What is the difference between using Align or using Positioned flutter

Question

Her's a concrete example of using both Positionned Widget and Align Widget! But I had a problem figuring what to use ! though original problem is to set some FABs's Offsets relatively to its Container not to the screen

Stack(
      children: <Widget>[
        Positioned(left: 0.0, child: Text("Top\nleft")),
        Positioned(bottom: 0.0, child: Text("Bottom\nleft")),
        Positioned(top: 0.0, right: 0.0, child: Text("Top\nright")),
        Positioned(bottom: 0.0, right: 0.0, child: Text("Bottom\nright")),
        Positioned(bottom: 0.0, right: 0.0, child: Text("Bottom\nright")),
        Positioned(left: width / 2, top: height / 2, child: Text("Center")),
        Positioned(top: height / 2, child: Text("Center\nleft")),
        Positioned(top: height / 2, right: 0.0, child: Text("Center\nright")),
        Positioned(left: width / 2, child: Text("Center\ntop")),
        Positioned(left: width / 2, bottom: 0.0, child: Text("Center\nbottom")),
      ],
    )
    Example #2 (Using Align in Stack)

    Stack(
      children: <Widget>[
        Align(alignment: Alignment.center, child: Text("Center"),),
        Align(alignment: Alignment.topRight, child: Text("Top\nRight"),),
        Align(alignment: Alignment.centerRight, child: Text("Center\nRight"),),
        Align(alignment: Alignment.bottomRight, child: Text("Bottom\nRight"),),
        Align(alignment: Alignment.topLeft, child: Text("Top\nLeft"),),
        Align(alignment: Alignment.centerLeft, child: Text("Center\nLeft"),),
        Align(alignment: Alignment.bottomLeft, child: Text("Bottom\nLeft"),),
        Align(alignment: Alignment.topCenter, child: Text("Top\nCenter"),),
        Align(alignment: Alignment.bottomCenter, child: Text("Bottom\nCenter"),),
        Align(alignment: Alignment(0.0, 0.5), child: Text("Custom\nPostition", style: TextStyle(color: Colors.red, fontSize: 20.0, fontWeight: FontWeight.w800),),),
      ],
    );

> Blockquot

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Answer 1

• Positioned 是一种基于偏移的对齐方式，它使用 DP 作为单位
• Align 使用父尺寸的 %

因此，Alignment(0.1, 0.1)不能使用 表示Positioned。同样，Align不能代表 a Positioned(top: 10, left: 10)。

其次，Positioned是在不同的流程上。

Stack可以根据其子代 之一的大小来调整自身大小，不包括Positioned小部件。

因此，使用AlignvsPositioned可能会导致Stack采用不同的大小。

Answer 2

Positioned can only be used within a Stack and positions a child relative to the Stack size.

https://docs.flutter.io/flutter/widgets/Positioned-class.html

Align将在其父级内尽可能大（或相对于子级的大小，如果heightFactor,widthFactor被传递）并将其子级相对于自身定位。Align可以在任何地方使用，而不仅仅是在Stack.

https://docs.flutter.io/flutter/widgets/Align-class.html