过滤没有数据绑定的DataGridView

Question

我有一个非数据绑定DGV(没有数据源等;手动添加行).为了过滤它,我一直在循环中检查并适当地设置行可见属性.这适用于较小的测试装置,但在较大的测试装置中完全失效.1k行以5000 /秒过滤.10k行仅以~250 /秒的速度过滤.50k,仅为40 /秒.我对正在发生的事情的假设是,每次我更改行可见性​​时,DGV都会重建显示的行列表,将过滤过程转换为O(n ^ 2)操作.

甚至10k行表示用户滥用系统; 表现不好的用户需要考虑,所以我需要做一些不同的事情.在没有使用数据绑定的情况下,是否有更快的方法来过滤大量的行,或者我是否需要回退清除/重新创建所有行(对于合理数量的数据,这显然更慢)？

//psuedocode.  runs slowly if more than a few thousand rows.
foreach (DataGridViewRow row in myDGV)
{
    row.Visible = CalculateFilter(row);
}

Answer 1

我几年前遇到过这个问题(在我了解数据绑定之前)并在微软发现了一个错误信息,说这已经得到证实,但这个问题可能无法解决.

但是,有一些可能解决这个问题.

1. 将行添加到datagridview,将行添加到数据表并将其绑定到datagridview.

   DataTable table = new DataTable();
   table.Columns.Add("Name", typeof(String));
   table.Columns.Add("...", typeof(String));
   
   foreach (var element in list)
      table.Rows.Add(element.Name, element.Something);
   
   dataGridView1.DataSource = table1;
   table.DefaultView.RowFilter = "Name Like '...'";
   

2. 创建一个继承自BindingList并实现IBindingList的类.然后将其绑定到DataGridView.

3. 将DataGridView VirtualMode设置为true.

方法二更复杂,因为您必须添加自己的逻辑来实现FindCore方法.

你应该看看这里:http://social.msdn.microsoft.com/Forums/en-US/winformsdatacontrols/thread/68c8b93e-d273-4289-b2b0-0e9ea644623a

Answer 2

如果在过滤时临时从dataGridView中删除行,则整体性能应该会大大提高.

1. 创建一个Windows窗体应用程序
2. 将DataGridView和四个按钮拖放到表单

3. 复制并粘贴此代码(不要忘记为按钮事件添加事件处理程序)

   public partial class Form1 : Form
   {
       public Form1()
       {
           InitializeComponent();
       }
   
       private Stopwatch watch = new Stopwatch();
       private void Form1_Load(object sender, EventArgs e)
       {
           // populate dataGridView
           for (int i = 0; i < 10000; i++)
               dataGridView1.Rows.Add("Column", i+1, 10000 - i);
   
           for (int i = 0; i < 10000; i = i + 2)
               dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.Red;
   
       }
   
       // remove filter
       private void button1_Click(object sender, EventArgs e)
       {
           watch.Reset();
           watch.Start();
   
           foreach (DataGridViewRow row in dataGridView1.Rows)
               row.Visible = true;
   
   
           watch.Stop();
           MessageBox.Show(watch.ElapsedMilliseconds.ToString());
       }
   
       // add filter (hide all odd rows)
       private void button2_Click(object sender, EventArgs e)
       {
           watch.Reset();
           watch.Start();
   
           foreach (DataGridViewRow row in dataGridView1.Rows)
           {
               if (Convert.ToInt32(row.Cells[1].Value) % 2 != 0)
                   row.Visible = false;
           }
   
           watch.Stop();
           MessageBox.Show(watch.ElapsedMilliseconds.ToString());
       }
   
       // remove filter (improved)
       private void button3_Click(object sender, EventArgs e)
       {
           watch.Reset();
           watch.Start();
   
           List<DataGridViewRow> rows = new List<DataGridViewRow>();
           foreach (DataGridViewRow row in dataGridView1.Rows)
           {
               rows.Add(row);
           }
   
           dataGridView1.Rows.Clear();
   
           foreach (DataGridViewRow row in rows)
               row.Visible = true;
   
           dataGridView1.Rows.AddRange(rows.ToArray());
   
           watch.Stop();
           MessageBox.Show(watch.ElapsedMilliseconds.ToString());
       }
   
       // add filer (improved)
       private void button4_Click(object sender, EventArgs e)
       {
           watch.Reset();
           watch.Start();
   
           List<DataGridViewRow> rows = new List<DataGridViewRow>();
           foreach (DataGridViewRow row in dataGridView1.Rows)
           {
               rows.Add(row);
           }
   
           dataGridView1.Rows.Clear();
   
           foreach (DataGridViewRow row in rows)
           {
               if (Convert.ToInt32(row.Cells[1].Value) % 2 != 0)
               {
                   row.Visible = false;
               }
           }
   
           dataGridView1.Rows.AddRange(rows.ToArray());
   
           watch.Stop();
           MessageBox.Show(watch.ElapsedMilliseconds.ToString());
       }
   }