This requires all AnimationController objects to be given a
TickerProvider, a class that can create the Ticker.
It also provides some nice mixins for people who want to have their
State provide a TickerProvider. And a schedulerTickerProvider for those
cases where you just want to see your battery burn.
Also, we now enforce destruction order for elements.
Overview
========
This patch refactors images to achieve the following goals:
* it allows references to unresolved assets to be passed
around (previously, almost every layer of the system had to know about
whether an image came from an asset bundle or the network or
elsewhere, and had to manually interact with the image cache).
* it allows decorations to use the same API for declaring images as the
widget tree.
It requires some minor changes to call sites that use images, as
discussed below.
Widgets
-------
Change this:
```dart
child: new AssetImage(
name: 'my_asset.png',
...
)
```
...to this:
```dart
child: new Image(
image: new AssetImage('my_asset.png'),
...
)
```
Decorations
-----------
Change this:
```dart
child: new DecoratedBox(
decoration: new BoxDecoration(
backgroundImage: new BackgroundImage(
image: DefaultAssetBundle.of(context).loadImage('my_asset.png'),
...
),
...
),
child: ...
)
```
...to this:
```dart
child: new DecoratedBox(
decoration: new BoxDecoration(
backgroundImage: new BackgroundImage(
image: new AssetImage('my_asset.png'),
...
),
...
),
child: ...
)
```
DETAILED CHANGE LOG
===================
The following APIs have been replaced in this patch:
* The `AssetImage` and `NetworkImage` widgets have been split in two,
with identically-named `ImageProvider` subclasses providing the
image-loading logic, and a single `Image` widget providing all the
widget tree logic.
* `ImageResource` is now `ImageStream`. Rather than configuring it with
a `Future<ImageInfo>`, you complete it with an `ImageStreamCompleter`.
* `ImageCache.load` and `ImageCache.loadProvider` are replaced by
`ImageCache.putIfAbsent`.
The following APIs have changed in this patch:
* `ImageCache` works in terms of arbitrary keys and caches
`ImageStreamCompleter` objects using those keys. With the new model,
you should never need to interact with the cache directly.
* `Decoration` can now be `const`. The state has moved to the
`BoxPainter` class. Instead of a list of listeners, there's now just a
single callback and a `dispose()` method on the painter. The callback
is passed in to the `createBoxPainter()` method. When invoked, you
should repaint the painter.
The following new APIs are introduced:
* `AssetBundle.loadStructuredData`.
* `SynchronousFuture`, a variant of `Future` that calls the `then`
callback synchronously. This enables the asynchronous and
synchronous (in-the-cache) code paths to look identical yet for the
latter to avoid returning to the event loop mid-paint.
* `ExactAssetImage`, a variant of `AssetImage` that doesn't do anything clever.
* `ImageConfiguration`, a class that describes parameters that configure
the `AssetImage` resolver.
The following APIs are entirely removed by this patch:
* `AssetBundle.loadImage` is gone. Use an `AssetImage` instead.
* `AssetVendor` is gone. `AssetImage` handles everything `AssetVendor`
used to handle.
* `RawImageResource` and `AsyncImage` are gone.
The following code-level changes are performed:
* `Image`, which replaces `AsyncImage`, `NetworkImage`, `AssetImage`,
and `RawResourceImage`, lives in `image.dart`.
* `DecoratedBox` and `Container` live in their own file now,
`container.dart` (they reference `image.dart`).
DIRECTIONS FOR FUTURE RESEARCH
==============================
* The `ImageConfiguration` fields are mostly aspirational. Right now
only `devicePixelRatio` and `bundle` are implemented. `locale` isn't
even plumbed through, it will require work on the localisation logic.
* We should go through and make `BoxDecoration`, `AssetImage`, and
`NetworkImage` objects `const` where possible.
* This patch makes supporting animated GIFs much easier.
