public static ReferenceKernelMap Calculate(IResampler sampler, int destinationSize, int sourceSize, bool normalize = true)
{
double ratio = (double)sourceSize / destinationSize;
double scale = ratio;
if (scale < 1F)
{
scale = 1F;
}
TolerantMath tolerantMath = TolerantMath.Default;
double radius = tolerantMath.Ceiling(scale * sampler.Radius);
var result = new List <ReferenceKernel>();
for (int i = 0; i < destinationSize; i++)
{
double center = ((i + .5) * ratio) - .5;
// Keep inside bounds.
int left = (int)tolerantMath.Ceiling(center - radius);
if (left < 0)
{
left = 0;
}
int right = (int)tolerantMath.Floor(center + radius);
if (right > sourceSize - 1)
{
right = sourceSize - 1;
}
double sum = 0;
double[] values = new double[right - left + 1];
for (int j = left; j <= right; j++)
{
double weight = sampler.GetValue((float)((j - center) / scale));
sum += weight;
values[j - left] = weight;
}
if (sum > 0 && normalize)
{
for (int w = 0; w < values.Length; w++)
{
values[w] /= sum;
}
}
float[] floatVals = values.Select(v => (float)v).ToArray();
result.Add(new ReferenceKernel(left, floatVals));
}
return(new ReferenceKernelMap(result.ToArray()));
}
protected override void Initialize()
{
// Build top corner data + one period of the mosaic data:
int startOfFirstRepeatedMosaic = this.cornerInterval + this.period;
for (int i = 0; i < startOfFirstRepeatedMosaic; i++)
{
ResizeKernel kernel = this.BuildKernel(i, i);
this.kernels[i] = kernel;
}
// Copy the mosaics:
int bottomStartDest = this.DestinationLength - this.cornerInterval;
for (int i = startOfFirstRepeatedMosaic; i < bottomStartDest; i++)
{
double center = ((i + .5) * this.ratio) - .5;
int left = (int)TolerantMath.Ceiling(center - this.radius);
ResizeKernel kernel = this.kernels[i - this.period];
this.kernels[i] = kernel.AlterLeftValue(left);
}
// Build bottom corner data:
int bottomStartData = this.cornerInterval + this.period;
for (int i = 0; i < this.cornerInterval; i++)
{
ResizeKernel kernel = this.BuildKernel(bottomStartDest + i, bottomStartData + i);
this.kernels[bottomStartDest + i] = kernel;
}
}
