datagridprinter.cs

本论文叙述了联机考试系统的现状以及C#语言的概况。重点介绍了联机考试系统的实现过程：包括系统分析、 系统调查、 数据流程分析、功能设计、 数据库设计、 系统物理配置方案、 系统实现、 系统测试和调试。

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Printing;
using System.Data;
using System.Collections;

namespace SupermarketProject
{
	public class DataGridPrinter
	{

		private PrintDocument ThePrintDocument;
		private DataTable TheTable;
		private DataGrid  TheDataGrid;
	

		public int RowCount = 0;  // current count of rows;
		private const int kVerticalCellLeeway = 10;
		public int PageNumber = 1;
		public ArrayList Lines = new ArrayList();

		int PageWidth;
		int PageHeight;
		int TopMargin;
		int BottomMargin;

		public DataGridPrinter(DataGrid aGrid, PrintDocument aPrintDocument, DataTable aTable)
		{
			//
			// TODO: Add constructor logic here
			//
			TheDataGrid = aGrid;
			ThePrintDocument = aPrintDocument;
			TheTable = aTable;

			PageWidth = ThePrintDocument.DefaultPageSettings.PaperSize.Width;
			PageHeight = ThePrintDocument.DefaultPageSettings.PaperSize.Height;
			TopMargin = ThePrintDocument.DefaultPageSettings.Margins.Top;
			BottomMargin = ThePrintDocument.DefaultPageSettings.Margins.Bottom;

		}

		public void DrawHeader(Graphics g)
		{
			SolidBrush ForeBrush = new SolidBrush(TheDataGrid.HeaderForeColor);
			SolidBrush BackBrush = new SolidBrush(TheDataGrid.HeaderBackColor);
			Pen TheLinePen = new Pen(TheDataGrid.GridLineColor, 1);
			StringFormat cellformat = new StringFormat();
			cellformat.Trimming = StringTrimming.EllipsisCharacter;
			cellformat.FormatFlags = StringFormatFlags.NoWrap | StringFormatFlags.LineLimit;


			int columnwidth = PageWidth/TheTable.Columns.Count;

			int initialRowCount = RowCount;

			// draw the table header
			float startxposition = TheDataGrid.Location.X;
			RectangleF nextcellbounds = new RectangleF(0,0, 0, 0);

			RectangleF HeaderBounds  = new RectangleF(0, 0, 0, 0);

			HeaderBounds.X = TheDataGrid.Location.X;
			HeaderBounds.Y = TheDataGrid.Location.Y + TopMargin + (RowCount - initialRowCount) * (TheDataGrid.Font.SizeInPoints  + kVerticalCellLeeway);
			HeaderBounds.Height = TheDataGrid.Font.SizeInPoints + kVerticalCellLeeway;
			HeaderBounds.Width = PageWidth;

			g.FillRectangle(BackBrush, HeaderBounds);

			for (int k = 0; k < TheTable.Columns.Count; k++)
			{
				string nextcolumn = TheTable.Columns[k].ToString();
				RectangleF cellbounds = new RectangleF(startxposition, TheDataGrid.Location.Y + TopMargin + (RowCount - initialRowCount) * (TheDataGrid.Font.SizeInPoints  + kVerticalCellLeeway),
					columnwidth, 
					TheDataGrid.HeaderFont.SizeInPoints + kVerticalCellLeeway);
				nextcellbounds = cellbounds;

				if (startxposition + columnwidth <= PageWidth)
				{
					g.DrawString(nextcolumn, TheDataGrid.HeaderFont, ForeBrush, cellbounds, cellformat);
				}

				startxposition = startxposition + columnwidth;

			}
	
			if (TheDataGrid.GridLineStyle != DataGridLineStyle.None)
				g.DrawLine(TheLinePen, TheDataGrid.Location.X, nextcellbounds.Bottom, PageWidth, nextcellbounds.Bottom);
		}

		public bool DrawRows(Graphics g)
		{
			int lastRowBottom = TopMargin;

			try
			{
				SolidBrush ForeBrush = new SolidBrush(TheDataGrid.ForeColor);
				SolidBrush BackBrush = new SolidBrush(TheDataGrid.BackColor);
				SolidBrush AlternatingBackBrush = new SolidBrush(TheDataGrid.AlternatingBackColor);
				Pen TheLinePen = new Pen(TheDataGrid.GridLineColor, 1);
				StringFormat cellformat = new StringFormat();
				cellformat.Trimming = StringTrimming.EllipsisCharacter;
				cellformat.FormatFlags = StringFormatFlags.NoWrap | StringFormatFlags.LineLimit;
				int columnwidth = PageWidth/TheTable.Columns.Count;

				int initialRowCount = RowCount;

