我已经完成了我的DataGridView代码与虚拟数据加载，它正在工作，但我想要排序也应该工作时，我将点击列标题列。我从这个帖子中读到了想法http://stackoverflow.com/questions/17087074/c-sharp-datagridview-virtual-mode-enable-sorting
但在启用DataGridView虚拟模式时仍然无法实现如何启用排序。
这里我发布了完整的代码，并为发布我的大代码而道歉。所以请一些人纠正我的代码或给我一些小代码部分，它帮助我排序网格数据和虚拟数据加载。单击列标题时，排序字形也会出现。
public partial class Form1 : Form
{
private string connectionString =
"Initial Catalog=Test1;Data Source=BBATRIDIP\\SQLSERVER2008R2;" +
"Integrated Security=SSPI;Persist Security Info=False";
private string table = "Orders";
private Cache memoryCache=null;
public Form1()
{
InitializeComponent();
this.dataGridView1.VirtualMode = true;
this.dataGridView1.ReadOnly = true;
this.dataGridView1.SelectionMode =
DataGridViewSelectionMode.FullRowSelect;
this.dataGridView1.CellValueNeeded += new DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
}
private void dataGridView1_CellValueNeeded(object sender,DataGridViewCellValueEventArgs e)
{
e.Value = memoryCache.RetrieveElement(e.RowIndex, e.ColumnIndex);
}
private void btnLoad_Click(object sender, EventArgs e)
{
try
{
DataRetriever retriever = new DataRetriever(connectionString, table,"OrderID");
memoryCache = new Cache(retriever, 16);
foreach (DataColumn column in retriever.Columns)
{
dataGridView1.Columns.Add(column.ColumnName, column.ColumnName);
}
this.dataGridView1.RowCount = retriever.RowCount;
}
catch (Exception ex)
{
MessageBox.Show("Connection could not be established. " + "Verify that the connection string is valid.");
Application.Exit();
}
// Adjust the column widths based on the displayed values.
this.dataGridView1.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.DisplayedCells);
}
private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
{
// this routine will add row no to HeaderCell which comes left most
var grid = sender as DataGridView;
var rowIdx = (e.RowIndex + 1).ToString();
var centerFormat = new StringFormat()
{
// right alignment might actually make more sense for numbers
Alignment = StringAlignment.Center,
LineAlignment = StringAlignment.Center
};
var headerBounds = new Rectangle(e.RowBounds.Left, e.RowBounds.Top, grid.RowHeadersWidth, e.RowBounds.Height);
e.Graphics.DrawString(rowIdx, this.Font, SystemBrushes.ControlText, headerBounds, centerFormat);
}
private void dataGridView1_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
{
//this.ValidateChildren();// force value be set to the underlying list.
string strSortCol = this.dataGridView1.Columns[e.ColumnIndex].Name;
string strSortOrder = "";
if (this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection == System.Windows.Forms.SortOrder.Ascending)
{
this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Descending;
strSortOrder = " ASC";
}
else if (this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection == System.Windows.Forms.SortOrder.Descending)
{
this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Ascending;
strSortOrder = " DESC";
}
DataRetriever retriever = new DataRetriever(connectionString, table, strSortCol);
//dataGridView1.Refresh();
}
}
public interface IDataPageRetriever
{
DataTable SupplyPageOfData(int lowerPageBoundary, int rowsPerPage);
}
public class DataRetriever : IDataPageRetriever
{
private string tableName;
private SqlCommand command;
private string sortColumn;
public DataRetriever(string connectionString, string tableName, string sortColumn)
{
SqlConnection connection = new SqlConnection(connectionString);
connection.Open();
command = connection.CreateCommand();
this.tableName = tableName;
this.sortColumn = sortColumn;
}
private int rowCountValue = -1;
public int RowCount
{
get
{
// Return the existing value if it has already been determined.
if (rowCountValue != -1)
{
return rowCountValue;
}
// Retrieve the row count from the database.
command.CommandText = "SELECT COUNT(*) FROM " + tableName;
rowCountValue = (int)command.ExecuteScalar();
return rowCountValue;
}
}
private DataColumnCollection columnsValue;
public DataColumnCollection Columns
{
get
{
// Return the existing value if it has already been determined.
if (columnsValue != null)
{
return columnsValue;
}
// Retrieve the column information from the database.
command.CommandText = "SELECT * FROM " + tableName;
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = command;
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
adapter.FillSchema(table, SchemaType.Source);
columnsValue = table.Columns;
return columnsValue;
}
}
private string commaSeparatedListOfColumnNamesValue = null;
private string CommaSeparatedListOfColumnNames
{
get
{
// Return the existing value if it has already been determined.
if (commaSeparatedListOfColumnNamesValue != null)
{
return commaSeparatedListOfColumnNamesValue;
}
// Store a list of column names for use in the
// SupplyPageOfData method.
