_malloc_guesssize_headerflag(const char *buffer, int len, int initial_size, int *outlen, int parse_header); static char *stbi_zlib_decode_malloc(const char *buffer, int len, int *outlen); static int stbi_zlib_decode_buffer(char *obuffer, int olen, const char *ibuffer, int ilen); static char *stbi_zlib_decode_noheader_malloc(const char *buffer, int len, int *outlen); static int stbi_zlib_decode_noheader_buffer(char *obuffer, int olen, const char *ibuffer, int ilen); static void stbi__refill_buffer(stbi__context *s); // initialize a memory-decode context static void stbi__start_mem(stbi__context *s, byte const *buffer, int len) { s->io.read = NULL; s->read_from_callbacks = 0; s->callback_already_read = 0; s->img_buffer = s->img_buffer_original = (byte *) buffer; s->img_buffer_end = s->img_buffer_original_end = (byte *) buffer+len; } // initialize a callback-based context static void stbi__start_callbacks(stbi__context *s, stbi_io_callbacks *c, void *user) { s->io = *c; s->io_user_data = user; s->buflen = sizeof(s->buffer_start); s->read_from_callbacks = 1; s->callback_already_read = 0; s->img_buffer = s->img_buffer_original = s->buffer_start; stbi__refill_buffer(s); s->img_buffer_original_end = s->img_buffer_end; } static int stbi__stdio_read(void *user, char *data, int size) { return (int) fread(data,1,size,(FILE*) user); } static void stbi__stdio_skip(void *user, int n) { int ch; fseek((FILE*) user, n, SEEK_CUR); ch = fgetc((FILE*) user); /* have to read a byte to reset feof()'s flag */ if (ch != EOF) { ungetc(ch, (FILE *) user); /* push byte back onto stream if valid. */ } } static int stbi__stdio_eof(void *user) { return feof((FILE*) user) || ferror((FILE *) user); } static stbi_io_callbacks stbi__stdio_callbacks = { stbi__stdio_read, stbi__stdio_skip, stbi__stdio_eof, }; static void stbi__start_file(stbi__context *s, FILE *f) { stbi__start_callbacks(s, &stbi__stdio_callbacks, (void *) f); } //static void stop_file(stbi__context *s) { } static void stbi__rewind(stbi__context *s) { // conceptually rewind SHOULD rewind to the beginning of the stream, // but we just rewind to the beginning of the initial buffer, because // we only use it after doing 'test', which only ever looks at at most 92 bytes s->img_buffer = s->img_buffer_original; s->img_buffer_end = s->img_buffer_original_end; } static int stbi__png_test(stbi__context *s); static void *stbi__png_load(stbi__context *s, int *x, int *y, stbi__result_info *ri); static void *stbi__malloc(ulong size) { return STBI_MALLOC(size); } // stb_image uses ints pervasively, including for offset calculations. // therefore the largest decoded image size we can support with the // current code, even on 64-bit targets, is INT_MAX. this is not a // significant limitation for the intended use case. // // we do, however, need to make sure our size calculations don't // overflow. hence a few helper functions for size calculations that // multiply integers together, making sure that they're non-negative // and no overflow occurs. // return 1 if the sum is valid, 0 on overflow. // negative terms are considered invalid. static int stbi__addsizes_valid(int a, int b) { if (b < 0) return 0; // now 0 <= b <= INT_MAX, hence also // 0 <= INT_MAX - b <= INTMAX. // And "a + b <= INT_MAX" (which might overflow) is the // same as a <= INT_MAX - b (no overflow) return a <= INT_MAX - b; } // returns 1 if the product is valid, 0 on overflow. // negative factors are considered invalid. static int stbi__mul2sizes_valid(int a, int b) { if (a < 0 || b < 0) return 0; if (b == 0) return 1; // mul-by-0 is always safe // portable way to check for no overflows in a*b return a <= INT_MAX/b; } // returns 1 if "a*b + add" has no negative terms/factors and doesn't overflow static int stbi__mad2sizes_valid(int a, int b, int add) { return stbi__mul2sizes_valid(a, b) && stbi__addsizes_valid(a*b, add); } // returns 1 if "a*b*c + add" has no negative terms/factors and doesn't overflow static int stbi__mad3sizes_valid(int a, int b, int c, int add) { return stbi__mul2sizes_valid(a, b) && stbi__mul2sizes_valid(a*b, c) && stbi__addsizes_valid(a*b*c, add); } // mallocs with size overflow checking static void *stbi__malloc_mad2(int a, int b, int add) { if (!stbi__mad2sizes_valid(a, b, add)) return NULL; return stbi__malloc(a*b + add); } static void *stbi__malloc_mad3(int a, int b, int c, int add) { if (!stbi__mad3sizes_valid(a, b, c, add)) return NULL; return stbi__malloc(a*b*c + add); } static void *stbi__load_main(stbi__context *s, int *x, int *y, stbi__result_info *ri) { memset(ri, 0, sizeof(*ri)); // make sure it's initialized if we add new fields ri->bits_per_channel = 8; // default is 8 so most paths don't have to be changed ri->num_channels = 0; if (stbi__png_test(s)) return stbi__png_load(s,x,y, ri); return stbi__errpuc("unknown image type", "Image not of any known type, or corrupt"); } static byte *stbi__convert_16_to_8(ushort *orig, int w, int h) { int i; int img_len = w * h * 4; byte *reduced; reduced = (byte *) stbi__malloc(img_len); if (reduced == NULL) return stbi__errpuc("outofmem", "Out of memory"); for (i = 0; i < img_len; ++i) reduced[i] = (byte)((orig[i] >> 8) & 0xFF); // top half of each byte is sufficient approx of 16->8 bit scaling STBI_FREE(orig); return reduced; } static void stbi__vertical_flip(void *image, int w, int h) { int row; ulong bytes_per_row = (ulong)w * 4 * sizeof(byte); byte temp[2048]; byte *bytes = (byte *)image; for (row = 0; row < (h>>1); row++) { byte *row0 = bytes + row*bytes_per_row; byte *row1 = bytes + (h - row - 1)*bytes_per_row; // swap row0 with row1 ulong bytes_left = bytes_per_row; while (bytes_left) { ulong bytes_copy = (bytes_left < sizeof(temp)) ? bytes_left : sizeof(temp); memcpy(temp, row0, bytes_copy); memcpy(row0, row1, bytes_copy); memcpy(row1, temp, bytes_copy); row0 += bytes_copy; row1 += bytes_copy; bytes_left -= bytes_copy; } } } static byte *stbi__load_and_postprocess_8bit(stbi__context *s, int *x, int *y, byte flip) { stbi__result_info ri; void *result = stbi__load_main(s, x, y, &ri); if (result == NULL) return NULL; // it is the responsibility of the loaders to make sure we get either 8 or 16 bit. sys_assert(ri.bits_per_channel == 8 || ri.bits_per_channel == 16); if (ri.bits_per_channel != 8) { result = stbi__convert_16_to_8((ushort *) result, *x, *y); ri.bits_per_channel = 8; } // @TODO: move stbi__convert_format to here if (flip) { stbi__vertical_flip(result, *x, *y); } return (byte *) result; } static byte *stbi_load(FILE *f, int *x, int *y, byte flip) { byte *result; stbi__context s; stbi__start_file(&s,f); result = stbi__load_and_postprocess_8bit(&s,x,y, flip); if (result) { // need to 'unget' all the characters in the IO buffer fseek(f, - (int) (s.img_buffer_end - s.img_buffer), SEEK_CUR); } return result; } static byte *stbi_load_mem(byte const *buffer, int len, int *x, int *y, byte flip) { stbi__context s; stbi__start_mem(&s,buffer,len); return stbi__load_and_postprocess_8bit(&s,x,y, flip); } ////////////////////////////////////////////////////////////////////////////// // // Common code used by all image loaders // static void stbi__refill_buffer(stbi__context *s) { int