Port EditableText to Scrollable2 (#8167)

packages/flutter/lib/rendering.dart

@@ -28,7 +28,7 @@ export 'src/rendering/block.dart';
 export 'src/rendering/box.dart';
 export 'src/rendering/custom_layout.dart';
 export 'src/rendering/debug.dart';
-export 'src/rendering/editable_line.dart';
+export 'src/rendering/editable.dart';
 export 'src/rendering/error.dart';
 export 'src/rendering/flex.dart';
 export 'src/rendering/flow.dart';

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

@@ -147,7 +147,6 @@ class _InputFieldState extends State<InputField> {
               cursorColor: themeData.textSelectionColor,
               selectionColor: themeData.textSelectionColor,
               selectionControls: materialTextSelectionControls,
-              platform: Theme.of(context).platform,
               keyboardType: config.keyboardType,
               onChanged: config.onChanged,
               onSubmitted: config.onSubmitted,

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

@@ -2,13 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:math' as math;
 import 'dart:ui' as ui show TextBox;
 
 import 'package:flutter/gestures.dart';
+import 'package:meta/meta.dart';
 
 import 'box.dart';
 import 'object.dart';
-import 'viewport.dart';
+import 'viewport_offset.dart';
 
 const double _kCaretGap = 1.0; // pixels
 const double _kCaretHeightOffset = 2.0; // pixels
@@ -39,14 +41,6 @@ class TextSelectionPoint {
   final TextDirection direction;
 }
 
-/// Signature for the callback used by [RenderEditable] to determine the paint offset when
-/// the dimensions of the render box change.
-///
-/// The return value should be the new paint offset to use.
-///
-/// Used by [RenderEditable.onPaintOffsetUpdateNeeded].
-typedef Offset RenderEditablePaintOffsetNeededCallback(ViewportDimensions dimensions, Rect caretRect);
-
 /// A single line of editable text.
 class RenderEditable extends RenderBox {
   /// Creates a render object for a single line of editable text.
@@ -58,15 +52,18 @@ class RenderEditable extends RenderBox {
     Color selectionColor,
     double textScaleFactor: 1.0,
     TextSelection selection,
+    @required ViewportOffset offset,
     this.onSelectionChanged,
-    Offset paintOffset: Offset.zero,
-    this.onPaintOffsetUpdateNeeded,
   }) : _textPainter = new TextPainter(text: text, textScaleFactor: textScaleFactor),
        _cursorColor = cursorColor,
        _showCursor = showCursor,
        _maxLines = maxLines,
        _selection = selection,
-       _paintOffset = paintOffset {
+       _offset = offset {
+    assert(showCursor != null);
+    assert(maxLines != null);
+    assert(textScaleFactor != null);
+    assert(offset != null);
     assert(!showCursor || cursorColor != null);
     _tap = new TapGestureRecognizer()
       ..onTapDown = _handleTapDown
@@ -79,9 +76,6 @@ class RenderEditable extends RenderBox {
   /// Called when the selection changes.
   SelectionChangedHandler onSelectionChanged;
 
-  /// Called when the inner or outer dimensions of this render object change.
-  RenderEditablePaintOffsetNeededCallback onPaintOffsetUpdateNeeded;
-
   /// The text to display
   TextSpan get text => _textPainter.text;
   final TextPainter _textPainter;
@@ -106,6 +100,7 @@ class RenderEditable extends RenderBox {
   bool get showCursor => _showCursor;
   bool _showCursor;
   set showCursor(bool value) {
+    assert(value != null);
     if (_showCursor == value)
       return;
     _showCursor = value;
@@ -118,6 +113,7 @@ class RenderEditable extends RenderBox {
   int get maxLines => _maxLines;
   int _maxLines;
   set maxLines(int value) {
+    assert(value != null);
     if (_maxLines == value)
       return;
     _maxLines = value;
@@ -165,15 +161,58 @@ class RenderEditable extends RenderBox {
   /// If the text content is larger than the editable line itself, the editable
   /// line clips the text. This property controls which part of the text is
   /// visible by shifting the text by the given offset before clipping.
-  Offset get paintOffset => _paintOffset;
-  Offset _paintOffset;
-  set paintOffset(Offset value) {
-    if (_paintOffset == value)
+  ViewportOffset get offset => _offset;
+  ViewportOffset _offset;
+  set offset(ViewportOffset value) {
+    assert(value != null);
+    if (_offset == value)
       return;
-    _paintOffset = value;
-    markNeedsPaint();
+    if (attached)
+      _offset.removeListener(markNeedsPaint);
+    _offset = value;
+    if (attached)
+      _offset.addListener(markNeedsPaint);
+    markNeedsLayout();
+  }
+
+  bool get _isMultiline => maxLines > 1;
+
+  Axis get _viewportAxis => _isMultiline ? Axis.vertical : Axis.horizontal;
+
+  Offset get _paintOffset {
+    switch (_viewportAxis) {
+      case Axis.horizontal:
+        return new Offset(-offset.pixels, 0.0);
+      case Axis.vertical:
+        return new Offset(0.0, -offset.pixels);
+    }
+    return null;
   }
 
