private void emit_jfif_app0()
{
/*
* Length of APP0 block (2 bytes)
* Block ID (4 bytes - ASCII "JFIF")
* Zero byte (1 byte to terminate the ID string)
* Version Major, Minor (2 bytes - major first)
* Units (1 byte - 0x00 = none, 0x01 = inch, 0x02 = cm)
* Xdpu (2 bytes - dots per unit horizontal)
* Ydpu (2 bytes - dots per unit vertical)
* Thumbnail X size (1 byte)
* Thumbnail Y size (1 byte)
*/
emit_marker(JPEG_MARKER.APP0);
emit_2bytes(2 + 4 + 1 + 2 + 1 + 2 + 2 + 1 + 1); /* length */
emit_byte(0x4A); /* Identifier: ASCII "JFIF" */
emit_byte(0x46);
emit_byte(0x49);
emit_byte(0x46);
emit_byte(0);
emit_byte(m_cinfo.m_JFIF_major_version); /* Version fields */
emit_byte(m_cinfo.m_JFIF_minor_version);
emit_byte((int)m_cinfo.m_density_unit); /* Pixel size information */
emit_2bytes(m_cinfo.m_X_density);
emit_2bytes(m_cinfo.m_Y_density);
emit_byte(0); /* No thumbnail image */
emit_byte(0);
}