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Dear ImGui: Bloat-free Graphical User interface for C++ with minimal dependencies
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imgui-docking/misc/fonts/binary_to_compressed_c.cpp

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// ImGui - binary_to_compressed_c.cpp
// Helper tool to turn a file into a C array, if you want to embed font data in your source code.
// The data is first compressed with stb_compress() to reduce source code size,
// then encoded in Base85 to fit in a string so we can fit roughly 4 bytes of compressed data into 5 bytes of source code (suggested by @mmalex)
// (If we used 32-bits constants it would require take 11 bytes of source code to encode 4 bytes, and be endianness dependent)
// Note that even with compression, the output array is likely to be bigger than the binary file..
// Load compressed TTF fonts with ImGui::GetIO().Fonts->AddFontFromMemoryCompressedTTF()
// Build with, e.g:
// # cl.exe binary_to_compressed_c.cpp
// # gcc binary_to_compressed_c.cpp
// You can also find a precompiled Windows binary in the binary/demo package available from https://github.com/ocornut/imgui
// Usage:
// binary_to_compressed_c.exe [-base85] [-nocompress] <inputfile> <symbolname>
// Usage example:
// # binary_to_compressed_c.exe myfont.ttf MyFont > myfont.cpp
// # binary_to_compressed_c.exe -base85 myfont.ttf MyFont > myfont.cpp
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
// stb_compress* from stb.h - declaration
typedef unsigned int stb_uint;
typedef unsigned char stb_uchar;
stb_uint stb_compress(stb_uchar *out,stb_uchar *in,stb_uint len);
static bool binary_to_compressed_c(const char* filename, const char* symbol, bool use_base85_encoding, bool use_compression);
int main(int argc, char** argv)
{
if (argc < 3)
{
printf("Syntax: %s [-base85] [-nocompress] <inputfile> <symbolname>\n", argv[0]);
return 0;
}
int argn = 1;
bool use_base85_encoding = false;
bool use_compression = true;
if (argv[argn][0] == '-')
{
if (strcmp(argv[argn], "-base85") == 0) { use_base85_encoding = true; argn++; }
else if (strcmp(argv[argn], "-nocompress") == 0) { use_compression = false; argn++; }
else
{
printf("Unknown argument: '%s'\n", argv[argn]);
return 1;
}
}
return binary_to_compressed_c(argv[argn], argv[argn+1], use_base85_encoding, use_compression) ? 0 : 1;
}
char Encode85Byte(unsigned int x)
{
x = (x % 85) + 35;
return (x>='\\') ? x+1 : x;
}
bool binary_to_compressed_c(const char* filename, const char* symbol, bool use_base85_encoding, bool use_compression)
{
// Read file
FILE* f = fopen(filename, "rb");
if (!f) return false;
int data_sz;
if (fseek(f, 0, SEEK_END) || (data_sz = (int)ftell(f)) == -1 || fseek(f, 0, SEEK_SET)) { fclose(f); return false; }
char* data = new char[data_sz+4];
if (fread(data, 1, data_sz, f) != (size_t)data_sz) { fclose(f); delete[] data; return false; }
memset((void *)(((char*)data) + data_sz), 0, 4);
fclose(f);
// Compress
int maxlen = data_sz + 512 + (data_sz >> 2) + sizeof(int); // total guess
char* compressed = use_compression ? new char[maxlen] : data;
int compressed_sz = use_compression ? stb_compress((stb_uchar*)compressed, (stb_uchar*)data, data_sz) : data_sz;
if (use_compression)
memset(compressed + compressed_sz, 0, maxlen - compressed_sz);
// Output as Base85 encoded
FILE* out = stdout;
fprintf(out, "// File: '%s' (%d bytes)\n", filename, (int)data_sz);
fprintf(out, "// Exported using binary_to_compressed_c.cpp\n");
const char* compressed_str = use_compression ? "compressed_" : "";
if (use_base85_encoding)
{
fprintf(out, "static const char %s_%sdata_base85[%d+1] =\n \"", symbol, compressed_str, (int)((compressed_sz+3)/4)*5);
char prev_c = 0;
for (int src_i = 0; src_i < compressed_sz; src_i += 4)
{
// This is made a little more complicated by the fact that ??X sequences are interpreted as trigraphs by old C/C++ compilers. So we need to escape pairs of ??.