+  double get _viewportExtent {
+    assert(hasSize);
+    switch (_viewportAxis) {
+      case Axis.horizontal:
+        return size.width;
+      case Axis.vertical:
+        return size.height;
+    }
+    return null;
+  }
+
+  double _getMaxScrollExtent(Size contentSize) {
+    assert(hasSize);
+    switch (_viewportAxis) {
+      case Axis.horizontal:
+        return math.max(0.0, contentSize.width - size.width);
+      case Axis.vertical:
+        return math.max(0.0, contentSize.height - size.height);
+    }
+    return null;
+  }
+
+  bool _hasVisualOverflow = false;
+
   /// Returns the global coordinates of the endpoints of the given selection.
   ///
   /// If the selection is collapsed (and therefore occupies a single point), the
@@ -187,17 +226,17 @@ class RenderEditable extends RenderBox {
     // clean at this point.
     _textPainter.layout(maxWidth: _maxContentWidth);
 
-    Offset offset = _paintOffset;
+    final Offset paintOffset = _paintOffset;
 
     if (selection.isCollapsed) {
       // TODO(mpcomplete): This doesn't work well at an RTL/LTR boundary.
-      Offset caretOffset = _textPainter.getOffsetForCaret(selection.extent, _caretPrototype);
-      Point start = new Point(0.0, _preferredLineHeight) + caretOffset + offset;
+      final Offset caretOffset = _textPainter.getOffsetForCaret(selection.extent, _caretPrototype);
+      final Point start = new Point(0.0, _preferredLineHeight) + caretOffset + paintOffset;
       return <TextSelectionPoint>[new TextSelectionPoint(localToGlobal(start), null)];
     } else {
-      List<ui.TextBox> boxes = _textPainter.getBoxesForSelection(selection);
-      Point start = new Point(boxes.first.start, boxes.first.bottom) + offset;
-      Point end = new Point(boxes.last.end, boxes.last.bottom) + offset;
+      final List<ui.TextBox> boxes = _textPainter.getBoxesForSelection(selection);
+      final Point start = new Point(boxes.first.start, boxes.first.bottom) + paintOffset;
+      final Point end = new Point(boxes.last.end, boxes.last.bottom) + paintOffset;
       return <TextSelectionPoint>[
         new TextSelectionPoint(localToGlobal(start), boxes.first.direction),
         new TextSelectionPoint(localToGlobal(end), boxes.last.direction),
@@ -207,26 +246,24 @@ class RenderEditable extends RenderBox {
 
   /// Returns the position in the text for the given global coordinate.
   TextPosition getPositionForPoint(Point globalPosition) {
-    globalPosition += -paintOffset;
+    globalPosition += -_paintOffset;
     return _textPainter.getPositionForOffset(globalToLocal(globalPosition).toOffset());
   }
 
   /// Returns the Rect in local coordinates for the caret at the given text
   /// position.
   Rect getLocalRectForCaret(TextPosition caretPosition) {
-    Offset caretOffset = _textPainter.getOffsetForCaret(caretPosition, _caretPrototype);
+    final Offset caretOffset = _textPainter.getOffsetForCaret(caretPosition, _caretPrototype);
     // This rect is the same as _caretPrototype but without the vertical padding.
     return new Rect.fromLTWH(0.0, 0.0, _kCaretWidth, _preferredLineHeight).shift(caretOffset + _paintOffset);
   }
 
