Quick fix for tap-to-show-keyboard regression (#26629)

* Fixes Android keyboard bug

packages/flutter/lib/src/gestures/force_press.dart

@@ -98,22 +98,21 @@ typedef GestureForceInterpolation = double Function(double pressureMin, double p
 /// force touch functionality, with the exception of the iPhone XR. In addition,
 /// a small handful of Android devices have this functionality as well.
 ///
-/// Reported pressure will always be in the range [0.0, 1.0], where 1.0 is
-/// maximum pressure and 0.0 is minimum pressure. If using a non-linear
-/// interpolation equation, the pressure reported will correspond with the
-/// custom curve. (ie. if the interpolation maps t(0.5) -> 0.1, a value of 0.1
-/// will be reported at a device pressure value of 0.5).
-///
+/// Reported pressure will always be in the range 0.0 to 1.0, where 1.0 is
+/// maximum pressure and 0.0 is minimum pressure. If using a custom
+/// [interpolation] callback, the pressure reported will correspond to that
+/// custom curve.
 class ForcePressGestureRecognizer extends OneSequenceGestureRecognizer {
   /// Creates a force press gesture recognizer.
   ///
   /// The [startPressure] defaults to 0.4, and [peakPressure] defaults to 0.85
   /// where a value of 0.0 is no pressure and a value of 1.0 is maximum pressure.
   ///
-  /// [startPressure], [peakPressure] and [interpolation] must not be null.
-  /// [peakPressure] must be greater than [startPressure]. [interpolation] must
-  /// always return a value in the range [0.0, 1.0] where
-  /// pressureMin <= pressure <= pressureMax.
+  /// The [startPressure], [peakPressure] and [interpolation] arguments must not
+  /// be null. The [peakPressure] argument must be greater than [startPressure].
+  /// The [interpolation] callback must always return a value in the range 0.0
+  /// to 1.0 for values of `pressure` that are between `pressureMin` and
+  /// `pressureMax`.
   ForcePressGestureRecognizer({
     this.startPressure = 0.4,
     this.peakPressure = 0.85,
@@ -172,21 +171,22 @@ class ForcePressGestureRecognizer extends OneSequenceGestureRecognizer {
   final double peakPressure;
 
   /// The function used to convert the raw device pressure values into a value
-  /// in the range [0, 1].
+  /// in the range 0.0 to 1.0.
   ///
-  /// The function takes in the device's min, max and raw touch
-  /// pressure and returns a value in the range [0.0, 1.0] denoting the
-  /// interpolated touch pressure.
+  /// The function takes in the device's minimum, maximum and raw touch pressure
+  /// and returns a value in the range 0.0 to 1.0 denoting the interpolated
+  /// touch pressure.
   ///
-  /// This function must always return values in the range [0, 1] when
-  /// pressureMin <= pressure <= pressureMax.
+  /// This function must always return values in the range 0.0 to 1.0 given a
+  /// pressure that is between the minimum and maximum pressures. It may return
+  /// [double.NaN] for values that it does not want to support.
   ///
-  /// By default, the the function is a simple linear interpolation, however,
-  /// changing the function could be useful to accommodate variations in the way
-  /// different devices respond to pressure, change how animations from pressure
-  /// feedback are rendered or for other custom functionality.
+  /// By default, the function is a linear interpolation; however, changing the
+  /// function could be useful to accommodate variations in the way different
+  /// devices respond to pressure, or to change how animations from pressure
+  /// feedback are rendered.
   ///
-  /// For example, an ease in curve can be used to determine the interpolated
+  /// For example, an ease-in curve can be used to determine the interpolated
   /// value:
   ///
   /// ```dart
@@ -216,7 +216,12 @@ class ForcePressGestureRecognizer extends OneSequenceGestureRecognizer {
     // A static pointer with changes in pressure creates PointerMoveEvent events.
     if (event is PointerMoveEvent || event is PointerDownEvent) {
       final double pressure = interpolation(event.pressureMin, event.pressureMax, event.pressure);
-      assert(pressure.isNaN ? true : (pressure <= 1.0 && pressure >= 0.0));
+      assert(
+        event.pressure < event.pressureMin || // contract is undefined for underflowing pressures...
+        event.pressure > event.pressureMax || // contract is undefined for overflowing pressures...
+        pressure.isNaN || // and interpolation may return NaN for values it doesn't want to support...
+        (pressure <= 1.0 && pressure >= 0.0) // but if everything is going well, it must be in the range 1.0..0.0.
+      );
       _lastPosition = event.position;
       _lastPressure = pressure;
 
