/// <summary>Transforms input image into one or several destinations.</summary>
/// <param name="jpegBuf">Pointer to a buffer containing the JPEG image to decompress. This buffer is not modified.</param>
/// <param name="transforms">Array of transform descriptions to be applied to the source image. </param>
/// <param name="flags">The bitwise OR of one or more of the <see cref="TJFlags"/> "flags".</param>
/// <returns>Array of transformed jpeg images.</returns>
/// <exception cref="ArgumentNullException"><paramref name="transforms"/> is <see langword="null" />.</exception>
/// <exception cref="ArgumentException">Transforms can not be empty.</exception>
/// <exception cref="TJException"> Throws if low level turbo jpeg function fails. </exception>
public byte[][] Transform(Span <byte> jpegBuf, TJTransformDescription[] transforms, TJFlags flags)
{
Verify.NotDisposed(this);
if (transforms == null)
{
throw new ArgumentNullException(nameof(transforms));
}
if (transforms.Length == 0)
{
throw new ArgumentException("Transforms can not be empty", nameof(transforms));
}
fixed(byte *jpegBufPtr = jpegBuf)
{
var count = transforms.Length;
var destBufs = new IntPtr[count];
var destSizes = new uint[count];
int subsampl;
int colorspace;
int width;
int height;
var funcResult = TurboJpegImport.TjDecompressHeader(
this.transformHandle,
jpegBufPtr,
(nuint)jpegBuf.Length,
out width,
out height,
out subsampl,
out colorspace);
TJUtils.ThrowOnError(funcResult);
Size mcuSize;
if (!TurboJpegImport.MCUSizes.TryGetValue((TJSubsamplingOption)subsampl, out mcuSize))
{
throw new TJException("Unable to read Subsampling Options from jpeg header");
}
var tjTransforms = new TJTransform[count];
for (var i = 0; i < count; i++)
{
var x = CorrectRegionCoordinate(transforms[i].Region.X, mcuSize.Width);
var y = CorrectRegionCoordinate(transforms[i].Region.Y, mcuSize.Height);
var w = CorrectRegionSize(transforms[i].Region.X, x, transforms[i].Region.W, width);
var h = CorrectRegionSize(transforms[i].Region.Y, y, transforms[i].Region.H, height);
tjTransforms[i] = new TJTransform
{
Op = (int)transforms[i].Operation,
Options = (int)transforms[i].Options,
R = new TJRegion
{
X = x,
Y = y,
W = w,
H = h,
},
Data = transforms[i].CallbackData,
CustomFilter = transforms[i].CustomFilter,
};
}
var transformsPtr = TJUtils.StructArrayToIntPtr(tjTransforms);
try
{
funcResult = TurboJpegImport.TjTransform(
this.transformHandle,
jpegBufPtr,
(nuint)jpegBuf.Length,
count,
destBufs,
destSizes,
transformsPtr,
(int)flags);
TJUtils.ThrowOnError(funcResult);
var result = new List <byte[]>();
for (var i = 0; i < destBufs.Length; i++)
{
var ptr = destBufs[i];
var size = destSizes[i];
var item = new byte[size];
Marshal.Copy(ptr, item, 0, (int)size);
result.Add(item);
TurboJpegImport.TjFree(ptr);
}
return(result.ToArray());
}
finally
{
TJUtils.FreePtr(transformsPtr);
}
}
}