-  Size _contentSize;
-
   double get _preferredLineHeight => _textPainter.preferredLineHeight;
 
   double get _maxContentWidth {
-    return _maxLines > 1 ?
-      constraints.maxWidth - (_kCaretGap + _kCaretWidth) :
-      double.INFINITY;
+    if (_maxLines > 1)
+      return constraints.maxWidth - (_kCaretGap + _kCaretWidth);
+    return double.INFINITY;
   }
 
   @override
@@ -257,15 +294,15 @@ class RenderEditable extends RenderBox {
   Point _lastTapDownPosition;
   Point _longPressPosition;
   void _handleTapDown(TapDownDetails details) {
-    _lastTapDownPosition = details.globalPosition + -paintOffset;
+    _lastTapDownPosition = details.globalPosition + -_paintOffset;
   }
 
   void _handleTap() {
     assert(_lastTapDownPosition != null);
-    final Point global = _lastTapDownPosition;
+    final Point globalPosition = _lastTapDownPosition;
     _lastTapDownPosition = null;
     if (onSelectionChanged != null) {
-      TextPosition position = _textPainter.getPositionForOffset(globalToLocal(global).toOffset());
+      TextPosition position = _textPainter.getPositionForOffset(globalToLocal(globalPosition).toOffset());
       onSelectionChanged(new TextSelection.fromPosition(position), this, false);
     }
   }
@@ -277,16 +314,16 @@ class RenderEditable extends RenderBox {
   }
 
   void _handleLongPress() {
-    final Point global = _longPressPosition;
+    final Point globalPosition = _longPressPosition;
     _longPressPosition = null;
     if (onSelectionChanged != null) {
-      TextPosition position = _textPainter.getPositionForOffset(globalToLocal(global).toOffset());
+      final TextPosition position = _textPainter.getPositionForOffset(globalToLocal(globalPosition).toOffset());
       onSelectionChanged(_selectWordAtOffset(position), this, true);
     }
   }
 
   TextSelection _selectWordAtOffset(TextPosition position) {
-    TextRange word = _textPainter.getWordBoundary(position);
+    final TextRange word = _textPainter.getWordBoundary(position);
     // When long-pressing past the end of the text, we want a collapsed cursor.
     if (position.offset >= word.end)
       return new TextSelection.fromPosition(position);
@@ -297,41 +334,34 @@ class RenderEditable extends RenderBox {
 
   @override
   void performLayout() {
-    Size oldSize = hasSize ? size : null;
     _caretPrototype = new Rect.fromLTWH(0.0, _kCaretHeightOffset, _kCaretWidth, _preferredLineHeight - 2.0 * _kCaretHeightOffset);
     _selectionRects = null;
     _textPainter.layout(maxWidth: _maxContentWidth);
     size = new Size(constraints.maxWidth, constraints.constrainHeight(
       _textPainter.height.clamp(_preferredLineHeight, _preferredLineHeight * _maxLines)
     ));
-    Size contentSize = new Size(_textPainter.width + _kCaretGap + _kCaretWidth, _textPainter.height);
-    assert(_selection != null);
-    Rect caretRect = getLocalRectForCaret(_selection.extent);
-    if (onPaintOffsetUpdateNeeded != null && (size != oldSize || contentSize != _contentSize || !_withinBounds(caretRect)))
-      onPaintOffsetUpdateNeeded(new ViewportDimensions(containerSize: size, contentSize: contentSize), caretRect);
-    _contentSize = contentSize;
-  }
-
-  bool _withinBounds(Rect caretRect) {
-    Rect bounds = new Rect.fromLTWH(0.0, 0.0, size.width, size.height);
-    return (bounds.contains(caretRect.topLeft) && bounds.contains(caretRect.bottomRight));
+    final Size contentSize = new Size(_textPainter.width + _kCaretGap + _kCaretWidth, _textPainter.height);
+    final double _maxScrollExtent = _getMaxScrollExtent(contentSize);
+    _hasVisualOverflow = _maxScrollExtent > 0.0;
+    offset.applyViewportDimension(_viewportExtent);
+    offset.applyContentDimensions(0.0, _maxScrollExtent);
   }
 
