Placeholder widget and Attributes

The Placeholder widget in Flutter is a simple widget used to occupy space in a layout without displaying any content. It's often used as a temporary placeholder while designing a UI layout, allowing developers to visualize the arrangement of widgets without providing actual content. The Placeholder widget is typically replaced with other widgets during the development process.

Attributes:

1. color (Color):

   • The color of the placeholder widget. It's optional and defaults to a gray color.

2. fallbackHeight (double):

   • The fallback height of the placeholder widget. It's optional and defaults to 400.0.

3. fallbackWidth (double):

   • The fallback width of the placeholder widget. It's optional and defaults to 400.0.

Example:

import 'package:flutter/material.dart';

class PlaceholderExample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Placeholder Widget Example'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Placeholder(
              color: Colors.blueGrey,
              fallbackHeight: 200,
              fallbackWidth: 200,
            ),
            SizedBox(height: 20),
            Text(
              'This is a Placeholder Widget',
              style: TextStyle(fontSize: 18),
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: PlaceholderExample(),
  ));
}

In this example:

• A Placeholder widget is used inside a Column to demonstrate its usage.

• The Placeholder widget has a specified color, fallbackHeight, and fallbackWidth, which will be used if the widget's size is not determined by the layout constraints.

• Below the Placeholder widget, there is a Text widget providing context about the Placeholder. This text will be displayed below the placeholder in the UI.