public static void AddConstraints(this UIView view, IEnumerable <FluentLayout> fluentLayouts) => view.AddConstraints(fluentLayouts
.Where(fluent => fluent != null)
.Select(fluent => fluent.Constraint.Value)
.ToArray());
void SetStackConstraints()
{
if (nativeView == null)
{
return;
}
CreateNativeViewsForChildren();
var horizontal = Orientation == StackOrientation.Horizontal;
var lefts = horizontal ?
children.Where(x => x.Layout.HorizontalAlignment == HorizontalAlignment.Left).ToList() :
children.Where(x => x.Layout.VerticalAlignment == VerticalAlignment.Top).ToList();
var centers = horizontal ?
children.Where(x => x.Layout.HorizontalAlignment == HorizontalAlignment.Center).ToList() :
children.Where(x => x.Layout.VerticalAlignment == VerticalAlignment.Center).ToList();
var rights = horizontal ?
children.Where(x => x.Layout.HorizontalAlignment == HorizontalAlignment.Right).ToList() :
children.Where(x => x.Layout.VerticalAlignment == VerticalAlignment.Bottom).ToList();
var newConstraints = new List <NSLayoutConstraint> ();
//
// Align the major axis
//
var leftAttr = horizontal ? NSLayoutAttribute.Left : NSLayoutAttribute.Top;
var rightAttr = horizontal ? NSLayoutAttribute.Right : NSLayoutAttribute.Bottom;
//var centerAttr = horizontal ? NSLayoutAttribute.CenterX : NSLayoutAttribute.CenterY;
Action <NativeView, NSLayoutAttribute, NativeView, NSLayoutAttribute> eq = (v1, a1, v2, a2) => {
newConstraints.Add(NSLayoutConstraint.Create(v1, a1, NSLayoutRelation.Equal, v2, a2, 1, 0));
};
Child prev = null;
if (lefts.Count > 0)
{
var first = lefts.First();
eq(nativeView, leftAttr, first.NativeView, leftAttr);
prev = first;
foreach (var c in lefts.Skip(1))
{
eq(prev.NativeView, rightAttr, c.NativeView, leftAttr);
prev = c;
}
}
Child subs = null;
if (rights.Count > 0)
{
var last = rights.Last();
eq(nativeView, rightAttr, last.NativeView, rightAttr);
subs = last;
foreach (var c in rights.Take(rights.Count - 1).Reverse())
{
eq(subs.NativeView, leftAttr, c.NativeView, rightAttr);
subs = c;
}
}
if (centers.Count > 0)
{
throw new NotImplementedException("Center alignment not yet supported");
}
//
// Align the minor axis
//
foreach (var c in children)
{
var a = NSLayoutAttribute.Left;
if (horizontal)
{
switch (c.Layout.VerticalAlignment)
{
case VerticalAlignment.Top:
a = NSLayoutAttribute.Top;
break;
case VerticalAlignment.Center:
a = NSLayoutAttribute.CenterY;
break;
default:
a = NSLayoutAttribute.Bottom;
break;
}
}
else
{
switch (c.Layout.HorizontalAlignment)
{
case HorizontalAlignment.Left:
a = NSLayoutAttribute.Left;
break;
case HorizontalAlignment.Center:
a = NSLayoutAttribute.CenterX;
break;
default:
a = NSLayoutAttribute.Right;
break;
}
}
eq(nativeView, a, c.NativeView, a);
}
// Swap out the old, put in the new
if (constraints != null)
{
nativeView.RemoveConstraints(constraints);
}
constraints = newConstraints.ToArray();
nativeView.AddConstraints(constraints);
}
public static void AddConstraints(this UIView view, params FluentLayout[] fluentLayouts) => view.AddConstraints(fluentLayouts.AsEnumerable());