   void _paintCaret(Canvas canvas, Offset effectiveOffset) {
-    Offset caretOffset = _textPainter.getOffsetForCaret(_selection.extent, _caretPrototype);
-    Paint paint = new Paint()..color = _cursorColor;
+    final Offset caretOffset = _textPainter.getOffsetForCaret(_selection.extent, _caretPrototype);
+    final Paint paint = new Paint()..color = _cursorColor;
     canvas.drawRect(_caretPrototype.shift(caretOffset + effectiveOffset), paint);
   }
 
   void _paintSelection(Canvas canvas, Offset effectiveOffset) {
     assert(_selectionRects != null);
-    Paint paint = new Paint()..color = _selectionColor;
+    final Paint paint = new Paint()..color = _selectionColor;
     for (ui.TextBox box in _selectionRects)
       canvas.drawRect(box.toRect().shift(effectiveOffset), paint);
   }
 
   void _paintContents(PaintingContext context, Offset offset) {
-    Offset effectiveOffset = offset + _paintOffset;
+    final Offset effectiveOffset = offset + _paintOffset;
 
     if (_selection != null) {
       if (_selection.isCollapsed && _showCursor && cursorColor != null) {
@@ -345,8 +375,6 @@ class RenderEditable extends RenderBox {
     _textPainter.paint(context.canvas, effectiveOffset);
   }
 
-  bool get _hasVisualOverflow => _contentSize.width > size.width;
-
   @override
   void paint(PaintingContext context, Offset offset) {
     if (_hasVisualOverflow)
@@ -357,4 +385,24 @@ class RenderEditable extends RenderBox {
 
   @override
   Rect describeApproximatePaintClip(RenderObject child) => _hasVisualOverflow ? Point.origin & size : null;
+
+  @override
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    description.add('cursorColor: $_cursorColor');
+    description.add('showCursor: $_showCursor');
+    description.add('maxLines: $_maxLines');
+    description.add('selectionColor: $_selectionColor');
+    description.add('textScaleFactor: $textScaleFactor');
+    description.add('selection: $_selection');
+    description.add('offset: $_offset');
+  }
+
+  @override
+  String debugDescribeChildren(String prefix) {
+    return '$prefix \u2558\u2550\u2566\u2550\u2550 text \u2550\u2550\u2550\n'
+           '${text.toString("$prefix   \u2551 ")}' // TextSpan includes a newline
+           '$prefix   \u255A\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\u2550\n'
+           '$prefix\n';
+  }
 }

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

@@ -5,14 +5,15 @@
 import 'dart:async';
 
 import 'package:flutter/foundation.dart';
-import 'package:flutter/rendering.dart' show RenderEditable, SelectionChangedHandler, RenderEditablePaintOffsetNeededCallback;
+import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 
 import 'basic.dart';
 import 'focus.dart';
 import 'framework.dart';
 import 'media_query.dart';
-import 'scroll_behavior.dart';
+import 'scroll_controller.dart';
+import 'scroll_physics.dart';
 import 'scrollable.dart';
 import 'text_selection.dart';
 
@@ -135,32 +136,33 @@ class InputValue {
 ///  * [InputField], which adds tap-to-focus and cut, copy, and paste commands.
 ///  * [TextField], which is a full-featured, material-design text input field
 ///    with placeholder text, labels, and [Form] integration.
-class EditableText extends Scrollable { // ignore: DEPRECATED_MEMBER_USE
+class EditableText extends StatefulWidget {
   /// Creates a basic text input control.
   ///
   /// The [value] argument must not be null.
   EditableText({
     Key key,
     @required this.value,
-    this.focusKey,
+    @required this.focusKey,
     this.obscureText: false,
-    this.style,
-    this.cursorColor,
+    @required this.style,
+    @required this.cursorColor,
     this.textScaleFactor,
-    int maxLines: 1,
+    this.maxLines: 1,
     this.autofocus: false,
     this.selectionColor,
     this.selectionControls,
-    @required this.platform,
     this.keyboardType,
     this.onChanged,
-    this.onSubmitted
-  }) : maxLines = maxLines, super(
-    key: key,
-    initialScrollOffset: 0.0,
-    scrollDirection: maxLines > 1 ? Axis.vertical : Axis.horizontal
-  ) {
+    this.onSubmitted,
+  }) : super(key: key) {
     assert(value != null);
+    assert(focusKey != null);
+    assert(obscureText != null);
+    assert(style != null);
+    assert(cursorColor != null);
+    assert(maxLines != null);
+    assert(autofocus != null);
   }
 
