Unlike FractionalOffset, Alignment uses the center as the zero of the
coordinate system, which makes the RTL math work out much cleaner.
Also, make FractionalOffset into a subclass of Alignment so that clients
can continue to use FractionalOffset.
Mainly, this adds documentation to members that were previously
lacking documentation.
It also adds a big block of documentation about improving performance
of widgets.
This also removes some references to package:collection and adds
global setEquals and listEquals methods in foundation that we can use.
(setEquals in particular should be much faster than the
package:collection equivalent, though both should be faster as they
avoid allocating new objects.) All remaining references now qualify
the import so we know what our remaining dependencies are.
Also lots of code reordering in Flutter driver to make the code
consistent and apply the style guide more thoroughly.
This splits the frame pipeline into two, beginFrame and drawFrame.
As part of making this change I added some debugging hooks that helped
debug the issues that came up:
* I added debugPrintScheduleFrameStacks which prints a stack whenever
a frame is actually scheduled, so you can see why frames are being
scheduled.
* I added some toString output to EditableText and RawKeyboardListener.
* I added a scheduler_tester.dart library for scheduler library tests.
* I changed the test framework to flush microtasks before pumping.
* Some asserts that had the old string literal form were replaced by
asserts with messages.
I also fixed a few subtle bugs that this uncovered:
* setState() now calls `ensureVisualUpdate`, rather than
`scheduleFrame`. This means that calling it from an
AnimationController callback does not actually schedule an extra
redundant frame as it used to.
* I corrected some documentation.
Previously, pumpWidget() would do a partial pump (it didn't trigger
Ticker callbacks or post-frame callbacks), and pump() would do a full
pump. This patch brings them closer together. It also makes runApp run a
full actual frame, rather than skipping the transient callback part of
the frame logic. Having "half-frames" in the system was confusing and
could lead to bugs where code expecting to run before the next layout
pass didn't because a "half-frame" ran first.
Also, make Tickers start ticking in the frame that they were started in,
if they were started during a frame. This means we no longer spin a
frame for t=0, we jump straight to the first actual frame.
Other changes in this patch:
* rename WidgetsBinding._runApp to WidgetsBinding.attachRootWidget, so
that tests can use it to more accurately mock out runApp.
* allow loadStructuredData to return synchronously.
* make handleBeginFrame handle not being given a time stamp.
* make DataPipeImageProvider.loadAsync protected (rather than private),
and document it. There wasn't really a reason for it to be private.
* fix ImageConfiguration.toString.
* introduce debugPrintBuildScope and debugPrintScheduleBuildForStacks,
which can help debug problems with widgets getting marked as dirty but
not cleaned.
* make debugPrintRebuildDirtyWidgets say "Building" the first time and
"Rebuilding" the second, to make it clearer when a widget is first
created. This makes debugging widget lifecycle issues much easier.
* make debugDumpApp more resilient.
* debugPrintStack now takes a label that is printed before the stack.
* improve the banner shown for debugPrintBeginFrameBanner.
* various and sundry documentation fixes
+ Add new demo to gallery to show data tables. (This currently doesn't
use a Card; I'll create a Card version in a subsequent patch.)
+ Fix checkbox alignment. It now centers in its box regardless.
+ Add Colors.black54.
+ Some minor fixes to dartdocs.
+ DataTable, DataColumn, DataRow, DataCell
+ RowInkWell
+ Augment dartdocs of materia/debug.dart.
+ DropDownButtonHideUnderline to hide the underline in a drop-down when
used in a DataTable.
+ Add new capabilities to InkResponse to support RowInkWell.
+ Augment dartdocs of materia/material.dart.
+ Add an assert to catch nested Blocks.
+ Fix a crash in RenderBox when you remove an object and an ancestor
used its baseline. (https://github.com/flutter/flutter/issues/2874)
+ Fix (and redocument) RenderBaseline/Baseline.
+ Add flex support to IntrinsicColumnWidth.
+ Document more stuff on the RenderTable side.
+ Fix a bug with parentData handling on RenderTable children.
+ Completely rewrite the column width computations. The old logic made
no sense at all.
+ Add dartdocs to widgets/debug.dart.
+ Add a toString for TableRow.
