private static bool ComputeDecomposedTransform(TransformOperations operations, int startOffset, out Matrix.Decomposed decomposed)
{
Matrix transform = operations.ApplyTransforms(startOffset);
if (!Matrix.TryDecomposeTransform(transform, out decomposed))
{
return(false);
}
return(true);
}
private static bool TryInterpolate(TransformOperations from, TransformOperations to, double progress, ref TransformOperations result)
{
bool fromIdentity = from.IsIdentity;
bool toIdentity = to.IsIdentity;
if (fromIdentity && toIdentity)
{
return(true);
}
int matchingPrefixLength = ComputeMatchingPrefixLength(from, to);
int fromSize = fromIdentity ? 0 : from._operations.Count;
int toSize = toIdentity ? 0 : to._operations.Count;
int numOperations = Math.Max(fromSize, toSize);
var builder = new Builder(matchingPrefixLength);
for (int i = 0; i < matchingPrefixLength; i++)
{
TransformOperation interpolated = new TransformOperation
{
Type = TransformOperation.OperationType.Identity
};
if (!TransformOperation.TryInterpolate(
i >= fromSize ? default(TransformOperation?) : from._operations[i],
i >= toSize ? default(TransformOperation?) : to._operations[i],
progress,
ref interpolated))
{
return(false);
}
builder.Append(interpolated);
}
if (matchingPrefixLength < numOperations)
{
if (!ComputeDecomposedTransform(from, matchingPrefixLength, out Matrix.Decomposed fromDecomposed) ||
!ComputeDecomposedTransform(to, matchingPrefixLength, out Matrix.Decomposed toDecomposed))
{
return(false);
}
var transform = InterpolationUtilities.InterpolateDecomposedTransforms(ref fromDecomposed, ref toDecomposed, progress);
builder.AppendMatrix(InterpolationUtilities.ComposeTransform(transform));
}
result = builder.Build();
return(true);
}
public static TransformOperations Interpolate(TransformOperations from, TransformOperations to, double progress)
{
TransformOperations result = Identity;
if (!TryInterpolate(from, to, progress, ref result))
{
// If the matrices cannot be interpolated, fallback to discrete animation logic.
// See https://drafts.csswg.org/css-transforms/#matrix-interpolation
result = progress < 0.5 ? from : to;
}
return(result);
}
private static int ComputeMatchingPrefixLength(TransformOperations from, TransformOperations to)
{
int numOperations = Math.Min(from._operations.Count, to._operations.Count);
for (int i = 0; i < numOperations; i++)
{
if (from._operations[i].Type != to._operations[i].Type)
{
return(i);
}
}
// If the operations match to the length of the shorter list, then pad its
// length with the matching identity operations.
// https://drafts.csswg.org/css-transforms/#transform-function-lists
return(Math.Max(from._operations.Count, to._operations.Count));
}