   /// The string being displayed in this widget.
@@ -206,12 +208,6 @@ class EditableText extends Scrollable { // ignore: DEPRECATED_MEMBER_USE
   /// Optional delegate for building the text selection handles and toolbar.
   final TextSelectionControls selectionControls;
 
-  /// The platform whose behavior should be approximated, in particular
-  /// for scroll physics. (See [ScrollBehavior.platform].)
-  ///
-  /// Must not be null.
-  final TargetPlatform platform;
-
   /// The type of keyboard to use for editing the text.
   final TextInputType keyboardType;
 
@@ -226,7 +222,7 @@ class EditableText extends Scrollable { // ignore: DEPRECATED_MEMBER_USE
 }
 
 /// State for a [EditableText].
-class EditableTextState extends ScrollableState<EditableText> implements TextInputClient { // ignore: DEPRECATED_MEMBER_USE
+class EditableTextState extends State<EditableText> implements TextInputClient {
   Timer _cursorTimer;
   bool _showCursor = false;
 
@@ -234,11 +230,7 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
   TextInputConnection _textInputConnection;
   TextSelectionOverlay _selectionOverlay;
 
-  @override
-  ExtentScrollBehavior createScrollBehavior() => new BoundedBehavior(platform: config.platform);
-
-  @override
-  BoundedBehavior get scrollBehavior => super.scrollBehavior;
+  final ScrollController _scrollController = new ScrollController();
 
   @override
   void initState() {
@@ -259,41 +251,17 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
 
   bool get _isMultiline => config.maxLines > 1;
 
-  double _contentExtent = 0.0;
-  double _containerExtent = 0.0;
-
-  Offset _handlePaintOffsetUpdateNeeded(ViewportDimensions dimensions, Rect caretRect) {
-    // We make various state changes here but don't have to do so in a
-    // setState() callback because we are called during layout and all
-    // we're updating is the new offset, which we are providing to the
-    // render object via our return value.
-    _contentExtent = _isMultiline ?
-      dimensions.contentSize.height :
-      dimensions.contentSize.width;
-    _containerExtent = _isMultiline ?
-      dimensions.containerSize.height :
-      dimensions.containerSize.width;
-    didUpdateScrollBehavior(scrollBehavior.updateExtents(
-      contentExtent: _contentExtent,
-      containerExtent: _containerExtent,
-      // TODO(ianh): We should really only do this when text is added,
-      // not generally any time the size changes.
-      scrollOffset: _getScrollOffsetForCaret(caretRect, _containerExtent)
-    ));
-    updateGestureDetector();
-    return scrollOffsetToPixelDelta(scrollOffset);
-  }
-
   // Calculate the new scroll offset so the cursor remains visible.
-  double _getScrollOffsetForCaret(Rect caretRect, double containerExtent) {
-    double caretStart = _isMultiline ? caretRect.top : caretRect.left;
-    double caretEnd = _isMultiline ? caretRect.bottom : caretRect.right;
-    double newScrollOffset = scrollOffset;
+  double _getScrollOffsetForCaret(Rect caretRect) {
+    final double caretStart = _isMultiline ? caretRect.top : caretRect.left;
+    final double caretEnd = _isMultiline ? caretRect.bottom : caretRect.right;
+    double scrollOffset = _scrollController.offset;
+    final double viewportExtent = _scrollController.position.viewportDimension;
     if (caretStart < 0.0)  // cursor before start of bounds
-      newScrollOffset += pixelOffsetToScrollOffset(-caretStart);
-    else if (caretEnd >= containerExtent)  // cursor after end of bounds
-      newScrollOffset += pixelOffsetToScrollOffset(-(caretEnd - containerExtent));
-    return newScrollOffset;
+      scrollOffset += caretStart;
+    else if (caretEnd >= viewportExtent)  // cursor after end of bounds
+      scrollOffset += caretEnd - viewportExtent;
+    return scrollOffset;
   }
 
