/// <summary>
/// Children will be stretched to fit horizontally (if vertically oriented) or vertically (if horizontally
/// oriented).
///
/// There are essentially three possible layout states:
/// 1. The track is enabled and the thumb is proportionally sizing.
/// 2. The track is enabled and the thumb has reached its minimum size.
/// 3. The track is disabled or there is not enough room for the thumb.
/// Track elements are not displayed, and will not be arranged.
/// <seealso cref="FrameworkElement.ArrangeOverride" />
/// </summary>
protected override Size ArrangeOverride(Size arrangeSize)
{
double decreaseButtonLength, thumbLength, increaseButtonLength;
bool isVertical = (Orientation == Orientation.Vertical);
double viewportSize = Math.Max(0.0, ViewportSize);
// If viewport is NaN, compute thumb's size based on its desired size,
// otherwise compute the thumb base on the viewport and extent properties
if (double.IsNaN(viewportSize))
{
ComputeSliderLengths(arrangeSize, isVertical, out decreaseButtonLength, out thumbLength, out increaseButtonLength);
}
else
{
// Don't arrange if there's not enough content or the track is too small
if (!ComputeScrollBarLengths(arrangeSize, viewportSize, isVertical, out decreaseButtonLength, out thumbLength, out increaseButtonLength))
{
return(arrangeSize);
}
}
// Layout the pieces of track
Point offset = new Point();
Size pieceSize = arrangeSize;
bool isDirectionReversed = IsDirectionReversed;
if (isVertical)
{
// Vertical Normal : |Inc Button |
// |Thumb |
// |Dec Button |
// Vertical Reversed : |Dec Button |
// |Thumb |
// |Inc Button |
CoerceLength(ref decreaseButtonLength, arrangeSize.Height);
CoerceLength(ref increaseButtonLength, arrangeSize.Height);
CoerceLength(ref thumbLength, arrangeSize.Height);
offset.Y = isDirectionReversed ? decreaseButtonLength + thumbLength : 0.0;
pieceSize.Height = increaseButtonLength;
if (IncreaseRepeatButton != null)
{
IncreaseRepeatButton.Arrange(new Rect(offset, pieceSize));
}
offset.Y = isDirectionReversed ? 0.0 : increaseButtonLength + thumbLength;
pieceSize.Height = decreaseButtonLength;
if (DecreaseRepeatButton != null)
{
DecreaseRepeatButton.Arrange(new Rect(offset, pieceSize));
}
offset.Y = isDirectionReversed ? decreaseButtonLength : increaseButtonLength;
pieceSize.Height = thumbLength;
if (Thumb != null)
{
Thumb.Arrange(new Rect(offset, pieceSize));
}
ThumbCenterOffset = offset.Y + (thumbLength * 0.5);
}
else
{
// Horizontal Normal : |Dec Button |Thumb| Inc Button|
// Horizontal Reversed : |Inc Button |Thumb| Dec Button|
CoerceLength(ref decreaseButtonLength, arrangeSize.Width);
CoerceLength(ref increaseButtonLength, arrangeSize.Width);
CoerceLength(ref thumbLength, arrangeSize.Width);
offset.X = isDirectionReversed ? increaseButtonLength + thumbLength : 0.0;
pieceSize.Width = decreaseButtonLength;
if (DecreaseRepeatButton != null)
{
DecreaseRepeatButton.Arrange(new Rect(offset, pieceSize));
}
offset.X = isDirectionReversed ? 0.0 : decreaseButtonLength + thumbLength;
pieceSize.Width = increaseButtonLength;
if (IncreaseRepeatButton != null)
{
IncreaseRepeatButton.Arrange(new Rect(offset, pieceSize));
}
offset.X = isDirectionReversed ? increaseButtonLength : decreaseButtonLength;
pieceSize.Width = thumbLength;
if (Thumb != null)
{
Thumb.Arrange(new Rect(offset, pieceSize));
}
ThumbCenterOffset = offset.X + (thumbLength * 0.5);
}
return(arrangeSize);
}
