private void ReleaseUnmanagedResources()
{
if (_decompressorHandle != IntPtr.Zero)
{
TurboJpeg.DestroyInstance(_decompressorHandle);
_decompressorHandle = IntPtr.Zero;
}
}
private void Initialize()
{
if (_decompressorHandle != IntPtr.Zero)
{
return;
}
_decompressorHandle = TurboJpeg.InitDecompressorInstance();
if (_decompressorHandle == IntPtr.Zero)
{
throw new RfbProtocolException($"Initializing TurboJPEG decompressor instance failed: {TurboJpeg.GetLastError()}");
}
}
public unsafe void DecodeJpegTo32Bit(Span <byte> jpegBuffer, Span <byte> pixelsBuffer, int expectedWidth, int expectedHeight, PixelFormat preferredPixelFormat,
out PixelFormat usedPixelFormat, CancellationToken cancellationToken = default)
{
if (_disposed)
{
throw new ObjectDisposedException(nameof(TurboJpegDecoder));
}
if (!TurboJpeg.IsAvailable)
{
throw new InvalidOperationException("The TurboJPEG decoder is unavailable on the current system.");
}
// Initialize on first use
if (_decompressorHandle == IntPtr.Zero)
{
Initialize();
}
cancellationToken.ThrowIfCancellationRequested();
int jpegBufferLength = jpegBuffer.Length;
int pixelsBufferLength = pixelsBuffer.Length;
// NOTE: We only use 32bit pixel formats, so we don't have to deal with padding here.
// Find a fitting pixel format that requires the least conversion later
var tjPixelFormat = TurboJpegPixelFormat.RGBA;
usedPixelFormat = RgbaCompatiblePixelFormat;
if (BgraCompatiblePixelFormat.IsBinaryCompatibleTo(preferredPixelFormat))
{
tjPixelFormat = TurboJpegPixelFormat.BGRA;
usedPixelFormat = BgraCompatiblePixelFormat;
}
else if (ArgbCompatiblePixelFormat.IsBinaryCompatibleTo(preferredPixelFormat))
{
tjPixelFormat = TurboJpegPixelFormat.ARGB;
usedPixelFormat = ArgbCompatiblePixelFormat;
}
else if (AbgrCompatiblePixelFormat.IsBinaryCompatibleTo(preferredPixelFormat))
{
tjPixelFormat = TurboJpegPixelFormat.ABGR;
usedPixelFormat = AbgrCompatiblePixelFormat;
}
fixed(byte *jpegBufferPtr = jpegBuffer)
fixed(byte *pixelsBufferPtr = pixelsBuffer)
{
// Retrieve the JPEG header information so we can make sure, that our buffer is large enough
if (TurboJpeg.DecompressHeader(_decompressorHandle, (IntPtr)jpegBufferPtr, (ulong)jpegBufferLength, out int width, out int height, out _, out _) == -1)
{
throw new RfbProtocolException($"Decompressiong JPEG header failed: {TurboJpeg.GetLastError()}");
}
// Validate the image size
if (width != expectedWidth || height != expectedHeight)
{
throw new RfbProtocolException(
$"Cannot decode JPEG image because it's size of {width}x{height} does not match the expected size {expectedWidth}x{expectedHeight}.");
}
// Validate the buffer size
int stride = width * 4;
int requiredBufferLength = stride * height;
if (pixelsBufferLength < requiredBufferLength)
{
throw new RfbProtocolException(
$"Cannot decode JPEG image ({width}x{height}) because it's size of {requiredBufferLength} bytes would exceed the pixels buffer size of {pixelsBufferLength} when decompressing. ");
}
Debug.Assert(pixelsBufferLength == requiredBufferLength, "pixelsBufferLength == requiredBufferLength");
// Decompress the image to the pixels buffer
if (TurboJpeg.Decompress(_decompressorHandle, (IntPtr)jpegBufferPtr, (ulong)jpegBufferLength, (IntPtr)pixelsBufferPtr, width, stride, height, (int)tjPixelFormat,
(int)(TurboJpegFlags.FastUpsample | TurboJpegFlags.FastDct | TurboJpegFlags.NoRealloc)) == -1)
{
throw new RfbProtocolException($"Decompressiong JPEG image failed: {TurboJpeg.GetLastError()}");
}
}
}
