flutter - InkWell 没有显示涟漪效应

Question

点击容器会触发 onTap() 处理程序，但不会显示任何墨水飞溅效果。

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(widget.title),
      ),
      body: new Center(
        child: new InkWell(
          onTap: (){print("tapped");},
          child: new Container(
            width: 100.0,
            height: 100.0,
            color: Colors.orange,
          ),
        ),
      ),
    );
  }
}

我也尝试将 InkWell 放入 Container 中，但没有成功。

Answer 1

我认为给容器添加颜色会覆盖墨水效果

https://api.flutter.dev/flutter/material/InkWell/InkWell.html

这段代码似乎可以工作

  body: new Center(
    child: new Container(
      child: new Material(
        child: new InkWell(
          onTap: (){print("tapped");},
          child: new Container(
            width: 100.0,
            height: 100.0,
          ),
        ),
        color: Colors.transparent,
      ),
      color: Colors.orange,
    ),
  ),

只需点击中间的方 block 。

编辑:我找到了错误报告。 https://github.com/flutter/flutter/issues/3782

This is actually as expected, though we should update the docs to make it clearer.

What's going on is that the Material spec says that the splashes are actually ink on the Material. So when we splash, what we do is we literally have the Material widget do the splash. If you have something on top of the Material, we splash under it, and you can't see it.

I have wanted to add a "MaterialImage" widget that conceptually prints its image into the Material as well so that then the splashes would be over the image. We could have a MaterialDecoration which does something similar for a Decoration. Or we could have Material itself take a decoration. Right now it takes a color, but we could extend that to taking a whole decoration. It's not clear whether it's really material-spec-compatible to have a material with a gradient, though, so I'm not sure whether we should do that.

In the short run, if you just need a workaround, you can put a Material on top of the container, with the material set to use the "transparency" type, and then put the ink well inside that.

--喜喜

更新:Hixie 去年合并了一个新的 Ink 解决方案。 Ink 提供了一种在图像上飞溅的便捷方式。

  testWidgets('Does the Ink widget render anything', (WidgetTester tester) async {
    await tester.pumpWidget(
      new Material(
        child: new Center(
          child: new Ink(
            color: Colors.blue,
            width: 200.0,
            height: 200.0,
            child: new InkWell(
              splashColor: Colors.green,
              onTap: () { },
            ),
          ),
        ),
      ),
    );


Material(
  color: Colors.grey[800],
  child: Center(
    child: Ink.image(
      image: AssetImage('cat.jpeg'),
      fit: BoxFit.cover,
      width: 300.0,
      height: 200.0,
      child: InkWell(
        onTap: () { /* ... */ },
        child: Align(
          alignment: Alignment.topLeft,
          child: Padding(
            padding: const EdgeInsets.all(10.0),
            child: Text('KITTEN', style: TextStyle(fontWeight: FontWeight.w900, color: Colors.white)),
          ),
        )
      ),
    ),
  ),
)

请注意:我没有测试新的 Ink Widget。我处理了 ink_paint_test.dart 和 Ink 类文档中的代码

https://github.com/Hixie/flutter/blob/1f6531984984f52328e66c0cd500a8d517964564/packages/flutter/test/material/ink_paint_test.dart

https://github.com/flutter/flutter/pull/13900

https://api.flutter.dev/flutter/material/Ink-class.html