WPF FlowDocument Table - AutoFit option?

Question

I want a table to logically size the columns according to the contents. Is this possible in WPF?

alt text http://img43.imageshack.us/img43/2640/flowdocument.jpg

Answer 1

You can write a simplified "AutoFit" function like below, that roughly compacts the width of columns within a given extent.

If you use Double, not Integer, and try to precisely calculate them, it may take much longer to converge wastefully.

using System;
using System.Windows;
using System.Windows.Input;
using System.Windows.Documents;
using System.Windows.Controls;
using System.Text.RegularExpressions;
using System.Linq;
using System.Collections.Generic;



namespace Example {

    //----------------------------------------------------------------------------------------------------
    public class MyTable : Table {

        ...

        //------------------------------------------------------------------------------------------------
        public MyTable() {

            ...

            AutoFit();

            ...

        }
        //------------------------------------------------------------------------------------------------

        ...

        //------------------------------------------------------------------------------------------------
        private void AutoFit() {

            int extent = 10;
            int[] lengths = new int[this.Columns.Count];

            // collect content lengths of each column of the first 5 rows
            foreach(TableRow row in this.RowGroups[0].Rows.Take(5)) {
                for(int i = 0; i < row.Cells.Count; i++) {
                    TableCell cell = row.Cells[i];
                    TextRange t = new TextRange(cell.ContentStart, cell.ContentEnd);
                    int length = new List(Regex.Split(t.Text, @"\r\n|[\r\n]")).Select(s => s.Length).Max();
                    lengths[i] = Math.Max(lengths[i], length);
                }
            }

            // keep content lengths with column index before sort
            List contentSizes = lengths.Select((length, index) => {
                return new ColumnSize() {Index = index, Size = length};
            }).OrderBy(e => e.Size).ToList();

            // assign compacted ratio to columns by recursion
            int[] compactedSizes = Compact(new int[contentSizes.Count], contentSizes, extent);

            // set width to columns
            for(int i = 0; i < compactedSizes.Length; i++) {
                this.Columns[i].Width = new GridLength(compactedSizes[i], GridUnitType.Star);
            }

        }
        //------------------------------------------------------------------------------------------------
        private int[] Compact(int[] sizes, List contentSizes, int extent) {

            int min = contentSizes.Min(e => e.Size);
            int max = extent - contentSizes.Count + 1;

            contentSizes = contentSizes.Select(e => {
                int size = (int)Math.Floor((double)e.Size / (double)min);
                e.Size = size > max ? max : size;
                return e;
            }).OrderBy(e => e.Size).ToList();

            if(contentSizes.Sum(e => e.Size) > extent) {
                if(sizes.All(v => v == 0)) {
                    sizes = sizes.Select(v => 1).ToArray();
                } else {
                    contentSizes.TakeWhile(e => e.Size == 1).ToList().ForEach(e => sizes[e.Index] += 1);
                }
                sizes = Compact(sizes, contentSizes.SkipWhile(e => e.Size <= 1).ToList(), extent);
            } else {
                contentSizes.ForEach(e => sizes[e.Index] = e.Size);
            }

            return sizes;

        }
        //------------------------------------------------------------------------------------------------
        private class ColumnSize {

            public int Index { get; set; }
            public int Size { get; set; }

        }
        //------------------------------------------------------------------------------------------------

        ...

    }
    //----------------------------------------------------------------------------------------------------

}