piechart.cs

ASP.NET 建立和发布可自定义 Web 报表的指南

using System;
using System.Collections;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;

namespace ASPNET.StarterKit.Chart
{
	//*********************************************************************
	//
	// PieChart Class
	//
	// This class uses GDI+ to render Pie Chart.
	//
	//*********************************************************************

	public class PieChart : Chart
	{
		private const int	_bufferSpace = 125;
		private ArrayList	_chartItems;
		private int			_perimeter;
		private Color		_backgroundColor;
		private Color		_borderColor;
		private float		_total;
		private int			_legendWidth;
		private int			_legendHeight;
		private int			_legendFontHeight;
		private string		_legendFontStyle;
		private float		_legendFontSize;

		public PieChart()
		{
			_chartItems = new ArrayList();
			_perimeter = 250;
			_backgroundColor = Color.White;
			_borderColor = Color.FromArgb(63,63,63);
			_legendFontSize = 8;
			_legendFontStyle = "Verdana";
		}

		public PieChart(Color bgColor)
		{
			_chartItems = new ArrayList();
			_perimeter = 250;
			_backgroundColor = bgColor;
			_borderColor = Color.FromArgb(63,63,63);
			_legendFontSize = 8;
			_legendFontStyle = "Verdana";
		}

		//*********************************************************************
		//
		// This method collects all data points and calculate all the necessary dimensions 
		// to draw the chart.  It is the first method called before invoking the Draw() method.
		//
		//*********************************************************************

		public void CollectDataPoints(string[] xValues, string[] yValues)
		{
			_total = 0.0f;
			
			for (int i = 0;i < xValues.Length;i++)
			{
				float ftemp = Convert.ToSingle(yValues[i]);
				_chartItems.Add(new ChartItem(xValues[i], xValues.ToString(), ftemp, 0, 0, Color.AliceBlue));
				_total += ftemp;
			}
			
			float nextStartPos = 0.0f;
			int counter = 0;
			foreach (ChartItem item in _chartItems)
			{
				item.StartPos = nextStartPos;
				item.SweepSize = item.Value / _total * 360;
				nextStartPos = item.StartPos + item.SweepSize;
				item.ItemColor = GetColor(counter++);
			}

			CalculateLegendWidthHeight();
		}

		//*********************************************************************
		//
		// This method returns a bitmap to the calling function.  This is the method
		// that actually draws the pie chart and the legend with it.
		//
		//*********************************************************************

		public override Bitmap Draw()
		{
			int perimeter = _perimeter;
			Rectangle pieRect = new Rectangle(0, 0, perimeter, perimeter-1);
			Bitmap bmp = new Bitmap(perimeter + _legendWidth, perimeter);
			Graphics grp = null;
			StringFormat sf = null;
			
			try
			{
				grp = Graphics.FromImage(bmp);
				sf = new StringFormat();

				//Paint Back ground
				grp.FillRectangle(new SolidBrush(_backgroundColor), 0, 0, perimeter + _legendWidth, perimeter);

				//Align text to the right
				sf.Alignment = StringAlignment.Far; 
			
				//Draw all wedges and legends
				for(int i=0; i<_chartItems.Count; i++)
				{
					ChartItem item = (ChartItem) _chartItems[i];
					SolidBrush brs = null;
					try
					{
						brs = new SolidBrush(item.ItemColor);
						grp.FillPie(brs, pieRect, item.StartPos, item.SweepSize);
						grp.FillRectangle(brs, perimeter + _bufferSpace, i * _legendFontHeight + 15, 10, 10);
					
						grp.DrawString(item.Label, new Font(_legendFontStyle, _legendFontSize), 
							new SolidBrush(Color.Black), perimeter + _bufferSpace + 20, i * _legendFontHeight + 13);

						grp.DrawString(item.Value.ToString("C"), new Font(_legendFontStyle, _legendFontSize), 
							new SolidBrush(Color.Black), perimeter + _bufferSpace + 200, i * _legendFontHeight + 13,sf);
					}
					finally
					{
						if (brs !=null)
							brs.Dispose();
					}
				}
			
				//draws the border around Pie
				grp.DrawEllipse(new Pen(_borderColor, 2), pieRect);  

				//draw border around legend
				grp.DrawRectangle(new Pen(_borderColor, 1), perimeter + _bufferSpace - 10, 10, 220, _chartItems.Count * _legendFontHeight + 25);

				//Draw Total under legend
				grp.DrawString("Total", new Font(_legendFontStyle, _legendFontSize, FontStyle.Bold), 
					new SolidBrush(Color.Black), perimeter + _bufferSpace + 30, (_chartItems.Count+1) * _legendFontHeight,sf);
				grp.DrawString(_total.ToString("C"), new Font(_legendFontStyle, _legendFontSize, FontStyle.Bold), 
					new SolidBrush(Color.Black), perimeter + _bufferSpace + 200, (_chartItems.Count+1) * _legendFontHeight,sf);
			
				grp.SmoothingMode = SmoothingMode.AntiAlias;
			}
			finally
			{
				if (sf != null)	sf.Dispose();
				if (grp != null) grp.Dispose();
			}
			return bmp;
		}

		//*********************************************************************
		//
		//	This method calculates the space required to draw the chart legend.
		//
		//*********************************************************************
		
		private void CalculateLegendWidthHeight()
		{
			Font fontLegend = new Font(_legendFontStyle, _legendFontSize);
			_legendFontHeight = fontLegend.Height+5;
			_legendHeight = fontLegend.Height * (_chartItems.Count + 1);
			if (_legendHeight > _perimeter) _perimeter = _legendHeight;

			_legendWidth = _perimeter + _bufferSpace;
		}
	}
}