/// <summary>
/// Arranges and sizes the
/// <see cref="T:WinRTXamlToolkit.Controls.WrapPanel" /> control and its
/// child elements.
/// </summary>
/// <param name="finalSize">
/// The area within the parent that the
/// <see cref="T:WinRTXamlToolkit.Controls.WrapPanel" /> should use
/// arrange itself and its children.
/// </param>
/// <returns>
/// The actual size used by the
/// <see cref="T:WinRTXamlToolkit.Controls.WrapPanel" />.
/// </returns>
protected override Size ArrangeOverride(Size finalSize)
{
// Variables tracking the size of the current line, and the maximum
// size available to fill. Note that the line might represent a row
// or a column depending on the orientation.
Orientation o = Orientation;
OrientedSize lineSize = new OrientedSize(o);
OrientedSize maximumSize = new OrientedSize(o, finalSize.Width, finalSize.Height);
// Determine the constraints for individual items
double itemWidth = ItemWidth;
double itemHeight = ItemHeight;
bool hasFixedWidth = !itemWidth.IsNaN();
bool hasFixedHeight = !itemHeight.IsNaN();
double indirectOffset = 0;
double? directDelta = (o == Orientation.Horizontal) ?
(hasFixedWidth ? (double?)itemWidth : null) :
(hasFixedHeight ? (double?)itemHeight : null);
// Measure each of the Children. We will process the elements one
// line at a time, just like during measure, but we will wait until
// we've completed an entire line of elements before arranging them.
// The lineStart and lineEnd variables track the size of the
// currently arranged line.
UIElementCollection children = Children;
int count = children.Count;
int lineStart = 0;
for (int lineEnd = 0; lineEnd < count; lineEnd++)
{
UIElement element = children[lineEnd];
// Get the size of the element
OrientedSize elementSize = new OrientedSize(
o,
hasFixedWidth ? itemWidth : element.DesiredSize.Width,
hasFixedHeight ? itemHeight : element.DesiredSize.Height);
// If this element falls of the edge of the line
if (NumericExtensions.IsGreaterThan(lineSize.Direct + elementSize.Direct, maximumSize.Direct))
{
// Then we just completed a line and we should arrange it
ArrangeLine(lineStart, lineEnd, directDelta, indirectOffset, lineSize.Indirect);
// Move the current element to a new line
indirectOffset += lineSize.Indirect;
lineSize = elementSize;
// If the current element is larger than the maximum size
if (NumericExtensions.IsGreaterThan(elementSize.Direct, maximumSize.Direct))
{
// Arrange the element as a single line
ArrangeLine(lineEnd, ++lineEnd, directDelta, indirectOffset, elementSize.Indirect);
// Move to a new line
indirectOffset += lineSize.Indirect;
lineSize = new OrientedSize(o);
}
// Advance the start index to a new line after arranging
lineStart = lineEnd;
}
else
{
// Otherwise just add the element to the end of the line
lineSize.Direct += elementSize.Direct;
lineSize.Indirect = Math.Max(lineSize.Indirect, elementSize.Indirect);
}
}
// Arrange any elements on the last line
if (lineStart < count)
{
ArrangeLine(lineStart, count, directDelta, indirectOffset, lineSize.Indirect);
}
return finalSize;
}
/// <summary>
/// Arrange a sequence of elements in a single line.
/// </summary>
/// <param name="lineStart">
/// Index of the first element in the sequence to arrange.
/// </param>
/// <param name="lineEnd">
/// Index of the last element in the sequence to arrange.
/// </param>
/// <param name="directDelta">
/// Optional fixed growth in the primary direction.
/// </param>
/// <param name="indirectOffset">
/// Offset of the line in the indirect direction.
/// </param>
/// <param name="indirectGrowth">
/// Shared indirect growth of the elements on this line.
/// </param>
private void ArrangeLine(int lineStart, int lineEnd, double? directDelta, double indirectOffset, double indirectGrowth)
{
double directOffset = 0.0;
Orientation o = Orientation;
bool isHorizontal = o == Orientation.Horizontal;
UIElementCollection children = Children;
for (int index = lineStart; index < lineEnd; index++)
{
// Get the size of the element
UIElement element = children[index];
OrientedSize elementSize = new OrientedSize(o, element.DesiredSize.Width, element.DesiredSize.Height);
// Determine if we should use the element's desired size or the
// fixed item width or height
double directGrowth = directDelta != null ?
directDelta.Value :
elementSize.Direct;
// Arrange the element
Rect bounds = isHorizontal ?
new Rect(directOffset, indirectOffset, directGrowth, indirectGrowth) :
new Rect(indirectOffset, directOffset, indirectGrowth, directGrowth);
element.Arrange(bounds);
directOffset += directGrowth;
}
}
protected override Size MeasureOverride(Size constraint)
{
// Variables tracking the size of the current line, the total size
// measured so far, and the maximum size available to fill. Note
// that the line might represent a row or a column depending on the
// orientation.
Orientation o = Orientation;
OrientedSize lineSize = new OrientedSize(o);
OrientedSize totalSize = new OrientedSize(o);
OrientedSize maximumSize = new OrientedSize(o, constraint.Width, constraint.Height);
// Determine the constraints for individual items
double itemWidth = ItemWidth;
double itemHeight = ItemHeight;
bool hasFixedWidth = !double.IsNaN(itemWidth);
bool hasFixedHeight = !double.IsNaN(itemHeight);
Size itemSize = new Size(
hasFixedWidth ? itemWidth : constraint.Width,
hasFixedHeight ? itemHeight : constraint.Height);
// Measure each of the Children
foreach (UIElement element in Children)
{
// Determine the size of the element
element.Measure(itemSize);
OrientedSize elementSize = new OrientedSize(
o,
hasFixedWidth ? itemWidth : element.DesiredSize.Width,
hasFixedHeight ? itemHeight : element.DesiredSize.Height);
// If this element falls of the edge of the line
if (NumericExtensions.IsGreaterThan(lineSize.Direct + elementSize.Direct, maximumSize.Direct))
{
// Update the total size with the direct and indirect growth
// for the current line
totalSize.Direct = Math.Max(lineSize.Direct, totalSize.Direct);
totalSize.Indirect += lineSize.Indirect;
// Move the element to a new line
lineSize = elementSize;
// If the current element is larger than the maximum size,
// place it on a line by itself
if (NumericExtensions.IsGreaterThan(elementSize.Direct, maximumSize.Direct))
{
// Update the total size for the line occupied by this
// single element
totalSize.Direct = Math.Max(elementSize.Direct, totalSize.Direct);
totalSize.Indirect += elementSize.Indirect;
// Move to a new line
lineSize = new OrientedSize(o);
}
}
else
{
// Otherwise just add the element to the end of the line
lineSize.Direct += elementSize.Direct;
lineSize.Indirect = Math.Max(lineSize.Indirect, elementSize.Indirect);
}
}
// Update the total size with the elements on the last line
totalSize.Direct = Math.Max(lineSize.Direct, totalSize.Direct);
totalSize.Indirect += lineSize.Indirect;
// Return the total size required as an un-oriented quantity
return new Size(totalSize.Width, totalSize.Height);
}