unsigned int d = *(unsigned int*)(compressed + src_i);
for (unsigned int n5 = 0; n5 < 5; n5++, d /= 85)
{
char c = Encode85Byte(d);
fprintf(out, (c == '?' && prev_c == '?') ? "\\%c" : "%c", c);
prev_c = c;
}
if ((src_i % 112) == 112-4)
fprintf(out, "\"\n \"");
}
fprintf(out, "\";\n\n");
}
else
{
fprintf(out, "static const unsigned int %s_%ssize = %d;\n", symbol, compressed_str, (int)compressed_sz);
fprintf(out, "static const unsigned int %s_%sdata[%d/4] =\n{", symbol, compressed_str, (int)((compressed_sz+3)/4)*4);
int column = 0;
for (int i = 0; i < compressed_sz; i += 4)
{
unsigned int d = *(unsigned int*)(compressed + i);
if ((column++ % 12) == 0)
fprintf(out, "\n 0x%08x, ", d);
else
fprintf(out, "0x%08x, ", d);
}
fprintf(out, "\n};\n\n");
}
// Cleanup
delete[] data;
if (use_compression)
delete[] compressed;
return true;
}
// stb_compress* from stb.h - definition
//////////////////// compressor ///////////////////////
static stb_uint stb_adler32(stb_uint adler32, stb_uchar *buffer, stb_uint buflen)
{
const unsigned long ADLER_MOD = 65521;
unsigned long s1 = adler32 & 0xffff, s2 = adler32 >> 16;
unsigned long blocklen, i;
blocklen = buflen % 5552;
while (buflen) {
for (i=0; i + 7 < blocklen; i += 8) {
s1 += buffer[0], s2 += s1;
s1 += buffer[1], s2 += s1;
s1 += buffer[2], s2 += s1;
s1 += buffer[3], s2 += s1;
s1 += buffer[4], s2 += s1;
s1 += buffer[5], s2 += s1;
s1 += buffer[6], s2 += s1;
s1 += buffer[7], s2 += s1;
buffer += 8;
}
for (; i < blocklen; ++i)
s1 += *buffer++, s2 += s1;
s1 %= ADLER_MOD, s2 %= ADLER_MOD;
buflen -= blocklen;
blocklen = 5552;
}
return (s2 << 16) + s1;
}
static unsigned int stb_matchlen(stb_uchar *m1, stb_uchar *m2, stb_uint maxlen)
{
stb_uint i;
for (i=0; i < maxlen; ++i)
if (m1[i] != m2[i]) return i;
return i;
}
// simple implementation that just takes the source data in a big block
static stb_uchar *stb__out;
static FILE *stb__outfile;
static stb_uint stb__outbytes;
static void stb__write(unsigned char v)
{
fputc(v, stb__outfile);
++stb__outbytes;
}
//#define stb_out(v) (stb__out ? *stb__out++ = (stb_uchar) (v) : stb__write((stb_uchar) (v)))
#define stb_out(v) do { if (stb__out) *stb__out++ = (stb_uchar) (v); else stb__write((stb_uchar) (v)); } while (0)
static void stb_out2(stb_uint v) { stb_out(v >> 8); stb_out(v); }
static void stb_out3(stb_uint v) { stb_out(v >> 16); stb_out(v >> 8); stb_out(v); }
static void stb_out4(stb_uint v) { stb_out(v >> 24); stb_out(v >> 16); stb_out(v >> 8 ); stb_out(v); }
static void outliterals(stb_uchar *in, int numlit)
{
while (numlit > 65536) {
outliterals(in,65536);
in += 65536;
numlit -= 65536;
}
if (numlit == 0) ;
else if (numlit <= 32) stb_out (0x000020 + numlit-1);
else if (numlit <= 2048) stb_out2(0x000800 + numlit-1);
else /* numlit <= 65536) */ stb_out3(0x070000 + numlit-1);
if (stb__out) {
memcpy(stb__out,in,numlit);
stb__out += numlit;
} else
fwrite(in, 1, numlit, stb__outfile);
}
static int stb__window = 0x40000; // 256K
static int stb_not_crap(int best, int dist)
{
return ((best > 2 && dist <= 0x00100)
|| (best > 5 && dist <= 0x04000)
|| (best > 7 && dist <= 0x80000));
}
static stb_uint stb__hashsize = 32768;
// note that you can play with the hashing functions all you
// want without needing to change the decompressor
#define stb__hc(q,h,c) (((h) << 7) + ((h) >> 25) + q[c])
#define stb__hc2(q,h,c,d) (((h) << 14) + ((h) >> 18) + (q[c] << 7) + q[d])
#define stb__hc3(q,c,d,e) ((q[c] << 14) + (q[d] << 7) + q[e])
static unsigned int stb__running_adler;
static int stb_compress_chunk(stb_uchar *history,
stb_uchar *start,
stb_uchar *end,
int length,
int *pending_literals,
stb_uchar **chash,
stb_uint mask)
{
(void)history;
int window = stb__window;
stb_uint match_max;
stb_uchar *lit_start = start - *pending_literals;
stb_uchar *q = start;
#define STB__SCRAMBLE(h) (((h) + ((h) >> 16)) & mask)
// stop short of the end so we don't scan off the end doing
// the hashing; this means we won't compress the last few bytes
// unless they were part of something longer
while (q < start+length && q+12 < end) {
int m;
stb_uint h1,h2,h3,h4, h;
stb_uchar *t;
int best = 2, dist=0;
if (q+65536 > end)
match_max = end-q;
else
match_max = 65536;
#define stb__nc(b,d) ((d) <= window && ((b) > 9 || stb_not_crap(b,d)))
#define STB__TRY(t,p) /* avoid retrying a match we already tried */ \
if (p ? dist != q-t : 1) \
if ((m = stb_matchlen(t, q, match_max)) > best) \
if (stb__nc(m,q-(t))) \
best = m, dist = q - (t)
// rather than search for all matches, only try 4 candidate locations,
// chosen based on 4 different hash functions of different lengths.