System.Text.StringBuilder commaSeparatedColumnNames =
new System.Text.StringBuilder();
bool firstColumn = true;
foreach (DataColumn column in Columns)
{
if (!firstColumn)
{
commaSeparatedColumnNames.Append(", ");
}
commaSeparatedColumnNames.Append(column.ColumnName);
firstColumn = false;
}
commaSeparatedListOfColumnNamesValue =
commaSeparatedColumnNames.ToString();
return commaSeparatedListOfColumnNamesValue;
}
}
// Declare variables to be reused by the SupplyPageOfData method.
private string columnToSortBy;
private SqlDataAdapter adapter = new SqlDataAdapter();
public DataTable SupplyPageOfData(int lowerPageBoundary, int rowsPerPage)
{
// Store the name of the ID column. This column must contain unique
// values so the SQL below will work properly.
if (columnToSortBy == null)
{
columnToSortBy = this.Columns[0].ColumnName;
}
if (!this.Columns[columnToSortBy].Unique)
{
throw new InvalidOperationException(String.Format(
"Column {0} must contain unique values.", columnToSortBy));
}
// Retrieve the specified number of rows from the database, starting
// with the row specified by the lowerPageBoundary parameter.
command.CommandText = "Select Top " + rowsPerPage + " " +
CommaSeparatedListOfColumnNames + " From " + tableName +
" WHERE " + columnToSortBy + " NOT IN (SELECT TOP " +
lowerPageBoundary + " " + columnToSortBy + " From " +
tableName + " Order By " + sortColumn +
") Order By " + sortColumn;
adapter.SelectCommand = command;
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
adapter.Fill(table);
return table;
}
}
public class Cache
{
private static int RowsPerPage;
// Represents one page of data.
public struct DataPage
{
public DataTable table;
private int lowestIndexValue;
private int highestIndexValue;
public DataPage(DataTable table, int rowIndex)
{
this.table = table;
lowestIndexValue = MapToLowerBoundary(rowIndex);
highestIndexValue = MapToUpperBoundary(rowIndex);
System.Diagnostics.Debug.Assert(lowestIndexValue >= 0);
System.Diagnostics.Debug.Assert(highestIndexValue >= 0);
}
public int LowestIndex
{
get
{
return lowestIndexValue;
}
}
public int HighestIndex
{
get
{
return highestIndexValue;
}
}
public static int MapToLowerBoundary(int rowIndex)
{
// Return the lowest index of a page containing the given index.
return (rowIndex / RowsPerPage) * RowsPerPage;
}
private static int MapToUpperBoundary(int rowIndex)
{
// Return the highest index of a page containing the given index.
return MapToLowerBoundary(rowIndex) + RowsPerPage - 1;
}
}
private DataPage[] cachePages;
private IDataPageRetriever dataSupply;
public Cache(IDataPageRetriever dataSupplier, int rowsPerPage)
{
dataSupply = dataSupplier;
Cache.RowsPerPage = rowsPerPage;
LoadFirstTwoPages();
}
// Sets the value of the element parameter if the value is in the cache.
private bool IfPageCached_ThenSetElement(int rowIndex,
int columnIndex, ref string element)
{
if (IsRowCachedInPage(0, rowIndex))
{
element = cachePages[0].table
.Rows[rowIndex % RowsPerPage][columnIndex].ToString();
return true;
}
else if (IsRowCachedInPage(1, rowIndex))
{
element = cachePages[1].table
.Rows[rowIndex % RowsPerPage][columnIndex].ToString();
return true;
}
return false;
}
public string RetrieveElement(int rowIndex, int columnIndex)
{
string element = null;
if (IfPageCached_ThenSetElement(rowIndex, columnIndex, ref element))
{
return element;
}
else
{
return RetrieveData_CacheIt_ThenReturnElement(
rowIndex, columnIndex);
}
}
private void LoadFirstTwoPages()
{
cachePages = new DataPage[]{
new DataPage(dataSupply.SupplyPageOfData(
DataPage.MapToLowerBoundary(0), RowsPerPage), 0),
new DataPage(dataSupply.SupplyPageOfData(
DataPage.MapToLowerBoundary(RowsPerPage),
RowsPerPage), RowsPerPage)};
}
private string RetrieveData_CacheIt_ThenReturnElement(
int rowIndex, int columnIndex)
{
// Retrieve a page worth of data containing the requested value.
