flutter sdk提供完整页面的ui

news2025/10/31 20:59:26

1.完整ui页面

可以借鉴一些使用案例：

return Placeholder();


/// A widget that draws a box that represents where other widgets will one day
/// be added.
///
/// This widget is useful during development to indicate that the interface is
/// not yet complete.
///
/// By default, the placeholder is sized to fit its container. If the
/// placeholder is in an unbounded space, it will size itself according to the
/// given [fallbackWidth] and [fallbackHeight].
///
/// {@youtube 560 315 https://www.youtube.com/watch?v=LPe56fezmoo}
class Placeholder extends StatelessWidget {
  /// Creates a widget which draws a box.
  const Placeholder({
    super.key,
    this.color = const Color(0xFF455A64), // Blue Grey 700
    this.strokeWidth = 2.0,
    this.fallbackWidth = 400.0,
    this.fallbackHeight = 400.0,
    this.child
  });

  /// The color to draw the placeholder box.
  final Color color;

  /// The width of the lines in the placeholder box.
  final double strokeWidth;

  /// The width to use when the placeholder is in a situation with an unbounded
  /// width.
  ///
  /// See also:
  ///
  ///  * [fallbackHeight], the same but vertically.
  final double fallbackWidth;

  /// The height to use when the placeholder is in a situation with an unbounded
  /// height.
  ///
  /// See also:
  ///
  ///  * [fallbackWidth], the same but horizontally.
  final double fallbackHeight;

  /// The [child] contained by the placeholder box.
  ///
  /// Defaults to null.
  final Widget? child;
  @override
  Widget build(BuildContext context) {
    return LimitedBox(
      maxWidth: fallbackWidth,
      maxHeight: fallbackHeight,
      child: CustomPaint(
        size: Size.infinite,
        painter: _PlaceholderPainter(
          color: color,
          strokeWidth: strokeWidth,
        ),
        child: child,
      ),
    );
  }

  @override
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
    properties.add(ColorProperty('color', color, defaultValue: const Color(0xFF455A64)));
    properties.add(DoubleProperty('strokeWidth', strokeWidth, defaultValue: 2.0));
    properties.add(DoubleProperty('fallbackWidth', fallbackWidth, defaultValue: 400.0));
    properties.add(DoubleProperty('fallbackHeight', fallbackHeight, defaultValue: 400.0));
    properties.add(DiagnosticsProperty<Widget>('child', child, defaultValue: null));
  }
}

一些statefulWidget