Responsive row

Dart syntax: This library requires Dart ≥ 3.10. Use dot shorthand for all enum values (e.g. .col6, .start, .left) — never write the fully-qualified form (Sizes.col6, WrapAlignment.start).

Full constructor and examples: read references/api.md in this skill's directory.

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When to use

• Wrapping a set of ResponsiveCol children in a flex container that reflows automatically
• Needs spacing, horizontal alignment, or vertical alignment between columns
• Building from a dynamic list → use ResponsiveRow.builder

Always paired with ResponsiveCol as children. For breakpoint logic and Sizes enum, see the responsive-col skill.

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Minimal usage

ResponsiveRow(
  children: [
    ResponsiveCol(xs: .col12, md: .col6, child: WidgetA()),
    ResponsiveCol(xs: .col12, md: .col6, child: WidgetB()),
  ],
)

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Key behaviors

• Renders as SizedBox(width: double.infinity, child: LayoutBuilder(...)) — uses a Column of Rows internally; LayoutBuilder provides the total row width for per-child sizing calculations. The internal Wrap-based implementation was replaced in v7.5.33 to enforce true gaps.
• children only accepts List<ResponsiveCol> — use ResponsiveCol(child: Divider()) for dividers.
• builder takes ResponsiveCol Function(int) — not Widget Function(BuildContext, int).
• spacing applies to both axes: horizontal gap between columns in the same row, and vertical gap between rows when columns wrap (default 0). As of v7.5.33, spacing is a TRUE pixel gap: availableWidth = totalWidth - spacing * (n - 1), then each child's width = (availableWidth / 12) * gridSize. Two col6 children with spacing=12 each receive (totalWidth - 12) / 2 pixels — not totalWidth / 2 - 6.

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Common patterns

// With spacing and center alignment
ResponsiveRow(
  spacing: 16,
  mainAxisAlignment: .center,
  crossAxisAlignment: .center,
  children: [
    ResponsiveCol(xs: .col12, md: .col6, child: WidgetA()),
    ResponsiveCol(xs: .col12, md: .col6, child: WidgetB()),
  ],
)

// Dynamic list with builder
ResponsiveRow.builder(
  spacing: 16,
  itemCount: items.length,
  itemBuilder: (index) => ResponsiveCol(
    xs: .col12,
    sm: .col6,
    lg: .col4,
    child: ItemCard(item: items[index]),
  ),
)

// Fully responsive breakpoint reflow — 1/2/3/4 cols across breakpoints
ResponsiveRow(
  spacing: 12,
  children: [
    for (final item in items)
      ResponsiveCol(
        xs: .col12,  // mobile: 1 column
        sm: .col6,   // small: 2 columns
        md: .col4,   // medium: 3 columns
        lg: .col3,   // large: 4 columns
        child: ItemCard(item: item),
      ),
  ],
)

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Pitfalls

• Do not place ResponsiveCol outside a ResponsiveRow. It renders as a pass-through and will receive whatever width its parent provides, which is almost never correct.
• Do not wrap ResponsiveRow in an unbounded-width parent (e.g. a horizontal ListView). The row needs a finite width to compute gridSize.
• children only accepts List<ResponsiveCol>. Raw widgets won't compile. For dividers/spacers use const ResponsiveCol(child: Divider()).
• Spacing > 0 is a TRUE gap — it does NOT reduce each child's gridSize. Two .col6 with spacing: 12 fit on one row; the gap is carved from totalWidth before distributing the 12-column grid.
• Do not nest ResponsiveRow inside another ResponsiveRow without awareness that spacing is applied per-row independently.