n = (s->io.read)(s->io_user_data,(char*)s->buffer_start,s->buflen); s->callback_already_read += (int) (s->img_buffer - s->img_buffer_original); if (n == 0) { // at end of file, treat same as if from memory, but need to handle case // where s->img_buffer isn't pointing to safe memory, e.g. 0-byte file s->read_from_callbacks = 0; s->img_buffer = s->buffer_start; s->img_buffer_end = s->buffer_start+1; *s->img_buffer = 0; } else { s->img_buffer = s->buffer_start; s->img_buffer_end = s->buffer_start + n; } } static byte stbi__get8(stbi__context *s) { if (s->img_buffer < s->img_buffer_end) return *s->img_buffer++; if (s->read_from_callbacks) { stbi__refill_buffer(s); return *s->img_buffer++; } return 0; } static void stbi__skip(stbi__context *s, int n) { if (n == 0) return; // already there! if (n < 0) { s->img_buffer = s->img_buffer_end; return; } if (s->io.read) { int blen = (int) (s->img_buffer_end - s->img_buffer); if (blen < n) { s->img_buffer = s->img_buffer_end; (s->io.skip)(s->io_user_data, n - blen); return; } } s->img_buffer += n; } static int stbi__getn(stbi__context *s, byte *buffer, int n) { if (s->io.read) { int blen = (int) (s->img_buffer_end - s->img_buffer); if (blen < n) { int res, count; memcpy(buffer, s->img_buffer, blen); count = (s->io.read)(s->io_user_data, (char*) buffer + blen, n - blen); res = (count == (n-blen)); s->img_buffer = s->img_buffer_end; return res; } } if (s->img_buffer+n <= s->img_buffer_end) { memcpy(buffer, s->img_buffer, n); s->img_buffer += n; return 1; } else return 0; } static int stbi__get16be(stbi__context *s) { int z = stbi__get8(s); return (z << 8) + stbi__get8(s); } static uint stbi__get32be(stbi__context *s) { uint z = stbi__get16be(s); return (z << 16) + stbi__get16be(s); } ////////////////////////////////////////////////////////////////////////////// // // generic converter from built-in img_n to req_comp // individual types do this automatically as much as possible (e.g. jpeg // does all cases internally since it needs to colorspace convert anyway, // and it never has alpha, so very few cases ). png can automatically // interleave an alpha=255 channel, but falls back to this for other cases // // assume data buffer is malloced, so malloc a new one and free that one // only failure mode is malloc failing static byte stbi__compute_y(int r, int g, int b) { return (byte) (((r*77) + (g*150) + (29*b)) >> 8); } static byte *stbi__convert_format(byte *data, int img_n, uint x, uint y) { int i,j; byte *good; if (4 == img_n) return data; good = (byte *) stbi__malloc_mad3(4, x, y, 0); if (good == NULL) { STBI_FREE(data); return stbi__errpuc("outofmem", "Out of memory"); } for (j=0; j < (int) y; ++j) { byte *src = data + j * x * img_n ; byte *dest = good + j * x * 4; #define STBI__COMBO(a,b) ((a)*8+(b)) #define STBI__CASE(a,b) case STBI__COMBO(a,b): for(i=x-1; i >= 0; --i, src += a, dest += b) // convert source image with img_n components to one with 4 components; // avoid switch per pixel, so use switch per scanline and massive macros switch (STBI__COMBO(img_n, 4)) { STBI__CASE(1,2) { dest[0]=src[0]; dest[1]=255; } break; STBI__CASE(1,3) { dest[0]=dest[1]=dest[2]=src[0]; } break; STBI__CASE(1,4) { dest[0]=dest[1]=dest[2]=src[0]; dest[3]=255; } break; STBI__CASE(2,1) { dest[0]=src[0]; } break; STBI__CASE(2,3) { dest[0]=dest[1]=dest[2]=src[0]; } break; STBI__CASE(2,4) { dest[0]=dest[1]=dest[2]=src[0]; dest[3]=src[1]; } break; STBI__CASE(3,4) { dest[0]=src[0];dest[1]=src[1];dest[2]=src[2];dest[3]=255; } break; STBI__CASE(3,1) { dest[0]=stbi__compute_y(src[0],src[1],src[2]); } break; STBI__CASE(3,2) { dest[0]=stbi__compute_y(src[0],src[1],src[2]); dest[1] = 255; } break; STBI__CASE(4,1) { dest[0]=stbi__compute_y(src[0],src[1],src[2]); } break; STBI__CASE(4,2) { dest[0]=stbi__compute_y(src[0],src[1],src[2]); dest[1] = src[3]; } break; STBI__CASE(4,3) { dest[0]=src[0];dest[1]=src[1];dest[2]=src[2]; } break; default: sys_assert(0); STBI_FREE(data); STBI_FREE(good); return stbi__errpuc("unsupported", "Unsupported format conversion"); } #undef STBI__CASE } STBI_FREE(data); return good; } static ushort stbi__compute_y_16(int r, int g, int b) { return (ushort) (((r*77) + (g*150) + (29*b)) >> 8); } static ushort *stbi__convert_format16(ushort *data, int img_n, uint x, uint y) { int i,j; ushort *good; if (4 == img_n) return data; good = (ushort *) stbi__malloc(4 * x * y * 2); if (good == NULL) { STBI_FREE(data); return (ushort *) stbi__errpuc("outofmem", "Out of memory"); } for (j=0; j < (int) y; ++j) { ushort *src = data + j * x * img_n ; ushort *dest = good + j * x * 4; #define STBI__COMBO(a,b) ((a)*8+(b)) #define STBI__CASE(a,b) case STBI__COMBO(a,b): for(i=x-1; i >= 0; --i, src += a, dest += b) // convert source image with img_n components to one with 4 components; // avoid switch per pixel, so use switch per scanline and massive macros switch (STBI__COMBO(img_n, 4)) { STBI__CASE(1,2) { dest[0]=src[0]; dest[1]=0xffff; } break; STBI__CASE(1,3) { dest[0]=dest[1]=dest[2]=src[0]; } break; STBI__CASE(1,4) { dest[0]=dest[1]=dest[2]=src[0]; dest[3]=0xffff; } break; STBI__CASE(2,1) { dest[0]=src[0]; } break; STBI__CASE(2,3) { dest[0]=dest[1]=dest[2]=src[0]; } break; STBI__CASE(2,4) { dest[0]=dest[1]=dest[2]=src[0]; dest[3]=src[1]; } break; STBI__CASE(3,4) { dest[0]=src[0];dest[1]=src[1];dest[2]=src[2];dest[3]=0xffff; } break; STBI__CASE(3,1) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]); } break; STBI__CASE(3,2) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]); dest[1] = 0xffff; } break; STBI__CASE(4,1) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]); } break; STBI__CASE(4,2) { dest[0]=stbi__compute_y_16(src[0],src[1],src[2]); dest[1] = src[3]; } break; STBI__CASE(4,3) { dest[0]=src[0];dest[1]=src[1];dest[2]=src[2]; } break; default: sys_assert(0); STBI_FREE(data); STBI_FREE(good); return (ushort*) stbi__errpuc("unsupported", "Unsupported format conversion"); } #undef STBI__CASE } STBI_FREE(data); return good; } // public domain zlib decode v0.2 Sean Barrett 2006-11-18 // simple implementation // - all input must be provided in an upfront buffer // - all output is written to a single output buffer (can malloc/realloc) // performance // - fast huffman static int stbi__bitreverse16(int n) { n = ((n & 0xAAAA) >> 1) | ((n & 0x5555) << 1); n = ((n & 0xCCCC) >> 2) | ((n & 0x3333) << 2); n = ((n & 0xF0F0) >> 4) | ((n & 0x0F0F) << 4); n = ((n & 0xFF00) >> 8) | ((n & 0x00FF) << 8); return n; } static int stbi__bit_reverse(int v, int bits) { sys_assert(bits <= 16); // to bit reverse n bits, reverse 16 and shift // e.g. 11 bits, bit reverse and shift away 5 return stbi__bitreverse16(v) >> (16-bits); } static int stbi__zbuild_huffman(stbi__zhuffman *z, const byte *sizelist, int num) { int i,k=0; int code, next_code[16], sizes[17]; // DEFLATE spec for generating codes memset(sizes, 0, sizeof(sizes)); memset(z->fast, 0, sizeof(z->fast)); for (i=0; i < num; ++i) ++sizes[sizelist[i]]; sizes[0] = 0; for (i=1; i < 16; ++i) if (sizes[i] > (1 << i)) return stbi__err("bad sizes", "Corrupt PNG"); code = 0; for (i=1; i < 16; ++i) { next_code[i] = code; z->firstcode[i] = (ushort) code; z->firstsymbol[i] = (ushort) k; code = (code + sizes[i]); if (sizes[i]) if (code-1 >= (1 << i)) return stbi__err("bad codelengths","Corrupt PNG"); z->maxcode[i] = code << (16-i); // preshift for inner loop code <<= 1; k += sizes[i]; } z->maxcode[16] = 0x10000; // sentinel for (i=0; i < num; ++i) { int s = sizelist[i]; if (s) { int c = next_code[s] - z->firstcode[s] + z->firstsymbol[s]; ushort fastv = (ushort) ((s << 9) | i); z->size [c] = (byte ) s; z->value[c] = (ushort) i; if (s <= STBI__ZFAST_BITS) { int j = stbi__bit_reverse(next_code[s],s); while (j < (1 << STBI__ZFAST_BITS)) { z->fast[j] = fastv; j += (1 << s); } } ++next_code[s]; } } return 1; } // zlib-from-memory implementation for PNG reading // because PNG allows splitting the zlib stream arbitrarily, // and it's annoying structurally to have PNG call ZLIB call PNG, // we require PNG read all the IDATs and combine them into a single // memory buffer static int stbi__zeof(stbi__zbuf *z) { return (z->zbuffer >= z->zbuffer_end); } static byte stbi__zget8(stbi__zbuf *z) { return stbi__zeof(z) ? 