Improve SOC of raw editor (#227)
Improve separation of concerns for RawEditor by moving the code for the text input client to a separate class, furthermore add more comments.pull/228/head
Till Friebe
4 years ago
committed by
GitHub
parent
1ac73b7cae
commit
5655920937
2 changed files with 205 additions and 154 deletions
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import 'package:flutter/foundation.dart'; |
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import 'package:flutter/services.dart'; |
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import 'package:flutter/widgets.dart'; |
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import '../../utils/diff_delta.dart'; |
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import '../editor.dart'; |
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mixin RawEditorStateTextInputClientMixin on EditorState |
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implements TextInputClient { |
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final List<TextEditingValue> _sentRemoteValues = []; |
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TextInputConnection? _textInputConnection; |
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TextEditingValue? _lastKnownRemoteTextEditingValue; |
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/// Whether to create an input connection with the platform for text editing |
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/// or not. |
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/// |
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/// Read-only input fields do not need a connection with the platform since |
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/// there's no need for text editing capabilities (e.g. virtual keyboard). |
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/// |
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/// On the web, we always need a connection because we want some browser |
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/// functionalities to continue to work on read-only input fields like: |
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/// |
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/// - Relevant context menu. |
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/// - cmd/ctrl+c shortcut to copy. |
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/// - cmd/ctrl+a to select all. |
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/// - Changing the selection using a physical keyboard. |
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bool get shouldCreateInputConnection => kIsWeb || !widget.readOnly; |
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/// Returns `true` if there is open input connection. |
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bool get hasConnection => |
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_textInputConnection != null && _textInputConnection!.attached; |
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/// Opens or closes input connection based on the current state of |
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/// [focusNode] and [value]. |
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void openOrCloseConnection() { |
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if (widget.focusNode.hasFocus && widget.focusNode.consumeKeyboardToken()) { |
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openConnectionIfNeeded(); |
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} else if (!widget.focusNode.hasFocus) { |
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closeConnectionIfNeeded(); |
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} |
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} |
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void openConnectionIfNeeded() { |
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if (!shouldCreateInputConnection) { |
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return; |
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} |
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if (!hasConnection) { |
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_lastKnownRemoteTextEditingValue = getTextEditingValue(); |
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_textInputConnection = TextInput.attach( |
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this, |
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TextInputConfiguration( |
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inputType: TextInputType.multiline, |
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readOnly: widget.readOnly, |
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inputAction: TextInputAction.newline, |
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enableSuggestions: !widget.readOnly, |
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keyboardAppearance: widget.keyboardAppearance, |
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textCapitalization: widget.textCapitalization, |
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), |
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); |
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_textInputConnection!.setEditingState(_lastKnownRemoteTextEditingValue!); |
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// _sentRemoteValues.add(_lastKnownRemoteTextEditingValue); |
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} |
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_textInputConnection!.show(); |
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} |
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/// Closes input connection if it's currently open. Otherwise does nothing. |
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void closeConnectionIfNeeded() { |
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if (!hasConnection) { |
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return; |
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} |
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_textInputConnection!.close(); |
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_textInputConnection = null; |
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_lastKnownRemoteTextEditingValue = null; |
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_sentRemoteValues.clear(); |
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} |
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/// Updates remote value based on current state of [document] and |
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/// [selection]. |
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/// |
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/// This method may not actually send an update to native side if it thinks |
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/// remote value is up to date or identical. |
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void updateRemoteValueIfNeeded() { |
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if (!hasConnection) { |
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return; |
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} |
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// Since we don't keep track of the composing range in value provided |
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// by the Controller we need to add it here manually before comparing |
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// with the last known remote value. |
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// It is important to prevent excessive remote updates as it can cause |
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// race conditions. |
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final actualValue = getTextEditingValue().copyWith( |
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composing: _lastKnownRemoteTextEditingValue!.composing, |
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); |
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if (actualValue == _lastKnownRemoteTextEditingValue) { |
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return; |
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} |
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final shouldRemember = |
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getTextEditingValue().text != _lastKnownRemoteTextEditingValue!.text; |
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_lastKnownRemoteTextEditingValue = actualValue; |
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_textInputConnection!.setEditingState(actualValue); |
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if (shouldRemember) { |
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// Only keep track if text changed (selection changes are not relevant) |
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_sentRemoteValues.add(actualValue); |
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} |
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} |
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@override |
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TextEditingValue? get currentTextEditingValue => |
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_lastKnownRemoteTextEditingValue; |
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// autofill is not needed |
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@override |
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AutofillScope? get currentAutofillScope => null; |
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@override |
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void updateEditingValue(TextEditingValue value) { |
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if (!shouldCreateInputConnection) { |
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return; |
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} |
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if (_sentRemoteValues.contains(value)) { |
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/// There is a race condition in Flutter text input plugin where sending |
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/// updates to native side too often results in broken behavior. |
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/// TextInputConnection.setEditingValue is an async call to native side. |
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/// For each such call native side _always_ sends an update which triggers |
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/// this method (updateEditingValue) with the same value we've sent it. |
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/// If multiple calls to setEditingValue happen too fast and we only |
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/// track the last sent value then there is no way for us to filter out |
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/// automatic callbacks from native side. |
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/// Therefore we have to keep track of all values we send to the native |
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/// side and when we see this same value appear here we skip it. |
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/// This is fragile but it's probably the only available option. |
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_sentRemoteValues.remove(value); |
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return; |
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} |
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if (_lastKnownRemoteTextEditingValue == value) { |
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// There is no difference between this value and the last known value. |
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return; |
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} |
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// Check if only composing range changed. |
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if (_lastKnownRemoteTextEditingValue!.text == value.text && |
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_lastKnownRemoteTextEditingValue!.selection == value.selection) { |
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// This update only modifies composing range. Since we don't keep track |
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// of composing range we just need to update last known value here. |
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// This check fixes an issue on Android when it sends |
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// composing updates separately from regular changes for text and |
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// selection. |
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_lastKnownRemoteTextEditingValue = value; |
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return; |
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} |
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final effectiveLastKnownValue = _lastKnownRemoteTextEditingValue!; |
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_lastKnownRemoteTextEditingValue = value; |
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final oldText = effectiveLastKnownValue.text; |
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final text = value.text; |
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final cursorPosition = value.selection.extentOffset; |
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final diff = getDiff(oldText, text, cursorPosition); |
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widget.controller.replaceText( |
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diff.start, diff.deleted.length, diff.inserted, value.selection); |
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} |
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@override |
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void performAction(TextInputAction action) { |
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// no-op |
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} |
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@override |
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void performPrivateCommand(String action, Map<String, dynamic> data) { |
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// no-op |
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} |
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@override |
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void updateFloatingCursor(RawFloatingCursorPoint point) { |
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throw UnimplementedError(); |
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} |
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@override |
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void showAutocorrectionPromptRect(int start, int end) { |
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throw UnimplementedError(); |
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} |
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@override |
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void connectionClosed() { |
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if (!hasConnection) { |
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return; |
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} |
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_textInputConnection!.connectionClosedReceived(); |
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_textInputConnection = null; |
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_lastKnownRemoteTextEditingValue = null; |
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_sentRemoteValues.clear(); |
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} |
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} |
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