Rectangle Click Event

[bcorbett]

Is there a Way to Add a Click event to a Rectangle that is created at run time?

I use the Following Code to Create the Rectangle:

        Dim g As Graphics = TableLayoutPanel1.CreateGraphics()
        Dim rect As RectangleF = New Rectangle(100, 100, 100, 400)
        g.FillRectangle(Brushes.Red, rect)
        g.Dispose()

I want this rectangle to trigger a Sub when the user clicks anywhere inside the Rectangle.

[sevenhalo]

2005:

Private g As Graphics
    Private x As Int32 = 100
    Private y As Int32 = 100
    Private h As Int32 = 100
    Private w As Int32 = 100
    Private rect As New RectangleF(x, y, w, h)
 
    Private Sub TableLayoutPanel1_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TableLayoutPanel1.MouseClick
        If rect.Contains(e.Location) Then
            MessageBox.Show("Inside")
        End If
    End Sub
    Private Sub TableLayoutPanel1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles TableLayoutPanel1.Paint
        g = e.Graphics
        g.FillRectangle(Brushes.Red, rect)
    End Sub

This also works if the box is ever relcoated (you would have to change the box's position obviously, but the event will adjust itself).

[sevenhalo]

At runtime:

Private g As Graphics
    Private x As Int32 = 100
    Private y As Int32 = 100
    Private h As Int32 = 100
    Private w As Int32 = 100
    Private rect As New RectangleF(x, y, w, h)
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        AddHandler TableLayoutPanel1.MouseClick, AddressOf MyMouseClicks
    End Sub
    Private Sub MyMouseClicks(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs)
        If rect.Contains(e.Location) Then
            MessageBox.Show("Inside")
        End If
    End Sub
    Private Sub TableLayoutPanel1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles TableLayoutPanel1.Paint
        g = e.Graphics
        g.FillRectangle(Brushes.Red, rect)
    End Sub

[michaelrawi]

AFAIK, it is not recommended to declare a graphics variable in class without dispose it immediately when it's done.

If you need a rectangle in your TableLayoutPanel, I suggest you insert a panel into it.

Also you can change this:

Dim g As Graphics = TableLayoutPanel1.CreateGraphics()
        Dim rect As RectangleF = New Rectangle(100, 100, 100, 400)
        g.FillRectangle(Brushes.Red, rect)
        g.Dispose()

With this:

Panel1.Backgroundcolor=Color.Red
Panel1.Parent=TableLayoutPanel1
Panel1.Size=New Size(100,100)
Panel1.Location=New Point(100,100)

Use Panel1_CLick event to make your code.

[sevenhalo]

AFAIK, it is not recommended to declare a graphics variable in class without dispose it immediately when it's done.

Why is that? Please give more information about this...


The reason i recommend drawing as opposed to panels is for overlapping. Say you have the following variation of the above:

Private g As Graphics
    Private x As Int32 = 100
    Private y As Int32 = 100
    Private h As Int32 = 100
    Private w As Int32 = 100
    Private rect As New RectangleF(x, y, w, h)
    Private rect2 As New RectangleF(x + 50, y + 50, w, h)
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        AddHandler TableLayoutPanel1.MouseClick, AddressOf MyMouseClicks
    End Sub
    Private Sub MyMouseClicks(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs)
        If rect.Contains(e.Location) Then MessageBox.Show("Inside rect")
        If rect2.Contains(e.Location) Then MessageBox.Show("Inside rect2")
    End Sub
    Private Sub TableLayoutPanel1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles TableLayoutPanel1.Paint
        g = e.Graphics
        g.FillRectangle(Brushes.Red, rect)
        g.FillRectangle(Brushes.Blue, rect2)
    End Sub

If you click in the overlapped area, this slight change will handle it. If you used a panel, that would be a checking nightmare to determine exactly where every panel is and if it's in the area.

Panels were designed to house controls. Plain and simple. I would highly recommend against using panels for this.

[michaelrawi]

I've read several articles on the net. And from what I read, graphics object should be disposed after used. So, when I playing with graphics, I put them within OnPaint, or Paint events or making my own sub to make sure that the object will be disposed after I use them. I'll try to search the link again. If I found them, I'll post here.

If you click in the overlapped area, this slight change will handle it. If you used a panel, that would be a checking nightmare to determine exactly where every panel is and if it's in the area.

Oops, I didn't think about overlapping before. I only assumed that those rectangle will be placed normally.

[jmcilhinney]

You should not be creating a Graphics object at all. You should be drawing the rectangle in the TLP's Paint event using the Graphics object provided by the event.

As for detecting clicks, you've got a problem if you have controls in the TLP because the click will never get to the TLP when a child control is clicked. I'd suggest a common Click event handler for the TLP and all child controls. You can then do this:

If myRectangle.Contains(myTableLayoutPanel.PointToClient(Cursor.Position)) Then
    'The user clicked within the rectangle.
End If