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The ConstrainedBox Widget

Explore how to apply the ConstrainedBox widget in Flutter to customize the size of child widgets by overriding default constraints. Understand how it manages width and height limitations and its behavior when parent constraints are strict. This lesson helps you design more readable and adaptable user interfaces across device types.

The Flutter framework does a good job of sizing and placing our widgets. However, sometimes we need to change the widget’s size because the framework calculation doesn’t fit our needs. Let’s take look at an example:

Both images represent the same Flutter application running on two different devices—a smartphone in portrait mode on the left, and a tablet in landscape mode on the right. The text fits the screen on the smartphone because the available width is limited. On the other hand, there is so much available width on the tablet version that the text becomes unreadable.

Constrain the width

Each widget in Flutter ...