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 // Copyright 2013 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // @dart = 2.12 part of dart.ui; /// Linearly interpolate between two numbers, `a` and `b`, by an extrapolation /// factor `t`. /// /// When `a` and `b` are equal or both NaN, `a` is returned. Otherwise, /// `a`, `b`, and `t` are required to be finite or null, and the result of `a + /// (b - a) * t` is returned, where nulls are defaulted to 0.0. double? lerpDouble(num? a, num? b, double t) { if (a == b || (a?.isNaN == true) && (b?.isNaN == true)) return a?.toDouble(); a ??= 0.0; b ??= 0.0; assert(a.isFinite, 'Cannot interpolate between finite and non-finite values'); assert(b.isFinite, 'Cannot interpolate between finite and non-finite values'); assert(t.isFinite, 't must be finite when interpolating between values'); return a * (1.0 - t) + b * t; } /// Linearly interpolate between two doubles. /// /// Same as [lerpDouble] but specialized for non-null `double` type. double _lerpDouble(double a, double b, double t) { return a * (1.0 - t) + b * t; } /// Linearly interpolate between two integers. /// /// Same as [lerpDouble] but specialized for non-null `int` type. double _lerpInt(int a, int b, double t) { return a + (b - a) * t; } /// Same as [num.clamp] but specialized for non-null [int]. int _clampInt(int value, int min, int max) { assert(min <= max); if (value < min) { return min; } else if (value > max) { return max; } else { return value; } }