0 : *z->zbuffer++; } static void stbi__fill_bits(stbi__zbuf *z) { do { if (z->code_buffer >= (1U << z->num_bits)) { z->zbuffer = z->zbuffer_end; /* treat this as EOF so we fail. */ return; } z->code_buffer |= (uint) stbi__zget8(z) << z->num_bits; z->num_bits += 8; } while (z->num_bits <= 24); } static uint stbi__zreceive(stbi__zbuf *z, int n) { uint k; if (z->num_bits < n) stbi__fill_bits(z); k = z->code_buffer & ((1 << n) - 1); z->code_buffer >>= n; z->num_bits -= n; return k; } static int stbi__zhuffman_decode_slowpath(stbi__zbuf *a, stbi__zhuffman *z) { int b,s,k; // not resolved by fast table, so compute it the slow way // use jpeg approach, which requires MSbits at top k = stbi__bit_reverse(a->code_buffer, 16); for (s=STBI__ZFAST_BITS+1; ; ++s) if (k < z->maxcode[s]) break; if (s >= 16) return -1; // invalid code! // code size is s, so: b = (k >> (16-s)) - z->firstcode[s] + z->firstsymbol[s]; if (b >= STBI__ZNSYMS) return -1; // some data was corrupt somewhere! if (z->size[b] != s) return -1; // was originally an sys_assert, but report failure instead. a->code_buffer >>= s; a->num_bits -= s; return z->value[b]; } static int stbi__zhuffman_decode(stbi__zbuf *a, stbi__zhuffman *z) { int b,s; if (a->num_bits < 16) { if (stbi__zeof(a)) { return -1; /* report error for unexpected end of data. */ } stbi__fill_bits(a); } b = z->fast[a->code_buffer & STBI__ZFAST_MASK]; if (b) { s = b >> 9; a->code_buffer >>= s; a->num_bits -= s; return b & 511; } return stbi__zhuffman_decode_slowpath(a, z); } static int stbi__zexpand(stbi__zbuf *z, char *zout, int n) // need to make room for n bytes { char *q; uint cur, limit; // , old_limit; z->zout = zout; if (!z->z_expandable) return stbi__err("output buffer limit","Corrupt PNG"); cur = (uint) (z->zout - z->zout_start); limit = /* old_limit = */ (unsigned) (z->zout_end - z->zout_start); if (UINT_MAX - cur < (unsigned) n) return stbi__err("outofmem", "Out of memory"); while (cur + n > limit) { if(limit > UINT_MAX / 2) return stbi__err("outofmem", "Out of memory"); limit *= 2; } q = (char *) STBI_REALLOC(z->zout_start, limit); // STBI_NOTUSED(old_limit); if (q == NULL) return stbi__err("outofmem", "Out of memory"); z->zout_start = q; z->zout = q + cur; z->zout_end = q + limit; return 1; } static const int stbi__zlength_base[31] = { 3,4,5,6,7,8,9,10,11,13, 15,17,19,23,27,31,35,43,51,59, 67,83,99,115,131,163,195,227,258,0,0 }; static const int stbi__zlength_extra[31]= { 0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0,0,0 }; static const int stbi__zdist_base[32] = { 1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193, 257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577,0,0}; static const int stbi__zdist_extra[32] = { 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13}; static int stbi__parse_huffman_block(stbi__zbuf *a) { char *zout = a->zout; for(;;) { int z = stbi__zhuffman_decode(a, &a->z_length); if (z < 256) { if (z < 0) return stbi__err("bad huffman code","Corrupt PNG"); // error in huffman codes if (zout >= a->zout_end) { if (!stbi__zexpand(a, zout, 1)) return 0; zout = a->zout; } *zout++ = (char) z; } else { byte *p; int len,dist; if (z == 256) { a->zout = zout; return 1; } if (z >= 286) return stbi__err("bad huffman code","Corrupt PNG"); // per DEFLATE, length codes 286 and 287 must not appear in compressed data z -= 257; len = stbi__zlength_base[z]; if (stbi__zlength_extra[z]) len += stbi__zreceive(a, stbi__zlength_extra[z]); z = stbi__zhuffman_decode(a, &a->z_distance); if (z < 0 || z >= 30) return stbi__err("bad huffman code","Corrupt PNG"); // per DEFLATE, distance codes 30 and 31 must not appear in compressed data dist = stbi__zdist_base[z]; if (stbi__zdist_extra[z]) dist += stbi__zreceive(a, stbi__zdist_extra[z]); if (zout - a->zout_start < dist) return stbi__err("bad dist","Corrupt PNG"); if (zout + len > a->zout_end) { if (!stbi__zexpand(a, zout, len)) return 0; zout = a->zout; } p = (byte *) (zout - dist); if (dist == 1) { // run of one byte; common in images. byte v = *p; if (len) { do *zout++ = v; while (--len); } } else { if (len) { do *zout++ = *p++; while (--len); } } } } } static int stbi__compute_huffman_codes(stbi__zbuf *a) { static const byte length_dezigzag[19] = { 16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15 }; stbi__zhuffman z_codelength; byte lencodes[286+32+137];//padding for maximum single op byte codelength_sizes[19]; int i,n; int hlit = stbi__zreceive(a,5) + 257; int hdist = stbi__zreceive(a,5) + 1; int hclen = stbi__zreceive(a,4) + 4; int ntot = hlit + hdist; memset(codelength_sizes, 0, sizeof(codelength_sizes)); for (i=0; i < hclen; ++i) { int s = stbi__zreceive(a,3); codelength_sizes[length_dezigzag[i]] = (byte) s; } if (!stbi__zbuild_huffman(&z_codelength, codelength_sizes, 19)) return 0; n = 0; while (n < ntot) { int c = stbi__zhuffman_decode(a, &z_codelength); if (c < 0 || c >= 19) return stbi__err("bad codelengths", "Corrupt PNG"); if (c < 16) lencodes[n++] = (byte) c; else { byte fill = 0; if (c == 16) { c = stbi__zreceive(a,2)+3; if (n == 0) return stbi__err("bad codelengths", "Corrupt PNG"); fill = lencodes[n-1]; } else if (c == 17) { c = stbi__zreceive(a,3)+3; } else if (c == 18) { c = stbi__zreceive(a,7)+11; } else { return stbi__err("bad codelengths", "Corrupt PNG"); } if (ntot - n < c) return stbi__err("bad codelengths", "Corrupt PNG"); memset(lencodes+n, fill, c); n += c; } } if (n != ntot) return stbi__err("bad codelengths","Corrupt PNG"); if (!stbi__zbuild_huffman(&a->z_length, lencodes, hlit)) return 0; if (!stbi__zbuild_huffman(&a->z_distance, lencodes+hlit, hdist)) return 0; return 1; } static int stbi__parse_uncompressed_block(stbi__zbuf *a) { byte header[4]; int len,nlen,k; if (a->num_bits & 7) stbi__zreceive(a, a->num_bits & 7); // discard // drain the bit-packed data into header k = 0; while (a->num_bits > 0) { header[k++] = (byte) (a->code_buffer & 255); // suppress MSVC run-time check a->code_buffer >>= 8; a->num_bits -= 8; } if (a->num_bits < 0) return stbi__err("zlib corrupt","Corrupt PNG"); // now fill header the normal way while (k < 4) header[k++] = stbi__zget8(a); len = header[1] * 256 + header[0]; nlen = header[3] * 256 + header[2]; if (nlen != (len ^ 0xffff)) return stbi__err("zlib corrupt","Corrupt PNG"); if (a->zbuffer + len > a->zbuffer_end) return stbi__err("read past buffer","Corrupt PNG"); if (a->zout + len > a->zout_end) if (!stbi__zexpand(a, a->zout, len)) return 0; memcpy(a->zout, a->zbuffer, len); a->zbuffer += len; a->zout += len; return 1; } static int stbi__parse_zlib_header(stbi__zbuf *a) { int cmf = stbi__zget8(a); int cm = cmf & 15; /* int cinfo = cmf >> 4; */ int flg = stbi__zget8(a); if (stbi__zeof(a)) return stbi__err("bad zlib header","Corrupt PNG"); // zlib spec if ((cmf*256+flg) % 31 != 0) return stbi__err("bad zlib header","Corrupt PNG"); // zlib spec if (flg & 32) return stbi__err("no preset dict","Corrupt PNG"); // preset dictionary not allowed in png if (cm != 8) return stbi__err("bad compression","Corrupt PNG"); // DEFLATE required for png // window = 1 << (8 + cinfo)... but who cares, we fully buffer output return 1; } static const byte stbi__zdefault_length[STBI__ZNSYMS] = { 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9, 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7, 7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8 }; static const byte stbi__zdefault_distance[32] = { 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5 }; /* Init algorithm: { int i; // use <= to match clearly with spec for (i=0; i <= 143; ++i) stbi__zdefault_length[i] = 8; for ( ; i <= 255; ++i) stbi__zdefault_length[i] = 9; for ( ; i <= 279; ++i) stbi__zdefault_length[i] = 7; for ( ; i <= 287; ++i) stbi__zdefault_length[i] = 8; for (i=0; i <= 31; ++i) stbi__zdefault_distance[i] = 5; } */ static int stbi__parse_zlib(stbi__zbuf *a, int parse_header) { int final, type; if (parse_header) if (!stbi__parse_zlib_header(a)) return 0; a->num_bits = 0; a->code_buffer = 0; do { final = stbi__zreceive(a,1); type = stbi__zreceive(a,2); if (type == 0) { if (!stbi__parse_uncompressed_block(a)) return 0; } else if (type == 3) { return 0; } else { if (type == 1) { // use fixed code lengths if (!stbi__zbuild_huffman(&a->z_length , stbi__zdefault_length , STBI__ZNSYMS)) return 0; if (!stbi__zbuild_huffman(&a->z_distance, stbi__zdefault_distance, 32)) return 0; } else { if (!stbi__compute_huffman_codes(a)) return 0; } if (!stbi__parse_huffman_block(a)) return 0; } } while (!final); return 1; } static int stbi__do_zlib(stbi__zbuf *a, char *obuf, int olen, int exp, int parse_header) { a->zout_start = obuf; a->zout = obuf; a->zout_end = obuf + olen; a->z_expandable = exp; return stbi__parse_zlib(a, parse_header); } static char *stbi_zlib_decode_malloc_guesssize(const char *buffer, int len, int initial_size, int *outlen) { stbi__zbuf a; char *p = (char *) stbi__malloc(initial_size); if (p == NULL) return NULL; a.zbuffer = (byte *) buffer; a.zbuffer_end = (byte *) buffer + len; if (stbi__do_zlib(&a, p, initial_size, 1, 1)) { if (outlen) *outlen = (int) (a.zout - a.zout_start); return a.zout_start; } else { STBI_FREE(a.zout_start); return NULL; } } static char *stbi_zlib_decode_malloc(char const *buffer, int len, int *outlen) { return stbi_zlib_decode_malloc_guesssize(buffer, len, 16384, outlen); } static char *stbi_zlib_decode_malloc_guesssize_headerflag(const char *buffer, int len, int initial_size, int *outlen, int parse_header) { stbi__zbuf a; char *p = (char *) stbi__malloc(initial_size); if (p == NULL) return NULL; a.zbuffer = (byte *) buffer; a.zbuffer_end = (byte *) buffer + len; if (stbi__do_zlib(&a, p, initial_size, 1, parse_header)) { if (outlen) *outlen = (int) (a.zout - a.zout_start); return a.zout_start; } else { STBI_FREE(a.zout_start); return NULL; } } static int stbi_zlib_decode_buffer(char *obuffer, int olen, char const *ibuffer, int ilen) { stbi__zbuf a; a.zbuffer = (byte *) ibuffer; a.zbuffer_end = (byte *) ibuffer + ilen; if (stbi__do_zlib(&a, obuffer, olen, 0, 1)) return (int) (a.zout - a.zout_start); else return -1; } static char *stbi_zlib_decode_noheader_malloc(char const *buffer, int len, int *outlen) { stbi__zbuf a; char *p = (char *) stbi__malloc(16384); if (p == NULL) return NULL; a.zbuffer = (byte *) buffer; a.zbuffer_end = (byte *) buffer+len; if (stbi__do_zlib(&a, p, 16384, 1, 0)) { if (outlen) *outlen = (int) (a.zout - a.zout_start); return a.zout_start; } else { STBI_FREE(a.zout_start); return NULL; } } static int stbi_zlib_decode_noheader_buffer(char *obuffer, int olen, const char *ibuffer, int ilen) { stbi__zbuf a; a.zbuffer = (byte *) ibuffer; a.zbuffer_end = (byte *) ibuffer + ilen; if (stbi__do_zlib(&a, obuffer, olen, 0, 0)) return (int) (a.zout - a.zout_start); else return -1; } // public domain "baseline" PNG decoder v0.10 Sean Barrett 2006-11-18 // simple implementation // - only 8-bit samples // - no CRC checking // - allocates lots of intermediate memory // - avoids problem of streaming data between subsystems // - avoids explicit window management // performance // - uses stb_zlib, a PD zlib implementation with fast huffman decoding static stbi__pngchunk stbi__get_chunk_header(stbi__context *s) { stbi__pngchunk c; c.length = stbi__get32be(s); c.type = stbi__get32be(s); return c; } static int stbi__check_png_header(stbi__context *s) { static const byte png_sig[8] = { 137,80,78,71,13,10,26,10 }; int i; for (i=0; i < 8; ++i) if (stbi__get8(s) != png_sig[i]) return stbi__err("bad png sig","Not a PNG"); return 1; } enum { STBI__F_none=0, STBI__F_sub=1, STBI__F_up=2, STBI__F_avg=3, STBI__F_paeth=4, // synthetic filters used for first scanline to avoid needing a dummy row of 0s STBI__F_avg_first, STBI__F_paeth_first }; static byte first_row_filter[5] = { STBI__F_none, STBI__F_sub, STBI__F_none, STBI__F_avg_first, STBI__F_paeth_first }; static int stbi__paeth(int a, int b, int c) { int p = a + b - c; int pa = abs(p-a); int pb = abs(p-b); int pc = abs(p-c); if (pa <= pb && pa <= pc) return a; if (pb <= pc) return b; return c; } static const byte stbi__depth_scale_table[9] = { 0, 0xff, 0x55, 0, 0x11, 0,0,0, 0x01 }; // create the png data from post-deflated data static int stbi__create_png_image_raw(stbi__png *a, byte *raw, uint raw_len, int out_n, uint x, uint y, int depth, int color) { int bytes = (depth == 16? 