/// <summary>
/// Read one row of pixels.
/// The image has been read into the whole_image array, but is otherwise
/// unprocessed. We must read it out in top-to-bottom row order, and if
/// it is an 8-bit image, we must expand colormapped pixels to 24bit format.
/// This version is for reading 8-bit colormap indexes.
/// </summary>
private int get_8bit_row()
{
/* Fetch next row from virtual array */
source_row--;
byte[][] image_ptr = whole_image.Access(source_row, 1);
/* Expand the colormap indexes to real data */
int imageIndex = 0;
int outIndex = 0;
for (int col = cinfo.Image_width; col > 0; col--)
{
int t = image_ptr[0][imageIndex];
imageIndex++;
buffer[0][outIndex] = colormap[0][t]; /* can omit GETbyte() safely */
outIndex++;
buffer[0][outIndex] = colormap[1][t];
outIndex++;
buffer[0][outIndex] = colormap[2][t];
outIndex++;
}
return(1);
}
/// <summary>
/// Initialize for a processing pass.
/// </summary>
public void start_pass(J_BUF_MODE pass_mode)
{
switch (pass_mode)
{
case J_BUF_MODE.JBUF_PASS_THRU:
if (m_cinfo.m_quantize_colors)
{
/* Single-pass processing with color quantization. */
m_processor = ProcessorType.OnePass;
/* We could be doing buffered-image output before starting a 2-pass
* color quantization; in that case, jinit_d_post_controller did not
* allocate a strip buffer. Use the virtual-array buffer as workspace.
*/
if (m_buffer == null)
{
m_buffer = m_whole_image.Access(0, m_strip_height);
}
}
else
{
/* For single-pass processing without color quantization,
* I have no work to do; just call the upsampler directly.
*/
m_processor = ProcessorType.Upsample;
}
break;
case J_BUF_MODE.JBUF_SAVE_AND_PASS:
/* First pass of 2-pass quantization */
if (m_whole_image == null)
{
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_BAD_BUFFER_MODE);
}
m_processor = ProcessorType.PrePass;
break;
case J_BUF_MODE.JBUF_CRANK_DEST:
/* Second pass of 2-pass quantization */
if (m_whole_image == null)
{
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_BAD_BUFFER_MODE);
}
m_processor = ProcessorType.SecondPass;
break;
default:
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_BAD_BUFFER_MODE);
break;
}
m_starting_row = m_next_row = 0;
}
/// <summary>
/// Finish up at the end of the file.
/// Here is where we really output the BMP file.
/// </summary>
public override void finish_output()
{
/* Write the header and colormap */
if (is_os2)
{
write_os2_header();
}
else
{
write_bmp_header();
}
cdjpeg_progress_mgr progress = cinfo.Progress as cdjpeg_progress_mgr;
/* Write the file body from our virtual array */
for (int row = cinfo.Output_height; row > 0; row--)
{
if (progress != null)
{
progress.Pass_counter = cinfo.Output_height - row;
progress.Pass_limit = cinfo.Output_height;
progress.Updated();
}
byte[][] image_ptr = whole_image.Access(row - 1, 1);
int imageIndex = 0;
for (int col = row_width; col > 0; col--)
{
output_file.WriteByte(image_ptr[0][imageIndex]);
imageIndex++;
}
}
if (progress != null)
{
progress.completed_extra_passes++;
}
/* Make sure we wrote the output file OK */
output_file.Flush();
}
