Fix analysis issues (#966)

* chore: rename Selectable to SelectableMixin

* chore: add platforms to pubspec.yaml

Author: LucasXu0

frontend/app_flowy/packages/appflowy_editor/example/lib/plugin/image_node_widget.dart

@@ -11,7 +11,7 @@ import 'package:flutter/material.dart';
 /// 2. create a class extends [NodeWidgetBuilder]
 /// 3. override the function `Widget build(NodeWidgetContext<Node> context)`
 ///     and return a widget to render. The returned widget should be
-///     a StatefulWidget and mixin with [Selectable].
+///     a StatefulWidget and mixin with [SelectableMixin].
 ///
 /// 4. override the getter `nodeValidator`
 ///     to verify the data structure in [Node].
@@ -50,7 +50,8 @@ class ImageNodeWidget extends StatefulWidget {
   State<ImageNodeWidget> createState() => _ImageNodeWidgetState();
 }
 
-class _ImageNodeWidgetState extends State<ImageNodeWidget> with Selectable {
+class _ImageNodeWidgetState extends State<ImageNodeWidget>
+    with SelectableMixin {
   bool isHovered = false;
   Node get node => widget.node;
   EditorState get editorState => widget.editorState;

frontend/app_flowy/packages/appflowy_editor/example/lib/plugin/network_image_node_widget.dart

@@ -31,7 +31,7 @@ class _NetworkImageNodeWidget extends StatefulWidget {
 }
 
 class __NetworkImageNodeWidgetState extends State<_NetworkImageNodeWidget>
-    with Selectable {
+    with SelectableMixin {
   RenderBox get _renderBox => context.findRenderObject() as RenderBox;
 
   @override

frontend/app_flowy/packages/appflowy_editor/example/lib/plugin/youtube_link_node_widget.dart

@@ -33,7 +33,7 @@ class LinkNodeWidget extends StatefulWidget {
 }
 
 class _YouTubeLinkNodeWidgetState extends State<LinkNodeWidget>
-    with Selectable {
+    with SelectableMixin {
   Node get node => widget.node;
   EditorState get editorState => widget.editorState;
   String get src => widget.node.attributes['youtube_link'] as String;

frontend/app_flowy/packages/appflowy_editor/lib/src/document/node_iterator.dart

@@ -1,7 +1,6 @@
 import 'package:appflowy_editor/src/document/node.dart';
 
 import './state_tree.dart';
-import './node.dart';
 
 /// [NodeIterator] is used to traverse the nodes in visual order.
 class NodeIterator implements Iterator<Node> {

frontend/app_flowy/packages/appflowy_editor/lib/src/document/text_delta.dart

@@ -4,7 +4,6 @@ import 'dart:math';
 import 'package:appflowy_editor/src/document/attributes.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-import './attributes.dart';
 
 // constant number: 2^53 - 1
 const int _maxInt = 9007199254740991;

frontend/app_flowy/packages/appflowy_editor/lib/src/extensions/node_extensions.dart

@@ -10,7 +10,8 @@ extension NodeExtensions on Node {
       key?.currentContext?.findRenderObject()?.unwrapOrNull<RenderBox>();
 
   BuildContext? get context => key?.currentContext;
-  Selectable? get selectable => key?.currentState?.unwrapOrNull<Selectable>();
+  SelectableMixin? get selectable =>
+      key?.currentState?.unwrapOrNull<SelectableMixin>();
 
   bool inSelection(Selection selection) {
     if (selection.start.path <= selection.end.path) {

frontend/app_flowy/packages/appflowy_editor/lib/src/render/image/image_node_widget.dart

@@ -32,7 +32,8 @@ class ImageNodeWidget extends StatefulWidget {
   State<ImageNodeWidget> createState() => _ImageNodeWidgetState();
 }
 
-class _ImageNodeWidgetState extends State<ImageNodeWidget> with Selectable {
+class _ImageNodeWidgetState extends State<ImageNodeWidget>
+    with SelectableMixin {
   final _imageKey = GlobalKey();
 
   double? _imageWidth;

frontend/app_flowy/packages/appflowy_editor/lib/src/render/rich_text/bulleted_list_text.dart

@@ -42,7 +42,7 @@ class BulletedListTextNodeWidget extends StatefulWidget {
 // customize
 
 class _BulletedListTextNodeWidgetState extends State<BulletedListTextNodeWidget>
-    with Selectable, DefaultSelectable {
+    with SelectableMixin, DefaultSelectable {
   @override
   final iconKey = GlobalKey();
 
@@ -51,8 +51,8 @@ class _BulletedListTextNodeWidgetState extends State<BulletedListTextNodeWidget>
   final _iconRightPadding = 5.0;
 
   @override
-  Selectable<StatefulWidget> get forward =>
-      _richTextKey.currentState as Selectable;
+  SelectableMixin<StatefulWidget> get forward =>
+      _richTextKey.currentState as SelectableMixin;
 
   @override
   Widget build(BuildContext context) {

frontend/app_flowy/packages/appflowy_editor/lib/src/render/rich_text/checkbox_text.dart

@@ -40,7 +40,7 @@ class CheckboxNodeWidget extends StatefulWidget {
 }
 
 class _CheckboxNodeWidgetState extends State<CheckboxNodeWidget>
-    with Selectable, DefaultSelectable {
+    with SelectableMixin, DefaultSelectable {
   @override
   final iconKey = GlobalKey();
 
@@ -49,8 +49,8 @@ class _CheckboxNodeWidgetState extends State<CheckboxNodeWidget>
   final _iconRightPadding = 5.0;
 
   @override
-  Selectable<StatefulWidget> get forward =>
-      _richTextKey.currentState as Selectable;
+  SelectableMixin<StatefulWidget> get forward =>
+      _richTextKey.currentState as SelectableMixin;
 
   @override
   Widget build(BuildContext context) {

frontend/app_flowy/packages/appflowy_editor/lib/src/render/rich_text/default_selectable.dart

@@ -4,7 +4,7 @@ import 'package:appflowy_editor/src/render/selection/selectable.dart';
 import 'package:flutter/material.dart';
 
 mixin DefaultSelectable {
-  Selectable get forward;
+  SelectableMixin get forward;
 
   GlobalKey? get iconKey;