c＃：winforms：tooltip：如何延迟tooltip.Show

Question

I'm using winforms ToolTip class on a DataGridView (not tooltip of datagridview since I need custom formatting.)

And I call toolTip.Show() in DataGridView's CellMouseEnter event.

toolTip.Show() shows the the tooltip immediately and InitialDelay property is not working since I called toolTip.Show().

Is there another way to delay toolTip.Show() just like regular initaldelay.

Answer 1

ToolTip Show method shows right away the tooltip text, if you want a delay you have to use SetToolTip instead, being 5000 milliseconds the maximun:

toolTip.InitialDelay = 5000;
toolTip.SetToolTip(dataGridView1, "Max InitialDelay is 5000 milliseconds");  

Note: for the above to work properly, remember you first have to disable DataGridView builtin tooltip :

dataGridView1.ShowCellToolTips = false;

EDIT : To show tool tip for each row (and cell). Note the use of CellMouseEnter and CellMouseLeave events

private ToolTip toolTip;

private void dataGridView1_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
{
    if (e.RowIndex == -1 || e.ColumnIndex == -1) return;
    var cell = dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];

    if (cell.Value != null){
        toolTip = new ToolTip();
        toolTip.InitialDelay = 3000;
        dataGridView1.ShowCellToolTips = false;
        toolTip.SetToolTip(dataGridView1, cell.Value.ToString());
    }    
}

private void dataGridView1_CellMouseLeave(object sender, DataGridViewCellEventArgs e)
{
     if (toolTip != null)
         toolTip.Dispose();
}

Answer 2

I have solved my problem; I created a new instance of ToolTip in DataGridView CellMouseEnter event and disposed it in CellMouseLeave event.

private void dataGridView1_CellMouseEnter(object sender, DataGridViewCellEventArgs e)
{
    if (e.RowIndex >= 0 && e.ColumnIndex >= 0)
    {
        // 
        // create and initilize toolTip1
        // 
        this.toolTip1 = new System.Windows.Forms.ToolTip(this.components);
        this.toolTip1.OwnerDraw = true;
        this.toolTip1.UseAnimation = false;
        this.toolTip1.UseFading = false;
        this.toolTip1.Draw += new System.Windows.Forms.DrawToolTipEventHandler(this.toolTip1_Draw);
        this.toolTip1.Popup += new System.Windows.Forms.PopupEventHandler(this.toolTip1_Popup);

        toolTip1.SetToolTip((DataGridView)sender, e.RowIndex.ToString() + " : " + e.ColumnIndex.ToString());
    }
}

private void dataGridView1_CellMouseLeave(object sender, DataGridViewCellEventArgs e)
{
    if (e.RowIndex >= 0 && e.ColumnIndex >= 0)
    {
        toolTip1.Dispose();
    }
}

But I m not sure if it is a good practice. I think it is not good for performance. because I can see it when scrolling datagridview up and down with mouse wheel, some rows seem like frozen for a moment until wheel stops.

if there is a better solution please advice.