2 : 1); stbi__context *s = a->s; uint i,j,stride = x*out_n*bytes; uint img_len, img_width_bytes; int k; int img_n = s->img_n; // copy it into a local for later int output_bytes = out_n*bytes; int filter_bytes = img_n*bytes; int width = x; sys_assert(out_n == s->img_n || out_n == s->img_n+1); a->out = (byte *) stbi__malloc_mad3(x, y, output_bytes, 0); // extra bytes to write off the end into if (!a->out) return stbi__err("outofmem", "Out of memory"); if (!stbi__mad3sizes_valid(img_n, x, depth, 7)) return stbi__err("too large", "Corrupt PNG"); img_width_bytes = (((img_n * x * depth) + 7) >> 3); img_len = (img_width_bytes + 1) * y; // we used to check for exact match between raw_len and img_len on non-interlaced PNGs, // but issue #276 reported a PNG in the wild that had extra data at the end (all zeros), // so just check for raw_len < img_len always. if (raw_len < img_len) return stbi__err("not enough pixels","Corrupt PNG"); for (j=0; j < y; ++j) { byte *cur = a->out + stride*j; byte *prior; int filter = *raw++; if (filter > 4) return stbi__err("invalid filter","Corrupt PNG"); if (depth < 8) { if (img_width_bytes > x) return stbi__err("invalid width","Corrupt PNG"); cur += x*out_n - img_width_bytes; // store output to the rightmost img_len bytes, so we can decode in place filter_bytes = 1; width = img_width_bytes; } prior = cur - stride; // bugfix: need to compute this after 'cur +=' computation above // if first row, use special filter that doesn't sample previous row if (j == 0) filter = first_row_filter[filter]; // handle first byte explicitly for (k=0; k < filter_bytes; ++k) { switch (filter) { case STBI__F_none : cur[k] = raw[k]; break; case STBI__F_sub : cur[k] = raw[k]; break; case STBI__F_up : cur[k] = STBI__BYTECAST(raw[k] + prior[k]); break; case STBI__F_avg : cur[k] = STBI__BYTECAST(raw[k] + (prior[k]>>1)); break; case STBI__F_paeth : cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(0,prior[k],0)); break; case STBI__F_avg_first : cur[k] = raw[k]; break; case STBI__F_paeth_first: cur[k] = raw[k]; break; } } if (depth == 8) { if (img_n != out_n) cur[img_n] = 255; // first pixel raw += img_n; cur += out_n; prior += out_n; } else if (depth == 16) { if (img_n != out_n) { cur[filter_bytes] = 255; // first pixel top byte cur[filter_bytes+1] = 255; // first pixel bottom byte } raw += filter_bytes; cur += output_bytes; prior += output_bytes; } else { raw += 1; cur += 1; prior += 1; } // this is a little gross, so that we don't switch per-pixel or per-component if (depth < 8 || img_n == out_n) { int nk = (width - 1)*filter_bytes; #define STBI__CASE(f) \ case f: \ for (k=0; k < nk; ++k) switch (filter) { // "none" filter turns into a memcpy here; make that explicit. case STBI__F_none: memcpy(cur, raw, nk); break; STBI__CASE(STBI__F_sub) { cur[k] = STBI__BYTECAST(raw[k] + cur[k-filter_bytes]); } break; STBI__CASE(STBI__F_up) { cur[k] = STBI__BYTECAST(raw[k] + prior[k]); } break; STBI__CASE(STBI__F_avg) { cur[k] = STBI__BYTECAST(raw[k] + ((prior[k] + cur[k-filter_bytes])>>1)); } break; STBI__CASE(STBI__F_paeth) { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k-filter_bytes],prior[k],prior[k-filter_bytes])); } break; STBI__CASE(STBI__F_avg_first) { cur[k] = STBI__BYTECAST(raw[k] + (cur[k-filter_bytes] >> 1)); } break; STBI__CASE(STBI__F_paeth_first) { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k-filter_bytes],0,0)); } break; } #undef STBI__CASE raw += nk; } else { sys_assert(img_n+1 == out_n); #define STBI__CASE(f) \ case f: \ for (i=x-1; i >= 1; --i, cur[filter_bytes]=255,raw+=filter_bytes,cur+=output_bytes,prior+=output_bytes) \ for (k=0; k < filter_bytes; ++k) switch (filter) { STBI__CASE(STBI__F_none) { cur[k] = raw[k]; } break; STBI__CASE(STBI__F_sub) { cur[k] = STBI__BYTECAST(raw[k] + cur[k- output_bytes]); } break; STBI__CASE(STBI__F_up) { cur[k] = STBI__BYTECAST(raw[k] + prior[k]); } break; STBI__CASE(STBI__F_avg) { cur[k] = STBI__BYTECAST(raw[k] + ((prior[k] + cur[k- output_bytes])>>1)); } break; STBI__CASE(STBI__F_paeth) { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k- output_bytes],prior[k],prior[k- output_bytes])); } break; STBI__CASE(STBI__F_avg_first) { cur[k] = STBI__BYTECAST(raw[k] + (cur[k- output_bytes] >> 1)); } break; STBI__CASE(STBI__F_paeth_first) { cur[k] = STBI__BYTECAST(raw[k] + stbi__paeth(cur[k- output_bytes],0,0)); } break; } #undef STBI__CASE // the loop above sets the high byte of the pixels' alpha, but for // 16 bit png files we also need the low byte set. we'll do that here. if (depth == 16) { cur = a->out + stride*j; // start at the beginning of the row again for (i=0; i < x; ++i,cur+=output_bytes) { cur[filter_bytes+1] = 255; } } } } // we make a separate pass to expand bits to pixels; for performance, // this could run two scanlines behind the above code, so it won't // intefere with filtering but will still be in the cache. if (depth < 8) { for (j=0; j < y; ++j) { byte *cur = a->out + stride*j; byte *in = a->out + stride*j + x*out_n - img_width_bytes; // unpack 1/2/4-bit into a 8-bit buffer. allows us to keep the common 8-bit path optimal at minimal cost for 1/2/4-bit // png guarante byte alignment, if width is not multiple of 8/4/2 we'll decode dummy trailing data that will be skipped in the later loop byte scale = (color == 0) ? stbi__depth_scale_table[depth] : 1; // scale grayscale values to 0..255 range // note that the final byte might overshoot and write more data than desired. // we can allocate enough data that this never writes out of memory, but it // could also overwrite the next scanline. can it overwrite non-empty data // on the next scanline? yes, consider 1-pixel-wide scanlines with 1-bit-per-pixel. // so we need to explicitly clamp the final ones if (depth == 4) { for (k=x*img_n; k >= 2; k-=2, ++in) { *cur++ = scale * ((*in >> 4) ); *cur++ = scale * ((*in ) & 0x0f); } if (k > 0) *cur++ = scale * ((*in >> 4) ); } else if (depth == 2) { for (k=x*img_n; k >= 4; k-=4, ++in) { *cur++ = scale * ((*in >> 6) ); *cur++ = scale * ((*in >> 4) & 0x03); *cur++ = scale * ((*in >> 2) & 0x03); *cur++ = scale * ((*in ) & 0x03); } if (k > 0) *cur++ = scale * ((*in >> 6) ); if (k > 1) *cur++ = scale * ((*in >> 4) & 0x03); if (k > 2) *cur++ = scale * ((*in >> 2) & 0x03); } else if (depth == 1) { for (k=x*img_n; k >= 8; k-=8, ++in) { *cur++ = scale * ((*in >> 7) ); *cur++ = scale * ((*in >> 6) & 0x01); *cur++ = scale * ((*in >> 5) & 0x01); *cur++ = scale * ((*in >> 4) & 0x01); *cur++ = scale * ((*in >> 3) & 0x01); *cur++ = scale * ((*in >> 2) & 0x01); *cur++ = scale * ((*in >> 1) & 0x01); *cur++ = scale * ((*in ) & 0x01); } if (k > 0) *cur++ = scale * ((*in >> 7) ); if (k > 1) *cur++ = scale * ((*in >> 6) & 0x01); if (k > 2) *cur++ = scale * ((*in >> 5) & 0x01); if (k > 3) *cur++ = scale * ((*in >> 4) & 0x01); if (k > 4) *cur++ = scale * ((*in >> 3) & 0x01); if (k > 5) *cur++ = scale * ((*in >> 2) & 0x01); if (k > 6) *cur++ = scale * ((*in >> 1) & 0x01); } if (img_n != out_n) { int q; // insert alpha = 255 cur = a->out + stride*j; if (img_n == 1) { for (q=x-1; q >= 0; --q) { cur[q*2+1] = 255; cur[q*2+0] = cur[q]; } } else { sys_assert(img_n == 3); for (q=x-1; q >= 0; --q) { cur[q*4+3] = 255; cur[q*4+2] = cur[q*3+2]; cur[q*4+1] = cur[q*3+1]; cur[q*4+0] = cur[q*3+0]; } } } } } else if (depth == 16) { // force the image data from big-endian to platform-native. // this is done in a separate pass due to the decoding relying // on the data being untouched, but could probably be done // per-line during decode if care is taken. byte *cur = a->out; ushort *cur16 = (ushort*)cur; for(i=0; i < x*y*out_n; ++i,cur16++,cur+=2) { *cur16 = (cur[0] << 8) | cur[1]; } } return 1; } static int stbi__create_png_image(stbi__png *a, byte *image_data, uint image_data_len, int out_n, int depth, int color, int interlaced) { int bytes = (depth == 16 ? 