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document StaticIconProvider (#120935)

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document StaticIconProvider
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Christopher Fujino 2023-04-07 19:45:14 -07:00 committed by GitHub
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1 changed files with 25 additions and 2 deletions
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27
packages/flutter/lib/src/widgets/icon_data.dart
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@ -8,6 +8,10 @@ import 'package:flutter/foundation.dart';
///
/// See [Icons] for a number of predefined icons available for material
/// design applications.
///
/// In release builds, the Flutter tool will tree shake out of bundled fonts
/// the code points (or instances of [IconData]) which are not referenced from
/// Dart app code. See the [staticIconProvider] annotation for more details.
@immutable
class IconData {
/// Creates icon data.
@ -17,6 +21,11 @@ class IconData {
///
/// The [fontPackage] argument must be non-null when using a font family that
/// is included in a package. This is used when selecting the font.
///
/// Instantiating non-const instances of this class in your app will
/// mean the app cannot be built in release mode with icon tree-shaking (it
/// need to be explicitly opted out at build time). See [staticIconProvider]
/// for more context.
const IconData(
this.codePoint, {
this.fontFamily,
@ -99,6 +108,20 @@ class _StaticIconProvider {
/// Annotation for classes that only provide static const [IconData] instances.
///
/// This is a hint to the font tree shaker to ignore the constant instances
/// of [IconData] appearing in the class when tracking which code points
/// should be retained in the bundled font.
/// of [IconData] appearing in the declaration of this class when tree-shaking
/// unused code points from the bundled font.
///
/// Classes with this annotation must have only "static const" members. The
/// presence of any non-const [IconData] instances will preclude apps
/// importing the declaration into their application from being able to use
/// icon tree-shaking during release builds, resulting in larger font assets.
///
/// ```dart
/// @staticIconProvider
/// abstract final class MyCustomIcons {
/// static const String fontFamily = 'MyCustomIcons';
/// static const IconData happyFace = IconData(1, fontFamily: fontFamily);
/// static const IconData sadFace = IconData(2, fontFamily: fontFamily);
/// }
/// ```
const Object staticIconProvider = _StaticIconProvider();