Creates a mask filter that takes the shape being drawn and blurs it.
This is commonly used to approximate shadows.
The style argument controls the kind of effect to draw; see BlurStyle.
The sigma argument controls the size of the effect. It is the standard
deviation of the Gaussian blur to apply. The value must be greater than
zero. The sigma corresponds to very roughly half the radius of the effect
in pixels.
If the ignoreTransform argument is set, then the current transform is
ignored when computing the blur. This makes the operation cheaper, but
lowers the quality of the effect. In particular, it means that the sigma
will be relative to the device pixel coordinate space, rather than the
logical pixel coordinate space, which means the blur will look different
on different devices.
If the highQuality argument is set, then the quality of the blur may be
slightly improved, at the cost of making the operation even more
expensive.
Even in the best conditions and with the lowest quality settings, a blur is an expensive operation and blurs should therefore be used sparingly.
Source
MaskFilter.blur(BlurStyle style, double sigma, {
bool ignoreTransform: false,
bool highQuality: false
}) {
_constructor(style.index, sigma, _makeBlurFlags(ignoreTransform, highQuality));
}