How to find out which DataGridView rows are currently onscreen?

Question

In my C# (2010) application I have a DataGridView in Virtual Mode which holds several thousand rows. Is it possible to find out which cells are onscreen at the moment?

score 35 · Accepted Answer · edited Jun 12 '18 at 08:41

public void GetVisibleCells(DataGridView dgv)
    {
        var visibleRowsCount = dgv.DisplayedRowCount(true);
        var firstDisplayedRowIndex = dgv.FirstDisplayedCell.RowIndex;
        var lastvisibleRowIndex = (firstDisplayedRowIndex + visibleRowsCount) - 1;
        for (int rowIndex = firstDisplayedRowIndex; rowIndex <= lastvisibleRowIndex; rowIndex++)
        {
            var cells = dgv.Rows[rowIndex].Cells;
            foreach (DataGridViewCell cell in cells)
            {
                if (cell.Displayed)
                {
                    // This cell is visible...
                    // Your code goes here...
                }
            }
        }
    }

Updated: It now finds visible cells.

ATTN: You cannot calculate lastvibileRowIndex like that if you are having invisible rows in the grid. In such case you have to check Visible property of row in for-loop and count those visible rows until you reach vivibleRowsCount. — Sir Kill A Lot, Jul 07 '14 at 12:48

score 1 · Answer 2 · answered Feb 18 '20 at 09:05

1

    private bool RowIsVisible(DataGridViewRow row)
    {
        DataGridView dgv = row.DataGridView;
        int firstVisibleRowIndex = dgv.FirstDisplayedCell.RowIndex;
        int lastVisibleRowIndex = firstVisibleRowIndex + dgv.DisplayedRowCount(false) - 1;
        return row.Index >= firstVisibleRowIndex && row.Index <= lastVisibleRowIndex;
    }

IMHO Regards

answered Feb 18 '20 at 09:05

Pierpaolo Simoncini

11
1

Welcome to SO. Please explain how it adds anything to the accepted answer from 2011, and how it addresses the comment made to it in 2014 about invisible rows. – AntoineL Feb 18 '20 at 09:47

score 1 · Answer 3 · answered May 18 '11 at 13:26

I haven't tried this myself, but it seems to me that determining the rectangle of a row using DataGridView.GetRowDisplayRectangle and checking if it overlaps the current DataGridView.DisplayRectangle would be the way to go. Rectangle.IntersectsWith is useful in to do this.

As an optimization I would use DataGridView .DisplayedRowCount after finding the first visible row to determine what rows are visible.

How to find out which DataGridView rows are currently onscreen?

3 Answers3

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