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Make FixedHeightScrollable mostly work in fn2

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We still need to add a clip and a way to integrate with layout, but those
changes are more invasive and I'll do them in separate CLs.

R=eseidel@chromium.org, ianh@google.com

Review URL: https://codereview.chromium.org/1166983003
This commit is contained in:
Adam Barth 2015-06-04 10:52:12 -07:00
parent 8afcb0fe2d
commit 4491168fcb
1 changed files with 22 additions and 43 deletions
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65
sdk/lib/framework/components2/fixed_height_scrollable.dart
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@ -3,27 +3,14 @@
// found in the LICENSE file.
import '../animation/scroll_behavior.dart';
import '../debug/tracing.dart';
import '../fn2.dart';
import 'dart:math' as math;
import 'dart:async';
import 'dart:math' as math;
import 'package:vector_math/vector_math.dart';
import 'scrollable.dart';
abstract class FixedHeightScrollable extends Scrollable {
static final Style _style = new Style('''
overflow: hidden;
position: relative;
will-change: transform;'''
);
static final Style _scrollAreaStyle = new Style('''
position:relative;
will-change: transform;'''
);
FixedHeightScrollable({
Object key
}) : super(key: key);
FixedHeightScrollable({ Object key }) : super(key: key);
ScrollBehavior createScrollBehavior() => new OverscrollBehavior();
OverscrollBehavior get scrollBehavior => super.scrollBehavior as OverscrollBehavior;
@ -42,23 +29,16 @@ abstract class FixedHeightScrollable extends Scrollable {
}
void _measureHeights() {
trace('FixedHeightScrollable::_measureHeights', () {
if (_itemHeight != null)
return;
var root = getRoot();
if (root == null)
return;
var item = root.firstChild.firstChild;
if (item == null)
return;
setState(() {
_height = root.height;
assert(_height > 0);
_itemHeight = item.height;
assert(_itemHeight > 0);
scrollBehavior.containerHeight = _height;
scrollBehavior.contentsHeight = _itemHeight * _itemCount;
});
if (_itemHeight != null)
return;
setState(() {
// TODO(abarth): Actually measure these heights.
_height = 500.0; // root.height;
assert(_height > 0);
_itemHeight = 100.0; // item.height;
assert(_itemHeight > 0);
scrollBehavior.containerHeight = _height;
scrollBehavior.contentsHeight = _itemHeight * _itemCount;
});
}
@ -70,12 +50,13 @@ abstract class FixedHeightScrollable extends Scrollable {
if (_itemHeight == null)
new Future.microtask(_measureHeights);
Matrix4 transform = new Matrix4.identity();
if (_height > 0.0 && _itemHeight != null) {
if (scrollOffset < 0.0) {
double visibleHeight = _height + scrollOffset;
drawCount = (visibleHeight / _itemHeight).round() + 1;
transformStyle =
'transform: translateY(${(-scrollOffset).toStringAsFixed(2)}px)';
transform.translate(0.0, -scrollOffset);
} else {
drawCount = (_height / _itemHeight).ceil() + 1;
double alignmentDelta = -scrollOffset % _itemHeight;
@ -85,18 +66,16 @@ abstract class FixedHeightScrollable extends Scrollable {
double drawStart = scrollOffset + alignmentDelta;
itemNumber = math.max(0, (drawStart / _itemHeight).floor());
transformStyle =
'transform: translateY(${(alignmentDelta).toStringAsFixed(2)}px)';
transform.translate(0.0, alignmentDelta);
}
}
return new Container(
style: _style,
// TODO(abarth): Add a clip.
return new BlockContainer(
children: [
new Container(
style: _scrollAreaStyle,
inlineStyle: transformStyle,
children: buildItems(itemNumber, drawCount)
new Transform(
transform: transform,
child: new BlockContainer(children: buildItems(itemNumber, drawCount))
)
]
);