如何在 flutter 中创建这种类型的边框

Question

I want to create this type of border inside GrideView but didn't succeed - help please.

And I also want to scroll the arrow but it is stuck:

But what I created here:

Code:

       Padding(
        padding: const EdgeInsets.only(left: 16, right: 16),
        child: Container(
          decoration: ShapeDecoration(
            color: Color.fromRGBO(247, 247, 247, 1),
            shape: MessageBorder(

                borderRadius:   BorderRadius.only(
                    topLeft: Radius.circular(8),
                    topRight: Radius.circular(8),
                    bottomLeft: Radius.circular(8),
                    bottomRight: Radius.circular(8)),
              usePadding: false
            ),
            shadows: [
              BoxShadow(color: Colors.black, ),
            ],
          ),
          child: GridView.builder(
            itemCount: subServices.length,
            // The length Of the array
            physics: const NeverScrollableScrollPhysics(),
            shrinkWrap: true,
            gridDelegate: SliverGridDelegateWithFixedCrossAxisCountAndFixedHeight(
              crossAxisCount: 4,
              crossAxisSpacing: 3,
              mainAxisSpacing: 3,
              height: 92.7, //48 dp of height
            ),
            itemBuilder: (context, index) =>
                Container(
                  decoration: myBoxDecoration(
                      index, 4),
                  child: Category(data: subServices[index]),
                ),
          ),
        ),
      )

Answer 1

this is the idea, but may not be the best, stack a white bordered container on the gridview:

Stack(
  alignment:Alignment.center,
  children:[
    /* your gridview */
    IgnorePointer(
      ignoring: true,
      child: Container(
      width: /* width of stack - 10 */
      height: /* height of stack - 10 */
      color: Colors.transparent,
      decoration: BoxDecoration(
        border: Border.all(
          color: Colors.white,
          width: 10.0,
        ),
      ),
    ),
    ),
  ],
),

Answer 2

this pseudo code might help you.

WhiteContainer(
child: Stack [
 gray container with padding 1,
 grid view in which every tile has padding 1
])