DataTable table = dataSupply.SupplyPageOfData(
DataPage.MapToLowerBoundary(rowIndex), RowsPerPage);
// Replace the cached page furthest from the requested cell
// with a new page containing the newly retrieved data.
cachePages[GetIndexToUnusedPage(rowIndex)] = new DataPage(table, rowIndex);
return RetrieveElement(rowIndex, columnIndex);
}
// Returns the index of the cached page most distant from the given index
// and therefore least likely to be reused.
private int GetIndexToUnusedPage(int rowIndex)
{
if (rowIndex > cachePages[0].HighestIndex &&
rowIndex > cachePages[1].HighestIndex)
{
int offsetFromPage0 = rowIndex - cachePages[0].HighestIndex;
int offsetFromPage1 = rowIndex - cachePages[1].HighestIndex;
if (offsetFromPage0 < offsetFromPage1)
{
return 1;
}
return 0;
}
else
{
int offsetFromPage0 = cachePages[0].LowestIndex - rowIndex;
int offsetFromPage1 = cachePages[1].LowestIndex - rowIndex;
if (offsetFromPage0 < offsetFromPage1)
{
return 1;
}
return 0;
}
}
// Returns a value indicating whether the given row index is contained
// in the given DataPage.
private bool IsRowCachedInPage(int pageNumber, int rowIndex)
{
return rowIndex <= cachePages[pageNumber].HighestIndex &&
rowIndex >= cachePages[pageNumber].LowestIndex;
}
}
答案 0 :(得分：0)
我在使用datagridview虚拟模式按需加载数据时解决了排序问题。在这里，我将再次发布我的完整工作代码。从Northwind订单表中获取数据。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
namespace DGVirtualScroll
{
public partial class Form1 : Form
{
private string connectionString =
"Initial Catalog=Test1;Data Source=BBATRIDIP\\SQLSERVER2008R2;" +
"Integrated Security=SSPI;Persist Security Info=False";
private string table = "Orders";
int Page_Size = 16;
private string strPrevSortCol = "";
private string strSortCol = "OrderID";
private string strSortOrder = "ASC";
private Cache memoryCache=null;
public Form1()
{
InitializeComponent();
// use DoubleBuffered to remove flicker when user load frequently clicking on load button
typeof(DataGridView).InvokeMember("DoubleBuffered",
BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.SetProperty,
null,
this.dataGridView1,
new object[] { true });
this.dataGridView1.VirtualMode = true;
this.dataGridView1.ReadOnly = true;
this.dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
this.dataGridView1.CellValueNeeded += new DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
}
private void dataGridView1_CellValueNeeded(object sender,DataGridViewCellValueEventArgs e)
{
e.Value = memoryCache.RetrieveElement(e.RowIndex, e.ColumnIndex);
}
private void btnLoad_Click(object sender, EventArgs e)
{
Resetsort();
LoadData(strSortCol, strSortOrder);
}
private void Resetsort()
{
strPrevSortCol = "OrderID";
strSortCol = "OrderID";
strSortOrder = "ASC";
}
private void LoadData(string strSortCol, string strSortOrder)
{
dataGridView1.Rows.Clear();
dataGridView1.Refresh();
dataGridView1.Columns.Clear();
dataGridView1.DataSource = null;
try
{
DataRetriever retriever = new DataRetriever(connectionString, table, strSortCol + " " + strSortOrder);
memoryCache = new Cache(retriever, Page_Size);
//foreach (DataColumn column in retriever.Columns)
//{
// dataGridView1.Columns.Add(column.ColumnName, column.ColumnName);
//}
retriever.Columns.Cast<DataColumn>().ToList().ForEach(n => dataGridView1.Columns.Add(n.ColumnName, n.ColumnName));
this.dataGridView1.RowCount = retriever.RowCount;
}
catch (Exception ex)
{
MessageBox.Show("Connection could not be established. " + "Verify that the connection string is valid.");
Application.Exit();
}
// Adjust the column widths based on the displayed values.
