public JpegCompressor()
{
var handle = JpegLibrary.tjInitCompress();
if (handle == IntPtr.Zero)
{
GetErrorAndThrow();
}
SetResourceHandle(handle);
}
/// <summary>
/// Compresses the bitmap to an output buffer, returning the length if the compressed data
/// </summary>
/// <remarks>
/// The buffer is re-allocated if too small, and can be larger than the compressed data!
/// </remarks>
public int Compress(
ref byte[] buffer,
int bufferOffset,
IntPtr srcPtr,
int stride,
int width,
int height,
PixelFormat pixelFormat,
int quality)
{
lock (this)
{
var bufferHandle = ObtainHandleUnderLock();
TJPixelFormats srcFormat = ConvertPixelFormat(pixelFormat);
JpegLibrary.CheckOptionsCompatibilityAndThrow(SubSampling, srcFormat);
ulong jpegSize = (ulong)MaxBufferSize;
lock (_compressor)
{
var compressorHandle = _compressor.ObtainHandleUnderLock();
if (JpegLibrary.tjCompress2(compressorHandle, srcPtr,
width, stride, height, (int)srcFormat, ref bufferHandle, ref jpegSize,
(int)SubSampling, quality, (int)(TJFlags.NOREALLOC | TJFlags.FASTDCT)) == -1)
{
GetErrorAndThrow();
}
int length = (int)jpegSize;
if (buffer == null || buffer.Length < (bufferOffset + length))
{
Array.Resize(ref buffer, bufferOffset + MaxBufferSize);
}
Marshal.Copy(bufferHandle, buffer, bufferOffset, length);
return(length);
}
}
}
public JpegFrame(JpegCompressor compressor, int width, int height, TJSubsamplingOptions subSampling)
{
_compressor = compressor;
checked
{
Width = width;
Height = height;
SubSampling = subSampling;
MaxBufferSize = (int)JpegLibrary.tjBufSize(width, height, (int)subSampling);
}
var bufferHandle = JpegLibrary.tjAlloc(MaxBufferSize);
if (bufferHandle == IntPtr.Zero)
{
throw new OutOfMemoryException(
$"Failed to allocate TurboJPEG buffer of size {width}x{height}, subSampling {subSampling}");
}
SetResourceHandle(bufferHandle);
}
protected override void Free(IntPtr handle)
{
JpegLibrary.tjDestroy(handle);
}
public static void GetErrorAndThrow()
{
throw new TJException(JpegLibrary.tjGetErrorStr());
}
protected override void Free(IntPtr handle)
{
_compressor = null;
JpegLibrary.tjFree(handle);
}
