public abstract Bitmap Load(QOIFHeader header, BinaryReader rd);
public override Bitmap Load(QOIFHeader header, BinaryReader rd)
{
Bitmap bitmap = new(header.Width, header.Height, PixelFormat.Format32bppArgb);
RGBAColor[] indexed = new RGBAColor[64];
RGBAColor previous = RGBAColor.Black;
int end_match = 0;
#if DEBUG_LOG
StringBuilder sb = new StringBuilder().AppendLine(header.ToString()).AppendLine("DECODING");
#endif
bitmap.LockRGBAPixels((ptr, w, h) =>
{
int index = 0;
#if DEBUG_LOG
void set_pixel(RGBAColor color, string log)
#else
void set_pixel(RGBAColor color)
#endif
{
if (index < w * h)
{
int cache = GetIndex(color);
#if DEBUG_LOG
sb.AppendLine($"I={index,6} X={index % w,5} Y={index / w,5} P={previous,12} C={color,12} (CH={cache,2}) {log}");
#endif
indexed[cache] = color;
ptr[index++] = color;
if (previous != color)
{
previous = color;
}
}
#if DEBUG_LOG
else
{
sb.AppendLine($" <<<< index {index} >= {w}x{h} = {w * h} >>>>");
}
#endif
}
try
{
while (index < w * h && end_match < END.Length && rd.ReadByte() is byte @byte)
{
if (@byte is TAG_OP_RGB or TAG_OP_RGBA)
{
RGBAColor color = new(
rd.ReadByte(),
rd.ReadByte(),
rd.ReadByte()
);
if (@byte is TAG_OP_RGBA)
{
color.A = rd.ReadByte();
}
#if DEBUG_LOG
set_pixel(color, "EXPLICIT");
#else
set_pixel(color);
#endif
}
else
{
int op = @byte & MASK_TAG2;
byte data = (byte)(@byte & ~MASK_TAG2);
if (op is TAG_OP_INDEX)
{
#if DEBUG_LOG
set_pixel(indexed[data], $"INDEXED {@byte:x2} I={data}");
#else
set_pixel(indexed[data]);
#endif
if (@byte == END[end_match])
{
++end_match;
}
else
{
end_match = 0;
}
}
else if (op is TAG_OP_DIFF)
{
int dr = (@byte & MASK_DIFF_R) >> SHIFT_DIFF_R;
int dg = (@byte & MASK_DIFF_G) >> SHIFT_DIFF_G;
int db = @byte & MASK_DIFF_B;
RGBAColor color = ComputeFrom2BitDistance(previous, dr, dg, db);
#if DEBUG_LOG
set_pixel(color, $"2BITDIFF {@byte:x2} ({dr} {dg} {db})");
#else
set_pixel(color);
#endif
}
else if (op is TAG_OP_LUMA)
{
@byte = rd.ReadByte();
int drg = (@byte & MASK_LUMA_RG) >> SHIFT_LUMA_RG;
int dbg = @byte & MASK_LUMA_BG;
RGBAColor color = ComputeFromLuma(previous, 6, 4, drg, data, dbg);
#if DEBUG_LOG
set_pixel(color, $"LUMADIFF {op | data:x2}{@byte:x2} ({data} {drg} {dbg})");
#else
set_pixel(color);
#endif
}
else if (op is TAG_OP_RUN)
{
for (int i = 0, c = data + 1; i < c && index < w * h; ++i)
#if DEBUG_LOG
{ set_pixel(previous, $"RUN {@byte:x2} R={data + 1}"); }
#else
{ set_pixel(previous); }
#endif
}
#if DEBUG_LOG
else
{
sb.AppendLine($" <<<< UNKNOWN INSTRUCTION {@byte:x2} >>>>");
}
#endif
}
}
}
