Scrolling DataGridView with Mouse

6
votes

So we are all familiar with the functionality of click and holding down the mouse button, then moving the mouse to the edge of a grid, and the columns/rows scroll and the selection grows.

I have a DataGridView-based control that I had to turn MultiSelect off and handle the selection process myself due to performance issues, and now the click+hold scrolling feature is disabled as well.

Any suggestions about how to go about writing back in this functionality?

I was thinking of using something simple like the MouseLeave event, but I'm not sure how to determine which position it left, as well as implementing a dynamic scroll speed.

3
c#winformsdatagridview
Can you be more specific with your question? Can you put piece of code(if you have did anything)? - Priyank
I have not done anything yet...I was hoping to get some (general) guidance on a reasonable way to approach this before coding it. - ChandlerPelhams

3 Answers

11
votes

Just add this code to your Form1_Load 

DataGridView1.MouseWheel += new MouseEventHandler(DataGridView1_MouseWheel);

And this one is for the MouseWheel event

void DataGridView1_MouseWheel(object sender, MouseEventArgs e)
{
    int currentIndex = this.DataGridView1.FirstDisplayedScrollingRowIndex;
    int scrollLines = SystemInformation.MouseWheelScrollLines;

    if (e.Delta > 0) 
    {
        this.DataGridView1.FirstDisplayedScrollingRowIndex 
            = Math.Max(0, currentIndex - scrollLines);
    }
    else if (e.Delta < 0)
    {
        this.DataGridView1.FirstDisplayedScrollingRowIndex 
            = currentIndex + scrollLines;
    }
}
4
votes

Complete Answer You need to set Focus Datagridview

private void DataGridView1_MouseEnter(object sender, EventArgs e)
        {
            DataGridView1.Focus();
        }

then Add Mouse wheel event in Load function 
DataGridView1.MouseWheel += new MouseEventHandler(DataGridView1_MouseWheel);

Finally Create Mouse wheel function

void DataGridView1_MouseWheel(object sender, MouseEventArgs e)
{
    int currentIndex = this.DataGridView1.FirstDisplayedScrollingRowIndex;
    int scrollLines = SystemInformation.MouseWheelScrollLines;

    if (e.Delta > 0) 
    {
        this.DataGridView1.FirstDisplayedScrollingRowIndex = Math.Max(0, currentIndex - scrollLines);
    }
    else if (e.Delta < 0)
    {
        if (this.DataGridView1.Rows.Count > (currentIndex + scrollLines))
            this.DataGridView1.FirstDisplayedScrollingRowIndex = currentIndex + scrollLines;
    }
}

It works fine for me.

1
votes

The System.ArgumentOutOfRangeException will not occur if :

void DataGridView1_MouseWheel(object sender, MouseEventArgs e)
{
    int currentIndex = this.DataGridView1.FirstDisplayedScrollingRowIndex;
    int scrollLines = SystemInformation.MouseWheelScrollLines;

    if (e.Delta > 0) 
    {
        this.DataGridView1.FirstDisplayedScrollingRowIndex = Math.Max(0, currentIndex - scrollLines);
    }
    else if (e.Delta < 0)
    {
        if (this.DataGridView1.Rows.Count > (currentIndex + scrollLines))
            this.DataGridView1.FirstDisplayedScrollingRowIndex = currentIndex + scrollLines;
    }
}