Simple Column Chart Generator

using System;
using System.Data;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using ForLogic.ColumnChartGenerator.ObjectModel;

namespace ForLogic.ColumnChartGenerator.Tests
{
	public partial class MainForm : Form
	{
		List<ColumnChartItem> _items = new List<ColumnChartItem>(); // load chart with list of columns
		DataTable _source = new DataTable(); // load chart with SetDataSource method
		
		public MainForm()
		{
			InitializeComponent();
			initValues();
		}
		
		#region events methods
		void BtnUpdateChartClick(object sender, EventArgs e)
		{
			updateChart();
		}
		
		void BtnAddColumnClick(object sender, EventArgs e)
		{
			addColumn();
		}
		
		void LvwColumnsSelectedIndexChanged(object sender, EventArgs e)
		{
			btnRemoveColumn.Enabled = (lvwColumns.SelectedItems.Count > 0);
		}
		
		void BtnRemoveColumnClick(object sender, EventArgs e)
		{
			removeColumn();
		}
		
		void MnuSaveAsClick(object sender, EventArgs e)
		{
			saveAs();
		}
		#endregion
		
		#region private methods
		void initValues()
		{
			// you can use it with a list of items (columns)
			_items.Add(new ColumnChartItem(Color.DarkOrange, "Data Column1", 5.3m));
			_items.Add(new ColumnChartItem(Color.DarkBlue, "Column 2", 10.7m));
			_items.Add(new ColumnChartItem(Color.Red, "Some More Data", 15.9m));

			// or with datatables (related to the line 105)
			//_source.Columns.Add("id", typeof(int));
			//_source.Columns.Add("name", typeof(string));
			//_source.Columns.Add("price", typeof(decimal));
			//_source.Rows.Add(1, "Product 1", 5.6m);
			//_source.Rows.Add(2, "Product 2", 7.85m);
			//_source.Rows.Add(3, "Product 3", 15.3m);
			//_source.Rows.Add(4, "Product 4", 9.2m);
			
			cboColumnColor.SelectedIndex = 3;
			updateListView();
			updateChart();
		}
		
		void updateListView()
		{
			lvwColumns.BeginUpdate();
			lvwColumns.Items.Clear();
			foreach (ColumnChartItem item in _items){
				ListViewItem lvwItem = new ListViewItem(item.Value.ToString());
				lvwItem.SubItems.Add(item.Description);
				lvwColumns.Items.Add(lvwItem);
			}
			lvwColumns.EndUpdate();
		}
		
		void updateChart()
		{
			ColumnChart cc = new ColumnChart();
			cc.BackgroundColor = Color.White;
			cc.ShowGuideLines = chkShowGuideLines.Checked;
			cc.ValueFont = new Font("Arial", Convert.ToSingle(nudFontSize.Value));
			cc.DescriptionFont = new Font("Arial", Convert.ToSingle(nudFontSize.Value));
			cc.Width = Convert.ToInt32(nudWidth.Value);
			cc.Height = Convert.ToInt32(nudHeight.Value);
			cc.ColumnSpacing = Convert.ToInt32(nudColumnSpacing.Value);
			cc.Margins = Convert.ToInt32(nudMargins.Value);
			cc.Depth = Convert.ToInt32(nudDepth.Value);
			cc.ValueFormat = txtValueFormat.Text;
			cc.GuideLineFormat = txtValueFormat.Text;
			cc.GuideLinesCount = Convert.ToInt32(nudGuideLinesCount.Value);
			cc.ShowDescriptions = chkShowDescriptions.Checked;
			cc.ShowValues = chkShowValues.Checked;
			
			// you can use it with a list of items (columns)
			foreach (ColumnChartItem item in _items)
				cc.Items.Add(item);
			// or with datatables
			//cc.SetDataSource(_source, "price", "name");
			
			pct.Image = cc.GetChart();
		}
		
		void addColumn()
		{
			ColumnChartItem item = new ColumnChartItem();
			item.Value = Convert.ToDecimal(nudColumnValue.Value);
			item.Description = txtColumnDescription.Text;
			item.FillColor = Color.FromName(cboColumnColor.Text);
			_items.Add(item);
			updateListView();
			updateChart();
		}
		
		void removeColumn()
		{
			String v = lvwColumns.SelectedItems[0].SubItems[0].Text;
			String d = lvwColumns.SelectedItems[0].SubItems[1].Text;
			for (int x=0; x<_items.Count; x++)
				if (_items[x].Value.ToString() == v && _items[x].Description == d)
					_items.RemoveAt(x);
			updateListView();
			updateChart();

			if (lvwColumns.Items.Count > 0)
				lvwColumns.Items[0].Selected = true;
			else
				btnRemoveColumn.Enabled = false;
		}
		
		void saveAs()
		{
			if (sfd.ShowDialog() != DialogResult.OK)
				return;
			pct.Image.Save(sfd.FileName, ImageFormat.Png);
		}
		#endregion
	}
}