* Added code snippet for Expanded class. ref:#21136

* Changed the code samples into snippet application samples.

* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change

Fix the spelling errors in the dartdocs for the framework.

There are no functionality changes here, just documentation fixes.

This converts all remaining "## Sample code" segments into snippets, and fixes
the snippet generator to handle multiple snippets in the same dartdoc block
properly.

I also generated, compiled, and ran each of the existing application samples,
and fixed them up to be more useful and/or just run without errors.

This PR fixes these problems with examples:

1. Switching tabs in a snippet now works if there is more than one snippet in
   a single dartdoc block.
2. Generation of snippet code now works if there is more than one snippet.
3. Contrast of text and links in the code sample block has been improved to
   recommended levels.
4. Added five new snippet templates, including a "freeform" template to make
   it possible to show examples that need to change the app instantiation.
5. Fixed several examples to run properly, a couple by adding the "Scaffold"
   widget to the template, a couple by just fixing their code.
6. Fixed visual look of some of the samples when they run by placing many
   samples inside of a Scaffold.
7. In order to make it easier to run locally, changed the sample analyzer to
   remove the contents of the supplied temp directory before running, since
   having files that hang around is problematic (only a problem when running
   locally with the `--temp` argument).
8. Added a `SampleCheckerException` class, and handle sample checking
   exceptions more gracefully.
9. Deprecated the old "## Sample code" designation, and added enforcement for
   the deprecation.
10. Removed unnecessary `new` from templates (although they never appeared in
   the samples thanks to dartfmt, but still).

Fixes #26398
Fixes #27411

This reverts commit 1d93e924.

In particular, make debugVisitOnstageChildren only work in debug mode, and add documentation.

Integrate Strut: Add StrutStyle, expose Strut API, wire up strut with dart:ui, Roll engine 31a7f4d..e7eb1c8 (7 commits) (#26332)

Includes a breaking change to dart:ui ParagraphStyle where lineHeight is renamed to height for consistency with TextStyle.

This implements support for hovering mouse pointers, so that mice connected to Android devices, and ChromeOS devices running Android apps will work properly.

It teaches flutter_test about hover events, which required changing how they are created and used.

Also modifies AnnotatedRegion to allow a region that can be located someplace other than just the origin.

Along with tests for all of the above.

Fixes #5504

This fixes https://github.com/flutter/flutter/issues/25092

This converts existing ## Sample code samples to {@tool sample}...{@end-tool} form.

Also:
1. Fixed a minor bug in analyze-sample-code.dart
2. Made the snippet tool only insert descriptions if the description is non-empty.
3. Moved the Card diagram to before the code sample.

This rewrites the sample code analysis script to be a little less of a hack (but still not pretty), and to handle snippets as well.

It also changes the semantics of how sample code is handled: the namespace for the sample code is now limited to the file that it appears in, so some additional "Examples can assume:" blocks were added. The upside of this is that there will be far fewer name collisions.

I fixed the output too: no longer will you get 4000 lines of numbered output with the error at the top and have to grep for the actual problem. It gives the filename and line number of the original location of the code (in the comment in the tree), and prints out the source code on the line that caused the problem along with the error.

For snippets, it prints out the location of the start of the snippet and the source code line that causes the problem. It can't print out the original line, because snippets get formatted when they are written, so the line might not be in the same place.

* Added a filterQuality parameter to images.

* Removed this break by accident.

* Modified the test case to check the filterQuality

* Update packages/flutter/lib/src/rendering/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Update packages/flutter/lib/src/rendering/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Update packages/flutter/lib/src/rendering/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Update packages/flutter/lib/src/widgets/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Update packages/flutter/lib/src/widgets/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Update packages/flutter/lib/src/rendering/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Update packages/flutter/lib/src/rendering/image.dart
Co-Authored-By: namanix <namanix@gmail.com>

* Added documentation for the new parameter and corrected some space issue's

See https://github.com/flutter/flutter/pull/22278#pullrequestreview-159230244

Is it possible to add a unit test to make sure that all links in our
Dart doc are valid?

Previously, the engine did not properly pass the AA flag on ClipRect.clipBehavior. flutter/engine#6199 fixes this and enables AA. However, default AA on clipRects has caused severe regressions in benchmark performance.

To maintain expected performance, we should now default the clipBehavior to hardEdge to disable default AA. This is consistent with any flutter projects that did not previously explicitly set the clipBehavior and should not change app appearance.

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

* lint unnecessary_new on samples

* fix tests

This reverts commit 8de0e15e and
updates the goldens versoin.

This requires https://github.com/flutter/flutter/pull/20751 to
land first.

* Visibility widget

This attempts to address the confusion around how to hide a widget subtree.

* Apply review comments

* More clarifications