[Documentation] Replaced lerp dart docs with macro (#22309)

packages/flutter/lib/src/material/chip_theme.dart

@@ -360,17 +360,7 @@ class ChipThemeData extends Diagnosticable {
   ///
   /// The arguments must not be null.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static ChipThemeData lerp(ChipThemeData a, ChipThemeData b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/material/slider_theme.dart

@@ -391,17 +391,7 @@ class SliderThemeData extends Diagnosticable {
   ///
   /// The arguments must not be null.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static SliderThemeData lerp(SliderThemeData a, SliderThemeData b, double t) {
     assert(a != null);
     assert(b != null);

packages/flutter/lib/src/material/tab_bar_theme.dart

@@ -61,6 +61,8 @@ class TabBarTheme extends Diagnosticable {
 
   /// Linearly interpolate between two tab bar themes.
   ///
+  /// The arguments must not be null.
+  ///
   /// {@macro flutter.material.themeData.lerp}
   static TabBarTheme lerp(TabBarTheme a, TabBarTheme b, double t) {
     assert(a != null);

packages/flutter/lib/src/material/theme_data.dart

@@ -730,8 +730,6 @@ class ThemeData extends Diagnosticable {
   /// Linearly interpolate between two themes.
   ///
   /// {@template flutter.material.themeData.lerp}
-  /// The arguments must not be null.
-  ///
   /// The `t` argument represents position on the timeline, with 0.0 meaning
   /// that the interpolation has not started, returning `a` (or something
   /// equivalent to `a`), 1.0 meaning that the interpolation has finished,

packages/flutter/lib/src/material/typography.dart

@@ -361,17 +361,7 @@ class TextTheme extends Diagnosticable {
   ///
   /// The arguments must not be null.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static TextTheme lerp(TextTheme a, TextTheme b, double t) {
     assert(a != null);
     assert(b != null);

packages/flutter/lib/src/painting/alignment.dart

@@ -85,17 +85,7 @@ abstract class AlignmentGeometry {
   /// representing a combination of both is returned. That object can be turned
   /// into a concrete [Alignment] using [resolve].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static AlignmentGeometry lerp(AlignmentGeometry a, AlignmentGeometry b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -334,17 +324,7 @@ class Alignment extends AlignmentGeometry {
   ///
   /// If either is null, this function interpolates from [Alignment.center].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static Alignment lerp(Alignment a, Alignment b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -525,17 +505,7 @@ class AlignmentDirectional extends AlignmentGeometry {
   ///
   /// If either is null, this function interpolates from [AlignmentDirectional.center].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static AlignmentDirectional lerp(AlignmentDirectional a, AlignmentDirectional b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/border_radius.dart

@@ -127,17 +127,7 @@ abstract class BorderRadiusGeometry {
   /// representing a combination of both is returned. That object can be turned
   /// into a concrete [BorderRadius] using [resolve].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BorderRadiusGeometry lerp(BorderRadiusGeometry a, BorderRadiusGeometry b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -481,17 +471,7 @@ class BorderRadius extends BorderRadiusGeometry {
   ///
   /// If either is null, this function interpolates from [BorderRadius.zero].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BorderRadius lerp(BorderRadius a, BorderRadius b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -708,17 +688,7 @@ class BorderRadiusDirectional extends BorderRadiusGeometry {
   ///
   /// If either is null, this function interpolates from [BorderRadiusDirectional.zero].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BorderRadiusDirectional lerp(BorderRadiusDirectional a, BorderRadiusDirectional b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/borders.dart

@@ -198,17 +198,7 @@ class BorderSide {
   ///
   /// The arguments must not be null.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BorderSide lerp(BorderSide a, BorderSide b, double t) {
     assert(a != null);
     assert(b != null);
@@ -414,17 +404,7 @@ abstract class ShapeBorder {
   /// function instead. If both return null, it returns `a` before `t=0.5`
   /// and `b` after `t=0.5`.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static ShapeBorder lerp(ShapeBorder a, ShapeBorder b, double t) {
     assert(t != null);
     ShapeBorder result;

packages/flutter/lib/src/painting/box_border.dart

@@ -98,17 +98,7 @@ abstract class BoxBorder extends ShapeBorder {
   /// For a more flexible approach, consider [ShapeBorder.lerp], which would
   /// instead [add] the two sets of sides and interpolate them simultaneously.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BoxBorder lerp(BoxBorder a, BoxBorder b, double t) {
     assert(t != null);
     if ((a is Border || a == null) && (b is Border || b == null))
@@ -431,17 +421,7 @@ class Border extends BoxBorder {
   /// If a border is null, it is treated as having four [BorderSide.none]
   /// borders.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static Border lerp(Border a, Border b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -731,17 +711,7 @@ class BorderDirectional extends BoxBorder {
   /// If a border is null, it is treated as having four [BorderSide.none]
   /// borders.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BorderDirectional lerp(BorderDirectional a, BorderDirectional b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/box_decoration.dart

@@ -216,17 +216,7 @@ class BoxDecoration extends Decoration {
   /// unmodified. Otherwise, the values are computed by interpolating the
   /// properties appropriately.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   ///
   /// See also:
   ///

packages/flutter/lib/src/painting/box_shadow.dart

@@ -94,17 +94,7 @@ class BoxShadow {
   /// a box shadow that matches the other box shadow in color but has a zero
   /// offset and a zero blurRadius.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BoxShadow lerp(BoxShadow a, BoxShadow b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -125,17 +115,7 @@ class BoxShadow {
   ///
   /// If the lists differ in length, excess items are lerped with null.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static List<BoxShadow> lerpList(List<BoxShadow> a, List<BoxShadow> b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/colors.dart

