// Load a JPEG image from the specified stream. The first 4 bytes
// have already been read and discarded.
public static void Load(Stream stream, Image image,
byte[] prime, int primeLen)
{
// Determine if we actually have the JPEG library.
if (!JpegLib.JpegLibraryPresent())
{
throw new FormatException("libjpeg is not available");
}
// Create the decompression object.
JpegLib.jpeg_decompress_struct cinfo;
cinfo = new JpegLib.jpeg_decompress_struct();
cinfo.err = JpegLib.CreateErrorHandler();
JpegLib.jpeg_create_decompress(ref cinfo);
// Initialize the source manager.
JpegLib.StreamToSourceManager
(ref cinfo, stream, prime, primeLen);
// Read the JPEG header.
JpegLib.jpeg_read_header(ref cinfo, (Int)1);
// Set the decompression parameters the way we want them.
cinfo.out_color_space = JpegLib.J_COLOR_SPACE.JCS_RGB;
// Start the decompression process.
JpegLib.jpeg_start_decompress(ref cinfo);
// Initialize the image to 24-bit RGB, to match the JPEG file.
image.Width = (int)(cinfo.output_width);
image.Height = (int)(cinfo.output_height);
image.PixelFormat = PixelFormat.Format24bppRgb;
if (prime[3] == 0xE1)
{
image.LoadFormat = Image.Exif;
}
else
{
image.LoadFormat = Image.Jpeg;
}
Frame frame = image.AddFrame();
// Read the scanlines from the image.
int posn, width, offset, stride, y, twidth;
width = frame.Width;
twidth = width * 3;
stride = frame.Stride;
byte[] data = frame.Data;
IntPtr buf = Marshal.AllocHGlobal(width * 3);
byte * pbuf = (byte *)buf;
y = 0;
while (((int)(cinfo.output_scanline)) <
((int)(cinfo.output_height)))
{
JpegLib.jpeg_read_scanlines
(ref cinfo, ref buf, (UInt)1);
offset = (y++) * stride;
for (posn = 0; posn < twidth; posn += 3)
{
// Convert the JPEG RGB data into BGR for the frame.
data[offset] = pbuf[posn + 2];
data[offset + 1] = pbuf[posn + 1];
data[offset + 2] = pbuf[posn];
offset += 3;
}
}
Marshal.FreeHGlobal(buf);
// Finish the decompression process.
JpegLib.jpeg_finish_decompress(ref cinfo);
// Clean everything up.
JpegLib.FreeSourceManager(ref cinfo);
JpegLib.jpeg_destroy_decompress(ref cinfo);
JpegLib.FreeErrorHandler(cinfo.err);
}
// Load a JPEG image from the specified stream. The first 4 bytes
// have already been read and discarded.
public static void Load(Stream stream, Image image,
byte[] prime, int primeLen)
{
// Determine if we actually have the JPEG library.
if(!JpegLib.JpegLibraryPresent())
{
throw new FormatException("libjpeg is not available");
}
// Create the decompression object.
JpegLib.jpeg_decompress_struct cinfo;
cinfo = new JpegLib.jpeg_decompress_struct();
cinfo.err = JpegLib.CreateErrorHandler();
JpegLib.jpeg_create_decompress(ref cinfo);
// Initialize the source manager.
JpegLib.StreamToSourceManager
(ref cinfo, stream, prime, primeLen);
// Read the JPEG header.
JpegLib.jpeg_read_header(ref cinfo, (Int)1);
// Set the decompression parameters the way we want them.
cinfo.out_color_space = JpegLib.J_COLOR_SPACE.JCS_RGB;
// Start the decompression process.
JpegLib.jpeg_start_decompress(ref cinfo);
// Initialize the image to 24-bit RGB, to match the JPEG file.
image.Width = (int)(cinfo.output_width);
image.Height = (int)(cinfo.output_height);
image.PixelFormat = PixelFormat.Format24bppRgb;
if(prime[3] == 0xE1)
{
image.LoadFormat = Image.Exif;
}
else
{
image.LoadFormat = Image.Jpeg;
}
Frame frame = image.AddFrame();
// Read the scanlines from the image.
int posn, width, offset, stride, y, twidth;
width = frame.Width;
twidth = width * 3;
stride = frame.Stride;
byte[] data = frame.Data;
IntPtr buf = Marshal.AllocHGlobal(width * 3);
byte *pbuf = (byte *)buf;
y = 0;
while(((int)(cinfo.output_scanline)) <
((int)(cinfo.output_height)))
{
JpegLib.jpeg_read_scanlines
(ref cinfo, ref buf, (UInt)1);
offset = (y++) * stride;
for(posn = 0; posn < twidth; posn += 3)
{
// Convert the JPEG RGB data into BGR for the frame.
data[offset] = pbuf[posn + 2];
data[offset + 1] = pbuf[posn + 1];
data[offset + 2] = pbuf[posn];
offset += 3;
}
}
Marshal.FreeHGlobal(buf);
// Finish the decompression process.
JpegLib.jpeg_finish_decompress(ref cinfo);
// Clean everything up.
JpegLib.FreeSourceManager(ref cinfo);
JpegLib.jpeg_destroy_decompress(ref cinfo);
JpegLib.FreeErrorHandler(cinfo.err);
}
