Introduce a Draggable class that wraps all the logic of dragging
something and dropping it on a DragTarget.
Update examples/widgets/drag_and_drop.dart accordingly.
Make the performance/transition part of routes optional.
Initial snap offset support for ScrollableWidgetList (and ScrollableList<T>) and ScrollableMixedWidgetList. If a ```toSnapOffset(scrollOffset)``` function is provided, fling Scrolls will coast to the returned value. If ```alignmentOffset``` is specified then fling scrolls conclude when toSnapOffset's value lines up with the Scrollable widget's origin + alignmentOffset. For example if the Scrollable widget's height was 200.0, and alignmentOffset:100.0 was specified, then fling scrolls would end with the value returned by toSnapOffset() lined up with the center of the Scrollable.
This approach to Scrollable snapping assumes that the layout of whatever the Scrollable contains is known at the outset. This is often true however a ScrollableMixedWidgetList may not know its items' sizes until they've been reached by scrolling.
This is a first cut at snapping support. Among the things that remain to be done:
- Scrolling limits trump snapping. Snapping should probably trump scrolling limits.
- Drag scrolls aren't snapped. This may be desirable so perhaps the feature should be controlled with a flag.
- Specifying alignmentOffset as a percentage would probably be more convenient.
- It would be nice if one could wrap items in a SnapOffset value like: ```new SnapOffset(0.5, child: myItem)``` to snap to the center of the item.
Updated the CardCollection example: snapping and fixed size items can be turned on/off with Drawer checkboxes.
Also, introduce Colors and Typography to hold the material colors and the
typography declarations. Previously we expected clients of these libraries to
import them into a namespace, but that doesn't play nice with re-exporting them
from material.dart.
Move the animation libraries into src/animation and change importers to use
package:sky/animation.dart. Also, move scheduler.dart into the animation
library so that the animation library can be self-contained.
Turns out many of the functions on BoxConstraints weren't used or had callers
that could easily be updated to other functions. I've added dartdoc to all the
public functions as well as renamed some functions that had similar names but
did different things.
```
enum DismissDirection {
vertical,
horizontal,
left,
right,
up,
down
}
```
To only enable dismissing to the right create the `Dismissable` with `direction: DismissDirection.right`. By default direction is `DismissDirection.horizontal` (left or right).
Updated the card_collection "Swipe Away" demo with a drawer that can be used to select one of the three X axis dismiss directions. Currently the MixedViewport class doesn't support horizontal scrolling, so the demo doesn't support the X axis dismiss directions.
Add a way of having keys based on numeric types or DateTimes by having a ValueKey<T> class.
Remove the redundant ways of declaring things, except for leaving one shorthand -- you can say `new Key(s)` instead of `new ValueKey<String>(s)`.
This still leaves Flex and FlexDirection available. At some point once
people have transitioned to Row/Column we should rename Flex to _Flex
and stop reexporting FlexDirection from basic.dart.
Adds itemsWrap:bool (default false) to ScrollableList and PageableList. If itemsWrap is true then scrolling past the last item wraps around to the first. Similarly, scrolling before the first item wraps around to the last.
Added abstract ExtentScrollBehavior of ScrollBehavior. Renamed fields called contentsExtents to contentExtent, containerExtents to containerExtent, contentSize to contentExtent, etc.
BoundedBehavior is now a subclass of ExtentScrollBehavior.
Added UnboundedBehavior subclass of ExtentScrollBehvaior; contentExtent and maxScrollOffset are double.INFINITY, minScrollExtent is double.NEGATIVE_INFINITY.
When laying out positioned children inside a stack, we should give them
unbounded constraints because if they draw outside of the stack, we'll just
clip them.
Changed the pageable_list.dart example: tapping on the toolbar changes
the scroll direction. This exposed some problems:
- Scrollable.syncFields() didn't update scrollDirection
- Viewport updated its RenderObject fields in the wrong order
- FixedHeightScrollable scrollDirection changes didn't update the scrollBehavior
There may be similar problems with VariableHeightList and ScrollableViewport.
I will fix those in a separate CL.
- PageableList extends ScrollableList
One fixed width or height item is visible and centered at a
time. Fling and drag gestures scroll to the next/previous item.
- Scrollable.scrollTo(), Scrollable.scrollBy(), ensureWidgetIsVisible() API changed
The named animation parameter for these methods was replaced by
duration and curve. All of the methods now return a Future. The Future
completes when the scroll does.
This change eliminates the need for Scrollable to temporarily take ownership
of a ValueAnimation object (see #645).
- Using Future.then() instead of an AnimationPerformance status listener
In ensure_visible.dart _handleTap() uses ensureWidgetIsVisible() to
center the card roughly as before and then. When the implicit scroll
animation is complete, it changes the centered card's label font. The
change is made when the Future returned by ensureWidgetIsVisible()
completes.
- FixedHeightScrollable's itemHeight parameter is now itemExtent
If scrollDirection is ScrollDirection.vertical (the default) then itemExtent should
be the height of each item; otherwise it should be the width of each item.
Replaced _velocityForFlingGesture() in scrollable.dart with Scrollable._eventVelocity()
The original version clamped pixels/ms against pixels/sec constants. The new version
also deals with scrollDirection.
- Plumbed scrollDirection though FixedHeightScrollable and ScrollableList
Both classes should now support horizontal scrolling.
Similar to widgets.dart, rendering.dart exports the entire rendering layer.
Also, update the examples to use rendering.dart and widgets.dart. Also clean up
some exports so that the examples have more sensible imports.
Sadly, box.dart has grown much longer than 1000 lines. This patch splits it up
into several files based on the class hierarchy. Fortunately, many of these
classes are loosely coupled to each other.
We had a remarkable number of analyzer failures.
I'll fix the bots to analyze across the whole project
in a follow-up patch, that should prevent this
in the future.
@abarth
Widgets that want to receive drops should include a DropTarget in their build.
Currently there's no widget for initiating a drag. Components can use the
DragController directly. In the future, we'll probably want to add a Draggable
that knows how to do some of this work automatically.
Fixes#612
