Class CompositeGenericTransform

lib/matplotlib/transforms.py:2391–2502

A composite transform formed by applying transform *a* then transform *b*. This "generic" version can handle any two arbitrary transformations.

class CompositeGenericTransform(Transform):
    """
    A composite transform formed by applying transform *a* then
    transform *b*.

    This "generic" version can handle any two arbitrary
    transformations.
    """
    pass_through = True

    def __init__(self, a, b, **kwargs):
        """
        Create a new composite transform that is the result of
        applying transform *a* then transform *b*.

        You will generally not call this constructor directly but write ``a +
        b`` instead, which will automatically choose the best kind of composite
        transform instance to create.
        """
        if a.output_dims != b.input_dims:
            raise ValueError("The output dimension of 'a' must be equal to "
                             "the input dimensions of 'b'")
        self.input_dims = a.input_dims
        self.output_dims = b.output_dims

        super().__init__(**kwargs)
        self._a = a
        self._b = b
        self.set_children(a, b)

    def frozen(self):
        # docstring inherited
        self._invalid = 0
        frozen = composite_transform_factory(
            self._a.frozen(), self._b.frozen())
        if not isinstance(frozen, CompositeGenericTransform):
            return frozen.frozen()
        return frozen

    def _invalidate_internal(self, level, invalidating_node):
        # When the left child is invalidated at AFFINE_ONLY level and the right child is
        # non-affine, the composite transform is FULLY invalidated.
        if invalidating_node is self._a and not self._b.is_affine:
            level = Transform._INVALID_FULL
        super()._invalidate_internal(level, invalidating_node)

    def __eq__(self, other):
        if isinstance(other, (CompositeGenericTransform, CompositeAffine2D)):
            return self is other or (self._a == other._a
                                     and self._b == other._b)
        else:
            return False

    def _iter_break_from_left_to_right(self):
        for left, right in self._a._iter_break_from_left_to_right():
            yield left, right + self._b
        for left, right in self._b._iter_break_from_left_to_right():
            yield self._a + left, right