custom_card_layout.dart

import 'package:flutter/material.dart';

class NewsCardLayout extends MultiChildLayoutDelegate {
  NewsCardLayout();

  static const String title = 'title';
  static const String description = 'description';
  static const String source = 'source';

  @override
  void performLayout(Size size) {
    final Size titleSize = layoutChild(title, new BoxConstraints.loose(size));
    final Size sourceSize = layoutChild(source, new BoxConstraints.loose(size));

    layoutChild(
      description,
      new BoxConstraints.loose(
        new Size(size.width, size.height - titleSize.height - sourceSize.height),
      )
    );

    positionChild(title, Offset.zero);
    positionChild(description, new Offset(0.0, titleSize.height));
    positionChild(source, new Offset(0.0, size.height - sourceSize.height));
  }

  @override
  bool shouldRelayout(NewsCardLayout oldDelegate) => false;
}

class NewsCard extends StatelessWidget {
  const NewsCard({ Key key, this.title, this.description, this.source }) : super(key: key);

  final String title;
  final String description;
  final String source;

  @override
  Widget build(BuildContext context) {
    final ThemeData theme = Theme.of(context);
    return new Card(
      child: new Container(
        height: 176.0,
        padding: const EdgeInsets.all(8.0),
        child: new CustomMultiChildLayout(
          delegate: new NewsCardLayout(),
          children: <Widget>[
            new LayoutId(
              id: NewsCardLayout.title,
              child: new Text(
                title,
                maxLines: 3,
                style: theme.textTheme.title,
                overflow: TextOverflow.ellipsis,
              ),
            ),
            new LayoutId(
              id: NewsCardLayout.description,
              child: new Padding(
                padding: const EdgeInsets.symmetric(vertical: 8.0),
                child: new LayoutBuilder(
                  builder: (BuildContext context, BoxConstraints constraints) {
                    final TextStyle style = theme.textTheme.subhead;
                    return new Text(
                      description,
                      maxLines: (constraints.biggest.height / style.fontSize).floor(),
                      style: style,
                      overflow: TextOverflow.ellipsis,
                    );
                  },
                ),
              ),
            ),
            new LayoutId(
              id: NewsCardLayout.source,
              child: new Text(
                source,
                style: theme.textTheme.caption,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class CustomCardLayoutDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: AppBar(
          title: const Text('Custom Card Layout'),
        ),
        body: new ListView(
          padding: const EdgeInsets.symmetric(
            vertical: 16.0,
            horizontal: 40.0,
          ),
          children: <Widget>[
            const NewsCard(
              title: 'A short title',
              description: 'A short description',
              source: 'source',
            ),
            const SizedBox(height: 24.0),
            const NewsCard(
              title: 'A much longer title that goes on and on and on and eventually spans more than three lines',
              description: 'An equally long descrption that goes on and on and eventually fills all of the available space because there just no end to it, no end at all',
              source: 'source',
            ),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(new CustomCardLayoutDemo());
}