   // True if the focus was explicitly requested last frame. This ensures we
@@ -302,8 +270,7 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
 
   void _attachOrDetachKeyboard(bool focused) {
     if (focused && !_isAttachedToKeyboard && (_requestingFocus || config.autofocus)) {
-      _textInputConnection = TextInput.attach(
-          this, new TextInputConfiguration(inputType: config.keyboardType))
+      _textInputConnection = TextInput.attach(this, new TextInputConfiguration(inputType: config.keyboardType))
         ..setEditingState(_getTextEditingStateFromInputValue(_currentValue))
         ..show();
     } else if (!focused) {
@@ -364,7 +331,7 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
     // EditableWidget, not just changes triggered by user gestures.
     requestKeyboard();
 
-    InputValue newInput = _currentValue.copyWith(selection: selection, composing: TextRange.empty);
+    final InputValue newInput = _currentValue.copyWith(selection: selection, composing: TextRange.empty);
     if (config.onChanged != null)
       config.onChanged(newInput);
 
@@ -393,14 +360,7 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
     assert(!newInput.composing.isValid);  // composing range must be empty while selecting
     if (config.onChanged != null)
       config.onChanged(newInput);
-
-    didUpdateScrollBehavior(scrollBehavior.updateExtents(
-      // TODO(mpcomplete): should just be able to pass
-      // scrollBehavior.containerExtent here (and remove the member var), but
-      // scrollBehavior gets re-created too often, and is sometimes
-      // uninitialized here. Investigate if this is a bug.
-      scrollOffset: _getScrollOffsetForCaret(caretRect, _containerExtent)
-    ));
+    _scrollController.jumpTo(_getScrollOffsetForCaret(caretRect));
   }
 
   /// Whether the blinking cursor is actually visible at this precise moment
@@ -429,9 +389,12 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
       _textInputConnection.close();
       _textInputConnection = null;
     }
+    assert(!_isAttachedToKeyboard);
     if (_cursorTimer != null)
       _stopCursorTimer();
+    assert(_cursorTimer == null);
     _selectionOverlay?.dispose();
+    _selectionOverlay = null;
     super.dispose();
   }
 
@@ -442,11 +405,7 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
   }
 
   @override
-  Widget buildContent(BuildContext context) {
-    assert(config.style != null);
-    assert(config.focusKey != null);
-    assert(config.cursorColor != null);
-
+  Widget build(BuildContext context) {
     bool focused = Focus.at(config.focusKey.currentContext);
     _attachOrDetachKeyboard(focused);
 
@@ -464,20 +423,24 @@ class EditableTextState extends ScrollableState<EditableText> implements TextInp
       }
     }
 
-    return new ClipRect(
-      child: new _Editable(
-        value: _currentValue,
-        style: config.style,
-        cursorColor: config.cursorColor,
-        showCursor: _showCursor,
-        maxLines: config.maxLines,
-        selectionColor: config.selectionColor,
-        textScaleFactor: config.textScaleFactor ?? MediaQuery.of(context).textScaleFactor,
-        obscureText: config.obscureText,
-        onSelectionChanged: _handleSelectionChanged,
-        paintOffset: scrollOffsetToPixelDelta(scrollOffset),
-        onPaintOffsetUpdateNeeded: _handlePaintOffsetUpdateNeeded
-      )
+    return new Scrollable2(
+      axisDirection: _isMultiline ? AxisDirection.down : AxisDirection.right,
+      controller: _scrollController,
+      physics: const ClampingScrollPhysics(),
+      viewportBuilder: (BuildContext context, ViewportOffset offset) {
+        return new _Editable(
+          value: _currentValue,
+          style: config.style,
+          cursorColor: config.cursorColor,
+          showCursor: _showCursor,
+          maxLines: config.maxLines,
+          selectionColor: config.selectionColor,
+          textScaleFactor: config.textScaleFactor ?? MediaQuery.of(context).textScaleFactor,
+          obscureText: config.obscureText,
+          offset: offset,
+          onSelectionChanged: _handleSelectionChanged,
+        );
+      },
     );
   }
 }
@@ -493,9 +456,8 @@ class _Editable extends LeafRenderObjectWidget {
     this.selectionColor,
     this.textScaleFactor,
     this.obscureText,
+    this.offset,
     this.onSelectionChanged,
-    this.paintOffset,
-    this.onPaintOffsetUpdateNeeded
   }) : super(key: key);
 
