您最多选择25个主题 主题必须以中文或者字母或数字开头,可以包含连字符 (-),并且长度不得超过35个字符
 
 
 
 
 
 

193 行
6.6 KiB

using System;
using System.Collections.Generic;
using System.Linq;
using RSG;
using Unity.UIWidgets.animation;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.ui;
namespace Unity.UIWidgets.widgets {
public class ScrollController : ChangeNotifier {
public ScrollController(
double initialScrollOffset = 0.0,
bool keepScrollOffset = true,
string debugLabel = null
) {
this._initialScrollOffset = initialScrollOffset;
this.keepScrollOffset = keepScrollOffset;
this.debugLabel = debugLabel;
}
public virtual double initialScrollOffset {
get { return this._initialScrollOffset; }
}
readonly double _initialScrollOffset;
public readonly bool keepScrollOffset;
public readonly string debugLabel;
public ICollection<ScrollPosition> positions {
get { return this._positions; }
}
readonly List<ScrollPosition> _positions = new List<ScrollPosition>();
public bool hasClients {
get { return this._positions.isNotEmpty(); }
}
public ScrollPosition position {
get {
D.assert(this._positions.isNotEmpty(), "ScrollController not attached to any scroll views.");
D.assert(this._positions.Count == 1, "ScrollController attached to multiple scroll views.");
return this._positions.Single();
}
}
public double offset {
get { return this.position.pixels; }
}
public IPromise animateTo(double to,
TimeSpan duration,
Curve curve
) {
D.assert(this._positions.isNotEmpty(), "ScrollController not attached to any scroll views.");
List<IPromise> animations = Enumerable.Repeat((IPromise) null, this._positions.Count).ToList();
for (int i = 0; i < this._positions.Count; i += 1) {
animations[i] = this._positions[i].animateTo(to, duration: duration, curve: curve);
}
return Promise.All(animations);
}
public void jumpTo(double value) {
D.assert(this._positions.isNotEmpty(), "ScrollController not attached to any scroll views.");
foreach (ScrollPosition position in new List<ScrollPosition>(this._positions)) {
position.jumpTo(value);
}
}
public virtual void attach(ScrollPosition position) {
D.assert(!this._positions.Contains(position));
this._positions.Add(position);
position.addListener(this.notifyListeners);
}
public virtual void detach(ScrollPosition position) {
D.assert(this._positions.Contains(position));
position.removeListener(this.notifyListeners);
this._positions.Remove(position);
}
public override void dispose() {
foreach (ScrollPosition position in this._positions) {
position.removeListener(this.notifyListeners);
}
base.dispose();
}
public virtual ScrollPosition createScrollPosition(
ScrollPhysics physics,
ScrollContext context,
ScrollPosition oldPosition
) {
return new ScrollPositionWithSingleContext(
physics: physics,
context: context,
initialPixels: this.initialScrollOffset,
keepScrollOffset: this.keepScrollOffset,
oldPosition: oldPosition,
debugLabel: this.debugLabel
);
}
public override string ToString() {
List<string> description = new List<string>();
this.debugFillDescription(description);
return $"{Diagnostics.describeIdentity(this)}({string.Join(", ", description.ToArray())})";
}
protected virtual void debugFillDescription(List<string> description) {
if (this.debugLabel != null) {
description.Add(this.debugLabel);
}
if (this.initialScrollOffset != 0.0) {
description.Add($"initialScrollOffset: {this.initialScrollOffset:F1}, ");
}
if (this._positions.isEmpty()) {
description.Add("no clients");
}
else if (this._positions.Count == 1) {
description.Add($"one client, offset {this.offset:F1}");
}
else {
description.Add(this._positions.Count + " clients");
}
}
}
public class TrackingScrollController : ScrollController {
public TrackingScrollController(
double initialScrollOffset = 0.0,
bool keepScrollOffset = true,
string debugLabel = null
) : base(initialScrollOffset: initialScrollOffset,
keepScrollOffset: keepScrollOffset,
debugLabel: debugLabel) {
}
readonly Dictionary<ScrollPosition, VoidCallback> _positionToListener =
new Dictionary<ScrollPosition, VoidCallback>();
ScrollPosition _lastUpdated;
double? _lastUpdatedOffset;
public ScrollPosition mostRecentlyUpdatedPosition {
get { return this._lastUpdated; }
}
public override double initialScrollOffset {
get { return this._lastUpdatedOffset ?? base.initialScrollOffset; }
}
public override void attach(ScrollPosition position) {
base.attach(position);
D.assert(!this._positionToListener.ContainsKey(position));
this._positionToListener[position] = () => {
this._lastUpdated = position;
this._lastUpdatedOffset = position.pixels;
};
position.addListener(this._positionToListener[position]);
}
public override void detach(ScrollPosition position) {
base.detach(position);
D.assert(this._positionToListener.ContainsKey(position));
position.removeListener(this._positionToListener[position]);
this._positionToListener.Remove(position);
if (this._lastUpdated == position) {
this._lastUpdated = null;
}
if (this._positionToListener.isEmpty()) {
this._lastUpdatedOffset = null;
}
}
public override void dispose() {
foreach (ScrollPosition position in this.positions) {
D.assert(this._positionToListener.ContainsKey(position));
position.removeListener(this._positionToListener[position]);
}
base.dispose();
}
}
}