How do I trigger the Painting of a rectangle over top of a DataGridView by cellmouse/click? - vb.net

Question

How do I trigger the instantaneous painting of a rectangle over the top of some specific cell [destination: col2, row4] in a DataGridView by an entirely different cell [trigger: col1, row3] being clicked?
Obviously I picked two random cell locations and I have tried to simplify my problem to the basic chunks. Clearly they cannot be forced as is to work together. I don't have a deep enough understanding of the event handler to call one event within the other due to lack of common signatures. I think frustration has clouded my vision and ability to see any logical possibilities.
Private Sub DataGridView1_Paint(sender As Object, e As PaintEventArgs) Handles DataGridView1.Paint
Using ColBlue As New SolidBrush(Color.Blue)
e.Graphics.FillRectangle(ColBlue, x, y, width, height)
'TODO: decide loc and rect size
End Using
End Sub
Private Sub Datagridview1_CellMouseClick(sender As Object, e As DataGridViewCellMouseEventArgs) Handles Datagridview1.CellMouseClick
'TODO: Gain a better understanding of the event handler
End Sub
My intuition tells me to write a custom sub or function, but I am not certain what they require, which eventargs to use or not use.

Answer 1

Thanks to Jimi for the patience in pointing out the main pieces required for my solution.
A simplified version of my code for those that find themselves lost and unable to trigger the painting a rectangle by mouse click.
Results [code]
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
‘Init new list of rectangles
Dim bluegradeT As New List(Of Rectangle) From {}‎
Dim ablue As New Rectangle
‘Programmatically adding the cells I want to paint to my list beforehand
bluegradeT.Add(DgvTall.GetCellDisplayRectangle(5, 1, False))
bluegradeT.Add(DgvTall.GetCellDisplayRectangle(7, 2, False))
bluegradeT.Add(DgvTall.GetCellDisplayRectangle(5, 5, False))
bluegradeT.Add(DgvTall.GetCellDisplayRectangle(5, 3, False))
bluegradeT.Add(DgvTall.GetCellDisplayRectangle(6, 2, False))
bluegradeT.Add(DgvTall.GetCellDisplayRectangle(4, 2, False))
End Sub
Private Sub DataGridView1_Paint(sender As Object, e As PaintEventArgs) Handles DataGridView1.Paint
‘I have multiple paint events of different colors that I wanted triggered by clicking
‘specific cells in the dgv
If DataGridView1.CurrentCell.ColumnIndex = 2 Then
If DataGridView1.CurrentCell.RowIndex = 1 Then
‘so if the clicked location is {2,1}, then paint
Using ColBlue As New SolidBrush(Color.FromArgb(50, Color.Blue))
‘this particular brush paints blue at 50 opacity
For Each ablue As Rectangle In bluegradeT
‘use a loop to retrieve all the rects stored for this paint
e.Graphics.FillRectangle(ColBlue, ablue)
Next
End Using
End If
End If
End Sub
Private Sub DataGridView1_CellMouseClick(sender As Object, e As DataGridViewCellMouseEventArgs) Handles DataGridView1.CellMouseClick
If DataGridView1.Rows(e.RowIndex).Selected Then
If DataGridView1.Columns.(e.ColumnIndex).Selected Then
‘If some cell has been selected…
DataGridView1.Invalidate(ablue)
‘trigger painting of dgv, but only in the area of tbe rectangles list
DataGridView1.Refresh()
‘to make sure the control updates immediately
End if
End If
End Sub
Notes
This began as an experiment to see what methods out on the internet can achieve the best color mixing by the required amount of work. I only really found an endless discussion board post with C++ theories and in various methodologies. I could see the only native method—aside from my clever trick--is colorblend(). Initially, color blend seemed impossibly more complex than my concept, but in truth, it is probably easier than I thought. [I’m sure someone else has done this before me, but I don’t care, today it’s my technique] Overall, it does an excellent job in combining colors that look natural by overlapping semi-transparent color rects on top of already painted DGV cells on the fly. It is undoubtedly faster than mixing colors by hand in Photoshop.