this.dataGridView1.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.DisplayedCells);
if (strSortOrder == "ASC")
this.dataGridView1.Columns[strSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Ascending;
else
this.dataGridView1.Columns[strSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Descending;
}
private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
{
// this routine will add row no to HeaderCell which comes left most
var grid = sender as DataGridView;
var rowIdx = (e.RowIndex + 1).ToString();
var centerFormat = new StringFormat()
{
// right alignment might actually make more sense for numbers
Alignment = StringAlignment.Center,
LineAlignment = StringAlignment.Center
};
var headerBounds = new Rectangle(e.RowBounds.Left, e.RowBounds.Top, grid.RowHeadersWidth, e.RowBounds.Height);
e.Graphics.DrawString(rowIdx, this.Font, SystemBrushes.ControlText, headerBounds, centerFormat);
}
private void dataGridView1_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
{
string strSortCol = this.dataGridView1.Columns[e.ColumnIndex].Name;
if (strPrevSortCol.Trim().ToUpper() != strSortCol.Trim().ToUpper())
{
this.dataGridView1.Columns[strPrevSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.None;
strPrevSortCol = strSortCol;
strSortOrder = "ASC";
}
if (this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection == System.Windows.Forms.SortOrder.Ascending)
{
this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Descending;
strSortOrder = "DESC";
}
else if (this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection == System.Windows.Forms.SortOrder.Descending)
{
this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Ascending;
strSortOrder = "ASC";
}
else
{
if (strSortOrder == "ASC")
this.dataGridView1.Columns[strSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Ascending;
else
this.dataGridView1.Columns[strSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Descending;
}
dataGridView1.Rows.Clear();
DataRetriever retriever = new DataRetriever(connectionString, table, strSortCol + " " + strSortOrder);
memoryCache = new Cache(retriever, Page_Size);
this.dataGridView1.RowCount = retriever.RowCount;
dataGridView1.Refresh();
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace DGVirtualScroll
{
public interface IDataPageRetriever
{
DataTable SupplyPageOfData(int lowerPageBoundary, int rowsPerPage);
}
public class DataRetriever : IDataPageRetriever
{
private string tableName;
private SqlCommand command;
private string sortColumn;
public DataRetriever(string connectionString, string tableName, string sortColumn)
{
SqlConnection connection = new SqlConnection(connectionString);
connection.Open();
command = connection.CreateCommand();
this.tableName = tableName;
this.sortColumn = sortColumn;
}
private int rowCountValue = -1;
public int RowCount
{
get
{
// Return the existing value if it has already been determined.
if (rowCountValue != -1)
{
return rowCountValue;
}
// Retrieve the row count from the database.
command.CommandText = "SELECT COUNT(*) FROM " + tableName;
rowCountValue = (int)command.ExecuteScalar();
return rowCountValue;
}
}
private DataColumnCollection columnsValue;
public DataColumnCollection Columns
{
get
{
// Return the existing value if it has already been determined.
if (columnsValue != null)
{
return columnsValue;
}
// Retrieve the column information from the database.
command.CommandText = "SELECT * FROM " + tableName;
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = command;
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
adapter.FillSchema(table, SchemaType.Source);
columnsValue = table.Columns;
return columnsValue;
}
}
private string commaSeparatedListOfColumnNamesValue = null;
private string CommaSeparatedListOfColumnNames
{
get
{
// Return the existing value if it has already been determined.
if (commaSeparatedListOfColumnNamesValue != null)
{
return commaSeparatedListOfColumnNamesValue;
}
// Store a list of column names for use in the
// SupplyPageOfData method.
