Alert Dialog with Rounded corners in flutter

Question

I am trying to create an alert dialog with rounded corners in Flutter same as below screenshot. also add my code here, but my output is exactly different from the expected o

Answer 1

The container where you set the BoxDecoration is in the widget tree under the alert dialog. Which means you are setting just a box within the padding of your Dialog. You need to create a custom AlertDialog/showDialog and set the radius there. In the custom widget you also add the button and everything where you need to work beyond that padding.

When you include the customShowDialog.dart file in your project (gist.github.com) where you can edit the radius here borderRadius: BorderRadius.all(Radius.circular(20.0)) and call it like this:

return new CustomAlertDialog(
    content: new Container(
        width: 260.0,
        height: 230.0,
        decoration: new BoxDecoration(
        shape: BoxShape.rectangle,
        color: const Color(0xFFFFFF),
        borderRadius:
            new BorderRadius.all(new Radius.circular(32.0)),
        ),
        child: new Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
            // dialog top
            new Expanded(
            child: new Row(
                children: [
                new Container(
                    // padding: new EdgeInsets.all(10.0),
                    decoration: new BoxDecoration(
                    color: Colors.white,
                    ),
                    child: new Text(
                    'Rate',
                    style: TextStyle(
                        color: Colors.black,
                        fontSize: 18.0,
                        fontFamily: 'helvetica_neue_light',
                    ),
                    textAlign: TextAlign.center,
                    ),
                ),
                ],
            ),
            ),

            // dialog centre
            new Expanded(
            child: new Container(
                child: new TextField(
                decoration: new InputDecoration(
                border: InputBorder.none,
                filled: false,
                contentPadding: new EdgeInsets.only(
                    left: 10.0,
                    top: 10.0,
                    bottom: 10.0,
                    right: 10.0),
                hintText: ' add review',
                hintStyle: new TextStyle(
                    color: Colors.grey.shade500,
                    fontSize: 12.0,
                    fontFamily: 'helvetica_neue_light',
                ),
                ),
            )),
            flex: 2,
            ),

            // dialog bottom
            new Expanded(
            child: new Container(
                padding: new EdgeInsets.all(16.0),
                decoration: new BoxDecoration(
                color: const Color(0xFF33b17c),
                ),
                child: new Text(
                'Rate product',
                style: TextStyle(
                    color: Colors.white,
                    fontSize: 18.0,
                    fontFamily: 'helvetica_neue_light',
                ),
                textAlign: TextAlign.center,
                ),
            ),
            ),
        ],
        ),
    ),
    );
});

You will get something like this:

EDIT:

Although Flutter lately introduced the shape property which would help you with the rounded corners by setting a ShapeBorder with e.g.

shape: RoundedRectangleBorder(
    borderRadius: BorderRadius.all(Radius.circular(20.0))
),

you would still need to quickly add a custom widget for some customizations, like custom padding, as stated above.