public static int stbi__paeth(int a, int b, int c)
{
var p = a + b - c;
var pa = CRuntime.abs(p - a);
var pb = CRuntime.abs(p - b);
var pc = CRuntime.abs(p - c);
if ((pa <= pb) && (pa <= pc))
{
return(a);
}
if (pb <= pc)
{
return(b);
}
return(c);
}
public static void *stbi__bmp_load(stbi__context s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
{
byte *_out_;
var mr = (uint)0;
var mg = (uint)0;
var mb = (uint)0;
var ma = (uint)0;
uint all_a = 0;
var pal = stackalloc byte[256 * 4];
var psize = 0;
var i = 0;
var j = 0;
var width = 0;
var flip_vertically = 0;
var pad = 0;
var target = 0;
var info = new stbi__bmp_data();
info.all_a = 255;
if (stbi__bmp_parse_header(s, &info) == null)
{
return(null);
}
flip_vertically = ((int)s.img_y > 0) ? 1 : 0;
s.img_y = (uint)CRuntime.abs((int)s.img_y);
mr = info.mr;
mg = info.mg;
mb = info.mb;
ma = info.ma;
all_a = info.all_a;
if (info.hsz == 12)
{
if (info.bpp < 24)
{
psize = (info.offset - 14 - 24) / 3;
}
}
else
{
if (info.bpp < 16)
{
psize = (info.offset - 14 - info.hsz) >> 2;
}
}
s.img_n = (ma != 0) ? 4 : 3;
if ((req_comp != 0) && (req_comp >= 3))
{
target = req_comp;
}
else
{
target = s.img_n;
}
if (stbi__mad3sizes_valid(target, (int)s.img_x, (int)s.img_y, 0) == 0)
{
return((byte *)(ulong)((stbi__err("too large") != 0) ? (byte *)null : null));
}
_out_ = (byte *)stbi__malloc_mad3(target, (int)s.img_x, (int)s.img_y, 0);
if (_out_ == null)
{
return((byte *)(ulong)((stbi__err("outofmem") != 0) ? (byte *)null : null));
}
if (info.bpp < 16)
{
var z = 0;
if ((psize == 0) || (psize > 256))
{
CRuntime.free(_out_);
return((byte *)(ulong)((stbi__err("invalid") != 0) ? (byte *)null : null));
}
for (i = 0; i < psize; ++i)
{
pal[i * 4 + 2] = stbi__get8(s);
pal[i * 4 + 1] = stbi__get8(s);
pal[i * 4 + 0] = stbi__get8(s);
if (info.hsz != 12)
{
stbi__get8(s);
}
pal[i * 4 + 3] = 255;
}
stbi__skip(s, info.offset - 14 - info.hsz - psize * ((info.hsz == 12) ? 3 : 4));
if (info.bpp == 1)
{
width = (int)((s.img_x + 7) >> 3);
}
else
{
if (info.bpp == 4)
{
width = (int)((s.img_x + 1) >> 1);
}
else
{
if (info.bpp == 8)
{
width = (int)s.img_x;
}
else
{
CRuntime.free(_out_);
return((byte *)(ulong)((stbi__err("bad bpp") != 0) ? (byte *)null : null));
}
}
}
pad = -width & 3;
if (info.bpp == 1)
{
for (j = 0; j < (int)s.img_y; ++j)
{
var bit_offset = 7;
var v = (int)stbi__get8(s);
for (i = 0; i < (int)s.img_x; ++i)
{
var color = (v >> bit_offset) & 0x1;
_out_[z++] = pal[color * 4 + 0];
_out_[z++] = pal[color * 4 + 1];
_out_[z++] = pal[color * 4 + 2];
if (target == 4)
{
_out_[z++] = 255;
}
if ((i + 1) == (int)s.img_x)
{
break;
}
if ((--bit_offset) < 0)
{
bit_offset = 7;
v = stbi__get8(s);
}
}
stbi__skip(s, pad);
}
}
else
{
for (j = 0; j < (int)s.img_y; ++j)
{
for (i = 0; i < (int)s.img_x; i += 2)
{
var v = (int)stbi__get8(s);