				RectangleF RowBounds  = new RectangleF(0, 0, 0, 0);

				// draw vertical lines




				// draw the rows of the table
				for (int i = initialRowCount; i < TheTable.Rows.Count; i++)
				{
					DataRow dr = TheTable.Rows[i];
					int startxposition = TheDataGrid.Location.X;

					RowBounds.X = TheDataGrid.Location.X;
					RowBounds.Y = TheDataGrid.Location.Y + TopMargin + ((RowCount - initialRowCount)+1) * (TheDataGrid.Font.SizeInPoints  + kVerticalCellLeeway);
					RowBounds.Height = TheDataGrid.Font.SizeInPoints + kVerticalCellLeeway;
					RowBounds.Width = PageWidth;
					Lines.Add(RowBounds.Bottom);

					if (i%2 == 0)
					{
						g.FillRectangle(BackBrush, RowBounds);
					}
					else
					{
						g.FillRectangle(AlternatingBackBrush, RowBounds);
					}


					for (int j = 0; j < TheTable.Columns.Count; j++)
					{
						RectangleF cellbounds = new RectangleF(startxposition, 
							TheDataGrid.Location.Y + TopMargin + ((RowCount - initialRowCount) + 1) * (TheDataGrid.Font.SizeInPoints  + kVerticalCellLeeway),
							columnwidth, 
							TheDataGrid.Font.SizeInPoints + kVerticalCellLeeway);
									

						if (startxposition + columnwidth <= PageWidth)
						{
							g.DrawString(dr[j].ToString(), TheDataGrid.Font, ForeBrush, cellbounds, cellformat);
							lastRowBottom = (int)cellbounds.Bottom;
						}

						startxposition = startxposition + columnwidth;
					}

					RowCount++;

					if (RowCount * (TheDataGrid.Font.SizeInPoints  + kVerticalCellLeeway) > (PageHeight * PageNumber) - (BottomMargin+TopMargin))
					{
						DrawHorizontalLines(g, Lines);
						DrawVerticalGridLines(g, TheLinePen, columnwidth, lastRowBottom);
						return true;
					}


				}

				DrawHorizontalLines(g, Lines);
				DrawVerticalGridLines(g, TheLinePen, columnwidth, lastRowBottom);
				return false;

			}
			catch (Exception ex)
			{
				MessageBox.Show(ex.Message.ToString());
				return false;
			}

		}

		void DrawHorizontalLines(Graphics g, ArrayList lines)
		{
			Pen TheLinePen = new Pen(TheDataGrid.GridLineColor, 1);

			if (TheDataGrid.GridLineStyle == DataGridLineStyle.None)
				return;

			for (int i = 0;  i < lines.Count; i++)
			{
					g.DrawLine(TheLinePen, TheDataGrid.Location.X, (float)lines[i], PageWidth, (float)lines[i]);
			}
		}

		void DrawVerticalGridLines(Graphics g, Pen TheLinePen, int columnwidth, int bottom)
		{
			if (TheDataGrid.GridLineStyle == DataGridLineStyle.None)
				return;

			for (int k = 0; k < TheTable.Columns.Count; k++)
			{
				g.DrawLine(TheLinePen, TheDataGrid.Location.X + k*columnwidth, 
					TheDataGrid.Location.Y + TopMargin,
					TheDataGrid.Location.X + k*columnwidth,
					bottom);
			}
		}


		public bool DrawDataGrid(Graphics g)
		  {

			try
			{
				DrawHeader(g);
				bool bContinue = DrawRows(g);
				return bContinue;
			}
			catch (Exception ex)
			{
			  MessageBox.Show(ex.Message.ToString());
			  return false;
			}

		  }
	
	}

}