public static byte *stbi__gif_load_next(StbiContext s, StbiGif g, int *comp, int reqComp, byte *twoBack)
{
var dispose = 0;
var first_frame = 0;
var pi = 0;
var pcount = 0;
first_frame = 0;
if (g.Out == null)
{
if (stbi__gif_header(s, g, comp, 0) == 0)
{
return(null);
}
if (stbi__mad3sizes_valid(4, g.W, g.H, 0) == 0)
{
return((byte *)(ulong)(stbi__err("too large") != 0 ? (byte *)null : null));
}
pcount = g.W * g.H;
g.Out = (byte *)stbi__malloc((ulong)(4 * pcount));
g.Background = (byte *)stbi__malloc((ulong)(4 * pcount));
g.History = (byte *)stbi__malloc((ulong)pcount);
if (g.Out == null || g.Background == null || g.History == null)
{
return((byte *)(ulong)(stbi__err("outofmem") != 0 ? (byte *)null : null));
}
CRuntime.Memset(g.Out, 0x00, (ulong)(4 * pcount));
CRuntime.Memset(g.Background, 0x00, (ulong)(4 * pcount));
CRuntime.Memset(g.History, 0x00, (ulong)pcount);
first_frame = 1;
}
else
{
dispose = (g.Eflags & 0x1C) >> 2;
pcount = g.W * g.H;
if (dispose == 3 && twoBack == null)
{
dispose = 2;
}
if (dispose == 3)
{
for (pi = 0; pi < pcount; ++pi)
{
if (g.History[pi] != 0)
{
CRuntime.Memcpy(&g.Out[pi * 4], &twoBack[pi * 4], (ulong)4);
}
}
}
else if (dispose == 2)
{
for (pi = 0; pi < pcount; ++pi)
{
if (g.History[pi] != 0)
{
CRuntime.Memcpy(&g.Out[pi * 4], &g.Background[pi * 4], (ulong)4);
}
}
}
CRuntime.Memcpy(g.Background, g.Out, (ulong)(4 * g.W * g.H));
}
CRuntime.Memset(g.History, 0x00, (ulong)(g.W * g.H));
for (; ;)
{
var tag = (int)stbi__get8(s);
switch (tag)
{
case 0x2C:
{
var x = 0;
var y = 0;
var w = 0;
var h = 0;
byte *o;
x = stbi__get16le(s);
y = stbi__get16le(s);
w = stbi__get16le(s);
h = stbi__get16le(s);
if (x + w > g.W || y + h > g.H)
{
return((byte *)(ulong)(stbi__err("bad Image Descriptor") != 0 ? (byte *)null : null));
}
g.LineSize = g.W * 4;
g.StartX = x * 4;
g.StartY = y * g.LineSize;
g.MaxX = g.StartX + w * 4;
g.MaxY = g.StartY + h * g.LineSize;
g.CurX = g.StartX;
g.CurY = g.StartY;
if (w == 0)
{
g.CurY = g.MaxY;
}
g.Lflags = stbi__get8(s);
if ((g.Lflags & 0x40) != 0)
{
g.Step = 8 * g.LineSize;
g.Parse = 3;
}
else
{
g.Step = g.LineSize;
g.Parse = 0;
}
if ((g.Lflags & 0x80) != 0)
{
stbi__gif_parse_colortable(s, g.Lpal, 2 << (g.Lflags & 7),
(g.Eflags & 0x01) != 0 ? g.Transparent : -1);
g.ColorTable = g.Lpal;
}
else if ((g.Flags & 0x80) != 0)
{
g.ColorTable = g.Pal;
}
else
{
return((byte *)(ulong)(stbi__err("missing color table") != 0 ? (byte *)null : null));
}
o = stbi__process_gif_raster(s, g);
if (o == null)
{
return(null);
}
pcount = g.W * g.H;
if (first_frame != 0 && g.Bgindex > 0)
{
for (pi = 0; pi < pcount; ++pi)
{
if (g.History[pi] == 0)
{
g.Pal[g.Bgindex * 4 + 3] = 255;
CRuntime.Memcpy(&g.Out[pi * 4], &g.Pal[g.Bgindex], (ulong)4);
}
}
}
return(o);
}
case 0x21:
{
var len = 0;
var ext = (int)stbi__get8(s);
if (ext == 0xF9)
{
len = stbi__get8(s);
if (len == 4)
{
g.Eflags = stbi__get8(s);
g.Delay = 10 * stbi__get16le(s);
if (g.Transparent >= 0)
{
g.Pal[g.Transparent * 4 + 3] = 255;
}
if ((g.Eflags & 0x01) != 0)
{
g.Transparent = stbi__get8(s);
if (g.Transparent >= 0)
{
g.Pal[g.Transparent * 4 + 3] = 0;
}
}
else
{
stbi__skip(s, 1);
g.Transparent = -1;
}
}
else
{
stbi__skip(s, len);
break;
}
}
while ((len = stbi__get8(s)) != 0)
{
stbi__skip(s, len);
}
break;
}
case 0x3B:
return(null);
default:
return((byte *)(ulong)(stbi__err("unknown code") != 0 ? (byte *)null : null));
}
}
}