private void BringIntoView(int index, BringIntoViewMode mode)
{
if (index < 0 || index >= ItemsCount)
{
return;
}
Offset = CalcBringIntoViewOffset(index, mode, Viewport, Extent, Offset);
_enqueueBringIntoViewRequest = null;
}
private Vector CalcBringIntoViewOffset(int index, BringIntoViewMode mode, Size viewport, Size extent, Vector offset)
{
if (index < 0 || index >= ItemsCount)
{
return(offset);
}
var orientation = Orientation;
var orientedViewPort = viewport.AsOriented(orientation);
var orientedExtent = extent.AsOriented(orientation);
var orientedOffset = offset.AsOriented(orientation);
var orientedViewer = new OrientedScrollView(orientation, orientedViewPort.Direct, orientedExtent.Direct,
orientedOffset.Direct);
orientedViewer.Offset = orientedViewer.Offset - index > 0.0 || mode == BringIntoViewMode.Top
? index
: index - orientedViewer.Viewport + 1.0;
orientedOffset.Direct = orientedViewer.Offset;
return(orientedOffset.Vector);
}
/// <summary>
/// Make a view visible into a scroll view
/// </summary>
/// <param name="scrollView">The scroll view to scroll to get the item visible.</param>
/// <param name="view">View to make visible.</param>
/// <param name="mode">Specifies a mode to use to place the view into the view port.</param>
/// <param name="padding">
/// Add an extra margin to the view from the edge of the view port when mode is
/// <seealso cref="BringIntoViewMode.TopLeftOfViewPort"/> or <seealso cref="BringIntoViewMode.BottomRightOfViewPort"/>.
/// </param>
/// <param name="animationMode">Specifies animation mode to use to animate the scrolling (or not).</param>
public static void BringIntoView(
this UIScrollView scrollView,
UIView view,
BringIntoViewMode mode = BringIntoViewMode.ClosestEdge,
int padding = 0,
ScrollingMode animationMode = ScrollingMode.Forced)
{
var boundsOfViewInScrollViewCoordinatesSystem = scrollView.ConvertRectFromView(view.Bounds, view);
var bounds = scrollView.Bounds;
var inset = scrollView.ContentInset;
var viewPort = new CGRect
(
bounds.X + inset.Left,
bounds.Y + inset.Top,
bounds.Width - inset.Left - inset.Right,
bounds.Height - inset.Top - inset.Bottom
);
nfloat x, y;
switch (mode)
{
case BringIntoViewMode.ClosestEdge:
scrollView.ScrollRectToVisible(boundsOfViewInScrollViewCoordinatesSystem, animationMode != ScrollingMode.NotAnimated);
return;
case BringIntoViewMode.TopLeftOfViewPort:
x = boundsOfViewInScrollViewCoordinatesSystem.Left - padding;
y = boundsOfViewInScrollViewCoordinatesSystem.Top - padding;
break;
case BringIntoViewMode.CenterOfViewPort:
x = boundsOfViewInScrollViewCoordinatesSystem.Left - (viewPort.Width / 2) + (boundsOfViewInScrollViewCoordinatesSystem.Width / 2);
y = boundsOfViewInScrollViewCoordinatesSystem.Top - (viewPort.Height / 2) + (boundsOfViewInScrollViewCoordinatesSystem.Height / 2);
break;
case BringIntoViewMode.BottomRightOfViewPort:
x = boundsOfViewInScrollViewCoordinatesSystem.Right - viewPort.Width + padding;
y = boundsOfViewInScrollViewCoordinatesSystem.Bottom - viewPort.Height + padding;
break;
default:
throw new NotSupportedException("Unknown scroll into view behavior");
}
var maxX = scrollView.ContentSize.Width - viewPort.Width;
var maxY = scrollView.ContentSize.Height - viewPort.Height;
x = (nfloat)Math.Max(0, (nfloat)Math.Min(maxX, x));
y = (nfloat)Math.Max(0, (nfloat)Math.Min(maxY, y));
switch (animationMode)
{
case ScrollingMode.NotAnimated:
scrollView.SetContentOffset(new CGPoint(x, y), false);
break;
case ScrollingMode.Animated:
scrollView.SetContentOffset(new CGPoint(x, y), true);
break;
case ScrollingMode.Forced:
scrollView.ContentOffset = new CGPoint(x, y);
break;
default:
throw new NotSupportedException("Unknown animation mode");
}
}
protected BringIntoViewRequest(int index, BringIntoViewMode mode, int fallbackIndex)
{
Index = index;
Mode = mode;
FallbackIndex = fallbackIndex;
}
