feat(Touchable): add TouchableHightlight widget and TouchaleOpacity widget

Author: 2534290808

lib/flutter_weui.dart

@@ -10,3 +10,4 @@ export 'switch.dart';
 export 'weui_icon.dart';
 export 'load_more.dart';
 export 'dialog.dart';
+export 'touchable.dart';

lib/touchable.dart

@@ -0,0 +1,80 @@
+import 'package:flutter/material.dart';
+
+/// 按下时高亮
+class TouchableHighlight extends StatefulWidget {
+  TouchableHighlight({Key key, @required this.child, this.onPressed}) : super(key: key);
+
+  final Widget child;
+  final VoidCallback onPressed;
+  @override
+  _TouchableHighlightState createState() => _TouchableHighlightState();
+}
+
+class _TouchableHighlightState extends State<TouchableHighlight> {
+  Color bg = Color(0xFFFFFFFF);
+
+  _onTapDown(e) {
+    setState(() {
+      bg = Color(0xFFDEDEDE);
+    });
+  }
+
+  _onTapUp(e) {
+    setState(() {
+      bg = Color(0xFFFFFFFF);
+    });
+    if (widget.onPressed != null) widget.onPressed();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTapDown: this._onTapDown,
+      onTapUp: this._onTapUp,
+      child: Container(
+        color: bg,
+        child: widget.child,
+      ),
+    );
+  }
+}
+
+/// 按下时不透明度发生变化
+class TouchableOpacity extends StatefulWidget {
+  TouchableOpacity({Key key, @required this.child, this.onPressed}) : super(key: key);
+
+  final Widget child;
+  final VoidCallback onPressed;
+
+  @override
+  _TouchableOpacityState createState() => _TouchableOpacityState();
+}
+
+class _TouchableOpacityState extends State<TouchableOpacity> {
+  double opacity = 1;
+
+  _onTapDown(e) {
+    setState(() {
+      opacity = 0.2;
+    });
+  }
+
+  _onTapUp(e) {
+    setState(() {
+      opacity = 1;
+    });
+    if (widget.onPressed != null) widget.onPressed();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTapDown: this._onTapDown,
+      onTapUp: this._onTapUp,
+      child: Opacity(
+        opacity: opacity,
+        child: widget.child,
+      ),
+    );
+  }
+}