private void UpdateContentOffset(bool animated, PagerScroll pagerScroll, CGRect toFrame, int toIndex)
{
if (pagerScroll != PagerScroll.No || (pagerScroll != PagerScroll.ScrollOnlyIfOutOfScreen && (toFrame.X < ContentOffset.X || toFrame.X >= (ContentOffset.X + Frame.Size.Width - ContentInset.Left))))
{
nfloat targetContentOffset = ContentSize.Width > Frame.Size.Width ? ContentOffsetForCell(toFrame, toIndex) : 0;
SetContentOffset(new CGPoint(targetContentOffset, 0), animated);
}
}
public void Move(nint fromIndex, nint toIndex, nfloat progressPercentage, PagerScroll pagerScroll)
{
SelectedIndex = progressPercentage > 0.5f ? toIndex : fromIndex;
var fromFrame = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(fromIndex, 0)).Frame;
var numberOfItems = DataSource.GetItemsCount(this, 0);
CGRect toFrame;
if (toIndex < 0 || toIndex > numberOfItems - 1)
{
if (toIndex < 0)
{
var cellAtts = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(0, 0));
toFrame = cellAtts.Frame;
toFrame.Offset(-cellAtts.Frame.Width, 0);
}
else
{
var cellAtts = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(numberOfItems - 1, 0));
toFrame = cellAtts.Frame;
toFrame.Offset(cellAtts.Frame.Width, 0);
}
}
else
{
toFrame = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(toIndex, 0)).Frame;
}
var targetFrame = fromFrame;
targetFrame.Height = SelectedBar.Frame.Height;
targetFrame.Width += (toFrame.Size.Width - fromFrame.Size.Width) * progressPercentage;
targetFrame.X += (toFrame.X - fromFrame.X) * progressPercentage;
SelectedBar.Frame = new CGRect(targetFrame.X, SelectedBar.Frame.Y, targetFrame.Width, SelectedBar.Frame.Height);
nfloat targetContentOffset = 0.0f;
if (ContentSize.Width > Frame.Width)
{
var toContentOffset = ContentOffsetForCell(toFrame, toIndex);
var fromContentOffset = ContentOffsetForCell(fromFrame, fromIndex);
targetContentOffset = fromContentOffset + ((toContentOffset - fromContentOffset) * progressPercentage);
}
var animated = Math.Abs(ContentOffset.X - targetContentOffset) > 30 || (fromIndex == toIndex);
SetContentOffset(new CGPoint(targetContentOffset, 0), animated);
}
public void MoveToIndex(int toIndex, bool animated, SwipeDirection swipeDirection, PagerScroll pagerScroll)
{
selectedIndex = toIndex;
UpdateSelectedBarPosition(animated, swipeDirection: swipeDirection, pagerScroll: pagerScroll);
}
public void UpdateSelectedBarPosition(bool animated, SwipeDirection swipeDirection, PagerScroll pagerScroll)
{
var selectedBarFrame = SelectedBar.Frame;
NSIndexPath selectedCellIndexPath = NSIndexPath.FromItemSection(new nint(selectedIndex), 0);
UICollectionViewLayoutAttributes attributes = GetLayoutAttributesForItem(selectedCellIndexPath);
CGRect selectedCellFrame = attributes.Frame;
UpdateContentOffset(animated, pagerScroll: pagerScroll, toFrame: selectedCellFrame, toIndex: selectedCellIndexPath.Row);
selectedBarFrame.Size = new CGSize(selectedCellFrame.Size.Width, selectedBarFrame.Size.Height);
selectedBarFrame.X = selectedCellFrame.X;
if (animated)
{
UIView.Animate(0.3, () =>
{
SelectedBar.Frame = selectedBarFrame;
});
}
else
{
SelectedBar.Frame = selectedBarFrame;
}
}
public void MoveFromIndex(int fromIndex, int toIndex, nfloat progressPercentage, PagerScroll pagerScroll)
{
selectedIndex = progressPercentage > 0.5 ? toIndex : fromIndex;
CGRect fromFrame = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(fromIndex, 0)).Frame;
var numberOfItems = DataSource.GetItemsCount(this, 0);
CGRect toFrame;
if (toIndex < 0 || toIndex > numberOfItems - 1)
{
if (toIndex < 0)
{
var cellAtts = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(0, 0));
toFrame = CGRect.Inflate(cellAtts.Frame, -cellAtts.Frame.Size.Width, 0);
}
else
{
var cellAtts = GetLayoutAttributesForItem(NSIndexPath.FromItemSection((numberOfItems - 1), 0));
toFrame = CGRect.Inflate(cellAtts.Frame, cellAtts.Frame.Size.Width, 0);
}
}
else
{
toFrame = GetLayoutAttributesForItem(NSIndexPath.FromItemSection(toIndex, 0)).Frame;
}
CGRect targetFrame = fromFrame;
if (this.SelectedBarWidth.HasValue)
{
targetFrame.Size = new CGSize(this.SelectedBarWidth.Value, SelectedBar.Frame.Size.Height);
targetFrame.X = fromFrame.X + (fromFrame.Width - this.SelectedBarWidth.Value) / 2;
targetFrame.X += (toFrame.X + (toFrame.Width - this.SelectedBarWidth.Value) / 2 - targetFrame.X) * progressPercentage;
}
else
{
var targetWidth = targetFrame.Size.Width + (toFrame.Size.Width - fromFrame.Size.Width) * progressPercentage;
targetFrame.Size = new CGSize(targetWidth, SelectedBar.Frame.Size.Height);
targetFrame.X += (toFrame.X - fromFrame.X) * progressPercentage;
}
SelectedBar.Frame = new CGRect(targetFrame.X, SelectedBar.Frame.Y, targetFrame.Size.Width, SelectedBar.Frame.Size.Height);
nfloat targetContentOffset = 0.0f;
if (ContentSize.Width > Frame.Size.Width)
{
var toContentOffset = ContentOffsetForCell(toFrame, toIndex);
var fromContentOffset = ContentOffsetForCell(fromFrame, fromIndex);
targetContentOffset = fromContentOffset + ((toContentOffset - fromContentOffset) * progressPercentage);
}
SetContentOffset(new CGPoint(targetContentOffset, 0), animated: false);
}
public void MoveTo(nint index, bool animated, SwipeDirection swipeDirection, PagerScroll pagerScroll)
{
SelectedIndex = index;
UpdateSelectedBarPosition(animated, swipeDirection, pagerScroll);
}
private void UpdateSelectedBarPosition(bool animated, SwipeDirection swipeDirection, PagerScroll pagerScroll)
{
var selectedBarFrame = SelectedBar.Frame;
var selectedCellIndexPath = NSIndexPath.FromItemSection(SelectedIndex, 0);
var attributes = GetLayoutAttributesForItem(selectedCellIndexPath);
var selectedCellFrame = attributes.Frame;
UpdateContentOffset(animated, pagerScroll, selectedCellFrame, (selectedCellIndexPath as NSIndexPath).Row);
selectedBarFrame.Width = selectedCellFrame.Width;
selectedBarFrame.X = selectedCellFrame.X;
if (animated)
{
UIView.Animate(duration: 0.3, animation: () =>
{
this.SelectedBar.Frame = selectedBarFrame;
});
}
else
{
SelectedBar.Frame = selectedBarFrame;
}
}