   final InputValue value;
@@ -506,9 +468,8 @@ class _Editable extends LeafRenderObjectWidget {
   final Color selectionColor;
   final double textScaleFactor;
   final bool obscureText;
+  final ViewportOffset offset;
   final SelectionChangedHandler onSelectionChanged;
-  final Offset paintOffset;
-  final RenderEditablePaintOffsetNeededCallback onPaintOffsetUpdateNeeded;
 
   @override
   RenderEditable createRenderObject(BuildContext context) {
@@ -520,9 +481,8 @@ class _Editable extends LeafRenderObjectWidget {
       selectionColor: selectionColor,
       textScaleFactor: textScaleFactor,
       selection: value.selection,
+      offset: offset,
       onSelectionChanged: onSelectionChanged,
-      paintOffset: paintOffset,
-      onPaintOffsetUpdateNeeded: onPaintOffsetUpdateNeeded
     );
   }
 
@@ -536,9 +496,8 @@ class _Editable extends LeafRenderObjectWidget {
       ..selectionColor = selectionColor
       ..textScaleFactor = textScaleFactor
       ..selection = value.selection
-      ..onSelectionChanged = onSelectionChanged
-      ..paintOffset = paintOffset
-      ..onPaintOffsetUpdateNeeded = onPaintOffsetUpdateNeeded;
+      ..offset = offset
+      ..onSelectionChanged = onSelectionChanged;
   }
 
   TextSpan get _styledTextSpan {

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

@@ -184,13 +184,13 @@ class _RenderSingleChildViewport extends RenderBox with RenderObjectWithChildMix
   @override
   bool get isRepaintBoundary => true;
 
-  double get _effectiveExtent {
+  double get _viewportExtent {
     assert(hasSize);
     switch (axis) {
-      case Axis.vertical:
-        return size.height;
       case Axis.horizontal:
         return size.width;
+      case Axis.vertical:
+        return size.height;
     }
     return null;
   }
@@ -265,7 +265,7 @@ class _RenderSingleChildViewport extends RenderBox with RenderObjectWithChildMix
       size = constraints.constrain(child.size);
     }
 
-    offset.applyViewportDimension(_effectiveExtent);
+    offset.applyViewportDimension(_viewportExtent);
     offset.applyContentDimensions(_minScrollExtent, _maxScrollExtent);
   }
 

packages/flutter/test/widgets/input_test.dart

@@ -581,7 +581,6 @@ void main() {
     expect(inputValue.text, cutValue);
   }, skip: Platform.isMacOS); // Skip due to https://github.com/flutter/flutter/issues/6961
 
-
   testWidgets('Can scroll multiline input', (WidgetTester tester) async {
     GlobalKey inputKey = new GlobalKey();
     InputValue inputValue = InputValue.empty;
@@ -640,6 +639,7 @@ void main() {
     // Now the first line is scrolled up, and the fourth line is visible.
     Point newFirstPos = textOffsetToPosition(tester, kFourLines.indexOf('First'));
     Point newFourthPos = textOffsetToPosition(tester, kFourLines.indexOf('Fourth'));
+
     expect(newFirstPos.y, lessThan(firstPos.y));
     expect(inputBox.hitTest(new HitTestResult(), position: inputBox.globalToLocal(newFirstPos)), isFalse);
     expect(inputBox.hitTest(new HitTestResult(), position: inputBox.globalToLocal(newFourthPos)), isTrue);