Text selection UI matches behavior on Android. (#3886)

- Handles appear with tap or long press.
- Toolbar appears with long press on text, or tap on handle.
- Correct toolbar items shown depending on context.

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

@@ -37,11 +37,12 @@ class _TextSelectionToolbar extends StatelessWidget {
       // TODO(mpcomplete): This should probably be grayed-out if there is nothing to paste.
       onPressed: _handlePaste
     ));
-    if (value.selection.isCollapsed) {
-      items.add(new FlatButton(child: new Text('SELECT ALL'), onPressed: _handleSelectAll));
+    if (value.text.isNotEmpty) {
+      if (value.selection.isCollapsed)
+        items.add(new FlatButton(child: new Text('SELECT ALL'), onPressed: _handleSelectAll));
+      // TODO(mpcomplete): implement `more` menu.
+      items.add(new IconButton(icon: Icons.more_vert));
     }
-    // TODO(mpcomplete): implement `more` menu.
-    items.add(new IconButton(icon: Icons.more_vert));
 
     return new Material(
       elevation: 1,

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

@@ -17,7 +17,7 @@ const double _kCaretWidth = 1.0; // pixels
 final String _kZeroWidthSpace = new String.fromCharCode(0x200B);
 
 /// Called when the user changes the selection (including cursor location).
-typedef void SelectionChangedHandler(TextSelection selection, RenderEditableLine renderObject);
+typedef void SelectionChangedHandler(TextSelection selection, RenderEditableLine renderObject, bool longPress);
 
 /// Represents a global screen coordinate of the point in a selection, and the
 /// text direction at that point.
@@ -128,7 +128,7 @@ class RenderEditableLine extends RenderBox {
     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(caretOffset.dx, _contentSize.height) + offset;
+      Point start = new Point(caretOffset.dx, size.height) + offset;
       return <TextSelectionPoint>[new TextSelectionPoint(localToGlobal(start), null)];
     } else {
       List<ui.TextBox> boxes = _textPainter.getBoxesForSelection(selection);
@@ -212,7 +212,7 @@ class RenderEditableLine extends RenderBox {
     _lastTapDownPosition = null;
     if (onSelectionChanged != null) {
       TextPosition position = _textPainter.getPositionForOffset(globalToLocal(global).toOffset());
-      onSelectionChanged(new TextSelection.fromPosition(position), this);
+      onSelectionChanged(new TextSelection.fromPosition(position), this, false);
     }
   }
 
@@ -227,12 +227,15 @@ class RenderEditableLine extends RenderBox {
     _longPressPosition = null;
     if (onSelectionChanged != null) {
       TextPosition position = _textPainter.getPositionForOffset(globalToLocal(global).toOffset());
-      onSelectionChanged(_selectWordAtOffset(position), this);
+      onSelectionChanged(_selectWordAtOffset(position), this, true);
     }
   }
 
   TextSelection _selectWordAtOffset(TextPosition position) {
     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);
     return new TextSelection(baseOffset: word.start, extentOffset: word.end);
   }
 

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

@@ -299,7 +299,7 @@ class RawInputLineState extends ScrollableState<RawInputLine> {
       config.onSubmitted(_keyboardClient.inputValue);
   }
 
-  void _handleSelectionChanged(TextSelection selection, RenderEditableLine renderObject) {
+  void _handleSelectionChanged(TextSelection selection, RenderEditableLine renderObject, bool longPress) {
     // Note that this will show the keyboard for all selection changes on the
     // EditableLineWidget, not just changes triggered by user gestures.
     requestKeyboard();
@@ -313,7 +313,7 @@ class RawInputLineState extends ScrollableState<RawInputLine> {
       _selectionOverlay = null;
     }
 
-    if (newInput.text.isNotEmpty && config.selectionHandleBuilder != null) {
+    if (config.selectionHandleBuilder != null) {
       _selectionOverlay = new TextSelectionOverlay(
         input: newInput,
         context: context,
@@ -323,7 +323,10 @@ class RawInputLineState extends ScrollableState<RawInputLine> {
         handleBuilder: config.selectionHandleBuilder,
         toolbarBuilder: config.selectionToolbarBuilder
       );
-      _selectionOverlay.show();
+      if (newInput.text.isNotEmpty || longPress)
+        _selectionOverlay.showHandles();
+      if (longPress)
+        _selectionOverlay.showToolbar();
     }
   }
 

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

@@ -73,40 +73,49 @@ class TextSelectionOverlay implements TextSelectionDelegate {
   /// second is hidden when the selection is collapsed.
   List<OverlayEntry> _handles;
 
+  /// A copy/paste toolbar.
   OverlayEntry _toolbar;
 
   TextSelection get _selection => _input.selection;
 
   /// Shows the handles by inserting them into the [context]'s overlay.
-  void show() {
+  void showHandles() {
     assert(_handles == null);
     _handles = <OverlayEntry>[
       new OverlayEntry(builder: (BuildContext c) => _buildOverlay(c, _TextSelectionHandlePosition.start)),
       new OverlayEntry(builder: (BuildContext c) => _buildOverlay(c, _TextSelectionHandlePosition.end)),
     ];
-    _toolbar = new OverlayEntry(builder: _buildToolbar);
     Overlay.of(context, debugRequiredFor: debugRequiredFor).insertAll(_handles);
+  }
+
+  /// Shows the toolbar by inserting it into the [context]'s overlay.
+  void showToolbar() {
+    assert(_toolbar == null);
+    _toolbar = new OverlayEntry(builder: _buildToolbar);
     Overlay.of(context, debugRequiredFor: debugRequiredFor).insert(_toolbar);
   }
 
