How do I call paint event

Question

My program draws text on its panel but if I d like to remove the text I have to repaint   How do I call raise  the paint event by hand

User · Answer

Call control invalidate and the paint event will be raised

User · Answer

use Control InvokePaint you can also use it for manual double buffering

User · Answer

I think you can also call Refresh

User · Answer

I found the Invalidate   creating too much of flickering  Here s my situation  A custom control I am developing draws its whole contents via handling the Paint event   this Paint    this OnPaint    This handler calls a custom routine that does the actual painting   private void OnPaint object sender  PaintEventArgs e        this DrawFrame e Graphics       To simulate scrolling I want to repaint my control every time the cursor moves while the left mouse button is pressed  My first choice was using the Invalidate   like the following   private void RedrawFrame         var r   new Rectangle          0  0  this Width  this Height        this Invalidate r       this Update        The control scrolls OK but flickers far beyond any comfortable level  So I decided  instead of repainting the control  to call my custom DrawFrame   method directly after handling the MouseMove event  That produced a smooth scrolling with no flickering   private void RedrawFrame         var g   Graphics FromHwnd this Handle       this DrawFrame g       This approach may not be applicable to all situations  but so far it suits me well

User · Answer

Refresh would probably also make for much more readable code  depending on context

User · Answer

Maybe this is an old question and that  s the reason why these answers didn t work for me     using Visual Studio 2019  after some investigating  this is the solution I ve found   this InvokePaint this  new PaintEventArgs this CreateGraphics    this DisplayRectangle

User · Answer

In a method of your Form or Control  you have 3 choices   this Invalidate        request a delayed Repaint by the normal MessageLoop system     this Update            forces Repaint of invalidated area  this Refresh           Combines Invalidate   and Update     Normally  you would just call Invalidate   and let the system combine that with other Screen updates  If you re in a hurry you should call Refresh   but then you run the risk that it will be repainted several times consecutively because of other controls  especially the Parent  Invalidating    The normal way Windows  Win32 and WinForms Net  handles this is to wait for the MessageQueue to run empty and then process all invalidated screen areas  That is efficient because when something changes that usually cascades into other things  controls  changing as well    The most common scenario for Update   is when you change a property  say  label1 Text  which will invalidate the Label  in a for-loop and that loop is temporarily blocking the Message-Loop  Whenever you use it  you should ask yourself if you shouldn t be using a Thread instead  But the answer is t always Yes

User · Answer

The Invalidate   Method will cause a repaint   MSDN Link

[c#] How do I call paint event?

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