public override object ConvertTo(
ITypeDescriptorContext context,
CultureInfo culture,
object value,
Type destinationType)
{
if (destinationType == null)
{
throw new ArgumentNullException("destinationType");
}
if ((value != null) && (value is DataGridLength))
{
DataGridLength length = (DataGridLength)value;
if (destinationType == typeof(string))
{
return(ConvertToString(length, culture));
}
if (destinationType == typeof(InstanceDescriptor))
{
ConstructorInfo ci = typeof(DataGridLength).GetConstructor(new Type[] { typeof(double), typeof(DataGridLengthUnitType) });
return(new InstanceDescriptor(ci, new object[] { length.Value, length.UnitType }));
}
}
// The default exception to throw from ConvertTo
throw GetConvertToException(value, destinationType);
}
/// <summary>
/// Converts a DataGridLength instance to a String given the CultureInfo.
/// </summary>
/// <param name="gl">DataGridLength instance to convert.</param>
/// <param name="cultureInfo">The culture to use.</param>
/// <returns>String representation of the object.</returns>
internal static string ConvertToString(DataGridLength length, CultureInfo cultureInfo)
{
switch (length.UnitType)
{
case DataGridLengthUnitType.Auto:
case DataGridLengthUnitType.SizeToCells:
case DataGridLengthUnitType.SizeToHeader:
return(length.UnitType.ToString());
// Star has one special case when value is "1.0" in which the value can be dropped.
case DataGridLengthUnitType.Star:
return(DoubleUtil.IsOne(length.Value) ? "*" : Convert.ToString(length.Value, cultureInfo) + "*");
// Print out the numeric value. "px" can be omitted.
default:
return(Convert.ToString(length.Value, cultureInfo));
}
}
/// <summary>
/// Invalidates a cell's panel if its column's width changes sufficiently.
/// </summary>
/// <param name="cell">The cell or header.</param>
/// <param name="e"></param>
public static void OnColumnWidthChanged(IProvideDataGridColumn cell, DependencyPropertyChangedEventArgs e)
{
Debug.Assert((cell is DataGridCell) || (cell is DataGridColumnHeader), "provideColumn should be one of the cell or header containers.");
UIElement element = (UIElement)cell;
DataGridColumn column = cell.Column;
bool isColumnHeader = (cell is DataGridColumnHeader);
if (column != null)
{
// determine the desired value of width for auto kind columns
DataGridLength width = column.Width;
if (width.IsAuto ||
(!isColumnHeader && width.IsSizeToCells) ||
(isColumnHeader && width.IsSizeToHeader))
{
DataGridLength oldWidth = (DataGridLength)e.OldValue;
double desiredWidth = 0.0;
if (oldWidth.UnitType != width.UnitType)
{
double constraintWidth = column.GetConstraintWidth(isColumnHeader);
if (!DoubleUtil.AreClose(element.DesiredSize.Width, constraintWidth))
{
element.InvalidateMeasure();
element.Measure(new Size(constraintWidth, double.PositiveInfinity));
}
desiredWidth = element.DesiredSize.Width;
}
else
{
desiredWidth = oldWidth.DesiredValue;
}
if (DoubleUtil.IsNaN(width.DesiredValue) ||
DoubleUtil.LessThan(width.DesiredValue, desiredWidth))
{
column.SetWidthInternal(new DataGridLength(width.Value, width.UnitType, desiredWidth, width.DisplayValue));
}
}
}
}