Add onLongPress to Buttons

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

@@ -38,6 +38,7 @@ class RawMaterialButton extends StatefulWidget {
   const RawMaterialButton({
     Key key,
     @required this.onPressed,
+    this.onLongPress,
     this.onHighlightChanged,
     this.textStyle,
     this.fillColor,
@@ -75,9 +76,22 @@ class RawMaterialButton extends StatefulWidget {
 
   /// Called when the button is tapped or otherwise activated.
   ///
-  /// If this is set to null, the button will be disabled, see [enabled].
+  /// If this callback and [onLongPress] are null, then the button will be disabled.
+  ///
+  /// See also:
+  ///
+  ///  * [enabled], which is true if the button is enabled.
   final VoidCallback onPressed;
 
+  /// Called when the button is long-pressed.
+  ///
+  /// If this callback and [onPressed] are null, then the button will be disabled.
+  ///
+  /// See also:
+  ///
+  ///  * [enabled], which is true if the button is enabled.
+  final VoidCallback onLongPress;
+
   /// Called by the underlying [InkWell] widget's [InkWell.onHighlightChanged]
   /// callback.
   ///
@@ -222,8 +236,8 @@ class RawMaterialButton extends StatefulWidget {
   /// Whether the button is enabled or disabled.
   ///
   /// Buttons are disabled by default. To enable a button, set its [onPressed]
-  /// property to a non-null value.
-  bool get enabled => onPressed != null;
+  /// or [onLongPress] properties to a non-null value.
+  bool get enabled => onPressed != null || onLongPress != null;
 
   /// Configures the minimum size of the tap target.
   ///
@@ -352,6 +366,7 @@ class _RawMaterialButtonState extends State<RawMaterialButton> {
           hoverColor: widget.hoverColor,
           onHover: _handleHoveredChanged,
           onTap: widget.onPressed,
+          onLongPress: widget.onLongPress,
           customBorder: effectiveShape,
           child: IconTheme.merge(
             data: IconThemeData(color: effectiveTextColor),

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

@@ -29,7 +29,7 @@ import 'theme_data.dart';
 /// interactive, with ink splashes, without also committing to these stylistic
 /// choices, consider using [InkWell] instead.
 ///
-/// If the [onPressed] callback is null, then the button will be disabled,
+/// If the [onPressed] and [onLongPress] callbacks are null, then this button will be disabled,
 /// will not react to touch, and will be colored as specified by
 /// the [disabledColor] property instead of the [color] property. If you are
 /// trying to change the button's [color] and it is not having any effect, check
@@ -102,6 +102,7 @@ class FlatButton extends MaterialButton {
   const FlatButton({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ValueChanged<bool> onHighlightChanged,
     ButtonTextTheme textTheme,
     Color textColor,
@@ -125,6 +126,7 @@ class FlatButton extends MaterialButton {
        super(
          key: key,
          onPressed: onPressed,
+         onLongPress: onLongPress,
          onHighlightChanged: onHighlightChanged,
          textTheme: textTheme,
          textColor: textColor,
@@ -155,6 +157,7 @@ class FlatButton extends MaterialButton {
   factory FlatButton.icon({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ValueChanged<bool> onHighlightChanged,
     ButtonTextTheme textTheme,
     Color textColor,
@@ -182,6 +185,7 @@ class FlatButton extends MaterialButton {
     final ButtonThemeData buttonTheme = ButtonTheme.of(context);
     return RawMaterialButton(
       onPressed: onPressed,
+      onLongPress: onLongPress,
       onHighlightChanged: onHighlightChanged,
       fillColor: buttonTheme.getFillColor(this),
       textStyle: theme.textTheme.button.copyWith(color: buttonTheme.getTextColor(this)),
@@ -215,6 +219,7 @@ class _FlatButtonWithIcon extends FlatButton with MaterialButtonWithIconMixin {
   _FlatButtonWithIcon({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ValueChanged<bool> onHighlightChanged,
     ButtonTextTheme textTheme,
     Color textColor,
@@ -241,6 +246,7 @@ class _FlatButtonWithIcon extends FlatButton with MaterialButtonWithIconMixin {
        super(
          key: key,
          onPressed: onPressed,
+         onLongPress: onLongPress,
          onHighlightChanged: onHighlightChanged,
          textTheme: textTheme,
          textColor: textColor,

