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
Prep to get us ready to pull in a new dev SDK and bump our analyzer DEP.
* updates `crypto` (required by fresh analyzer)
* fixes newly flagged dead code warnings
* fixes switches that fall through and don't return
Our track and head were slightly off in size.
These now exactly match the sizes in
https://material.google.com/components/selection-controls.html#selection-controls-switch
We took the liberty of assuming the head overlaps the edge
of the track by 2 pixels (instead of the head and the track ending at the same point)
which the provided designs were conflicted about.
Huge thanks to @DaveShuckerow for noticing this issue!
@abarth
We now use the `@required` annotation to encourage developers to
explicitly set onPressed and onChanged callbacks to null when that would
disable the widget.
Fixes#287
If you tap outside the drop down menu while its animating in, we should
animate it away smoothly. Previously, we jumped to the reverseCurve,
which made the menu disappear immediately. Now we hold the animations as
state, which means we keep their _curveDirection property and don't
switch curves unless the animation actually finishes.
Also, fix a subtle bug in CurvedAnimation whereby we'd never set the
_curveDirection if we didn't see a status change in the parent
animation. Now we initialize _curveDirection based on the current value
of the parent's status.
Fixes#4379
Instead of using getTotalMatrix and setMatrix, we can just use
save/restore, which is more idiomatic.
The getTotalMatrix/setMatrix pattern was introduced to improve
performance, but the original code was calling getTotalMatrix/setMatrix
at every node in the sprite tree, which is much slower than the normal
save/transform/restore pattern.
Related to #4254
1. Use the primary color brightness to determine the color of the status bar.
The status bar overlaps the toolbar, which has the primary color.
2. Use Roboto for text.
Also:
* Make PaginatedDataTable able to scroll itself horizontally.
* Make drop down buttons support having an explicit text style and icon
size given.
* Fix a bug with drop-down buttons asserting when opened partly
off-screen.
* Make sure to pop the drop-down button's route if the drop-down button
is discarded while the route is up.
* Remove extraneous padding on drop-down buttons. (Couldn't figure out
why it was there, and it breaks alignment when a drop-down is mixed
with other text.)
* Some docs improvements.
* Add Route.isActive
* Add a setState() method to ModalRoutes.
This fix isn't completely statisfying because it has a scaling limit. The ideal
fix would actually viewport the tiles in the grid. However, this fix is much
easier at the moment.
Fixes#4395
Assigning to `size` called our intrinsic sizing functions re-entrantly, which
is a destructive operation on TextPainter. Ideally we'd made that a
non-destructive operation, but in the meantime we can fix the tab fading issue
by grabbing the text size before assigning to `size`.
Fixes#4365
Previously we supplied individual parameters to the various drag and pan
callbacks. However, that approach isn't extensible because each new
parameter is a breaking change to the API.
This patch makes a one-time breaking change to the API to provide a
"details" object that we can extend over time as we need to expose more
information. The first planned extension is adding enough information to
accurately produce an overscroll glow on Android.
