Question

I’ve created a simple solution with 2 projects. The 1st project (class library) contains a custom control called Container which draws itself with rounded corners. The 2nd project (windows forms) is a test application.

If I add a Container instance to main Form in the 2nd project it shows the rounded corners nicely. Also when I run the 2nd project I can see the Container.

However when I start moving the form (click and hold the title bar), especially when I move it very fast, all the drawing is messed up, drawn over and over again but not clearing it’s surface first…

I can call Container1.Refresh() in the Form1.Move event, but I don’t want to set this every time because this also means I have to call Container1.Refresh() in the Form1.Resize event and who knows which other event…

Is there an event in the Container (control) class itself where I should call Me.Refresh() or Me.Update() or Me.Invalidate() ?

For reference (Form1.vb)

Public Class Form1  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load  End Sub  Private Sub Form1_Move(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Move     Me.Container1.Refresh() End Sub End Class 

for reference (Container.vb):

Imports System.Windows.Forms Imports System.Drawing Imports System.Drawing.Drawing2D  Public Class Container : Inherits Control     Private _Gp As GraphicsPath      Private Sub Container_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint          Dim r As Rectangle = e.ClipRectangle         Dim gp As New GraphicsPath         Dim cs As Integer = 25 'CornerSize'          r.Inflate(-5, -5)          gp.AddArc(r.X, r.Y, cs, cs, 180, 90)         gp.AddArc(r.X + r.Width - cs, r.Y, cs, cs, 270, 90)         gp.AddArc(r.X + r.Width - cs, r.Y + r.Height - cs, cs, cs, 0, 90)         gp.AddArc(r.X, r.Y + r.Height - cs, cs, cs, 90, 90)          Dim t As Single = cs / 2 + r.Y         gp.AddLine(r.X, r.Y + r.Height - cs, r.X, t)          e.Graphics.SmoothingMode = Drawing.Drawing2D.SmoothingMode.AntiAlias         e.Graphics.DrawPath(Pens.Black, gp)     End Sub  End Class 

Answer 1

This is your problem:

Dim r As Rectangle = e.ClipRectangle 

Change it to:

Dim r As Rectangle = Me.ClientRectangle