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

@@ -21,8 +21,8 @@ import 'theme_data.dart';
 ///
 /// The button's size will expand to fit the child widget, if necessary.
 ///
-/// MaterialButtons whose [onPressed] handler is null will be disabled. To have
-/// an enabled button, make sure to pass a non-null value for onPressed.
+/// MaterialButtons whose [onPressed] and [onLongPress] callbacks are null will be disabled. To have
+/// an enabled button, make sure to pass a non-null value for [onPressed] or [onLongPress].
 ///
 /// Rather than using this class directly, consider using [FlatButton],
 /// [OutlineButton], or [RaisedButton], which configure this class with
@@ -51,6 +51,7 @@ class MaterialButton extends StatelessWidget {
   const MaterialButton({
     Key key,
     @required this.onPressed,
+    this.onLongPress,
     this.onHighlightChanged,
     this.textTheme,
     this.textColor,
@@ -88,9 +89,22 @@ class MaterialButton extends StatelessWidget {
 
   /// The callback that is called when the button is tapped or otherwise activated.
   ///
-  /// If this is set to null, the button will be disabled.
+  /// If this callback and [onLongPress] are null, then the button will be disabled.
+  ///
+  /// See also:
+  ///
+  ///  * [enabled], which is true if the button is enabled.
   final VoidCallback onPressed;
 
+  /// The callback that is called when the button is long-pressed.
+  ///
+  /// If this callback and [onPressed] are null, then the button will be disabled.
+  ///
+  /// See also:
+  ///
+  ///  * [enabled], which is true if the button is enabled.
+  final VoidCallback onLongPress;
+
   /// Called by the underlying [InkWell] widget's [InkWell.onHighlightChanged]
   /// callback.
   ///
@@ -287,8 +301,8 @@ class MaterialButton extends StatelessWidget {
   /// Whether the button is enabled or disabled.
   ///
   /// Buttons are disabled by default. To enable a button, set its [onPressed]
-  /// property to a non-null value.
-  bool get enabled => onPressed != null;
+  /// or [onLongPress] properties to a non-null value.
+  bool get enabled => onPressed != null || onLongPress != null;
 
   /// The internal padding for the button's [child].
   ///
@@ -348,6 +362,7 @@ class MaterialButton extends StatelessWidget {
 
     return RawMaterialButton(
       onPressed: onPressed,
+      onLongPress: onLongPress,
       onHighlightChanged: onHighlightChanged,
       fillColor: buttonTheme.getFillColor(this),
       textStyle: theme.textTheme.button.copyWith(color: buttonTheme.getTextColor(this)),
@@ -377,7 +392,7 @@ class MaterialButton extends StatelessWidget {
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.add(ObjectFlagProperty<VoidCallback>('onPressed', onPressed, ifNull: 'disabled'));
+    properties.add(FlagProperty('enabled', value: enabled, ifFalse: 'disabled'));
     properties.add(DiagnosticsProperty<ButtonTextTheme>('textTheme', textTheme, defaultValue: null));
     properties.add(ColorProperty('textColor', textColor, defaultValue: null));
     properties.add(ColorProperty('disabledTextColor', disabledTextColor, defaultValue: null));

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

@@ -28,7 +28,7 @@ const Duration _kElevationDuration = Duration(milliseconds: 75);
 /// wide grey rounded rectangle that does not change when the button is
 /// pressed or disabled. By default the button's background is transparent.
 ///
-/// If the [onPressed] callback is null, then the button will be disabled and by
+/// If the [onPressed] or [onLongPress] callbacks are null, then the button will be disabled and by
 /// default will resemble a flat button in the [disabledColor].
 ///
 /// The button's [highlightElevation], which defines the size of the
@@ -61,6 +61,7 @@ class OutlineButton extends MaterialButton {
   const OutlineButton({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ButtonTextTheme textTheme,
     Color textColor,
     Color disabledTextColor,
@@ -85,6 +86,7 @@ class OutlineButton extends MaterialButton {
        super(
          key: key,
          onPressed: onPressed,
+         onLongPress: onLongPress,
          textTheme: textTheme,
          textColor: textColor,
          disabledTextColor: disabledTextColor,
@@ -113,6 +115,7 @@ class OutlineButton extends MaterialButton {
   factory OutlineButton.icon({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ButtonTextTheme textTheme,
     Color textColor,
     Color disabledTextColor,
@@ -169,6 +172,7 @@ class OutlineButton extends MaterialButton {
     final ButtonThemeData buttonTheme = ButtonTheme.of(context);
     return _OutlineButton(
       onPressed: onPressed,
+      onLongPress: onLongPress,
       brightness: buttonTheme.getBrightness(this),
       textTheme: textTheme,
       textColor: buttonTheme.getTextColor(this),
@@ -207,6 +211,7 @@ class _OutlineButtonWithIcon extends OutlineButton with MaterialButtonWithIconMi
   _OutlineButtonWithIcon({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ButtonTextTheme textTheme,
     Color textColor,
     Color disabledTextColor,
@@ -234,6 +239,7 @@ class _OutlineButtonWithIcon extends OutlineButton with MaterialButtonWithIconMi
        super(
          key: key,
          onPressed: onPressed,
+         onLongPress: onLongPress,
          textTheme: textTheme,
          textColor: textColor,
          disabledTextColor: disabledTextColor,
@@ -266,6 +272,7 @@ class _OutlineButton extends StatefulWidget {
   const _OutlineButton({
     Key key,
     @required this.onPressed,
+    this.onLongPress,
     this.brightness,
     this.textTheme,
     this.textColor,
@@ -292,6 +299,7 @@ class _OutlineButton extends StatefulWidget {
        super(key: key);
 
