protected override Vector2 ArrangeOverride(Vector2 finalSize)
{
var separation = (int)(ActualSeparation * UIScale);
#region Scroll
var cHeight = _totalHeight;
var vBarSize = _vScrollBar.DesiredSize.X;
var(sWidth, sHeight) = finalSize;
try
{
// Suppress events to avoid weird recursion.
_suppressScrollValueChanged = true;
if (sHeight < cHeight)
{
sWidth -= vBarSize;
}
if (sHeight < cHeight)
{
_vScrollBar.Visible = true;
_vScrollBar.Page = sHeight;
_vScrollBar.MaxValue = cHeight;
}
else
{
_vScrollBar.Visible = false;
}
}
finally
{
_suppressScrollValueChanged = false;
}
if (_vScrollBar.Visible)
{
_vScrollBar.Arrange(UIBox2.FromDimensions(Vector2.Zero, finalSize));
}
#endregion
#region Rebuild Children
/*
* Example:
*
* var _itemHeight = 32;
* var separation = 3;
* 32 | 32 | Control.Size.Y 0
* 35 | 3 | Padding
* 67 | 32 | Control.Size.Y 1
* 70 | 3 | Padding
* 102 | 32 | Control.Size.Y 2
* 105 | 3 | Padding
* 137 | 32 | Control.Size.Y 3
*
* If viewport height is 60
* visible should be 2 items (start = 0, end = 1)
*
* scroll.Y = 11
* visible should be 3 items (start = 0, end = 2)
*
* start expected: 11 (item: 0)
* var start = (int) (scroll.Y
*
* if (scroll == 32) then { start = 1 }
* var start = (int) (scroll.Y + separation / (_itemHeight + separation));
* var start = (int) (32 + 3 / (32 + 3));
* var start = (int) (35 / 35);
* var start = (int) (1);
*
* scroll = 0, height = 36
* if (scroll + height == 36) then { end = 2 }
* var end = (int) Math.Ceiling(scroll.Y + height / (_itemHeight + separation));
* var end = (int) Math.Ceiling(0 + 36 / (32 + 3));
* var end = (int) Math.Ceiling(36 / 35);
* var end = (int) Math.Ceiling(1.02857);
* var end = (int) 2;
*
*/
var scroll = GetScrollValue();
var oldTopIndex = _topIndex;
_topIndex = (int)((scroll.Y + separation) / (_itemHeight + separation));
if (_topIndex != oldTopIndex)
{
_updateChildren = true;
}
var oldBottomIndex = _bottomIndex;
_bottomIndex = (int)Math.Ceiling((scroll.Y + Height) / (_itemHeight + separation));
_bottomIndex = Math.Min(_bottomIndex, _count);
if (_bottomIndex != oldBottomIndex)
{
_updateChildren = true;
}
// When scrolling only rebuild visible list when a new item should be visible
if (_updateChildren)
{
_updateChildren = false;
foreach (var child in Children.ToArray())
{
if (child == _vScrollBar)
{
continue;
}
RemoveChild(child);
}
if (_entityUids != null)
{
for (var i = _topIndex; i < _bottomIndex; i++)
{
var entity = _entityUids[i];
var button = new EntityContainerButton(entity);
button.OnPressed += OnItemPressed;
GenerateItem?.Invoke(entity, button);
AddChild(button);
}
}
_vScrollBar.SetPositionLast();
}
#endregion
#region Layout Children
// Use pixel position
var pixelWidth = (int)(sWidth * UIScale);
var offset = (int)-((scroll.Y - _topIndex * (_itemHeight + separation)) * UIScale);
var first = true;
foreach (var child in Children)
{
if (child == _vScrollBar)
{
continue;
}
if (!first)
{
offset += separation;
}
first = false;
var size = child.DesiredPixelSize.Y;
var targetBox = new UIBox2i(0, offset, pixelWidth, offset + size);
child.ArrangePixel(targetBox);
offset += size;
}
#endregion
return(finalSize);
}