/// <summary>
/// Writes the image data.
/// </summary>
/// <param name="writer">The writer.</param>
/// <param name="count">The count of bits (pels) to encode.</param>
/// <param name="white">The color of the pels.</param>
private static void WriteSample(BitWriter writer, uint count, bool white)
{
uint[] terminatingCodes = white ? WhiteTerminatingCodes : BlackTerminatingCodes;
uint[] makeUpCodes = white ? WhiteMakeUpCodes : BlackMakeUpCodes;
// The make-up code for 2560 will be written as often as required:
while (count >= 2624)
{
writer.WriteTableLine(makeUpCodes, 39); // Magic: 2560
count -= 2560;
}
// A make-up code for a multiple of 64 will be written if required:
if (count > 63)
{
uint line = count / 64 - 1;
writer.WriteTableLine(makeUpCodes, line);
count -= (line + 1) * 64;
}
// And finally the terminating code for the remaining value (0 through 63):
writer.WriteTableLine(terminatingCodes, count);
}
/// <summary>
/// Encodes a bitonal bitmap using 2D group 4 CCITT fax encoding.
/// </summary>
/// <param name="imageData">Space reserved for the fax encoded bitmap. An exception will be thrown if this buffer is too small.</param>
/// <param name="imageBits">The bitmap to be encoded.</param>
/// <param name="bytesFileOffset">Offset of image data in bitmap file.</param>
/// <param name="width">The width of the image.</param>
/// <param name="height">The height of the image.</param>
/// <returns>The size of the fax encoded image (0 on failure).</returns>
internal static int DoFaxEncodingGroup4(ref byte[] imageData, byte[] imageBits, uint bytesFileOffset, uint width, uint height)
{
try
{
uint bytesPerLineBmp = ((width + 31) / 32) * 4;
BitWriter writer = new BitWriter(ref imageData);
for (uint y = 0; y < height; ++y)
{
FaxEncode2DRow(writer, bytesFileOffset, imageBits, y, (y != 0) ? y - 1 : 0xffffffff, width, height, bytesPerLineBmp);
}
writer.FlushBuffer();
return writer.BytesWritten();
}
catch (Exception ex)
{
ex.GetType();
return 0;
}
}
/// <summary>
/// 2d-encode a row of pixels. Consult the CCITT documentation for the algorithm.
/// </summary>
/// <param name="writer">The writer.</param>
/// <param name="bytesFileOffset">Offset of image data in bitmap file.</param>
/// <param name="imageBits">The bitmap file.</param>
/// <param name="currentRow">Index of the current row.</param>
/// <param name="referenceRow">Index of the reference row (0xffffffff if there is none).</param>
/// <param name="width">The width of the image.</param>
/// <param name="height">The height of the image.</param>
/// <param name="bytesPerLineBmp">The bytes per line in the bitmap file.</param>
static void FaxEncode2DRow(BitWriter writer, uint bytesFileOffset, byte[] imageBits, uint currentRow, uint referenceRow, uint width, uint height, uint bytesPerLineBmp)
{
// Translated from LibTiff
uint bytesOffsetRead = bytesFileOffset + (height - 1 - currentRow) * bytesPerLineBmp;
BitReader reader = new BitReader(imageBits, bytesOffsetRead, width);
BitReader readerReference;
if (referenceRow != 0xffffffff)
{
uint bytesOffsetReadReference = bytesFileOffset + (height - 1 - referenceRow) * bytesPerLineBmp;
readerReference = new BitReader(imageBits, bytesOffsetReadReference, width);
}
else
{
byte[] tmpImageBits = new byte[bytesPerLineBmp];
for (int i = 0; i < bytesPerLineBmp; ++i)
tmpImageBits[i] = 255;
readerReference = new BitReader(tmpImageBits, 0, width);
}
uint a0 = 0;
uint a1 = !reader.GetBit(0) ? 0 : FindDifference(reader, 0, width, true);
uint b1 = !readerReference.GetBit(0) ? 0 : FindDifference(readerReference, 0, width, true);
// ReSharper disable TooWideLocalVariableScope
uint a2, b2;
// ReSharper restore TooWideLocalVariableScope
for (;;)
{
b2 = FindDifferenceWithCheck(readerReference, b1, width, readerReference.GetBit(b1));
if (b2 >= a1)
{
int d = (int)b1 - (int)a1;
if (!(-3 <= d && d <= 3))
{
/* horizontal mode */
a2 = FindDifferenceWithCheck(reader, a1, width, reader.GetBit(a1));
writer.WriteTableLine(HorizontalCodes, 0);
if (a0 + a1 == 0 || reader.GetBit(a0))
{
WriteSample(writer, a1 - a0, true);
WriteSample(writer, a2 - a1, false);
}
else
{
WriteSample(writer, a1 - a0, false);
WriteSample(writer, a2 - a1, true);
}
a0 = a2;
}
else
{
/* vertical mode */
writer.WriteTableLine(VerticalCodes, (uint)(d + 3));
a0 = a1;
}
}
else
{
/* pass mode */
writer.WriteTableLine(PassCodes, 0);
a0 = b2;
}
if (a0 >= width)
break;
bool bitA0 = reader.GetBit(a0);
a1 = FindDifference(reader, a0, width, bitA0/*reader.GetBit(a0)*/);
b1 = FindDifference(readerReference, a0, width, !bitA0/*reader.GetBit(a0)*/);
b1 = FindDifferenceWithCheck(readerReference, b1, width, bitA0/*reader.GetBit(a0)*/);
}
}
/// <summary>
/// Encodes a bitonal bitmap using 1D CCITT fax encoding.
