Add kernel_size properties

vskernels/kernels/bicubic.py

@@ -68,6 +68,10 @@ def get_params_args(
             return args | dict(b=self.b, c=self.c)
         return args | dict(filter_param_a=self.b, filter_param_b=self.c)
 
+    @property
+    def kernel_size(self) -> int:
+        return 1 + ((self.b, self.c) != (0, 0))
+
 
 class BSpline(Bicubic):
     """Bicubic b=1, c=0"""

vskernels/kernels/placebo.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from math import ceil
 from typing import TYPE_CHECKING, Any
 
 from vstools import Transfer, TransferT, core, inject_self, vs
@@ -82,3 +83,16 @@ def get_params_args(
             antiring=self.antiring, cutoff=self.cutoff,
             lut_entries=self.lut_entries, trc=curve.value_libplacebo
         )
+
+    def _kernel_size(self, taps: float | None = None, b: int | None = None, c: int | None = None) -> int
+        if taps:
+            return ceil(self.taps)
+
+        if b or c:
+            return 1 + ((b if b and b != 0 else 0, c if c and c != 0 else 0.5) != (0, 0))
+
+        return 1
+
+    @property
+    def kernel_size(self) -> int:
+        return self._kernel_size(self.taps, self.b, self.c)

vskernels/kernels/resize.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from math import ceil
 from typing import Any
 
 from vstools import core, vs
@@ -25,6 +26,10 @@ class Bilinear(ZimgComplexKernel):
     scale_function = resample_function = core.lazy.resize.Bilinear
     descale_function = core.lazy.descale.Debilinear
 
+    @property
+    def kernel_size(self) -> int:
+        return 1
+
 
 class Lanczos(ZimgComplexKernel):
     """
@@ -51,3 +56,7 @@ def get_params_args(
         if is_descale:
             return args | dict(taps=self.taps)
         return args | dict(filter_param_a=self.taps)
+
+    @property
+    def kernel_size(self) -> int:
+        return ceil(self.taps)

vskernels/kernels/spline.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import re
+from math import ceil, isqrt
 from typing import Any
 
 from vstools import core
@@ -15,6 +17,19 @@
 ]
 
 
+class _SplineKernelSize:
+    """Spline kernel size sub-class."""
+
+    @property
+    def kernel_size(self) -> int:
+        radius = re.search(r'\d+$', self.__class__.__name__)
+
+        if not radius:
+            return 1
+
+        return ceil(isqrt(int(radius.group())) / 2)
+
+
 class Spline(FmtConv):
     """fmtconv's spline resizer."""
 
@@ -23,8 +38,12 @@ class Spline(FmtConv):
     def __init__(self, taps: int = 2, **kwargs: Any) -> None:
         super().__init__(taps=taps, **kwargs)
 
+    @property
+    def kernel_size(self) -> int:
+        return ceil(self.taps)
+
 
-class Spline16(ZimgComplexKernel):
+class Spline16(ZimgComplexKernel, _SplineKernelSize):
     """
     Built-in spline16 resizer.
 
@@ -37,7 +56,7 @@ class Spline16(ZimgComplexKernel):
     descale_function = core.lazy.descale.Despline16
 
 
-class Spline36(ZimgComplexKernel):
+class Spline36(ZimgComplexKernel, _SplineKernelSize):
     """
     Built-in spline36 resizer.
 
@@ -50,7 +69,7 @@ class Spline36(ZimgComplexKernel):
     descale_function = core.lazy.descale.Despline36
 
 
-class Spline64(ZimgComplexKernel):
+class Spline64(ZimgComplexKernel, _SplineKernelSize):
     """
     Built-in spline64 resizer.
 

vskernels/kernels/various.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from math import log, sqrt
+from math import ceil, log, sqrt
 from typing import Any
 
 from vstools import CustomValueError, to_singleton
@@ -104,10 +104,7 @@ class EwaBicubic(Placebo):
     _kernel = 'ewa_robidoux'
 
     def __init__(self, b: float = 0.0, c: float = 0.5, radius: int | None = None, **kwargs: Any) -> None:
-        radius = kwargs.pop('taps', radius)
-
-        if radius is None:
-            radius = 1 if (b, c) == (0, 0) else 2
+        radius = self._kernel_size(kwargs.pop('taps', radius), b, c)
 
         super().__init__(radius, b, c, **kwargs)