2 : 1); int out_bytes = out_n * bytes; byte *final; int p; if (!interlaced) return stbi__create_png_image_raw(a, image_data, image_data_len, out_n, a->s->img_x, a->s->img_y, depth, color); // de-interlacing final = (byte *) stbi__malloc_mad3(a->s->img_x, a->s->img_y, out_bytes, 0); if (!final) return stbi__err("outofmem", "Out of memory"); for (p=0; p < 7; ++p) { int xorig[] = { 0,4,0,2,0,1,0 }; int yorig[] = { 0,0,4,0,2,0,1 }; int xspc[] = { 8,8,4,4,2,2,1 }; int yspc[] = { 8,8,8,4,4,2,2 }; int i,j,x,y; // pass1_x[4] = 0, pass1_x[5] = 1, pass1_x[12] = 1 x = (a->s->img_x - xorig[p] + xspc[p]-1) / xspc[p]; y = (a->s->img_y - yorig[p] + yspc[p]-1) / yspc[p]; if (x && y) { uint img_len = ((((a->s->img_n * x * depth) + 7) >> 3) + 1) * y; if (!stbi__create_png_image_raw(a, image_data, image_data_len, out_n, x, y, depth, color)) { STBI_FREE(final); return 0; } for (j=0; j < y; ++j) { for (i=0; i < x; ++i) { int out_y = j*yspc[p]+yorig[p]; int out_x = i*xspc[p]+xorig[p]; memcpy(final + out_y*a->s->img_x*out_bytes + out_x*out_bytes, a->out + (j*x+i)*out_bytes, out_bytes); } } STBI_FREE(a->out); image_data += img_len; image_data_len -= img_len; } } a->out = final; return 1; } static int stbi__compute_transparency(stbi__png *z, byte tc[3], int out_n) { stbi__context *s = z->s; uint i, pixel_count = s->img_x * s->img_y; byte *p = z->out; // compute color-based transparency, assuming we've // already got 255 as the alpha value in the output sys_assert(out_n == 2 || out_n == 4); if (out_n == 2) { for (i=0; i < pixel_count; ++i) { p[1] = (p[0] == tc[0] ? 0 : 255); p += 2; } } else { for (i=0; i < pixel_count; ++i) { if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2]) p[3] = 0; p += 4; } } return 1; } static int stbi__compute_transparency16(stbi__png *z, ushort tc[3], int out_n) { stbi__context *s = z->s; uint i, pixel_count = s->img_x * s->img_y; ushort *p = (ushort*) z->out; // compute color-based transparency, assuming we've // already got 65535 as the alpha value in the output sys_assert(out_n == 2 || out_n == 4); if (out_n == 2) { for (i = 0; i < pixel_count; ++i) { p[1] = (p[0] == tc[0] ? 0 : 65535); p += 2; } } else { for (i = 0; i < pixel_count; ++i) { if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2]) p[3] = 0; p += 4; } } return 1; } static int stbi__expand_png_palette(stbi__png *a, byte *palette, int pal_img_n) { uint i, pixel_count = a->s->img_x * a->s->img_y; byte *p, *temp_out, *orig = a->out; p = (byte *) stbi__malloc_mad2(pixel_count, pal_img_n, 0); if (p == NULL) return stbi__err("outofmem", "Out of memory"); // between here and free(out) below, exitting would leak temp_out = p; if (pal_img_n == 3) { for (i=0; i < pixel_count; ++i) { int n = orig[i]*4; p[0] = palette[n ]; p[1] = palette[n+1]; p[2] = palette[n+2]; p += 3; } } else { for (i=0; i < pixel_count; ++i) { int n = orig[i]*4; p[0] = palette[n ]; p[1] = palette[n+1]; p[2] = palette[n+2]; p[3] = palette[n+3]; p += 4; } } STBI_FREE(a->out); a->out = temp_out; // STBI_NOTUSED(len); return 1; } static void stbi__de_iphone(stbi__png *z) { stbi__context *s = z->s; uint i, pixel_count = s->img_x * s->img_y; byte *p = z->out; if (s->img_out_n == 3) { // convert bgr to rgb for (i=0; i < pixel_count; ++i) { byte t = p[0]; p[0] = p[2]; p[2] = t; p += 3; } } else { sys_assert(s->img_out_n == 4); if (stbi__unpremultiply_on_load) { // convert bgr to rgb and unpremultiply for (i=0; i < pixel_count; ++i) { byte a = p[3]; byte t = p[0]; if (a) { byte half = a / 2; p[0] = (p[2] * 255 + half) / a; p[1] = (p[1] * 255 + half) / a; p[2] = ( t * 255 + half) / a; } else { p[0] = p[2]; p[2] = t; } p += 4; } } else { // convert bgr to rgb for (i=0; i < pixel_count; ++i) { byte t = p[0]; p[0] = p[2]; p[2] = t; p += 4; } } } } static int stbi__parse_png_file(stbi__png *z) { byte palette[1024], pal_img_n=0; byte has_trans=0, tc[3]={0}; ushort tc16[3]; uint ioff=0, idata_limit=0, i, pal_len=0; int first=1,k,interlace=0, color=0, is_iphone=0; stbi__context *s = z->s; z->expanded = NULL; z->idata = NULL; z->out = NULL; if (!stbi__check_png_header(s)) return 0; // if (scan == STBI__SCAN_type) return 1; for (;;) { stbi__pngchunk c = stbi__get_chunk_header(s); switch (c.type) { case STBI__PNG_TYPE('C','g','B','I'): is_iphone = 1; stbi__skip(s, c.length); break; case STBI__PNG_TYPE('I','H','D','R'): { int comp,filter; if (!first) return stbi__err("multiple IHDR","Corrupt PNG"); first = 0; if (c.length != 13) return stbi__err("bad IHDR len","Corrupt PNG"); s->img_x = stbi__get32be(s); s->img_y = stbi__get32be(s); if (s->img_y > STBI_MAX_DIMENSIONS) return stbi__err("too large","Very large image (corrupt?)"); if (s->img_x > STBI_MAX_DIMENSIONS) return stbi__err("too large","Very large image (corrupt?)"); z->depth = stbi__get8(s); if (z->depth != 1 && z->depth != 2 && z->depth != 4 && z->depth != 8 && z->depth != 16) return stbi__err("1/2/4/8/16-bit only","PNG not supported: 1/2/4/8/16-bit only"); color = stbi__get8(s); if (color > 6) return stbi__err("bad ctype","Corrupt PNG"); if (color == 3 && z->depth == 16) return stbi__err("bad ctype","Corrupt PNG"); if (color == 3) pal_img_n = 3; else if (color & 1) return stbi__err("bad ctype","Corrupt PNG"); comp = stbi__get8(s); if (comp) return stbi__err("bad comp method","Corrupt PNG"); filter= stbi__get8(s); if (filter) return stbi__err("bad filter method","Corrupt PNG"); interlace = stbi__get8(s); if (interlace>1) return stbi__err("bad interlace method","Corrupt PNG"); if (!s->img_x || !s->img_y) return stbi__err("0-pixel image","Corrupt PNG"); if (!pal_img_n) { s->img_n = (color & 2 ? 3 : 1) + (color & 4 ? 1 : 0); if ((1 << 30) / s->img_x / s->img_n < s->img_y) return stbi__err("too large", "Image too large to decode"); } else { // if paletted, then pal_n is our final components, and // img_n is # components to decompress/filter. s->img_n = 1; if ((1 << 30) / s->img_x / 4 < s->img_y) return stbi__err("too large","Corrupt PNG"); } // even with SCAN_header, have to scan to see if we have a tRNS break; } case STBI__PNG_TYPE('P','L','T','E'): { if (first) return stbi__err("first not IHDR", "Corrupt PNG"); if (c.length > 256*3) return stbi__err("invalid PLTE","Corrupt PNG"); pal_len = c.length / 3; if (pal_len * 3 != c.length) return stbi__err("invalid PLTE","Corrupt PNG"); for (i=0; i < pal_len; ++i) { palette[i*4+0] = stbi__get8(s); palette[i*4+1] = stbi__get8(s); palette[i*4+2] = stbi__get8(s); palette[i*4+3] = 255; } break; } case STBI__PNG_TYPE('t','R','N','S'): { if (first) return stbi__err("first not IHDR", "Corrupt PNG"); if (z->idata) return stbi__err("tRNS after IDAT","Corrupt PNG"); if (pal_img_n) { // if (scan == STBI__SCAN_header) { s->img_n = 4; return 1; } if (pal_len == 0) return stbi__err("tRNS before PLTE","Corrupt PNG"); if (c.length > pal_len) return stbi__err("bad tRNS len","Corrupt PNG"); pal_img_n = 4; for (i=0; i < c.length; ++i) palette[i*4+3] = stbi__get8(s); } else { if (!