* This patch makes it possible to create an abstract concept of an
"Icon" that could be either an image or a font-based glyph (using
`IconData` or similar). (see
https://github.com/flutter/flutter/issues/4494)
RELATED ISSUES
==============
Fixes https://github.com/flutter/flutter/issues/4500
Fixes https://github.com/flutter/flutter/issues/4495
Obsoletes https://github.com/flutter/flutter/issues/4496
* add import guidance to library-level docs
* add import docs to other packages
* fix review comment
* clarify which libraries aren't meant to be directly imported
Only partially works. Editing the selected text doesn't work very well,
which probably will require engine changes. Currently only draws the
selected text and allows you to manipulate the selection with draggable
selection handles.
LazyBlock is intended as a replacement for MixedViewport. Rather than
maintaining a table of all the observed child sizes (like
MixedViewport), LazyBlock works by dead reckoning the location of the
children based on the existing viewport. This approach makes it easier
to resize children because LazyBlock doesn't cache any additional
information that would need to be invalidated.
This patch contains a first draft of LazyBlock that works in a simple
usage scenario. Subsequent patches will replace
ScrollableMixedWidgetList with LazyBlock and port the existing
ScrollableMixedWidgetList tests over to LazyBlock.
Related to #3075
- Add x and y to the parent data, in case it's useful. In point of fact,
I ended up not needing it.
- Make columnWidths settable rather than having a setter so that the
code in the widgets layer is more idiomatic.
- Teach setFlatChildren about avoiding unnecessary drop/adopt loops.
- Assert that the child list length is correct more aggressively so that
we catch the dumb bug I had more quickly next time.
- Improve the toString() to handle empty tables better.
- Resort the imports in framework.dart.
- Introduce a LocalKey for cases where you don't want to allow use of
GlobalKey.
- Make inflateWidget and deactivateChild public for subclass use.
- Table widget.
- Cell widget.
- TableRow fake widget.
This patch teaches the widget framework how to use Cassowary-based
autolayout. To integrate autolayout with widgets, I had to refactor how
RenderAutoLayout worked a bit. Now RenderAutoLayout follows the same
delegate pattern we use for custom paint and custom layout.
This patch sketches out the basic widgets for creating Mozart child
views. We're still missing some of the machinery, so we can't quite
create child views yet, but once we supply the ViewHost and teach the
compositor how to actually display the child scenes, we'll have
something that works.
This patch restructures how we size the editing region of the Input widget. Now
RenderEditableLine understands that it's a single-line editing widget and sizes
itself correctly.
ScrollableList2 uses the same pattern as ScrollableGrid, which requires the
client to allocate widgets for every list item but doesn't inflate them unless
they're actually needed for the view. It improves on the original
ScrollableList by not requiring a rebuild of the whole visible portion of the
list when scrolling. In fact, small scrolls can often be handled entirely by
repainting.
We now support (vertically) scrollable grids with viewporting. If the
scroll doesn't reveal any new rows, we execute the scroll with a repaint
(i.e., no layout). If the scroll reveals a new row, we trigger a layout
to change the set of materialized children in the viewport.
Users of MaterialApp can provide an onLocaleChanged handler that will be
called to asynchronously fetch locale-specific data. MaterialApp will
then instantiate a LocaleQuery that supplies the locale data to its
descendants.
PageRoute is now MaterialPageRoute.
This also changes the following:
- Now the HeroController is a Navigator observer, rather than a feature
of HeroPageRoutes, which are gone. This means heroes can work between
any kind of ModalRoute now.
- ModalPageRoute is moved from modal_barrier.dart to routes.dart.
- It allows routes to opt-out of their modal barrier being a shortcut to
popping the route.
- Features of PageRoute that aren't Material-specific get promoted to
ModalRoute features: storage, the subtree key, offstageness...
The AnimatedModalBarrier is still a ModalRoute feature.
This patch introduces the notion of a ModalRoute that puts up a modal barrier
and makes the route invisible to hit testing when its animating out. This patch
also uses this mechanism in a number of places (including PageRoute). There are
still a few more cases to convert, but that's work for a future patch.
Fixes#1684
