How to suspend a DataGridView while updating its columns

15
votes

How can I suspend a .NET DataGridView from displaying anything while I update its Columns?

Here's my current code. It works ok, but it is very slow on the foreach loop; you can see the horiz scroll bar grow slowly as each column is added. I'm building the UI columns myself as I do not want to use dataGridView1.AutoGenerateColumns for various reasons.

// Disconnect and reset DataGridView
dataGridView1.DataSource = null;
dataGridView1.SuspendLayout();
dataGridView1.Columns.Clear();

// Get data from SQL
DataTable dt = new DataTable();
SqlDataAdapter adapter = new SqlDataAdapter("select * from employeehist", conn);
adapter.Fill(dt);

// Build DataGridView columns
foreach (DataColumn c in dt.Columns)
{
    DataGridViewTextBoxColumn col = new DataGridViewTextBoxColumn();
    col.SortMode = DataGridViewColumnSortMode.NotSortable;
    col.DataPropertyName = c.ColumnName;
    col.HeaderText = c.Caption;
    dataGridView1.Columns.Add(col);
}

// Reconnect DataGridView
dataGridView1.DataSource = dt;
dataGridView1.ResumeLayout(true);
7
c#.netwinformsdatagridview
Hmm. That should do it... Try placing dataGridView1.DataSource = null after the SuspendLayout call? Do you expect the columns to change between two requests? If not, you might want to remove column creation from this method entirely. - Adam Lear
Yes, the column count can change. The queried result set can vary depending on a date range the user selects. Also, tried moving the ' = null' and it didn't help. Thanks though, - Lane
@Lane, I have the same problem, but not the datagridview. I am using GridView to bind data, and during the loop, it's extremely slow, and GridView doesn't have Columns.AddRange function...wondering why and how did you fix for your case? Thanks. - Princa

7 Answers

4
votes

You can use VirtualMode with DataGridView in order to very efficiently update the grid. See this article: http://msdn.microsoft.com/en-us/library/ms171622.aspx

From what I remember, it seems to update the entire collection before updating anything on the UI, as opposed to adding to the UI for each new row added/etc.

4
votes

You may want to consider using the AddRange method instead of Add. The Data Grid behaves a little better when you add them all at once.

DataGridViewColumn[] columns = new DataGridViewColumn[dt.Columns.Count];

for (int i = 0; i < dt.Columns.Count; i++ )
{
    DataColumn c = dt.Columns[i];
    DataGridViewTextBoxColumn col = new DataGridViewTextBoxColumn();
    col.SortMode = DataGridViewColumnSortMode.NotSortable;
    col.DataPropertyName = c.ColumnName;
    col.HeaderText = c.Caption;

    columns[i] = col;
}


dataGridView1.Columns.AddRange(columns);
4
votes

In my case suspend and resume layout did not work. I resolved disabling the dataGridView (dgv.Enabled = false) before update and re-enabling it (dgv.Enabled = true) at the end of the update process.

1
votes

You could try and prevent it from completely redrawing by using the code in this post. The parent would be the parent of the dataGridView1.

0
votes

If you are using timer then use SynchronizingObject. This removes the flickering completly for me.

var dgv = new DataGridView();
System.Timers.Timer timer = new System.Timers.Timer();
timer.Interval = 1000;
timer.SynchronizingObject = dgv;  // syncronise
timer.Start();
timer.Elapsed += Timer_Elapsed;
void Timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
    refreshDGV();  // in here I refresh the DataGridView
}
0
votes

Significant performance increase:

var dgv = new DataGridView();
dgv.SuspendLayout();
// Do update, change values
dgv.ResumeLayout();

May not be ultimate high performance.

0
votes

This will speed it up 10 times.

dataGridView1.Visible = false;
//Build/populate datagridview
dataGridView1.Visible = true;

It's not the most professional approach but it performs.