ColumnBuilder.cs


using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Reflection;
using BrightIdeasSoftware;

namespace RiggsHill.Windows.Forms.OLVHelper
{
    [AttributeUsage( AttributeTargets.Property, AllowMultiple = false, Inherited = true )]
    public class OLVColumnAttribute : Attribute
    {
        public string Title { get; set; }
        public string ToolTipText { get; set; }
        public int DisplayIndex { get; set; }
        public bool IsVisible { get; set; }
        public bool UseInitialLetterForGroup { get; set; }
        public bool FillsFreeSpace { get; set; }
        public int FreeSpaceProportion { get; set; }
        public int MaximumWidth { get; set; }
        public int MinimumWidth { get; set; }
        public int Width { get; set; }
        public string Tag { get; set; }

        public HorizontalAlignment TextAlign { get; set; }

        public object[] GroupValues { get; set; }
        public string[] GroupDescrs { get; set; }

        public OLVColumnAttribute( string colTitle )
        {
            Title = colTitle;
            DisplayIndex = 0;
            IsVisible = true;
            UseInitialLetterForGroup = true;
            FillsFreeSpace = false;
            MaximumWidth = MinimumWidth = -1;
            Width = 0;
        }
    }


    public class ColumnBuilder
    {
        private ColumnBuilder() { }

        static public List<OLVColumn> BuildColumns<T>( ObjectListView list )
        {
            // columns collected here
            List<OLVColumn> cols = new List<OLVColumn>();
            // 
            // iterate all public properties in the class
            foreach ( PropertyInfo pinfo in typeof( T ).GetProperties() ) {
                // get our attribute - dig into inherited classes
                object[] propAttrs =  pinfo.GetCustomAttributes( typeof( OLVColumnAttribute ), true );
                if ( propAttrs.Length <= 0 )
                    continue;
                //
                // there's only one allowed so we know the index
                OLVColumnAttribute colAttr = (OLVColumnAttribute)propAttrs[ 0 ];
                //
                // property name becomes the default Aspect
                OLVColumn col = new OLVColumn( colAttr.Title, pinfo.Name );
                //
                // set the column properties
                col.DisplayIndex = colAttr.DisplayIndex;
                col.UseInitialLetterForGroup = colAttr.UseInitialLetterForGroup;
                col.ToolTipText = colAttr.ToolTipText;
                col.IsVisible = colAttr.IsVisible;
                col.FreeSpaceProportion = colAttr.FreeSpaceProportion;
                col.FillsFreeSpace = colAttr.FillsFreeSpace;
                col.MaximumWidth = colAttr.MaximumWidth;
                col.MinimumWidth = colAttr.MinimumWidth;
                col.Width = colAttr.Width;
                col.TextAlign = colAttr.TextAlign;
                col.Tag = colAttr.Tag;
                //
                // if group values & descriptions are assigned, make the groups
                // note: if the descrs array is not the right size, an exception will
                // come up from MakeGroupies<T>
                if ( colAttr.GroupValues != null && colAttr.GroupDescrs != null )
                    MakeGroupies( col, colAttr );
                cols.Add( col );
            }
            //
            // we may be reinstalling columns so verify that we have something to install
            if ( cols.Count > 0 ) {
                cols.Sort( ( a, b ) => a.DisplayIndex.CompareTo( b.DisplayIndex ) );
                list.Columns.Clear();
                list.AllColumns = cols;
                list.RebuildColumns();
            }
            return cols;
        }


        private static MethodInfo c_makeGroupieInfo = null;
        static private void MakeGroupies( OLVColumn col, OLVColumnAttribute attr )
        {
            //
            // find MakeGroupies<T> if we haven't before
            if ( c_makeGroupieInfo == null )
                c_makeGroupieInfo = col.GetType().GetMethod( "MakeGroupies" );
            if ( c_makeGroupieInfo == null )
                throw new ApplicationException( "MakeGroupies<T> not found in OLVColumn" );
            //
            // fetch the type of the values array and generate the type specific method info
            Type valType = attr.GroupValues[ 0 ].GetType();
            MethodInfo m = c_makeGroupieInfo.MakeGenericMethod( valType );
            //
            // since the GroupValues property is of type object[] we need to 
            // create and populate a properly typed array - i.e. if it's actually an 
            // array if Int32 then the array needs to be of that type.
            Array typedVals = Array.CreateInstance( valType, attr.GroupValues.Length );
            Array.Copy( attr.GroupValues, typedVals, typedVals.Length );
            //
            // data is ready - invoke the method 
            m.Invoke( col, new object[] { typedVals, attr.GroupDescrs } );
        }
    }
}

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