public Viewport(
Key key = null,
AxisDirection axisDirection = AxisDirection.down,
AxisDirection?crossAxisDirection = null,
float anchor = 0.0f,
ViewportOffset offset = null,
Key center = null,
float?cacheExtent = null,
CacheExtentStyle cacheExtentStyle = CacheExtentStyle.pixel,
List <Widget> slivers = null
) : base(key: key, children: slivers)
{
D.assert(offset != null);
D.assert(slivers != null);
D.assert(center == null || LinqUtils <Widget> .WhereList(slivers, ((Widget child) => child.key == center)).Count() == 1);
D.assert(cacheExtentStyle != null);
D.assert(cacheExtentStyle != CacheExtentStyle.viewport || cacheExtent != null);
this.axisDirection = axisDirection;
this.crossAxisDirection = crossAxisDirection;
this.anchor = anchor;
this.offset = offset;
this.center = center;
this.cacheExtent = cacheExtent;
this.cacheExtentStyle = cacheExtentStyle;
}
public static ScrollMetrics copyWith(ScrollMetrics it,
float?minScrollExtent = null,
float?maxScrollExtent = null,
float?pixels = null,
float?viewportDimension = null,
AxisDirection?axisDirection = null,
float?viewportFraction = null
)
{
if (it is IPageMetrics)
{
return(new PageMetrics(
minScrollExtent: minScrollExtent ?? it.minScrollExtent,
maxScrollExtent: maxScrollExtent ?? it.maxScrollExtent,
pixels: pixels ?? it.pixels,
viewportDimension: viewportDimension ?? it.viewportDimension,
axisDirection: axisDirection ?? it.axisDirection,
viewportFraction: viewportFraction ?? ((IPageMetrics)it).viewportFraction
));
}
return(new FixedScrollMetrics(
minScrollExtent: minScrollExtent ?? it.minScrollExtent,
maxScrollExtent: maxScrollExtent ?? it.maxScrollExtent,
pixels: pixels ?? it.pixels,
viewportDimension: viewportDimension ?? it.viewportDimension,
axisDirection: axisDirection ?? it.axisDirection
));
}
public ShrinkWrappingViewport(
Key key = null,
AxisDirection?axisDirection = AxisDirection.down,
AxisDirection?crossAxisDirection = null,
ViewportOffset offset = null,
List <Widget> slivers = null
) : base(key: key, children: slivers ?? new List <Widget>())
{
D.assert(offset != null);
this.axisDirection = axisDirection;
this.crossAxisDirection = crossAxisDirection;
this.offset = offset;
}
AxisDirection?_getDirection(BuildContext context)
{
switch (widget.scrollDirection)
{
case Axis.horizontal:
D.assert(WidgetsD.debugCheckHasDirectionality(context));
TextDirection textDirection = Directionality.of(context);
AxisDirection?axisDirection = AxisUtils.textDirectionToAxisDirection(textDirection);
return(widget.reverse ? AxisUtils.flipAxisDirection(axisDirection) : axisDirection);
case Axis.vertical:
return(widget.reverse ? AxisDirection.up : AxisDirection.down);
}
throw new UIWidgetsError("fail to get axis direction");
}
public static bool axisDirectionIsReversed(AxisDirection?axisDirection)
{
D.assert(axisDirection != null);
switch (axisDirection)
{
case AxisDirection.up:
case AxisDirection.left:
return(true);
case AxisDirection.down:
case AxisDirection.right:
return(false);
}
throw new Exception("unknown axisDirection");
}
public static Axis?axisDirectionToAxis(AxisDirection?axisDirection)
{
D.assert(axisDirection != null);
switch (axisDirection)
{
case AxisDirection.up:
case AxisDirection.down:
return(Axis.vertical);
case AxisDirection.left:
case AxisDirection.right:
return(Axis.horizontal);
}
return(null);
}
public static AxisDirection?applyGrowthDirectionToAxisDirection(
AxisDirection?axisDirection, GrowthDirection?growthDirection)
{
D.assert(axisDirection != null);
D.assert(growthDirection != null);
switch (growthDirection)
{
case GrowthDirection.forward:
return(axisDirection);
case GrowthDirection.reverse:
return(AxisUtils.flipAxisDirection(axisDirection));
}
throw new Exception("unknown growthDirection");
}
public override Widget build(BuildContext context)
{
AxisDirection?axisDirection = _getDirection(context);
ScrollPhysics physics = new _ForceImplicitScrollPhysics(
allowImplicitScrolling: widget.allowImplicitScrolling
).applyTo(widget.pageSnapping
? PageViewUtils._kPagePhysics.applyTo(widget.physics)
: widget.physics);
return(new NotificationListener <ScrollNotification>(
onNotification: (ScrollNotification notification) => {
if (notification.depth == 0 && widget.onPageChanged != null &&
notification is ScrollUpdateNotification)
{
IPageMetrics metrics = (IPageMetrics)notification.metrics;
int currentPage = metrics.page.round();
if (currentPage != _lastReportedPage)
{
_lastReportedPage = currentPage;
widget.onPageChanged(currentPage);
}
}
return false;
},
child: new Scrollable(
dragStartBehavior: widget.dragStartBehavior,
axisDirection: axisDirection,
controller: widget.controller,
physics: physics,
viewportBuilder: (BuildContext _context, ViewportOffset position) => {
return new Viewport(