System.Text.StringBuilder commaSeparatedColumnNames =
new System.Text.StringBuilder();
bool firstColumn = true;
foreach (DataColumn column in Columns)
{
if (!firstColumn)
{
commaSeparatedColumnNames.Append(", ");
}
commaSeparatedColumnNames.Append(column.ColumnName);
firstColumn = false;
}
commaSeparatedListOfColumnNamesValue =
commaSeparatedColumnNames.ToString();
return commaSeparatedListOfColumnNamesValue;
}
}
// Declare variables to be reused by the SupplyPageOfData method.
private string columnToSortBy;
private SqlDataAdapter adapter = new SqlDataAdapter();
public DataTable SupplyPageOfData(int lowerPageBoundary, int rowsPerPage)
{
// Store the name of the ID column. This column must contain unique
// values so the SQL below will work properly.
if (columnToSortBy == null)
{
columnToSortBy = this.Columns[0].ColumnName;
}
if (!this.Columns[columnToSortBy].Unique)
{
throw new InvalidOperationException(String.Format(
"Column {0} must contain unique values.", columnToSortBy));
}
// Retrieve the specified number of rows from the database, starting
// with the row specified by the lowerPageBoundary parameter.
command.CommandText = "Select Top " + rowsPerPage + " " +
CommaSeparatedListOfColumnNames + " From " + tableName +
" WHERE " + columnToSortBy + " NOT IN (SELECT TOP " +
lowerPageBoundary + " " + columnToSortBy + " From " +
tableName + " Order By " + sortColumn +
") Order By " + sortColumn ;
adapter.SelectCommand = command;
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
adapter.Fill(table);
return table;
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace DGVirtualScroll
{
public class Cache
{
private static int RowsPerPage;
// Represents one page of data.
public struct DataPage
{
public DataTable table;
private int lowestIndexValue;
private int highestIndexValue;
public DataPage(DataTable table, int rowIndex)
{
this.table = table;
lowestIndexValue = MapToLowerBoundary(rowIndex);
highestIndexValue = MapToUpperBoundary(rowIndex);
System.Diagnostics.Debug.Assert(lowestIndexValue >= 0);
System.Diagnostics.Debug.Assert(highestIndexValue >= 0);
}
public int LowestIndex
{
get
{
return lowestIndexValue;
}
}
public int HighestIndex
{
get
{
return highestIndexValue;
}
}
public static int MapToLowerBoundary(int rowIndex)
{
// Return the lowest index of a page containing the given index.
return (rowIndex / RowsPerPage) * RowsPerPage;
}
private static int MapToUpperBoundary(int rowIndex)
{
// Return the highest index of a page containing the given index.
return MapToLowerBoundary(rowIndex) + RowsPerPage - 1;
}
}
private DataPage[] cachePages;
private IDataPageRetriever dataSupply;
public Cache(IDataPageRetriever dataSupplier, int rowsPerPage)
{
dataSupply = dataSupplier;
Cache.RowsPerPage = rowsPerPage;
LoadFirstTwoPages();
}
// Sets the value of the element parameter if the value is in the cache.
private bool IfPageCached_ThenSetElement(int rowIndex,
int columnIndex, ref string element)
{
if (IsRowCachedInPage(0, rowIndex))
{
element = cachePages[0].table
.Rows[rowIndex % RowsPerPage][columnIndex].ToString();
return true;
}
else if (IsRowCachedInPage(1, rowIndex))
{
element = cachePages[1].table
.Rows[rowIndex % RowsPerPage][columnIndex].ToString();
return true;
}
return false;
}
public string RetrieveElement(int rowIndex, int columnIndex)
{
string element = null;
if (IfPageCached_ThenSetElement(rowIndex, columnIndex, ref element))
{
return element;
}
else
{
return RetrieveData_CacheIt_ThenReturnElement(
rowIndex, columnIndex);
}
}
private void LoadFirstTwoPages()
{
cachePages = new DataPage[]
{
new DataPage(dataSupply.SupplyPageOfData(DataPage.MapToLowerBoundary(0), RowsPerPage), 0),
new DataPage(dataSupply.SupplyPageOfData(DataPage.MapToLowerBoundary(RowsPerPage), RowsPerPage), RowsPerPage)
};
}
private string RetrieveData_CacheIt_ThenReturnElement(int rowIndex, int columnIndex)
{
// Retrieve a page worth of data containing the requested value.