@@ -300,6 +305,7 @@ class ForcePressGestureRecognizer extends OneSequenceGestureRecognizer {
   }
 
   static double _inverseLerp(double min, double max, double t) {
+    assert(min <= max);
     return (t - min) / (max - min);
   }
 

packages/flutter/lib/src/gestures/monodrag.dart

@@ -280,7 +280,7 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.add(EnumProperty<DragStartBehavior>('Start Behavior', dragStartBehavior));
+    properties.add(EnumProperty<DragStartBehavior>('start behavior', dragStartBehavior));
   }
 }
 

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

@@ -613,16 +613,9 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
 
   void _handleForcePressStarted(ForcePressDetails details) {
     if (widget.selectionEnabled) {
-      switch (Theme.of(context).platform) {
-        case TargetPlatform.iOS:
       // The cause is not technically double tap, but we would like to show
       // the toolbar.
       _renderEditable.selectWordsInRange(from: details.globalPosition, cause: SelectionChangedCause.doubleTap);
-          break;
-        case TargetPlatform.android:
-        case TargetPlatform.fuchsia:
-          break;
-      }
     }
   }
 
@@ -724,6 +717,20 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
     if (widget.maxLength != null && widget.maxLengthEnforced)
       formatters.add(LengthLimitingTextInputFormatter(widget.maxLength));
 
+    bool forcePressEnabled;
+    TextSelectionControls textSelectionControls;
+    switch (themeData.platform) {
+      case TargetPlatform.iOS:
+        forcePressEnabled = true;
+        textSelectionControls = cupertinoTextSelectionControls;
+        break;
+      case TargetPlatform.android:
+      case TargetPlatform.fuchsia:
+        forcePressEnabled = false;
+        textSelectionControls = materialTextSelectionControls;
+        break;
+    }
+
     Widget child = RepaintBoundary(
       child: EditableText(
         key: _editableTextKey,
@@ -740,11 +747,7 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
         autocorrect: widget.autocorrect,
         maxLines: widget.maxLines,
         selectionColor: themeData.textSelectionColor,
-        selectionControls: widget.selectionEnabled
-          ? (themeData.platform == TargetPlatform.iOS
-             ? cupertinoTextSelectionControls
-             : materialTextSelectionControls)
-          : null,
+        selectionControls: widget.selectionEnabled ? textSelectionControls : null,
         onChanged: widget.onChanged,
         onEditingComplete: widget.onEditingComplete,
         onSubmitted: widget.onSubmitted,
@@ -789,7 +792,7 @@ class _TextFieldState extends State<TextField> with AutomaticKeepAliveClientMixi
         ignoring: !(widget.enabled ?? widget.decoration?.enabled ?? true),
         child: TextSelectionGestureDetector(
           onTapDown: _handleTapDown,
-          onForcePressStart: _handleForcePressStarted,
+          onForcePressStart: forcePressEnabled ? _handleForcePressStarted : null,
           onSingleTapUp: _handleSingleTapUp,
           onSingleTapCancel: _handleSingleTapCancel,
           onSingleLongTapDown: _handleSingleLongTapDown,

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

@@ -761,8 +761,8 @@ class _TextSelectionGestureDetectorState extends State<TextSelectionGestureDetec
     return GestureDetector(
       onTapDown: _handleTapDown,
       onTapUp: _handleTapUp,
-      onForcePressStart: _forcePressStarted,
-      onForcePressEnd: _forcePressEnded,
+      onForcePressStart: widget.onForcePressStart != null ? _forcePressStarted : null,
+      onForcePressEnd: widget.onForcePressEnd != null ? _forcePressEnded : null,
       onTapCancel: _handleTapCancel,
       onLongPress: _handleLongPress,
       excludeFromSemantics: true,