cacheExtent: widget.allowImplicitScrolling ? 1.0f : 0.0f,
cacheExtentStyle: CacheExtentStyle.viewport,
axisDirection: axisDirection,
offset: position,
slivers: new List <Widget> {
new SliverFillViewport(
viewportFraction: widget.controller.viewportFraction,
_delegate: widget.childrenDelegate
)
}
);
}
)
));
}
public PageMetrics copyWith(
float?minScrollExtent = null,
float?maxScrollExtent = null,
float?pixels = null,
float?viewportDimension = null,
AxisDirection?axisDirection = null,
float?viewportFraction = null
)
{
return(new PageMetrics(
minScrollExtent: minScrollExtent ?? this.minScrollExtent,
maxScrollExtent: maxScrollExtent ?? this.maxScrollExtent,
pixels: pixels ?? this.pixels,
viewportDimension: viewportDimension ?? this.viewportDimension,
axisDirection: axisDirection ?? this.axisDirection,
viewportFraction: viewportFraction ?? this.viewportFraction
));
}
public FixedExtentMetrics copyWith(
float?minScrollExtent = null,
float?maxScrollExtent = null,
float?pixels = null,
float?viewportDimension = null,
AxisDirection?axisDirection = null,
int?itemIndex = null
)
{
return(new FixedExtentMetrics(
minScrollExtent: minScrollExtent ?? this.minScrollExtent,
maxScrollExtent: maxScrollExtent ?? this.maxScrollExtent,
pixels: pixels ?? this.pixels,
viewportDimension: viewportDimension ?? this.viewportDimension,
axisDirection: axisDirection ?? this.axisDirection,
itemIndex: itemIndex ?? this.itemIndex
));
}
public Scrollable(
Key key = null,
AxisDirection?axisDirection = AxisDirection.down,
ScrollController controller = null,
ScrollPhysics physics = null,
ViewportBuilder viewportBuilder = null,
ScrollIncrementCalculator incrementCalculator = null,
DragStartBehavior dragStartBehavior = DragStartBehavior.start
) : base(key: key)
{
D.assert(axisDirection != null);
D.assert(viewportBuilder != null);
this.axisDirection = axisDirection.Value;
this.controller = controller;
this.physics = physics;
this.viewportBuilder = viewportBuilder;
this.incrementCalculator = incrementCalculator;
this.dragStartBehavior = dragStartBehavior;
}
public static AxisDirection?flipAxisDirection(AxisDirection?axisDirection)
{
D.assert(axisDirection != null);
switch (axisDirection.Value)
{
case AxisDirection.up:
return(AxisDirection.down);
case AxisDirection.right:
return(AxisDirection.left);
case AxisDirection.down:
return(AxisDirection.up);
case AxisDirection.left:
return(AxisDirection.right);
}
return(null);
}
public Viewport(
Key key = null,
AxisDirection axisDirection = AxisDirection.down,
AxisDirection?crossAxisDirection = null,
float anchor = 0.0f,
ViewportOffset offset = null,
Key center = null,
float?cacheExtent = null,
List <Widget> slivers = null
) : base(key: key, children: slivers)
{
D.assert(offset != null);
D.assert(center == null || this.children.Count(child => child.key == center) == 1);
this.axisDirection = axisDirection;
this.crossAxisDirection = crossAxisDirection;
this.anchor = anchor;
this.offset = offset;
this.center = center;
this.cacheExtent = cacheExtent;
}
public override Widget build(BuildContext context)
{
List <Widget> slivers = buildSlivers(context);
AxisDirection?axisDirection = getDirection(context);
ScrollController scrollController = primary ? PrimaryScrollController.of(context) : controller;
Scrollable scrollable = new Scrollable(
dragStartBehavior: dragStartBehavior,
axisDirection: axisDirection,
controller: scrollController,
physics: physics,
viewportBuilder: (viewportContext, offset) =>
buildViewport(viewportContext, offset, axisDirection, slivers)
);
Widget scrollableResult = primary && scrollController != null
? (Widget)PrimaryScrollController.none(child: scrollable)
: scrollable;
if (keyboardDismissBehavior == ScrollViewKeyboardDismissBehavior.onDrag)
{
return(new NotificationListener <ScrollUpdateNotification>(
child: scrollableResult,
onNotification: (ScrollUpdateNotification notification) => {
FocusScopeNode focusScope = FocusScope.of(context);
if (notification.dragDetails != null && focusScope.hasFocus)
{
focusScope.unfocus();
}
return false;
}
));
}
else
{
return(scrollableResult);
}
}
public void update(ScrollMetrics metrics, AxisDirection axisDirection)
{
this._lastMetrics = metrics;
this._lastAxisDirection = axisDirection;
this.notifyListeners();
}
public static AxisDirection?getDefaultCrossAxisDirection(BuildContext context, AxisDirection?axisDirection)
{
D.assert(axisDirection != null);
switch (axisDirection)
{
case AxisDirection.up:
return(AxisUtils.textDirectionToAxisDirection(Directionality.of(context)));
case AxisDirection.right:
return(AxisDirection.down);
case AxisDirection.down:
return(AxisUtils.textDirectionToAxisDirection(Directionality.of(context)));
case AxisDirection.left:
return(AxisDirection.down);
}
return(null);
}