DataTable table = dataSupply.SupplyPageOfData(
DataPage.MapToLowerBoundary(rowIndex), RowsPerPage);
// Replace the cached page furthest from the requested cell
// with a new page containing the newly retrieved data.
cachePages[GetIndexToUnusedPage(rowIndex)] = new DataPage(table, rowIndex);
return RetrieveElement(rowIndex, columnIndex);
}
// Returns the index of the cached page most distant from the given index
// and therefore least likely to be reused.
private int GetIndexToUnusedPage(int rowIndex)
{
if (rowIndex > cachePages[0].HighestIndex &&
rowIndex > cachePages[1].HighestIndex)
{
int offsetFromPage0 = rowIndex - cachePages[0].HighestIndex;
int offsetFromPage1 = rowIndex - cachePages[1].HighestIndex;
if (offsetFromPage0 < offsetFromPage1)
{
return 1;
}
return 0;
}
else
{
int offsetFromPage0 = cachePages[0].LowestIndex - rowIndex;
int offsetFromPage1 = cachePages[1].LowestIndex - rowIndex;
if (offsetFromPage0 < offsetFromPage1)
{
return 1;
}
return 0;
}
}
// Returns a value indicating whether the given row index is contained
// in the given DataPage.
private bool IsRowCachedInPage(int pageNumber, int rowIndex)
{
return rowIndex <= cachePages[pageNumber].HighestIndex &&
rowIndex >= cachePages[pageNumber].LowestIndex;
}
}
}
答案 1 :(得分：0)
在这里，我会发布或多或少相同的代码，但是在方法上有点差异。完整代码如下
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
namespace DGVirtualScroll
{
public partial class Form1 : Form
{
private string connectionString =
"Initial Catalog=Test1;Data Source=BBATRIDIP\\SQLSERVER2008R2;" +
"Integrated Security=SSPI;Persist Security Info=False";
private string table = "Orders";
private string strSortCol = "OrderID";
private string strSortOrder = "ASC";
private Cache memoryCache=null;
public Form1()
{
InitializeComponent();
typeof(DataGridView).InvokeMember("DoubleBuffered",
BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.SetProperty,
null,
this.dataGridView1,
new object[] { true });
this.dataGridView1.VirtualMode = true;
this.dataGridView1.ReadOnly = true;
this.dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
this.dataGridView1.CellValueNeeded += new DataGridViewCellValueEventHandler(dataGridView1_CellValueNeeded);
}
private void dataGridView1_CellValueNeeded(object sender,DataGridViewCellValueEventArgs e)
{
e.Value = memoryCache.RetrieveElement(e.RowIndex, e.ColumnIndex);
}
private void btnLoad_Click(object sender, EventArgs e)
{
Resetsort();
LoadData(strSortCol, strSortOrder);
}
private void Resetsort()
{
strSortCol = "OrderID";
strSortOrder = "ASC";
}
private void LoadData(string strSortCol, string strSortOrder)
{
dataGridView1.Rows.Clear();
dataGridView1.Refresh();
dataGridView1.Columns.Clear();
dataGridView1.DataSource = null;
try
{
DataRetriever retriever = new DataRetriever(connectionString, table, strSortCol, strSortOrder);
memoryCache = new Cache(retriever, 16);
foreach (DataColumn column in retriever.Columns)
{
dataGridView1.Columns.Add(column.ColumnName, column.ColumnName);
}
this.dataGridView1.RowCount = retriever.RowCount;
}
catch (Exception ex)
{
MessageBox.Show("Connection could not be established. " + "Verify that the connection string is valid.");
Application.Exit();
}
// Adjust the column widths based on the displayed values.
