public static void Write <TImage>(ImageBinWriter state, TImage image)
where TImage : IPixelRowProvider
{
// we only support RGB and RGBA, no palette indexing
// TODO: support for palette indexing
if (state == null)
{
throw new ArgumentNullException(nameof(state));
}
if (image == null)
{
throw new ArgumentNullException(nameof(image));
}
image.ThrowIfCancelled();
int bytesPerPixel = image.Components == 4 ? 4 : 3;
int bitDepth = bytesPerPixel * 8;
int pad = (-image.Width * bytesPerPixel) & bytesPerPixel;
int compressionHeaders = image.Components == 4 ? 17 : 0;
int extraPad = compressionHeaders * sizeof(int); // extra bytes for compression headers
int dataSize = (image.Width * bytesPerPixel + pad) * image.Height;
int dibHeaderLen = 40 + extraPad;
int fileSize = 14 + dibHeaderLen + dataSize;
int dataOffset = 14 + dibHeaderLen;
int compression = image.Components == 4 ? 3 : 0; // 3 == bitfields | 0 == no compression
Span <long> header = stackalloc long[]
{
// BMP header:
'B',
'M',
fileSize,
0,
0,
dataOffset,
// DIB header:
dibHeaderLen,
image.Width,
image.Height,
1,
bitDepth,
compression,
dataSize,
0,
0,
0,
0,
// Data needed for 32bit bitmaps:
0x00ff0000,
0x0000ff00,
0x000000ff,
0xff000000, // RGBA masks
0x206E6957, // little-endian (value equal to string "Win ")
0,
0,
0,
0,
0,
0,
0,
0,
0, // colorspace endpoints (unused)
0,
0,
0 // RGB gamma (unused)
};
int alphaDir = image.Components == 4 ? 1 : 0;
string format =
"11 4 22 44 44 22 444444 " + // base header
"4444 4 444444444 444"; // compression header
int headerCount = 17 + compressionHeaders;
ImageWriteHelpers.OutFile(
state, image, true, -1, true, alphaDir, pad, format, header.Slice(0, headerCount));
}
}
public static void Write <TImage>(ImageBinWriter state, TImage image, bool useRLE)
where TImage : IPixelRowProvider
{
if (state == null)
{
throw new ArgumentNullException(nameof(state));
}
if (image == null)
{
throw new ArgumentNullException(nameof(image));
}
int width = image.Width;
int height = image.Height;
int comp = image.Components;
if ((height < 0) || (width < 0))
{
throw new ArgumentException("Invalid image dimensions.", nameof(state));
}
image.ThrowIfCancelled();
int hasAlpha = (comp == 2 || comp == 4) ? 1 : 0;
int colorbytes = hasAlpha != 0 ? comp - 1 : comp;
int format = colorbytes < 2 ? 3 : 2;
if (!useRLE)
{
Span <long> headerValues = stackalloc long[]
{
0,
0,
format,
0,
0,
0,
0,
0,
width,
height,
(colorbytes + hasAlpha) * 8,
hasAlpha * 8
};
ImageWriteHelpers.OutFile(
state, image, true, -1, false, hasAlpha, 0, "111 221 2222 11", headerValues);
}
else
{
Span <long> headerValues = stackalloc long[]
{
0,
0,
format + 8,
0,
0,
0,
0,
0,
width,
height,
(colorbytes + hasAlpha) * 8,
hasAlpha * 8
};
ImageWriteHelpers.WriteFormat(state, "111 221 2222 11", headerValues);
Span <byte> rowScratch = new byte[width * comp].AsSpan();
Span <byte> outBuffer = stackalloc byte[4];
for (int y = height; y-- > 0;)
{
image.GetByteRow(y, rowScratch);
int len;
for (int x = 0; x < width; x += len)
{
Span <byte> begin = rowScratch[(x * comp)..];