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Explain why the Padding widget exists (#9523)

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Fixes #5166
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Adam Barth 2017-04-21 14:09:35 -07:00 committed by GitHub
parent 930183916c
commit 1abb6f5d74
1 changed files with 20 additions and 0 deletions
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packages/flutter/lib/src/widgets/basic.dart
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@ -643,6 +643,26 @@ class RotatedBox extends SingleChildRenderObjectWidget {
/// constraints by the given padding, causing the child to layout at a smaller /// constraints by the given padding, causing the child to layout at a smaller
/// size. Padding then sizes itself to its child's size, inflated by the /// size. Padding then sizes itself to its child's size, inflated by the
/// padding, effectively creating empty space around the child. /// padding, effectively creating empty space around the child.
///
/// ## Design discussion
///
/// ### Why use a [Padding] widget rather than a [Container] with a [Container.padding] property?
///
/// There isn't really any difference between the two. If you supply a
/// [Container.padding] argument, [Container] simply builds a [Padding] widget
/// for you.
///
/// [Container] doesn't implement its properties directly. Instead, [Container]
/// combines a number of simpler widgets together into a convenient package. For
/// example, the [Container.padding] property causes the container to build a
/// [Padding] widget and the [Container.decoration] property causes the
/// container to build a [DecoratedBox] widget. If you find [Container]
/// convenient, feel free to use it. If not, feel free to build these simpler
/// widgets in whatever combination meets your needs.
///
/// In fact, the majority of widgets in Flutter are simply combinations of other
/// simpler widgets. Composition, rather than inheritance, is the primary
/// mechansim for building up widgets.
class Padding extends SingleChildRenderObjectWidget { class Padding extends SingleChildRenderObjectWidget {
/// Creates a widget that insets its child. /// Creates a widget that insets its child.
/// ///