public static void _focusAndEnsureVisible(
FocusNode node,
ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicitPolicy
)
{
node.requestFocus();
Scrollable.ensureVisible(node.context, alignment: 1.0f, alignmentPolicy: alignmentPolicy);
}
public Future ensureVisible(
RenderObject renderObject,
float alignment = 0.0f,
TimeSpan?duration = null,
Curve curve = null,
ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicitPolicy
)
{
D.assert(renderObject.attached);
RenderAbstractViewport viewport = RenderViewportUtils.of(renderObject);
D.assert(viewport != null);
float target = 0f;
switch (alignmentPolicy)
{
case ScrollPositionAlignmentPolicy.explicitPolicy:
target = viewport.getOffsetToReveal(renderObject, alignment).offset.clamp(minScrollExtent, maxScrollExtent);
break;
case ScrollPositionAlignmentPolicy.keepVisibleAtEnd:
target = viewport.getOffsetToReveal(renderObject, 1.0f).offset.clamp(minScrollExtent, maxScrollExtent);
if (target < pixels)
{
target = pixels;
}
break;
case ScrollPositionAlignmentPolicy.keepVisibleAtStart:
target = viewport.getOffsetToReveal(renderObject, 0.0f).offset.clamp(minScrollExtent, maxScrollExtent);
if (target > pixels)
{
target = pixels;
}
break;
}
if (foundation_.FloatEqual(target, pixels))
{
return(Future.value());
}
duration = duration ?? TimeSpan.Zero;
if (duration == TimeSpan.Zero)
{
jumpTo(target);
return(Future.value());
}
curve = curve ?? Curves.ease;
return(animateTo(target, duration: duration.Value, curve: curve));
}
public static Future ensureVisible(
BuildContext context,
float alignment = 0.0f,
TimeSpan?duration = null,
Curve curve = null,
ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicitPolicy
)
{
duration = duration ?? TimeSpan.Zero;
curve = curve ?? Curves.ease;
List <Future> futures = new List <Future>();
ScrollableState scrollable = of(context);
while (scrollable != null)
{
futures.Add(scrollable.position.ensureVisible(
context.findRenderObject(),
alignment: alignment,
duration: duration,
curve: curve,
alignmentPolicy: alignmentPolicy
));
context = scrollable.context;
scrollable = of(context);
}
if (futures.isEmpty() || duration == TimeSpan.Zero)
{
return(Future.value());
}
if (futures.Count == 1)
{
return(futures.Single());
}
return(Future.wait <object>(futures));
}
public bool _popPolicyDataIfNeeded(TraversalDirection direction, FocusScopeNode nearestScope, FocusNode focusedChild)
{
_DirectionalPolicyData policyData = _policyData[nearestScope];
if (policyData != null && policyData.history.isNotEmpty() && policyData.history.First().direction != direction)
{
if (policyData.history.Last().node.parent == null)
{
invalidateScopeData(nearestScope);
return(false);
}
bool popOrInvalidate(TraversalDirection _direction)
{
FocusNode lastNode = policyData.history.removeLast().node;
if (Scrollable.of(lastNode.context) != Scrollable.of(FocusManagerUtils.primaryFocus.context))
{
invalidateScopeData(nearestScope);
return(false);
}
ScrollPositionAlignmentPolicy alignmentPolicy = ScrollPositionAlignmentPolicy.explicitPolicy;
switch (_direction)
{
case TraversalDirection.up:
case TraversalDirection.left:
alignmentPolicy = ScrollPositionAlignmentPolicy.keepVisibleAtStart;
break;
case TraversalDirection.right:
case TraversalDirection.down:
alignmentPolicy = ScrollPositionAlignmentPolicy.keepVisibleAtEnd;
break;
}
FocusTravesalUtils._focusAndEnsureVisible(
lastNode,
alignmentPolicy: alignmentPolicy
);
return(true);
}
switch (direction)
{
case TraversalDirection.down:
case TraversalDirection.up:
switch (policyData.history.First().direction)
{
case TraversalDirection.left:
case TraversalDirection.right:
invalidateScopeData(nearestScope);
break;
case TraversalDirection.up:
case TraversalDirection.down:
if (popOrInvalidate(direction))
{
return(true);
}
break;
}
break;
case TraversalDirection.left:
case TraversalDirection.right:
switch (policyData.history.First().direction)
{
case TraversalDirection.left:
case TraversalDirection.right:
if (popOrInvalidate(direction))
{
return(true);
}
break;
case TraversalDirection.up:
case TraversalDirection.down:
invalidateScopeData(nearestScope);
break;
}
break;
}
}
if (policyData != null && policyData.history.isEmpty())
{
invalidateScopeData(nearestScope);
}
return(false);
}