C# – Dynamically Populated TableLayoutPanel Performance Degredation

cnettablelayoutpanelwinforms

I have a user control that contains a 2-column TableLayoutPanel and accepts commands to dynamically add rows to display details of an item selected in a separate control. So, the user will select a row in the other control (a DataGridView), and in the SelectedItemChanged event handler for the DataGridView I clear the detail control and then regenerate all the rows for the new selected item (which may have a totally different detail display from the previously selected item). This works great for a while. But if I keep moving from one selected item to another for quite a long time, the refreshes become VERY slow (3-5 seconds each). That makes it sound like I'm not disposing everything properly, but I can't figure out what I'm missing. Here's my code for clearing the TableLayoutPanel:

private readonly List<Control> controls;

public void Clear()
{
    detailTable.Visible = false;
    detailTable.SuspendLayout();
    SuspendLayout();
    detailTable.RowStyles.Clear();
    detailTable.Controls.Clear();
    DisposeAndClearControls();
    detailTable.RowCount = 0;
    detailTable.ColumnCount = 2;
}

private void DisposeAndClearControls()
{
    foreach (Control control in controls)
    {
        control.Dispose();
    }
    controls.Clear();
}

And once I get finished loading up all the controls I want into the TableLayoutPanel for the next detail display here's what I call:

public void Render()
{
    detailTable.ResumeLayout(false);
    detailTable.PerformLayout();
    ResumeLayout(false);
    detailTable.Visible = true;
}

I'm not using anything but labels (and a TextBox very rarely) inside the TableLayoutPanel, and I add the Labels and TextBoxes to the controls list (referenced in DisposeAndClearControls()) when I create them. I tried just iterating over detailTable.Controls and disposing them that way, but it seemed to miss half the controls (determined by stepping through it in the debugger). This way I know I get them all.

I'd be interested in any suggestions to improve drawing performance, but particularly what's causing the degradation over multiple selections.

Best Answer

Just use a custom control that inherits from TableLayoutPanel and set the DoubleBuffered property on true, works great... especially when you dynamically add or remove rows.

public CustomLayout()
{
   this.DoubleBuffered = true;
   InitializeComponent();
}

Related Solutions

C# – Winforms TableLayoutPanel adding rows programmatically

I just did this last week. Set the GrowStyle on the TableLayoutPanel to AddRows or AddColumns, then your code should work:

// Adds "myControl" to the first column of each row
myTableLayoutPanel.Controls.Add(myControl1, 0 /* Column Index */, 0 /* Row index */);
myTableLayoutPanel.Controls.Add(myControl2, 0 /* Column Index */, 1 /* Row index */);
myTableLayoutPanel.Controls.Add(myControl3, 0 /* Column Index */, 2 /* Row index */);

Here is some working code that seems similar to what you are doing:

    private Int32 tlpRowCount = 0;

    private void BindAddress()
    {
        Addlabel(Addresses.Street);
        if (!String.IsNullOrEmpty(Addresses.Street2))
        {
            Addlabel(Addresses.Street2);
        }
        Addlabel(Addresses.CityStateZip);
        if (!String.IsNullOrEmpty(Account.Country))
        {
            Addlabel(Address.Country);
        }
        Addlabel(String.Empty); // Notice the empty label...
    }

    private void Addlabel(String text)
    {            
        label = new Label();
        label.Dock = DockStyle.Fill;
        label.Text = text;
        label.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
        tlpAddress.Controls.Add(label, 1, tlpRowCount);
        tlpRowCount++;
    }

The TableLayoutPanel always gives me fits with size. In my example above, I'm filing an address card that might grow or shrink depending on the account having an address line two, or a country. Because the last row, or column, of the table layout panel will stretch, I throw the empty label in there to force a new empty row, then everything lines up nicely.

Here is the designer code so you can see the table I start with:

        //
        // tlpAddress
        // 
        this.tlpAddress.AutoSize = true;
        this.tlpAddress.BackColor = System.Drawing.Color.Transparent;
        this.tlpAddress.ColumnCount = 2;
        this.tlpAddress.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Absolute, 25F));
        this.tlpAddress.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle(System.Windows.Forms.SizeType.Percent, 100F));
        this.tlpAddress.Controls.Add(this.pictureBox1, 0, 0);
        this.tlpAddress.Dock = System.Windows.Forms.DockStyle.Fill;
        this.tlpAddress.Location = new System.Drawing.Point(0, 0);
        this.tlpAddress.Name = "tlpAddress";
        this.tlpAddress.Padding = new System.Windows.Forms.Padding(3);
        this.tlpAddress.RowCount = 2;
        this.tlpAddress.RowStyles.Add(new System.Windows.Forms.RowStyle());
        this.tlpAddress.RowStyles.Add(new System.Windows.Forms.RowStyle());
        this.tlpAddress.Size = new System.Drawing.Size(220, 95);
        this.tlpAddress.TabIndex = 0;

C# – .Net TableLayoutPanel – Clearing Controls is Very Slow

I've run into issues with slowness using TableLayoutPanels as well. Rather than setting the DoubleBuffered property on the form, the best solution I have found is to create a new class that inherits from TableLayoutPanel, and in that class' constructor, enable double-buffering:

public class DoubleBufferedTableLayoutPanel : TableLayoutPanel
{
    public DoubleBufferedTableLayoutPanel()
    {
        DoubleBuffered = true;
    }
}

Then, use the DoubleBufferedTableLayoutPanel wherever you would normally use a TableLayoutPanel.

Best Answer

Related Solutions

C# – Winforms TableLayoutPanel adding rows programmatically

C# – .Net TableLayoutPanel – Clearing Controls is Very Slow

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