protected override Size MeasureOverride(Size constraint)
{
int num;
double width;
UIElementCollection internalChildren = base.InternalChildren;
Size size = new Size();
Size availableSize = constraint;
bool flag = this.Orientation == Orientation.Horizontal;
int num2 = -1;
if (flag)
{
availableSize.Width = double.PositiveInfinity;
if (this.IsScrolling && this.CanVerticallyScroll)
{
availableSize.Height = double.PositiveInfinity;
}
num = this.IsScrolling ? CoerceOffsetToInteger(this._scrollData._offset.X, internalChildren.Count) : 0;
width = constraint.Width;
}
else
{
availableSize.Height = double.PositiveInfinity;
if (this.IsScrolling && this.CanHorizontallyScroll)
{
availableSize.Width = double.PositiveInfinity;
}
num = this.IsScrolling ? CoerceOffsetToInteger(this._scrollData._offset.Y, internalChildren.Count) : 0;
width = constraint.Height;
}
int num5 = 0;
int count = internalChildren.Count;
while (num5 < count)
{
UIElement element = internalChildren[num5];
if (element != null)
{
double height;
element.Measure(availableSize);
Size desiredSize = element.DesiredSize;
if (flag)
{
size.Width += desiredSize.Width;
size.Height = Math.Max(size.Height, desiredSize.Height);
height = desiredSize.Width;
}
else
{
size.Width = Math.Max(size.Width, desiredSize.Width);
size.Height += desiredSize.Height;
height = desiredSize.Height;
}
if ((this.IsScrolling && (num2 == -1)) && (num5 >= num))
{
width -= height;
if (DoubleUtil.LessThanOrClose(width, 0.0))
{
num2 = num5;
}
}
}
num5++;
}
if (this.IsScrolling)
{
Size viewport = constraint;
Size extent = size;
Vector offset = this._scrollData._offset;
if (num2 == -1)
{
num2 = internalChildren.Count - 1;
}
int num10 = (num > Children.Count - 1) ? Children.Count : num;
num10 = num10 < 0 ? num10 + Children.Count : num10;
while (num10 > 0)
{
double num7 = width;
if (flag)
{
num7 -= internalChildren[(num10 - 1) % Children.Count].DesiredSize.Width;
}
else
{
num7 -= internalChildren[(num10 - 1) % Children.Count].DesiredSize.Height;
}
if (DoubleUtil.LessThan(num7, 0.0))
{
break;
}
num10--;
width = num7;
}
int num8 = internalChildren.Count;
int num9 = num2 - num10;
if ((num9 == 0) || DoubleUtil.GreaterThanOrClose(width, 0.0))
{
num9++;
}
if (flag)
{
this._scrollData._physicalViewport = viewport.Width;
viewport.Width = num9;
extent.Width = num8;
offset.X = num;
offset.Y = Math.Max(0.0, Math.Min(offset.Y, extent.Height - viewport.Height));
}
else
{
this._scrollData._physicalViewport = viewport.Height;
viewport.Height = num9;
extent.Height = num8;
offset.Y = num;
offset.X = Math.Max(0.0, Math.Min(offset.X, extent.Width - viewport.Width));
}
size.Width = Math.Min(size.Width, constraint.Width);
size.Height = Math.Min(size.Height, constraint.Height);
this.VerifyScrollingData(viewport, extent, offset);
}
return(size);
}
private void MakeVisibleLogicalHelper(int childIndex, ref Vector newOffset, ref Rect newRect)
{
int x;
int width;
bool flag = this.Orientation == Orientation.Horizontal;
double num4 = 0.0;
if (flag)
{
x = (int)this._scrollData._computedOffset.X;
width = (int)this._scrollData._viewport.Width;
}
else
{
x = (int)this._scrollData._computedOffset.Y % Children.Count;
width = (int)this._scrollData._viewport.Height;
}
int num2 = x;
bool needsScroll = (childIndex >= x && childIndex < x + width || childIndex + Children.Count < x + width) ? false : true;
if (needsScroll)
{
int abst = (x + width - childIndex + Children.Count) % Children.Count;
bool scrollUp = false;
if ((childIndex < x) && (x - childIndex < abst))
{
abst = x - childIndex;
scrollUp = true;
}
if (abst > (Children.Count - width) / 2)
{
scrollUp = !scrollUp;
}
if (scrollUp)
{
num2 = childIndex;
}
else
{
Size desiredSize = base.InternalChildren[childIndex].DesiredSize;
double num5 = flag ? desiredSize.Width : desiredSize.Height;
double num6 = this._scrollData._physicalViewport - num5;
int num7 = childIndex;
while (DoubleUtil.GreaterThanOrClose(num6, 0.0))
{
num7 = ((num7 - 1) + Children.Count) % Children.Count;
desiredSize = base.InternalChildren[num7].DesiredSize;
num5 = flag ? desiredSize.Width : desiredSize.Height;
num4 += num5;
num6 -= num5;
}
if ((num7 != childIndex) && DoubleUtil.LessThan(num6, 0.0))
{
num4 -= num5;
num7++;
}
num2 = num7;
}
}
if (flag)
{
newOffset.X = num2;
newRect.X = num4;
newRect.Width = base.InternalChildren[childIndex].DesiredSize.Width;
}
else
{
newOffset.Y = num2;
newRect.Y = num4;
newRect.Height = base.InternalChildren[childIndex].DesiredSize.Height;
}
}
