Setting DataGridView Row Heights Fast

Question

I have a virtual datagridview that I want to set varying row heights for. I was hoping to find a method for setting all the row heights at once, rather than looping through each one at a time.

This is the method that I tried to set the heights, but the performance is horrible ~1 second per 1,000 rows. For me, an average row count is ~20k-30k rows so this is unacceptable.

public void PopulateData()
    {
        this.SuspendLayout();

        this.RowCount = Data.RowCount;

        for (int i = 0; i < Data.RowCount; i++)
        {
            this.Rows[i].Height = Data.RowHeights[i];
        }

        this.ResumeLayout();
    }

I made sure to turn off auto-sizing first also, but performance is still poor.

this.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.None;
        this.AutoSizeRowsMode = DataGridViewAutoSizeRowsMode.None;

Is there any way to pass in an array of row heights or prevent OnRowHeightChanged from being called when resizing rows?

score 3 · Accepted Answer · answered Jun 15 '12 at 16:47

Apparently if you create the rows independently of the datagridview, the performance-hindering features do not apply.

The trick is to create an array of rows, size them, and then add the range of rows to the datagridview afterwards:

public void PopulateData()
    {
        this.SuspendLayout();

        DataGridViewRow[] rows = new DataGridViewRow[Data.RowCount];
        for (int i = 0; i < rows.Length; i++)
        {
            DataGridViewRow row = new DataGridViewRow();
            row.Height = Data.RowHeights[i];
            rows[i] = row;
        }
        this.Rows.AddRange(rows);

        this.ResumeLayout();
    }

For 15,000 rows this only took 150 ms compared to 15 seconds without creating a seperate array, 100 times faster!

score 1 · Answer 2 · answered Jun 15 '12 at 16:29

1

Try this instead of your code & see if you have any performance gains. Usually with virtual grids this works faster -

Add a handler for DataGridView.RowPrePaint:

dataGridView1.RowPrePaint += new DataGridViewRowPrePaintEventHandler(dataGridView1_RowPrePaint);

private void dataGridView1_RowPrePaint(object sender, DataGridViewRowPrePaintEventArgs e)
{
    dataGridView1.AutoResizeRow(e.RowIndex);
}

answered Jun 15 '12 at 16:29

Angshuman Agarwal

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The problem with this is that the scroll bar won't be sized correctly. – ChandlerPelhams Jun 15 '12 at 16:43
Until the row pre paint method gets called on each row, the grid will still think the rows are all the default rowtemplate height. Only once the user scrolls through all the rows will the correct heights be set and the grid scroll correctly. – ChandlerPelhams Jun 15 '12 at 20:07
What is the `AutoSizeRowsMode` set to ? – Angshuman Agarwal Jun 15 '12 at 20:45

Setting DataGridView Row Heights Fast

2 Answers2