   final VoidCallback onPressed;
+  final VoidCallback onLongPress;
   final Brightness brightness;
   final ButtonTextTheme textTheme;
   final Color textColor;
@@ -312,7 +320,7 @@ class _OutlineButton extends StatefulWidget {
   final bool autofocus;
   final Widget child;
 
-  bool get enabled => onPressed != null;
+  bool get enabled => onPressed != null || onLongPress != null;
 
   @override
   _OutlineButtonState createState() => _OutlineButtonState();
@@ -440,6 +448,7 @@ class _OutlineButtonState extends State<_OutlineButton> with SingleTickerProvide
           highlightColor: widget.highlightColor,
           disabledColor: Colors.transparent,
           onPressed: widget.onPressed,
+          onLongPress: widget.onLongPress,
           elevation: 0.0,
           disabledElevation: 0.0,
           focusElevation: 0.0,

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

@@ -20,10 +20,10 @@ import 'theme_data.dart';
 /// in long busy lists of content, or in wide spaces. Avoid using raised buttons
 /// on already-raised content such as dialogs or cards.
 ///
-/// If the [onPressed] callback is null, then the button will be disabled and by
+/// If [onPressed] and [onLongPress] callbacks are null, then the button will be disabled and by
 /// default will resemble a flat button in the [disabledColor]. If you are
 /// trying to change the button's [color] and it is not having any effect, check
-/// that you are passing a non-null [onPressed] handler.
+/// that you are passing a non-null [onPressed] or [onLongPress] callbacks.
 ///
 /// If you want an ink-splash effect for taps, but don't want to use a button,
 /// consider using [InkWell] directly.
@@ -108,6 +108,7 @@ class RaisedButton extends MaterialButton {
   const RaisedButton({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ValueChanged<bool> onHighlightChanged,
     ButtonTextTheme textTheme,
     Color textColor,
@@ -142,6 +143,7 @@ class RaisedButton extends MaterialButton {
        super(
          key: key,
          onPressed: onPressed,
+         onLongPress: onLongPress,
          onHighlightChanged: onHighlightChanged,
          textTheme: textTheme,
          textColor: textColor,
@@ -179,6 +181,7 @@ class RaisedButton extends MaterialButton {
   factory RaisedButton.icon({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ValueChanged<bool> onHighlightChanged,
     ButtonTextTheme textTheme,
     Color textColor,
@@ -209,6 +212,7 @@ class RaisedButton extends MaterialButton {
     final ButtonThemeData buttonTheme = ButtonTheme.of(context);
     return RawMaterialButton(
       onPressed: onPressed,
+      onLongPress: onLongPress,
       onHighlightChanged: onHighlightChanged,
       clipBehavior: clipBehavior,
       fillColor: buttonTheme.getFillColor(this),
@@ -252,6 +256,7 @@ class _RaisedButtonWithIcon extends RaisedButton with MaterialButtonWithIconMixi
   _RaisedButtonWithIcon({
     Key key,
     @required VoidCallback onPressed,
+    VoidCallback onLongPress,
     ValueChanged<bool> onHighlightChanged,
     ButtonTextTheme textTheme,
     Color textColor,
@@ -284,6 +289,7 @@ class _RaisedButtonWithIcon extends RaisedButton with MaterialButtonWithIconMixi
        super(
          key: key,
          onPressed: onPressed,
+         onLongPress: onLongPress,
          onHighlightChanged: onHighlightChanged,
          textTheme: textTheme,
          textColor: textColor,

packages/flutter/test/material/buttons_test.dart

@@ -1187,6 +1187,7 @@ void main() {
         child: MaterialButton(
           disabledColor: Color(0xff00ff00),
           onPressed: null,
+          onLongPress: null,
           child: Text('button'),
         ),
       ),