(s->img_n & 1)) return stbi__err("tRNS with alpha","Corrupt PNG"); if (c.length != (uint) s->img_n*2) return stbi__err("bad tRNS len","Corrupt PNG"); has_trans = 1; // non-paletted with tRNS = constant alpha. if header-scanning, we can stop now. // if (scan == STBI__SCAN_header) { ++s->img_n; return 1; } if (z->depth == 16) { for (k = 0; k < s->img_n; ++k) tc16[k] = (ushort)stbi__get16be(s); // copy the values as-is } else { for (k = 0; k < s->img_n; ++k) tc[k] = (byte)(stbi__get16be(s) & 255) * stbi__depth_scale_table[z->depth]; // non 8-bit images will be larger } } break; } case STBI__PNG_TYPE('I','D','A','T'): { if (first) return stbi__err("first not IHDR", "Corrupt PNG"); if (pal_img_n && !pal_len) return stbi__err("no PLTE","Corrupt PNG"); // if (scan == STBI__SCAN_header) { // header scan definitely stops at first IDAT // if (pal_img_n) // s->img_n = pal_img_n; // return 1; // } if (c.length > (1u << 30)) return stbi__err("IDAT size limit", "IDAT section larger than 2^30 bytes"); if ((int)(ioff + c.length) < (int)ioff) return 0; if (ioff + c.length > idata_limit) { // uint idata_limit_old = idata_limit; byte *p; if (idata_limit == 0) idata_limit = c.length > 4096 ? c.length : 4096; while (ioff + c.length > idata_limit) idata_limit *= 2; // STBI_NOTUSED(idata_limit_old); p = (byte *) STBI_REALLOC(z->idata, idata_limit); if (p == NULL) return stbi__err("outofmem", "Out of memory"); z->idata = p; } if (!stbi__getn(s, z->idata+ioff,c.length)) return stbi__err("outofdata","Corrupt PNG"); ioff += c.length; break; } case STBI__PNG_TYPE('I','E','N','D'): { uint raw_len, bpl; if (first) return stbi__err("first not IHDR", "Corrupt PNG"); // if (scan != STBI__SCAN_load) return 1; if (z->idata == NULL) return stbi__err("no IDAT","Corrupt PNG"); // initial guess for decoded data size to avoid unnecessary reallocs bpl = (s->img_x * z->depth + 7) / 8; // bytes per line, per component raw_len = bpl * s->img_y * s->img_n /* pixels */ + s->img_y /* filter mode per row */; z->expanded = (byte *) stbi_zlib_decode_malloc_guesssize_headerflag((char *) z->idata, ioff, raw_len, (int *) &raw_len, !is_iphone); if (z->expanded == NULL) return 0; // zlib should set error STBI_FREE(z->idata); z->idata = NULL; if ((4 == s->img_n+1 && !pal_img_n) || has_trans) s->img_out_n = s->img_n+1; else s->img_out_n = s->img_n; if (!stbi__create_png_image(z, z->expanded, raw_len, s->img_out_n, z->depth, color, interlace)) return 0; if (has_trans) { if (z->depth == 16) { if (!stbi__compute_transparency16(z, tc16, s->img_out_n)) return 0; } else { if (!stbi__compute_transparency(z, tc, s->img_out_n)) return 0; } } if (is_iphone && stbi__de_iphone_flag && s->img_out_n > 2) stbi__de_iphone(z); if (pal_img_n) { // pal_img_n == 3 or 4 s->img_n = pal_img_n; // record the actual colors we had // s->img_out_n = pal_img_n; s->img_out_n = 4; if (!stbi__expand_png_palette(z, palette, /* pal_len, */ s->img_out_n)) return 0; } else if (has_trans) { // non-paletted image with tRNS -> source image has (constant) alpha ++s->img_n; } STBI_FREE(z->expanded); z->expanded = NULL; // end of PNG chunk, read and skip CRC stbi__get32be(s); return 1; } default: // if critical, fail if (first) return stbi__err("first not IHDR", "Corrupt PNG"); if ((c.type & (1 << 29)) == 0) { // not threadsafe static char invalid_chunk[] = "XXXX PNG chunk not known"; invalid_chunk[0] = STBI__BYTECAST(c.type >> 24); invalid_chunk[1] = STBI__BYTECAST(c.type >> 16); invalid_chunk[2] = STBI__BYTECAST(c.type >> 8); invalid_chunk[3] = STBI__BYTECAST(c.type >> 0); return stbi__err(invalid_chunk, "PNG not supported: unknown PNG chunk type"); } stbi__skip(s, c.length); break; } // end of PNG chunk, read and skip CRC stbi__get32be(s); } } static void *stbi__do_png(stbi__png *p, int *x, int *y, stbi__result_info *ri) { void *result=NULL; if (stbi__parse_png_file(p)) { if (p->depth <= 8) ri->bits_per_channel = 8; else if (p->depth == 16) ri->bits_per_channel = 16; else return stbi__errpuc("bad bits_per_channel", "PNG not supported: unsupported color depth"); result = p->out; p->out = NULL; if (4 != p->s->img_out_n) { if (ri->bits_per_channel == 8) result = stbi__convert_format((byte *) result, p->s->img_out_n, p->s->img_x, p->s->img_y); else result = stbi__convert_format16((ushort *) result, p->s->img_out_n, p->s->img_x, p->s->img_y); p->s->img_out_n = 4; if (result == NULL) return result; } *x = p->s->img_x; *y = p->s->img_y; } STBI_FREE(p->out); p->out = NULL; STBI_FREE(p->expanded); p->expanded = NULL; STBI_FREE(p->idata); p->idata = NULL; return result; } static void *stbi__png_load(stbi__context *s, int *x, int *y, stbi__result_info *ri) { stbi__png p; p.s = s; return stbi__do_png(&p, x,y, ri); } static int stbi__png_test(stbi__context *s) { int r; r = stbi__check_png_header(s); stbi__rewind(s); return r; } ////////////////////////////////////////////////////////////////////////////// // // PNG writer // static void *stbiw__sbgrowf(void **arr, int increment, int itemsize) { int m = *arr ? 2*stbiw__sbm(*arr)+increment : increment+1; void *p = STBI_REALLOC(*arr ? stbiw__sbraw(*arr) : 0, /* *arr ? (stbiw__sbm(*arr)*itemsize + sizeof(int)*2) : 0, */ itemsize * m + sizeof(int)*2); sys_assert(p); if (p) { if (!*arr) ((int *) p)[1] = 0; *arr = (void *) ((int *) p + 2); stbiw__sbm(*arr) = m; } return *arr; } static byte *stbiw__zlib_flushf(byte *data, uint *bitbuffer, int *bitcount) { while (*bitcount >= 8) { stbiw__sbpush(data, STBI__BYTECAST(*bitbuffer)); *bitbuffer >>= 8; *bitcount -= 8; } return data; } static int stbiw__zlib_bitrev(int code, int codebits) { int res=0; while (codebits--) { res = (res << 1) | (code & 1); code >>= 1; } return res; } static uint stbiw__zlib_countm(byte *a, byte *b, int limit) { int i; for (i=0; i < limit && i < 258; ++i) if (a[i] != b[i]) break; return i; } static uint stbiw__zhash(byte *data) { uint hash = data[0] + (data[1] << 8) + (data[2] << 16); hash ^= hash << 3; hash += hash >> 5; hash ^= hash << 4; hash += hash >> 17; hash ^= hash << 25; hash += hash >> 6; return hash; } static byte * stbi_zlib_compress(byte *data, int data_len, int *out_len, int quality) { static ushort lengthc[] = { 3,4,5,6,7,8,9,10,11,13,15,17,19,23,27,31,35,43,51,59,67,83,99,115,131,163,195,227,258, 259 }; static byte lengtheb[]= { 0,0,0,0,0,0,0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0 }; static ushort distc[] = { 1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577, 32768 }; static byte disteb[] = { 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13 }; uint bitbuf=0; int i,j, bitcount=0; byte *out = NULL; byte ***hash_table = (byte***) STBI_MALLOC(stbiw__ZHASH * sizeof(byte**)); if (hash_table == NULL) return NULL; if (quality < 5) quality = 5; stbiw__sbpush(out, 0x78); // DEFLATE 32K window stbiw__sbpush(out, 0x5e); // FLEVEL = 1 stbiw__zlib_add(1,1); // BFINAL = 1 stbiw__zlib_add(1,2); // BTYPE = 1 -- fixed huffman for (i=0; i < stbiw__ZHASH; ++i) hash_table[i] = NULL; i=0; while (i < data_len-3) { // hash next 3 bytes of data to be compressed int h = stbiw__zhash(data+i)&(stbiw__ZHASH-1), best=3; byte *bestloc = 0; byte **hlist = hash_table[h]; int n = stbiw__sbcount(hlist); for (j=0; j < n; ++j) { if (hlist[j]-data > i-32768) { // if entry lies within window int d = stbiw__zlib_countm(hlist[j], data+i, data_len-i); if (d >= best) { best=d; bestloc=hlist[j]; } } } // when hash table entry is too long, delete half the entries if (hash_table[h] && stbiw__sbn(hash_table[h]) == 2*quality) { STBI_MEMMOVE(hash_table[h], hash_table[h]+quality, sizeof(hash_table[h][0])*quality); stbiw__sbn(hash_table[h]) = quality; } stbiw__sbpush(hash_table[h],data+i); if (bestloc) { // "lazy matching" - check match at *next* byte, and if it's better, do cur byte as literal h = stbiw__zhash(data+i+1)&(stbiw__ZHASH-1); hlist = hash_table[h]; n = stbiw__sbcount(hlist); for (j=0; j < n; ++j) { if (hlist[j]-data > i-32767) { int e = stbiw__zlib_countm(hlist[j], data+i+1, data_len-i-1); if (e > best) { // if next match is better, bail on current match bestloc = NULL; break; } } } } if (bestloc) { int d = (int) (data+i - bestloc); // distance back sys_assert(d <= 32767 && best <= 258); for (j=0; best > lengthc[j+1]-1; ++j); stbiw__zlib_huff(j+257); if (lengtheb[j]) stbiw__zlib_add(best - lengthc[j], lengtheb[j]); for (j=0; d > distc[j+1]-1; ++j); stbiw__zlib_add(stbiw__zlib_bitrev(j,5),5); if (disteb[j]) stbiw__zlib_add(d - distc[j], disteb[j]); i += best; } else { stbiw__zlib_huffb(data[i]); ++i; } } // write out final bytes for (;i < data_len; ++i) stbiw__zlib_huffb(data[i]); stbiw__zlib_huff(256); // end of block // pad with 0 bits to byte boundary while (bitcount) stbiw__zlib_add(0,1); for (i=0; i < stbiw__ZHASH; ++i) (void) stbiw__sbfree(hash_table[i]); STBI_FREE(hash_table); // store uncompressed instead if compression was worse if (stbiw__sbn(out) > data_len + 2 + ((data_len+32766)/32767)*5) { stbiw__sbn(out) = 2; // truncate to DEFLATE 32K window and FLEVEL = 1 for (j = 0; j < data_len;) { int blocklen = data_len - j; if (blocklen > 32767) blocklen = 32767; stbiw__sbpush(out, data_len - j == blocklen); // BFINAL = ?, BTYPE = 0 -- no compression stbiw__sbpush(out, STBI__BYTECAST(blocklen)); // LEN stbiw__sbpush(out, STBI__BYTECAST(blocklen >> 8)); stbiw__sbpush(out, STBI__BYTECAST(~blocklen)); // NLEN stbiw__sbpush(out, STBI__BYTECAST(~blocklen >> 8)); memcpy(out+stbiw__sbn(out), data+j, blocklen); stbiw__sbn(out) += blocklen; j += blocklen; } } { // compute adler32 on input uint s1=1, s2=0; int blocklen = (int) (data_len % 5552); j=0; while (j < data_len) { for (i=0; i < blocklen; ++i) { s1 += data[j+i]; s2 += s1; } s1 %= 65521; s2 %= 65521; j += blocklen; blocklen = 5552; } stbiw__sbpush(out, STBI__BYTECAST(s2 >> 8)); stbiw__sbpush(out, STBI__BYTECAST(s2)); stbiw__sbpush(out, STBI__BYTECAST(s1 >> 8)); stbiw__sbpush(out, STBI__BYTECAST(s1)); } *out_len = stbiw__sbn(out); // make returned pointer freeable STBI_MEMMOVE(stbiw__sbraw(out), out, *out_len); return (byte *) stbiw__sbraw(out); } static uint stbiw__crc32(byte *buffer, int len) { static uint crc_table[256] = { 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0eDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F, 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9, 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D }; uint crc = ~0u; int i; for (i=0; i < len; ++i) crc = (crc >> 8) ^ crc_table[buffer[i] ^ (crc & 0xff)]; return ~crc; } static void stbiw__wpcrc(byte **data, int len) { uint crc = stbiw__crc32(*data - len - 4, len+4); stbiw__wp32(*data, crc); } static byte stbiw__paeth(int a, int b, int c) { int p = a + b - c, pa = abs(p-a), pb = abs(p-b), pc = abs(p-c); if (pa <= pb && pa <= pc) return STBI__BYTECAST(a); if (pb <= pc) return STBI__BYTECAST(b); return STBI__BYTECAST(c); } // @OPTIMIZE: provide an option that always forces left-predict or paeth predict static void stbiw__encode_png_line(byte *pixels, int stride_bytes, int width, int height, int y, int n, int filter_type, char *line_buffer, byte flip) { static int mapping[] = { 0,1,2,3,4 }; static int firstmap[] = { 0,1,0,5,6 }; int *mymap = (y != 0) ? mapping : firstmap; int i; int type = mymap[filter_type]; byte *z = pixels + stride_bytes * (flip ? height-1-y : y); int signed_stride = flip ? -stride_bytes : stride_bytes; if (type==0) { memcpy(line_buffer, z, width*n); return; } // first loop isn't optimized since it's just one pixel for (i = 0; i < n; ++i) { switch (type) { case 1: line_buffer[i] = z[i]; break; case 2: line_buffer[i] = z[i] - z[i-signed_stride]; break; case 3: line_buffer[i] = z[i] - (z[i-signed_stride]>>1); break; case 4: line_buffer[i] = (char) (z[i] - stbiw__paeth(0,z[i-signed_stride],0)); break; case 5: line_buffer[i] = z[i]; break; case 6: line_buffer[i] = z[i]; break; } } switch (type) { case 1: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - z[i-n]; break; case 2: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - z[i-signed_stride]; break; case 3: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - ((z[i-n] + z[i-signed_stride])>>1); break; case 4: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - stbiw__paeth(z[i-n], z[i-signed_stride], z[i-signed_stride-n]); break; case 5: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - (z[i-n]>>1); break; case 6: for (i=n; i < width*n; ++i) line_buffer[i] = z[i] - stbiw__paeth(z[i-n], 0,0); break; } } // For PNG, "stride_in_bytes" is the distance in bytes from the first byte of // a row of pixels to the first byte of the next row of pixels. static byte *stbi_write_png_to_mem(const byte *pixels, int stride_bytes, int x, int y, int n, int *out_len, byte flip) { int force_filter = stbi_write_force_png_filter; int ctype[5] = { -1, 0, 4, 2, 6 }; byte sig[8] = { 137,80,78,71,13,10,26,10 }; byte *out,*o, *filt, *zlib; char *line_buffer; int j,zlen; if (stride_bytes == 0) stride_bytes = x * n; if (force_filter >= 5) { force_filter = -1; } filt = (byte *) STBI_MALLOC((x*n+1) * y); if (!filt) return 0; line_buffer = (char *) STBI_MALLOC(x * n); if (!line_buffer) { STBI_FREE(filt); return 0; } for (j=0; j < y; ++j) { int filter_type; if (force_filter > -1) { filter_type = force_filter; stbiw__encode_png_line((byte*)(pixels), stride_bytes, x, y, j, n, force_filter, line_buffer, flip); } else { // Estimate the best filter by running through all of them: int best_filter = 0, best_filter_val = 0x7fffffff, est, i; for (filter_type = 0; filter_type < 5; filter_type++) { stbiw__encode_png_line((byte*)(pixels), stride_bytes, x, y, j, n, filter_type, line_buffer, flip); // Estimate the entropy of the line using this filter; the less, the better. est = 0; for (i = 0; i < x*n; ++i) { est += abs((char) line_buffer[i]); } if (est < best_filter_val) { best_filter_val = est; best_filter = filter_type; } } if (filter_type != best_filter) { // If the last iteration already got us the best filter, don't redo it stbiw__encode_png_line((byte*)(pixels), stride_bytes, x, y, j, n, best_filter, line_buffer, flip); filter_type = best_filter; } } // when we get here, filter_type contains the filter type, and line_buffer contains the data filt[j*(x*n+1)] = (byte) filter_type; STBI_MEMMOVE(filt+j*(x*n+1)+1, line_buffer, x*n); } STBI_FREE(line_buffer); zlib = stbi_zlib_compress(filt, y*( x*n+1), &zlen, stbi_write_png_compression_level); STBI_FREE(filt); if (!zlib) return 0; // each tag requires 12 bytes of overhead out = (byte *) STBI_MALLOC(8 + 12+13 + 12+zlen + 12); if (!out) return 0; *out_len = 8 + 12+13 + 12+zlen + 12; o=out; STBI_MEMMOVE(o,sig,8); o+= 8; stbiw__wp32(o, 13); // header length stbiw__wptag(o, "IHDR"); stbiw__wp32(o, x); stbiw__wp32(o, y); *o++ = 8; *o++ = STBI__BYTECAST(ctype[n]); *o++ = 0; *o++ = 0; *o++ = 0; stbiw__wpcrc(&o,13); stbiw__wp32(o, zlen); stbiw__wptag(o, "IDAT"); STBI_MEMMOVE(o, zlib, zlen); o += zlen; STBI_FREE(zlib); stbiw__wpcrc(&o, zlen); stbiw__wp32(o,0); stbiw__wptag(o, "IEND"); stbiw__wpcrc(&o,0); sys_assert(o == out + *out_len); return out; }