@@ -194,19 +194,9 @@ class HSVColor {
   /// that will interpolate from a transparent red and cycle through the hues to
   /// match the target color, regardless of what that color's hue is.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
+  /// {@macro flutter.material.themeData.lerp}
   ///
   /// Values outside of the valid range for each channel will be clamped.
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
   static HSVColor lerp(HSVColor a, HSVColor b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/decoration.dart

@@ -124,17 +124,7 @@ abstract class Decoration extends Diagnosticable {
   /// respectively to find a solution. If the two values can't directly be
   /// interpolated, then the interpolation is done via null (at `t == 0.5`).
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static Decoration lerp(Decoration a, Decoration b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/edge_insets.dart

@@ -190,17 +190,7 @@ abstract class EdgeInsetsGeometry {
   /// representing a combination of both is returned. That object can be turned
   /// into a concrete [EdgeInsets] using [resolve].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static EdgeInsetsGeometry lerp(EdgeInsetsGeometry a, EdgeInsetsGeometry b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -556,17 +546,7 @@ class EdgeInsets extends EdgeInsetsGeometry {
   ///
   /// If either is null, this function interpolates from [EdgeInsets.zero].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static EdgeInsets lerp(EdgeInsets a, EdgeInsets b, double t) {
     assert(t != null);
     if (a == null && b == null)
@@ -790,17 +770,7 @@ class EdgeInsetsDirectional extends EdgeInsetsGeometry {
   /// (either [EdgeInsets] or [EdgeInsetsDirectional]), consider the
   /// [EdgeInsetsGeometry.lerp] static method.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static EdgeInsetsDirectional lerp(EdgeInsetsDirectional a, EdgeInsetsDirectional b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/flutter_logo.dart

@@ -127,17 +127,7 @@ class FlutterLogoDecoration extends Decoration {
   /// non-null value. If one of the values is null, then the result is obtained
   /// by scaling the other value's opacity and [margin].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   ///
   /// See also:
   ///

packages/flutter/lib/src/painting/fractional_offset.dart

@@ -178,17 +178,7 @@ class FractionalOffset extends Alignment {
   ///
   /// If either is null, this function interpolates from [FractionalOffset.center].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static FractionalOffset lerp(FractionalOffset a, FractionalOffset b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/painting/gradient.dart

@@ -185,17 +185,7 @@ abstract class Gradient {
   /// function instead. If both return null, it returns `a` before `t == 0.5`
   /// and `b` after `t == 0.5`.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static Gradient lerp(Gradient a, Gradient b, double t) {
     assert(t != null);
     Gradient result;

packages/flutter/lib/src/painting/shape_decoration.dart

@@ -204,17 +204,7 @@ class ShapeDecoration extends Decoration {
   /// fields are all null (including the [shape], which cannot normally be
   /// null).
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   ///
   /// See also:
   ///

packages/flutter/lib/src/painting/text_style.dart

@@ -560,17 +560,7 @@ class TextStyle extends Diagnosticable {
   ///
   /// This will not work well if the styles don't set the same fields.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   ///
   /// If [foreground] is specified on either of `a` or `b`, both will be treated
   /// as if they have a [foreground] paint (creating a new [Paint] if necessary

packages/flutter/lib/src/rendering/box.dart

@@ -449,17 +449,7 @@ class BoxConstraints extends Constraints {
   /// If either is null, this function interpolates from a [BoxConstraints]
   /// object whose fields are all set to 0.0.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static BoxConstraints lerp(BoxConstraints a, BoxConstraints b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/rendering/stack.dart

@@ -131,17 +131,7 @@ class RelativeRect {
   ///
   /// If either rect is null, this function interpolates from [RelativeRect.fill].
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static RelativeRect lerp(RelativeRect a, RelativeRect b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/rendering/table_border.dart

@@ -147,17 +147,7 @@ class TableBorder {
   /// If a border is null, it is treated as having only [BorderSide.none]
   /// borders.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static TableBorder lerp(TableBorder a, TableBorder b, double t) {
     assert(t != null);
     if (a == null && b == null)

packages/flutter/lib/src/widgets/icon_theme_data.dart

@@ -68,17 +68,7 @@ class IconThemeData extends Diagnosticable {
 
   /// Linearly interpolate between two icon theme data objects.
   ///
-  /// The `t` argument represents position on the timeline, with 0.0 meaning
-  /// that the interpolation has not started, returning `a` (or something
-  /// equivalent to `a`), 1.0 meaning that the interpolation has finished,
-  /// returning `b` (or something equivalent to `b`), and values in between
-  /// meaning that the interpolation is at the relevant point on the timeline
-  /// between `a` and `b`. The interpolation can be extrapolated beyond 0.0 and
-  /// 1.0, so negative values and values greater than 1.0 are valid (and can
-  /// easily be generated by curves such as [Curves.elasticInOut]).
-  ///
-  /// Values for `t` are usually obtained from an [Animation<double>], such as
-  /// an [AnimationController].
+  /// {@macro flutter.material.themeData.lerp}
   static IconThemeData lerp(IconThemeData a, IconThemeData b, double t) {
     assert(t != null);
     return IconThemeData(