-  /// Updates the handles after the [selection] has changed.
+  /// Updates the overlay after the [selection] has changed.
   void update(InputValue newInput) {
-    _input = newInput;
-    if (_handles == null)
+    if (_input == newInput)
       return;
-    _handles[0].markNeedsBuild();
-    _handles[1].markNeedsBuild();
-    _toolbar.markNeedsBuild();
+
+    _input = newInput;
+    if (_handles != null) {
+      _handles[0].markNeedsBuild();
+      _handles[1].markNeedsBuild();
+    }
+    _toolbar?.markNeedsBuild();
   }
 
-  /// Hides the handles.
+  /// Hides the overlay.
   void hide() {
-    if (_handles == null)
-      return;
-    _handles[0].remove();
-    _handles[1].remove();
-    _handles = null;
-    _toolbar.remove();
+    if (_handles != null) {
+      _handles[0].remove();
+      _handles[1].remove();
+      _handles = null;
+    }
+    _toolbar?.remove();
     _toolbar = null;
   }
 
@@ -116,6 +125,7 @@ class TextSelectionOverlay implements TextSelectionDelegate {
       return new Container();  // hide the second handle when collapsed
     return new _TextSelectionHandleOverlay(
       onSelectionHandleChanged: _handleSelectionHandleChanged,
+      onSelectionHandleTapped: _handleSelectionHandleTapped,
       renderObject: renderObject,
       selection: _selection,
       builder: handleBuilder,
@@ -143,6 +153,17 @@ class TextSelectionOverlay implements TextSelectionDelegate {
     inputValue = _input.copyWith(selection: newSelection, composing: TextRange.empty);
   }
 
+  void _handleSelectionHandleTapped() {
+    if (inputValue.selection.isCollapsed) {
+      if (_toolbar != null) {
+        _toolbar?.remove();
+        _toolbar = null;
+      } else {
+        showToolbar();
+      }
+    }
+  }
+
   @override
   InputValue get inputValue => _input;
 
@@ -167,6 +188,7 @@ class _TextSelectionHandleOverlay extends StatefulWidget {
     this.position,
     this.renderObject,
     this.onSelectionHandleChanged,
+    this.onSelectionHandleTapped,
     this.builder
   }) : super(key: key);
 
@@ -174,6 +196,7 @@ class _TextSelectionHandleOverlay extends StatefulWidget {
   final _TextSelectionHandlePosition position;
   final RenderEditableLine renderObject;
   final ValueChanged<TextSelection> onSelectionHandleChanged;
+  final VoidCallback onSelectionHandleTapped;
   final TextSelectionHandleBuilder builder;
 
   @override
@@ -217,6 +240,10 @@ class _TextSelectionHandleOverlayState extends State<_TextSelectionHandleOverlay
     config.onSelectionHandleChanged(newSelection);
   }
 
+  void _handleTap() {
+    config.onSelectionHandleTapped();
+  }
+
   @override
   Widget build(BuildContext context) {
     List<TextSelectionPoint> endpoints = config.renderObject.getEndpointsForSelection(config.selection);
@@ -240,6 +267,7 @@ class _TextSelectionHandleOverlayState extends State<_TextSelectionHandleOverlay
     return new GestureDetector(
       onHorizontalDragStart: _handleDragStart,
       onHorizontalDragUpdate: _handleDragUpdate,
+      onTap: _handleTap,
       child: new Stack(
         children: <Widget>[
           new Positioned(

packages/flutter/test/widget/input_test.dart

@@ -342,9 +342,14 @@ void main() {
     enterText(testValue);
     tester.pumpWidget(builder());
 
-    // Tap the text to bring up the "paste / select all" menu.
+    // Tap the selection handle to bring up the "paste / select all" menu.
     tester.tapAt(textOffsetToPosition(tester, testValue.indexOf('e')));
     tester.pumpWidget(builder());
+    RenderEditableLine renderLine = findRenderEditableLine(tester);
+    List<TextSelectionPoint> endpoints = renderLine.getEndpointsForSelection(
+        inputValue.selection);
+    tester.tapAt(endpoints[0].point + new Offset(1.0, 1.0));
+    tester.pumpWidget(builder());
 
     // SELECT ALL should select all the text.
     tester.tap(find.text('SELECT ALL'));
@@ -360,6 +365,10 @@ void main() {
     // Tap again to bring back the menu.
     tester.tapAt(textOffsetToPosition(tester, testValue.indexOf('e')));
     tester.pumpWidget(builder());
+    renderLine = findRenderEditableLine(tester);
+    endpoints = renderLine.getEndpointsForSelection(inputValue.selection);
+    tester.tapAt(endpoints[0].point + new Offset(1.0, 1.0));
+    tester.pumpWidget(builder());
 
     // PASTE right before the 'e'.
     tester.tap(find.text('PASTE'));