this.dataGridView1.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.DisplayedCells);
if (strSortOrder == "ASC")
this.dataGridView1.Columns[strSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Ascending;
else
this.dataGridView1.Columns[strSortCol].HeaderCell.SortGlyphDirection = System.Windows.Forms.SortOrder.Descending;
}
private void dataGridView1_RowPostPaint(object sender, DataGridViewRowPostPaintEventArgs e)
{
// this routine will add row no to HeaderCell which comes left most
var grid = sender as DataGridView;
var rowIdx = (e.RowIndex + 1).ToString();
var centerFormat = new StringFormat()
{
// right alignment might actually make more sense for numbers
Alignment = StringAlignment.Center,
LineAlignment = StringAlignment.Center
};
var headerBounds = new Rectangle(e.RowBounds.Left, e.RowBounds.Top, grid.RowHeadersWidth, e.RowBounds.Height);
e.Graphics.DrawString(rowIdx, this.Font, SystemBrushes.ControlText, headerBounds, centerFormat);
}
private void dataGridView1_ColumnHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e)
{
if (strSortCol.Trim().ToUpper() != this.dataGridView1.Columns[e.ColumnIndex].Name.Trim().ToUpper())
{
strSortOrder = "ASC";
}
else
{
strSortOrder = (this.dataGridView1.Columns[e.ColumnIndex].HeaderCell.SortGlyphDirection == System.Windows.Forms.SortOrder.Ascending ? "DESC" : "ASC");
}
strSortCol = this.dataGridView1.Columns[e.ColumnIndex].Name;
LoadData(strSortCol, strSortOrder);
}
void RefreshGrid()
{
//dataGridView1.Rows.Clear();
//dataGridView1.Refresh();
//dataGridView1.Columns.Clear();
//dataGridView1.DataSource = null;
//LoadData(strSortCol, strSortOrder);
}
}
}
******************
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace DGVirtualScroll
{
public interface IDataPageRetriever
{
DataTable SupplyPageOfData(int lowerPageBoundary, int rowsPerPage);
}
public class DataRetriever : IDataPageRetriever
{
private string tableName;
private SqlCommand command;
private string sortColumn;
private string Sortorder;
public DataRetriever(string connectionString, string tableName, string sortColumn,string Sortorder)
{
SqlConnection connection = new SqlConnection(connectionString);
connection.Open();
command = connection.CreateCommand();
this.tableName = tableName;
this.sortColumn = sortColumn;
this.Sortorder = (Sortorder.Trim() == "" ? "ASC" : Sortorder.Trim());
}
private int rowCountValue = -1;
public int RowCount
{
get
{
// Return the existing value if it has already been determined.
if (rowCountValue != -1)
{
return rowCountValue;
}
// Retrieve the row count from the database.
command.CommandText = "SELECT COUNT(*) FROM " + tableName;
rowCountValue = (int)command.ExecuteScalar();
return rowCountValue;
}
}
private DataColumnCollection columnsValue;
public DataColumnCollection Columns
{
get
{
// Return the existing value if it has already been determined.
if (columnsValue != null)
{
return columnsValue;
}
// Retrieve the column information from the database.
command.CommandText = "SELECT * FROM " + tableName;
SqlDataAdapter adapter = new SqlDataAdapter();
adapter.SelectCommand = command;
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
adapter.FillSchema(table, SchemaType.Source);
columnsValue = table.Columns;
return columnsValue;
}
}
private string commaSeparatedListOfColumnNamesValue = null;
private string CommaSeparatedListOfColumnNames
{
get
{
// Return the existing value if it has already been determined.
if (commaSeparatedListOfColumnNamesValue != null)
{
return commaSeparatedListOfColumnNamesValue;
}
// Store a list of column names for use in the
// SupplyPageOfData method.
System.Text.StringBuilder commaSeparatedColumnNames =
new System.Text.StringBuilder();
bool firstColumn = true;
foreach (DataColumn column in Columns)
{
if (!firstColumn)
{
commaSeparatedColumnNames.Append(", ");
}
commaSeparatedColumnNames.Append(column.ColumnName);
firstColumn = false;
}
commaSeparatedListOfColumnNamesValue =
commaSeparatedColumnNames.ToString();
return commaSeparatedListOfColumnNamesValue;
}
}
// Declare variables to be reused by the SupplyPageOfData method.
private string columnToSortBy;
private SqlDataAdapter adapter = new SqlDataAdapter();
public DataTable SupplyPageOfData(int lowerPageBoundary, int rowsPerPage)
{
// Store the name of the ID column. This column must contain unique
// values so the SQL below will work properly.
if (columnToSortBy == null)
{
columnToSortBy = this.Columns[0].ColumnName;
}
if (!this.Columns[columnToSortBy].Unique)
{
throw new InvalidOperationException(String.Format(
"Column {0} must contain unique values.", columnToSortBy));
}
// Retrieve the specified number of rows from the database, starting
// with the row specified by the lowerPageBoundary parameter.
command.CommandText = "Select Top " + rowsPerPage + " " +
CommaSeparatedListOfColumnNames + " From " + tableName +
" WHERE " + columnToSortBy + " NOT IN (SELECT TOP " +
lowerPageBoundary + " " + columnToSortBy + " From " +
tableName + " Order By " + sortColumn + " "+Sortorder+
") Order By " + sortColumn + " " + Sortorder;
adapter.SelectCommand = command;
DataTable table = new DataTable();
table.Locale = System.Globalization.CultureInfo.InvariantCulture;
adapter.Fill(table);
return table;
}
}
}
*****************
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace DGVirtualScroll
{
public class Cache
{
private static int RowsPerPage;
// Represents one page of data.
