Creates an axial shading (Type 2) that blends between gradient stops along the line from start to end.
public PdfAxialShading CreateAxialShading(PathPoint start, PathPoint end, IReadOnlyList<PdfGradientStop> stops, PdfShadingOptions? options)
The point where offset 0 lies, in the shading's target space.
The point where offset 1 lies; not start.
The stops, as for CreateGradientFunction(IReadOnlyList<PdfGradientStop>); their colour space is the shading's.
The optional entries; null for none.
ISO 32000-2 §8.7.4.5.3, Table 79 (PDF 1.3). Coords is the axis, Domain [0 1], and the Function is written
inline as CreateGradientFunction(IReadOnlyList<PdfGradientStop>) builds it. Paint it with PaintShading(PdfShading) or through
CreateShadingPattern(PdfShading, Nullable<Matrix>). Records PDF 1.3. A mutation.