CupertinoTextField vertical alignment (#34723)

CupertinoTextField now supports vertical alignment via the textAlignVertical parameter.

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

@@ -174,6 +174,7 @@ class CupertinoTextField extends StatefulWidget {
     this.style,
     this.strutStyle,
     this.textAlign = TextAlign.start,
+    this.textAlignVertical,
     this.readOnly = false,
     this.showCursor,
     this.autofocus = false,
@@ -324,6 +325,9 @@ class CupertinoTextField extends StatefulWidget {
   /// {@macro flutter.widgets.editableText.textAlign}
   final TextAlign textAlign;
 
+  /// {@macro flutter.material.inputDecorator.textAlignVertical}
+  final TextAlignVertical textAlignVertical;
+
   /// {@macro flutter.widgets.editableText.readOnly}
   final bool readOnly;
 
@@ -491,10 +495,13 @@ class CupertinoTextField extends StatefulWidget {
     properties.add(FlagProperty('selectionEnabled', value: selectionEnabled, defaultValue: true, ifFalse: 'selection disabled'));
     properties.add(DiagnosticsProperty<ScrollController>('scrollController', scrollController, defaultValue: null));
     properties.add(DiagnosticsProperty<ScrollPhysics>('scrollPhysics', scrollPhysics, defaultValue: null));
+    properties.add(EnumProperty<TextAlign>('textAlign', textAlign, defaultValue: TextAlign.start));
+    properties.add(DiagnosticsProperty<TextAlignVertical>('textAlignVertical', textAlignVertical, defaultValue: null));
   }
 }
 
 class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticKeepAliveClientMixin {
+  final GlobalKey _clearGlobalKey = GlobalKey();
   final GlobalKey<EditableTextState> _editableTextKey = GlobalKey<EditableTextState>();
 
   TextEditingController _controller;
@@ -584,6 +591,18 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
   }
 
   void _handleSingleTapUp(TapUpDetails details) {
+    // Because TextSelectionGestureDetector listens to taps that happen on
+    // widgets in front of it, tapping the clear button will also trigger
+    // this handler. If the the clear button widget recognizes the up event,
+    // then do not handle it.
+    if (_clearGlobalKey.currentContext != null) {
+      final RenderBox renderBox = _clearGlobalKey.currentContext.findRenderObject();
+      final Offset localOffset = renderBox.globalToLocal(details.globalPosition);
+      if(renderBox.hitTest(BoxHitTestResult(), position: localOffset)) {
+        return;
+      }
+    }
+
     if (widget.selectionEnabled) {
       _renderEditable.selectWordEdge(cause: SelectionChangedCause.tap);
     }
@@ -719,16 +738,31 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
     );
   }
 
+  // True if any surrounding decoration widgets will be shown.
+  bool get _hasDecoration {
+    return widget.placeholder != null ||
+      widget.clearButtonMode != OverlayVisibilityMode.never ||
+      widget.prefix != null ||
+      widget.suffix != null;
+  }
+
+  // Provide default behavior if widget.textAlignVertical is not set.
+  // CupertinoTextField has top alignment by default, unless it has decoration
+  // like a prefix or suffix, in which case it's aligned to the center.
+  TextAlignVertical get _textAlignVertical {
+    if (widget.textAlignVertical != null) {
+      return widget.textAlignVertical;
+    }
+    return _hasDecoration ? TextAlignVertical.center : TextAlignVertical.top;
+  }
+
   Widget _addTextDependentAttachments(Widget editableText, TextStyle textStyle, TextStyle placeholderStyle) {
     assert(editableText != null);
     assert(textStyle != null);
     assert(placeholderStyle != null);
     // If there are no surrounding widgets, just return the core editable text
     // part.
-    if (widget.placeholder == null &&
-        widget.clearButtonMode == OverlayVisibilityMode.never &&
-        widget.prefix == null &&
-        widget.suffix == null) {
+    if (!_hasDecoration) {
       return editableText;
     }
 