var v2 = 0;
if (info.bpp == 4)
{
v2 = v & 15;
v >>= 4;
}
_out_[z++] = pal[v * 4 + 0];
_out_[z++] = pal[v * 4 + 1];
_out_[z++] = pal[v * 4 + 2];
if (target == 4)
{
_out_[z++] = 255;
}
if ((i + 1) == (int)s.img_x)
{
break;
}
v = (info.bpp == 8) ? stbi__get8(s) : v2;
_out_[z++] = pal[v * 4 + 0];
_out_[z++] = pal[v * 4 + 1];
_out_[z++] = pal[v * 4 + 2];
if (target == 4)
{
_out_[z++] = 255;
}
}
stbi__skip(s, pad);
}
}
}
else
{
var rshift = 0;
var gshift = 0;
var bshift = 0;
var ashift = 0;
var rcount = 0;
var gcount = 0;
var bcount = 0;
var acount = 0;
var z = 0;
var easy = 0;
stbi__skip(s, info.offset - 14 - info.hsz);
if (info.bpp == 24)
{
width = (int)(3 * s.img_x);
}
else
{
if (info.bpp == 16)
{
width = (int)(2 * s.img_x);
}
else
{
width = 0;
}
}
pad = -width & 3;
if (info.bpp == 24)
{
easy = 1;
}
else
{
if (info.bpp == 32)
{
if ((mb == 0xff) && (mg == 0xff00) && (mr == 0x00ff0000) && (ma == 0xff000000))
{
easy = 2;
}
}
}
if (easy == 0)
{
if ((mr == 0) || (mg == 0) || (mb == 0))
{
CRuntime.free(_out_);
return((byte *)(ulong)((stbi__err("bad masks") != 0) ? (byte *)null : null));
}
rshift = stbi__high_bit(mr) - 7;
rcount = stbi__bitcount(mr);
gshift = stbi__high_bit(mg) - 7;
gcount = stbi__bitcount(mg);
bshift = stbi__high_bit(mb) - 7;
bcount = stbi__bitcount(mb);
ashift = stbi__high_bit(ma) - 7;
acount = stbi__bitcount(ma);
}
for (j = 0; j < (int)s.img_y; ++j)
{
if (easy != 0)
{
for (i = 0; i < (int)s.img_x; ++i)
{
byte a = 0;
_out_[z + 2] = stbi__get8(s);
_out_[z + 1] = stbi__get8(s);
_out_[z + 0] = stbi__get8(s);
z += 3;
a = (byte)((easy == 2) ? stbi__get8(s) : 255);
all_a |= a;
if (target == 4)
{
_out_[z++] = a;
}
}
}
else
{
var bpp = info.bpp;
for (i = 0; i < (int)s.img_x; ++i)
{
var v = (bpp == 16) ? (uint)stbi__get16le(s) : stbi__get32le(s);
uint a = 0;
_out_[z++] = (byte)(stbi__shiftsigned(v & mr, rshift, rcount) & 255);
_out_[z++] = (byte)(stbi__shiftsigned(v & mg, gshift, gcount) & 255);
_out_[z++] = (byte)(stbi__shiftsigned(v & mb, bshift, bcount) & 255);
a = (uint)((ma != 0) ? stbi__shiftsigned(v & ma, ashift, acount) : 255);
all_a |= a;
if (target == 4)
{
_out_[z++] = (byte)(a & 255);
}
}
}
stbi__skip(s, pad);
}
}
if ((target == 4) && (all_a == 0))
{
for (i = (int)(4 * s.img_x * s.img_y - 1); i >= 0; i -= 4)
{
_out_[i] = 255;
}
}
if (flip_vertically != 0)
{
byte t = 0;
for (j = 0; j < (int)s.img_y >> 1; ++j)
{
var p1 = _out_ + j * s.img_x * target;
var p2 = _out_ + (s.img_y - 1 - j) * s.img_x * target;
for (i = 0; i < (int)s.img_x * target; ++i)
{
t = p1[i];
p1[i] = p2[i];
p2[i] = t;
}
}
}
if ((req_comp != 0) && (req_comp != target))
{
_out_ = stbi__convert_format(_out_, target, req_comp, s.img_x, s.img_y);
if (_out_ == null)
{
return(_out_);
}
}
*x = (int)s.img_x;
*y = (int)s.img_y;
if (comp != null)
{
*comp = s.img_n;
}
return(_out_);
}