// this strategy is inspired by LZO; hashing is unrolled here using the
// 'hc' macro
h = stb__hc3(q,0, 1, 2); h1 = STB__SCRAMBLE(h);
t = chash[h1]; if (t) STB__TRY(t,0);
h = stb__hc2(q,h, 3, 4); h2 = STB__SCRAMBLE(h);
h = stb__hc2(q,h, 5, 6); t = chash[h2]; if (t) STB__TRY(t,1);
h = stb__hc2(q,h, 7, 8); h3 = STB__SCRAMBLE(h);
h = stb__hc2(q,h, 9,10); t = chash[h3]; if (t) STB__TRY(t,1);
h = stb__hc2(q,h,11,12); h4 = STB__SCRAMBLE(h);
t = chash[h4]; if (t) STB__TRY(t,1);
// because we use a shared hash table, can only update it
// _after_ we've probed all of them
chash[h1] = chash[h2] = chash[h3] = chash[h4] = q;
if (best > 2)
assert(dist > 0);
// see if our best match qualifies
if (best < 3) { // fast path literals
++q;
} else if (best > 2 && best <= 0x80 && dist <= 0x100) {
outliterals(lit_start, q-lit_start); lit_start = (q += best);
stb_out(0x80 + best-1);
stb_out(dist-1);
} else if (best > 5 && best <= 0x100 && dist <= 0x4000) {
outliterals(lit_start, q-lit_start); lit_start = (q += best);
stb_out2(0x4000 + dist-1);
stb_out(best-1);
} else if (best > 7 && best <= 0x100 && dist <= 0x80000) {
outliterals(lit_start, q-lit_start); lit_start = (q += best);
stb_out3(0x180000 + dist-1);
stb_out(best-1);
} else if (best > 8 && best <= 0x10000 && dist <= 0x80000) {
outliterals(lit_start, q-lit_start); lit_start = (q += best);
stb_out3(0x100000 + dist-1);
stb_out2(best-1);
} else if (best > 9 && dist <= 0x1000000) {
if (best > 65536) best = 65536;
outliterals(lit_start, q-lit_start); lit_start = (q += best);
if (best <= 0x100) {
stb_out(0x06);
stb_out3(dist-1);
stb_out(best-1);
} else {
stb_out(0x04);
stb_out3(dist-1);
stb_out2(best-1);
}
} else { // fallback literals if no match was a balanced tradeoff
++q;
}
}
// if we didn't get all the way, add the rest to literals
if (q-start < length)
q = start+length;
// the literals are everything from lit_start to q
*pending_literals = (q - lit_start);
stb__running_adler = stb_adler32(stb__running_adler, start, q - start);
return q - start;
}
static int stb_compress_inner(stb_uchar *input, stb_uint length)
{
int literals = 0;
stb_uint len,i;
stb_uchar **chash;
chash = (stb_uchar**) malloc(stb__hashsize * sizeof(stb_uchar*));
if (chash == NULL) return 0; // failure
for (i=0; i < stb__hashsize; ++i)
chash[i] = NULL;
// stream signature
stb_out(0x57); stb_out(0xbc);
stb_out2(0);
stb_out4(0); // 64-bit length requires 32-bit leading 0
stb_out4(length);
stb_out4(stb__window);
stb__running_adler = 1;
len = stb_compress_chunk(input, input, input+length, length, &literals, chash, stb__hashsize-1);
assert(len == length);
outliterals(input+length - literals, literals);
free(chash);
stb_out2(0x05fa); // end opcode
stb_out4(stb__running_adler);
return 1; // success
}
stb_uint stb_compress(stb_uchar *out, stb_uchar *input, stb_uint length)
{
stb__out = out;
stb__outfile = NULL;
stb_compress_inner(input, length);
return stb__out - out;
}