/// <summary>
/// Computes the optimal size for all columns in a table
/// and return an array of widths in pixels
/// </summary>
/// <param name="table">table to compute</param>
/// <param name="preferredWidth">desired width (pixels) to fit in</param>
/// <returns></returns>
public int[] GetColumnSizes(DataTable table, int preferredWidth)
{
var columns = table.Columns.Count;
var width = preferredWidth;
var maxText = new int[columns]; // max. text width over all rows
var maxWord = new int[columns]; // max. width of longest word
var isFlex = new bool[columns]; // is column flexible?
var canWrap = new bool[columns]; // can column be wrapped?
var colw = new int[columns]; // final width of columns
for (var r = 0; r < table.Rows.Count; r++)
{
var row = table.Rows[r];
for (var i = 0; i < columns; i++)
{
var args = new MeasureCellEventArgs(r, i, DefaultFont, DefaultCellPadding);
OnMeasuringCell(args);
var cell = string.Format("{0}", row[i]);
var pad = 2 * args.CellPadding;
maxText[i] = args.MaxTextWidth >= 0
? args.MaxTextWidth
: Math.Max(maxText[i], PixelRuler.MeasureString(cell, args.CellFont, pad));
if (args.MaxWordWidth >= 0)
{
maxWord[i] = args.MaxWordWidth;
}
else
{
if (PixelRuler.CanWrap(cell))
{
canWrap[i] = true;
maxWord[i] = Math.Max(maxWord[i], PixelRuler.MeasureWord(cell, args.CellFont, pad));
}
else
{
maxWord[i] = maxText[i];
}
}
}
var left = width - (columns - 1) * TableBorderSize;
var avg = left / columns;
var nflex = 0;
// Determine whether columns should be flexible and assign width of non-flexible cells
for (var i = 0; i < columns; i++)
{
isFlex[i] = maxText[i] > 2 * avg;
if (isFlex[i])
{
nflex++;
}
else
{
colw[i] = maxText[i];
left -= colw[i];
}
}
// if there is not enough space, make columns that could be word-wrapped flexible, too
if (left < nflex * avg)
{
for (var i = 0; i < columns; i++)
{
if (!isFlex[i] && canWrap[i])
{
left += width; //???
colw[i] = 0;
isFlex[i] = true;
nflex += 1;
}
}
}
// Calculate weights for flexible columns. The max width is capped at the page width
// to treat columns that have to be wrapped more or less equal
var tot = 0;
for (var i = 0; i < columns; i++)
{
if (isFlex[i])
{
maxText[i] = Math.Min(maxText[i], width);
tot += maxText[i];
}
}
// Assign the actual width for flexible columns.
// Make sure that it is at least as long as the longest word length
for (var i = 0; i < columns; i++)
{
if (isFlex[i])
{
if (tot > 0)
{
colw[i] = left * maxText[i] / tot;
}
colw[i] = Math.Max(colw[i], maxWord[i]);
left -= colw[i];
}
}
}
return(colw);
}
private void OnMeasuringCell(MeasureCellEventArgs e)
{
MeasuringCell?.Invoke(this, e);
}