@@ -776,6 +810,7 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
         } else if (_showClearButton(text)) {
           rowChildren.add(
             GestureDetector(
+              key: _clearGlobalKey,
               onTap: widget.enabled ?? true ? () {
                 // Special handle onChanged for ClearButton
                 // Also call onChanged when the clear button is tapped.
@@ -825,20 +860,7 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
       ? widget.decoration
       : widget.decoration?.copyWith(color: widget.decoration?.color ?? disabledColor);
 
-    final Widget paddedEditable = TextSelectionGestureDetector(
-      onTapDown: _handleTapDown,
-      onForcePressStart: _handleForcePressStarted,
-      onForcePressEnd: _handleForcePressEnded,
-      onSingleTapUp: _handleSingleTapUp,
-      onSingleLongTapStart: _handleSingleLongTapStart,
-      onSingleLongTapMoveUpdate: _handleSingleLongTapMoveUpdate,
-      onSingleLongTapEnd: _handleSingleLongTapEnd,
-      onDoubleTapDown: _handleDoubleTapDown,
-      onDragSelectionStart: _handleMouseDragSelectionStart,
-      onDragSelectionUpdate: _handleMouseDragSelectionUpdate,
-      onDragSelectionEnd: _handleMouseDragSelectionEnd,
-      behavior: HitTestBehavior.translucent,
-      child: Padding(
+    final Widget paddedEditable = Padding(
       padding: widget.padding,
       child: RepaintBoundary(
         child: EditableText(
@@ -884,7 +906,6 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
           enableInteractiveSelection: widget.enableInteractiveSelection,
         ),
       ),
-      ),
     );
 
     return Semantics(
@@ -898,9 +919,28 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with AutomaticK
         ignoring: !enabled,
         child: Container(
           decoration: effectiveDecoration,
+          child: TextSelectionGestureDetector(
+            onTapDown: _handleTapDown,
+            onForcePressStart: _handleForcePressStarted,
+            onForcePressEnd: _handleForcePressEnded,
+            onSingleTapUp: _handleSingleTapUp,
+            onSingleLongTapStart: _handleSingleLongTapStart,
+            onSingleLongTapMoveUpdate: _handleSingleLongTapMoveUpdate,
+            onSingleLongTapEnd: _handleSingleLongTapEnd,
+            onDoubleTapDown: _handleDoubleTapDown,
+            onDragSelectionStart: _handleMouseDragSelectionStart,
+            onDragSelectionUpdate: _handleMouseDragSelectionUpdate,
+            onDragSelectionEnd: _handleMouseDragSelectionEnd,
+            behavior: HitTestBehavior.translucent,
+            child: Align(
+              alignment: Alignment(-1.0, _textAlignVertical.y),
+              widthFactor: 1.0,
+              heightFactor: 1.0,
               child: _addTextDependentAttachments(paddedEditable, textStyle, placeholderStyle),
             ),
           ),
+        ),
+      ),
     );
   }
 }

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

@@ -3576,42 +3576,3 @@ class InputDecorationTheme extends Diagnosticable {
     properties.add(DiagnosticsProperty<bool>('alignLabelWithHint', alignLabelWithHint, defaultValue: defaultTheme.alignLabelWithHint));
   }
 }
-
-/// The vertical alignment of text within an input.
-///
-/// A single [y] value that can range from -1.0 to 1.0. -1.0 aligns to the top
-/// of the input so that the top of the first line of text fits within the input
-/// and its padding. 0.0 aligns to the center of the input. 1.0 aligns so that
-/// the bottom of the last line of text aligns with the bottom interior edge of
-/// the input.
-///
-/// See also:
-///
-///  * [TextField.textAlignVertical], which is passed on to the [InputDecorator].
-///  * [InputDecorator.textAlignVertical], which defines the alignment of
-///    prefix, input, and suffix, within the [InputDecorator].
-class TextAlignVertical {
-  /// Construct TextAlignVertical from any given y value.
-  const TextAlignVertical({
-    @required this.y,
-  }) : assert(y != null),
-       assert(y >= -1.0 && y <= 1.0);
-
-  /// A value ranging from -1.0 to 1.0 that defines the topmost and bottommost
-  /// locations of the top and bottom of the input text box.
-  final double y;
-
-  /// Aligns a TextField's input Text with the topmost location within the
-  /// TextField.
-  static const TextAlignVertical top = TextAlignVertical(y: -1.0);
-  /// Aligns a TextField's input Text to the center of the TextField.
-  static const TextAlignVertical center = TextAlignVertical(y: 0.0);
-  /// Aligns a TextField's input Text with the bottommost location within the
-  /// TextField.
-  static const TextAlignVertical bottom = TextAlignVertical(y: 1.0);
-
-  @override
-  String toString() {
-    return '$runtimeType(y: $y)';
-  }
-}

