public ImageDifferenceResultEnum TryCalculateCombinedDifference(byte differenceThreshold)
{
if (this.CurrentDifferenceState != ImageDifferenceEnum.Combined)
{
return(ImageDifferenceResultEnum.NotCalculable);
}
// We need three valid images: the current one, the previous one, and the next one.
if (this.Current == null || this.Current.IsVideo || this.Current.IsDisplayable(this.Database.FolderPath) == false)
{
this.CurrentDifferenceState = ImageDifferenceEnum.Unaltered;
return(ImageDifferenceResultEnum.CurrentImageNotAvailable);
}
if (this.TryGetPreviousBitmapAsWriteable(out WriteableBitmap previousBitmap) == false)
{
return(ImageDifferenceResultEnum.PreviousImageNotAvailable);
}
if (this.TryGetNextBitmapAsWriteable(out WriteableBitmap nextBitmap) == false)
{
return(ImageDifferenceResultEnum.NextImageNotAvailable);
}
WriteableBitmap unalteredBitmap = this.differenceBitmapCache[ImageDifferenceEnum.Unaltered].AsWriteable();
this.differenceBitmapCache[ImageDifferenceEnum.Unaltered] = unalteredBitmap;
// all three images are available, so calculate and cache difference
BitmapSource differenceBitmap = unalteredBitmap.CombinedDifference(previousBitmap, nextBitmap, differenceThreshold);
this.differenceBitmapCache[ImageDifferenceEnum.Combined] = differenceBitmap;
return(differenceBitmap != null ? ImageDifferenceResultEnum.Success : ImageDifferenceResultEnum.NotCalculable);
}