Modified versions of Flutter's Flex, Column and Row widgets that can space their children with positive or negative spacing.

Features

• All the bells and whistles of Flutter's original Flex, Column and Row widgets.
• Space the children apart with positive spacing.
• Cause the children to overlap with negative spacing.
• Set the order in which the children should be stacked when they overlap.
• MainAxisAlignment.spaceAround, MainAxisAlignment.spaceBetween and MainAxisAlignment.spaceEvenly or not supported. (There's no need for them here. Just use Flutter's original widgets.)

Getting started

Install it:

flutter pub add signed_spacing_flex

Import it:

import 'package:signed_spacing_flex/signed_spacing_flex.dart';

Usage

Checkout Flutter's guides to the Flex, Column and Row widgets. This package is basically same just with some added features.

1. Replace Flex, Column or Row with SignedSpacingFlex, SignedSpacingColumn or SignedSpacingRow.

// Flex(
SignedSpacingFlex(
    children: [],
)

// Column(
SignedSpacingColumn(
    children: [],
)

// Row(
SignedSpacingRow(
    children: [],
)

2. Use spacing to space the children apart or cause them to overlap:

SignedSpacingColumn(
    spacing: 25, // Creates a 25px tall gap between the children.
    children: [],
)

SignedSpacingColumn(
    spacing: -25, // Makes the children overlap eachother by 25px.
    children: [],
)

3. Use stackingOrder to set the order in which the children should be stacked when they overlap:

SignedSpacingColumn(
    spacing: -25, // Makes the children overlap eachother by 25px.
    stackingOrder: StackingOrder.firstOnTop // The children will be rendered first to last - top to bottom.
    children: [],
)

SignedSpacingColumn(
    spacing: -25, // Makes the children overlap eachother by 25px.
    stackingOrder: StackingOrder.lastOnTop // The children will be rendered first to last - bottom to top.
    children: [],
)

Additional information

These are modified versions of Flutter's flutter/packages/flutter/lib/src/widgets/basic.dart and flutter/packages/flutter/lib/src/rendering/flex.dart files. I am not the original author of this code.