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

@@ -633,3 +633,44 @@ class _MixedAlignment extends AlignmentGeometry {
     return null;
   }
 }
+
+/// The vertical alignment of text within an input box.
+///
+/// A single [y] value that can range from -1.0 to 1.0. -1.0 aligns to the top
+/// of an input box so that the top of the first line of text fits within the
+/// box and its padding. 0.0 aligns to the center of the box. 1.0 aligns so that
+/// the bottom of the last line of text aligns with the bottom interior edge of
+/// the input box.
+///
+/// See also:
+///
+///  * [TextField.textAlignVertical], which is passed on to the [InputDecorator].
+///  * [CupertinoTextField.textAlignVertical], which behaves in the same way as
+///    the parameter in TextField.
+///  * [InputDecorator.textAlignVertical], which defines the alignment of
+///    prefix, input, and suffix within an [InputDecorator].
+class TextAlignVertical {
+  /// Creates a TextAlignVertical from any y value between -1.0 and 1.0.
+  const TextAlignVertical({
+    @required this.y,
+  }) : assert(y != null),
+       assert(y >= -1.0 && y <= 1.0);
+
+  /// A value ranging from -1.0 to 1.0 that defines the topmost and bottommost
+  /// locations of the top and bottom of the input box.
+  final double y;
+
+  /// Aligns a TextField's input Text with the topmost location within a
+  /// TextField's input box.
+  static const TextAlignVertical top = TextAlignVertical(y: -1.0);
+  /// Aligns a TextField's input Text to the center of the TextField.
+  static const TextAlignVertical center = TextAlignVertical(y: 0.0);
+  /// Aligns a TextField's input Text with the bottommost location within a
+  /// TextField.
+  static const TextAlignVertical bottom = TextAlignVertical(y: 1.0);
+
+  @override
+  String toString() {
+    return '$runtimeType(y: $y)';
+  }
+}

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

@@ -1252,7 +1252,7 @@ class RenderEditable extends RenderBox {
   double get preferredLineHeight => _textPainter.preferredLineHeight;
 
   double _preferredHeight(double width) {
-    // Lock height to maxLines if needed
+    // Lock height to maxLines if needed.
     final bool lockedMax = maxLines != null && minLines == null;
     final bool lockedBoth = minLines != null && minLines == maxLines;
     final bool singleLine = maxLines == 1;
@@ -1260,7 +1260,7 @@ class RenderEditable extends RenderBox {
       return preferredLineHeight * maxLines;
     }
 
-    // Clamp height to minLines or maxLines if needed
+    // Clamp height to minLines or maxLines if needed.
     final bool minLimited = minLines != null && minLines > 1;
     final bool maxLimited = maxLines != null;
     if (minLimited || maxLimited) {
@@ -1273,7 +1273,7 @@ class RenderEditable extends RenderBox {
       }
     }
 
-    // Set the height based on the content
+    // Set the height based on the content.
     if (width == double.infinity) {
       final String text = _textPainter.text.toPlainText();
       int lines = 1;