Add border to a Container with borderRadius in Flutter

问题

Container(
      child: Text(
          'This is a Container',
          textScaleFactor: 2,
          style: TextStyle(color: Colors.black),
      ),

      decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(10),
          color: Colors.white,
          border: Border(
              left: BorderSide(
                  color: Colors.green,
                  width: 3,
              ),
            ),
          ),
      height: 50,
     ),

This is supposed to show a rounded-edged container with a green left border 3px wide, and the child Text "This is a Container". However, it just shows a rounded-edged container with an invisible child and an invisible left border.

When I take out the borderRadius object, the child Text and the green left border is visible, but introducing it hides the left border and child Text again.

The major problem seems to be the custom left border, because using border: Border.all(width: 0) and borderRadius: BorderRadius.circular(10) makes the edges rounded as needed and also shows the child. But now I cant apply the green left border which is quite important in this particular setup.

So is there something I'm doing wrong, or is this a bug in flutter, or is it just something that is not allowed?

Thank you in advance.

Edit: The image below is the end result. The colors don't matter

回答1:

It's not possible to add border: and borderRadius: at the same time, you'll get this error:

A borderRadius can only be given for uniform borders.

You can achieve what you want using the borderRadius: and a boxShadow: instead of border: like this:

boxShadow: [
  BoxShadow(color: Colors.green, spreadRadius: 3)
]

Your sample code would be like this:

Container(
  child: Text(
    'This is a Container',
    textScaleFactor: 2,
    style: TextStyle(color: Colors.black),
  ),
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(10),
    color: Colors.white,
    boxShadow: [
      BoxShadow(color: Colors.green, spreadRadius: 3),
    ],
  ),
  height: 50,
),

---

Edit: To achieve the example you now provided, you could do this:

Container(
  padding: EdgeInsets.only(left: 12.0),
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(10.0),
    color: Colors.green,
  ),
  height: 50,
  child: Container(
    decoration: BoxDecoration(
      borderRadius: BorderRadius.only(
          topRight: Radius.circular(10.0),
          bottomRight: Radius.circular(10.0)),
      color: Colors.white,
    ),
    child: Text(
      'This is a Container',
      textScaleFactor: 2,
      style: TextStyle(color: Colors.black),
    ),
  ),
),

Another solution:

Container(
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(10.0),
    color: Colors.white,
  ),
  height: 50,
  child: Row(
    mainAxisSize: MainAxisSize.min,
    children: <Widget>[
      Container(
        width: 12.0,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.only(
              topLeft: Radius.circular(10.0),
              bottomLeft: Radius.circular(10.0)),
          color: Colors.green,
        ),
      ),
      Text(
        'This is a Container',
        textScaleFactor: 2,
        style: TextStyle(color: Colors.black),
      )
    ],
  ),
),

回答2:

There are a couple ways to add a border to a Flutter widget. The most basic way is to wrap your widget in a DecoratedBox. However, the Container widget also has a DecoratedBox built in.

For output as above use a Stack instead of Row because of Stack allows us to make multiple widgets overlay each other and you can align or position your widget using the Align or Positioned widget.

 Container(
  height: 65,
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(10),
    color: Colors.deepPurple.shade100,
  ),
  child: Stack(
    children: <Widget>[
      Container(
        width: 8,

        decoration: BoxDecoration(
          borderRadius: BorderRadius.only(
              topLeft: Radius.circular(15),
              bottomLeft: Radius.circular(15)),
          color: Colors.deepPurple,
        ),
      )
    ],
  ),
)

回答3:

I think an easier way inspired by @pablo 's answer would be to just make a boxShadow with and offset but without any blur.

decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.vertical(
          top: Radius.circular(10),
        ),
        boxShadow: [
          // to make elevation
          BoxShadow(
            color: Colors.black45,
            offset: Offset(2, 2),
            blurRadius: 4,
          ),
          // to make the coloured border
          BoxShadow(
            color: Colors.blue,
            offset: Offset(0, 4),
          ),
        ],
      ),

The decoration above will give us an elevated box which has a blue border in the bottom. Another benefit of this approcah is that you can use it with

borderRadius: BorderRadius.circular(num)

Which means you can have a container with all rounded sides + a colored border.

Please note that the coloured border comes under the original shadow. This is done to prevent the elevation color from darkening the border.

回答4:

There is an answer here

Container(
            decoration: BoxDecoration(
                border: Border.all(
                    color: Color(0xFFF05A22),
                    style: BorderStyle.solid,
                    width: 1.0,
                ),
                color: Colors.transparent,
                borderRadius: BorderRadius.circular(30.0),
            ),
),

来源：https://stackoverflow.com/questions/58350235/add-border-to-a-container-with-borderradius-in-flutter