/// </summary>
/// <param name="imageData">Space reserved for the fax encoded bitmap. An exception will be thrown if this buffer is too small.</param>
/// <param name="imageBits">The bitmap to be encoded.</param>
/// <param name="bytesFileOffset">Offset of image data in bitmap file.</param>
/// <param name="width">The width of the image.</param>
/// <param name="height">The height of the image.</param>
/// <returns>The size of the fax encoded image (0 on failure).</returns>
private static int DoFaxEncoding(ref byte[] imageData, byte[] imageBits, uint bytesFileOffset, uint width, uint height)
{
try
{
uint bytesPerLineBmp = ((width + 31) / 32) * 4;
BitWriter writer = new BitWriter(ref imageData);
for (uint y = 0; y < height; ++y)
{
uint bytesOffsetRead = bytesFileOffset + (height - 1 - y) * bytesPerLineBmp;
BitReader reader = new BitReader(imageBits, bytesOffsetRead, width);
for (uint bitsRead = 0; bitsRead < width;)
{
uint white = CountOneBits(reader, width - bitsRead);
WriteSample(writer, white, true);
bitsRead += white;
if (bitsRead < width)
{
uint black = CountZeroBits(reader, width - bitsRead);
WriteSample(writer, black, false);
bitsRead += black;
}
}
}
writer.FlushBuffer();
return writer.BytesWritten();
}
catch (Exception /*ex*/)
{
//ex.GetType();
return 0;
}
}
/// <summary>
/// 2d-encode a row of pixels. Consult the CCITT documentation for the algorithm.
/// </summary>
/// <param name="writer">The writer.</param>
/// <param name="bytesFileOffset">Offset of image data in bitmap file.</param>
/// <param name="imageBits">The bitmap file.</param>
/// <param name="currentRow">Index of the current row.</param>
/// <param name="referenceRow">Index of the reference row (0xffffffff if there is none).</param>
/// <param name="width">The width of the image.</param>
/// <param name="height">The height of the image.</param>
/// <param name="bytesPerLineBmp">The bytes per line in the bitmap file.</param>
static void FaxEncode2DRow(BitWriter writer, uint bytesFileOffset, byte[] imageBits, uint currentRow, uint referenceRow, uint width, uint height, uint bytesPerLineBmp)
{
// Translated from LibTiff
uint bytesOffsetRead = bytesFileOffset + (height - 1 - currentRow) * bytesPerLineBmp;
BitReader reader = new BitReader(imageBits, bytesOffsetRead, width);
BitReader readerReference;
if (referenceRow != 0xffffffff)
{
uint bytesOffsetReadReference = bytesFileOffset + (height - 1 - referenceRow) * bytesPerLineBmp;
readerReference = new BitReader(imageBits, bytesOffsetReadReference, width);
}
else
{
byte[] tmpImageBits = new byte[bytesPerLineBmp];
for (int i = 0; i < bytesPerLineBmp; ++i)
{
tmpImageBits[i] = 255;
}
readerReference = new BitReader(tmpImageBits, 0, width);
}
uint a0 = 0;
uint a1 = !reader.GetBit(0) ? 0 : FindDifference(reader, 0, width, true);
uint b1 = !readerReference.GetBit(0) ? 0 : FindDifference(readerReference, 0, width, true);
// ReSharper disable TooWideLocalVariableScope
uint a2, b2;
// ReSharper restore TooWideLocalVariableScope
for (; ;)
{
b2 = FindDifferenceWithCheck(readerReference, b1, width, readerReference.GetBit(b1));
if (b2 >= a1)
{
int d = (int)b1 - (int)a1;
if (!(-3 <= d && d <= 3))
{
/* horizontal mode */
a2 = FindDifferenceWithCheck(reader, a1, width, reader.GetBit(a1));
writer.WriteTableLine(HorizontalCodes, 0);
if (a0 + a1 == 0 || reader.GetBit(a0))
{
WriteSample(writer, a1 - a0, true);
WriteSample(writer, a2 - a1, false);
}
else
{
WriteSample(writer, a1 - a0, false);
WriteSample(writer, a2 - a1, true);
}
a0 = a2;
}
else
{
/* vertical mode */
writer.WriteTableLine(VerticalCodes, (uint)(d + 3));
a0 = a1;
}
}
else
{
/* pass mode */
writer.WriteTableLine(PassCodes, 0);
a0 = b2;
}
if (a0 >= width)
{
break;
}
bool bitA0 = reader.GetBit(a0);
a1 = FindDifference(reader, a0, width, bitA0 /*reader.GetBit(a0)*/);
b1 = FindDifference(readerReference, a0, width, !bitA0 /*reader.GetBit(a0)*/);
b1 = FindDifferenceWithCheck(readerReference, b1, width, bitA0 /*reader.GetBit(a0)*/);
}
}