public struct DataPage
{
public DataTable table;
private int lowestIndexValue;
private int highestIndexValue;
public DataPage(DataTable table, int rowIndex)
{
this.table = table;
lowestIndexValue = MapToLowerBoundary(rowIndex);
highestIndexValue = MapToUpperBoundary(rowIndex);
System.Diagnostics.Debug.Assert(lowestIndexValue >= 0);
System.Diagnostics.Debug.Assert(highestIndexValue >= 0);
}
public int LowestIndex
{
get
{
return lowestIndexValue;
}
}
public int HighestIndex
{
get
{
return highestIndexValue;
}
}
public static int MapToLowerBoundary(int rowIndex)
{
// Return the lowest index of a page containing the given index.
return (rowIndex / RowsPerPage) * RowsPerPage;
}
private static int MapToUpperBoundary(int rowIndex)
{
// Return the highest index of a page containing the given index.
return MapToLowerBoundary(rowIndex) + RowsPerPage - 1;
}
}
private DataPage[] cachePages;
private IDataPageRetriever dataSupply;
public Cache(IDataPageRetriever dataSupplier, int rowsPerPage)
{
dataSupply = dataSupplier;
Cache.RowsPerPage = rowsPerPage;
LoadFirstTwoPages();
}
// Sets the value of the element parameter if the value is in the cache.
private bool IfPageCached_ThenSetElement(int rowIndex,
int columnIndex, ref string element)
{
if (IsRowCachedInPage(0, rowIndex))
{
element = cachePages[0].table
.Rows[rowIndex % RowsPerPage][columnIndex].ToString();
return true;
}
else if (IsRowCachedInPage(1, rowIndex))
{
element = cachePages[1].table
.Rows[rowIndex % RowsPerPage][columnIndex].ToString();
return true;
}
return false;
}
public string RetrieveElement(int rowIndex, int columnIndex)
{
string element = null;
if (IfPageCached_ThenSetElement(rowIndex, columnIndex, ref element))
{
return element;
}
else
{
return RetrieveData_CacheIt_ThenReturnElement(
rowIndex, columnIndex);
}
}
private void LoadFirstTwoPages()
{
cachePages = new DataPage[]
{
new DataPage(dataSupply.SupplyPageOfData(DataPage.MapToLowerBoundary(0), RowsPerPage), 0),
new DataPage(dataSupply.SupplyPageOfData(DataPage.MapToLowerBoundary(RowsPerPage), RowsPerPage), RowsPerPage)
};
}
private string RetrieveData_CacheIt_ThenReturnElement(int rowIndex, int columnIndex)
{
// Retrieve a page worth of data containing the requested value.
DataTable table = dataSupply.SupplyPageOfData(
DataPage.MapToLowerBoundary(rowIndex), RowsPerPage);
// Replace the cached page furthest from the requested cell
// with a new page containing the newly retrieved data.
cachePages[GetIndexToUnusedPage(rowIndex)] = new DataPage(table, rowIndex);
return RetrieveElement(rowIndex, columnIndex);
}
// Returns the index of the cached page most distant from the given index
// and therefore least likely to be reused.
private int GetIndexToUnusedPage(int rowIndex)
{
if (rowIndex > cachePages[0].HighestIndex &&
rowIndex > cachePages[1].HighestIndex)
{
int offsetFromPage0 = rowIndex - cachePages[0].HighestIndex;
int offsetFromPage1 = rowIndex - cachePages[1].HighestIndex;
if (offsetFromPage0 < offsetFromPage1)
{
return 1;
}
return 0;
}
else
{
int offsetFromPage0 = cachePages[0].LowestIndex - rowIndex;
int offsetFromPage1 = cachePages[1].LowestIndex - rowIndex;
if (offsetFromPage0 < offsetFromPage1)
{
return 1;
}
return 0;
}
}
// Returns a value indicating whether the given row index is contained
// in the given DataPage.
private bool IsRowCachedInPage(int pageNumber, int rowIndex)
{
return rowIndex <= cachePages[pageNumber].HighestIndex &&
rowIndex >= cachePages[pageNumber].LowestIndex;
}
}
}